JP2012075224A - Power storage system for renewable energy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system that enables the power generation side to take charge of part of a leveling measure of generated power derived from renewable energy, and enables cross trading.SOLUTION: A power storage system for renewable energy comprises: a renewable energy generating apparatus; a power storage apparatus storing power derived from renewable energy; a generating apparatus DC-DC converter converting the output power from the renewable energy generating apparatus into a prescribed voltage; a DC bus to which the power storage apparatus and the generating apparatus DC-DC converter are connected; a system interconnection apparatus having an inverter which inversely converts the direct-current power from the power storage apparatus into an alternating-current power being capable of interconnecting to a power system and supplies it to a load and the power system; and a control apparatus capable of receiving expected data of the power generation amount. The power storage system for renewable energy is characterized in that the control apparatus sets a target value of the residual charge quantity based on the expected data of the power generation amount and an expected power consumption, and performs control so as to change the output of the system interconnection apparatus by a fixed time unit based on the target value of the residual charge quantity and its actual value.

Description

  The present invention relates to a technology capable of controlling transmission power and distribution line voltage and performing a relative transaction in a storage system for renewable energy such as solar power generation and wind power generation generated in a detached house or the like. .

  In recent years, the introduction of renewable energy has been promoted as an environmental measure, and small-sized (several kW) solar power generation and micro wind power generation devices (about 1 kW) are also being promoted in detached houses and the like. These renewable energy power generators are usually operated by connecting to distribution lines of electric power companies. When the amount of power generation exceeds the consumption, electric power is sold to the electric power companies.

  In the current electricity bill system, even power generated by renewable energy with large fluctuations (low power quality) can be unconditionally sold to power companies at high cost. Under these conditions, it is most economical for a person who generates power with renewable energy to consider the output fluctuation and the influence on the distribution line, and to have the entire amount taken by the power company. No special measures have been taken except for the installation of a protective relay that disconnects the generator in the event of an accident. However, when a large number of renewable energy power generation devices are connected to distribution lines of electric power companies, it is known that the following problems regarding the voltage and transmission capacity of distribution lines occur.

・ Renewable energy power generation devices have large fluctuations in the amount of power generated, which causes voltage fluctuations (flicker) in distribution lines.
・ If the transmission from the renewable energy power generation device to the distribution line increases, the distribution line voltage rises and deviates from the allowable value, and the current power generation device automatically suppresses power transmission and cannot effectively use the power generation device.
-If too much power is transmitted from the renewable energy power generation equipment to the distribution line, the transmission capacity of the distribution line will be exceeded, and transmission will not be possible, and in some cases, power will be interrupted. Moreover, when deviating from the frequency adjustment capability of the electric power company, the frequency becomes unstable.

  At present, no major problems have occurred since the amount of power generated by renewable energy is small, but in the near future, when the amount of power generated by renewable energy is more than tens of times as estimated by government agencies, The impact on capital investment is enormous. That is, mass transmission of renewable energy power generation causes distribution line voltage fluctuations due to fluctuations in power generation, distribution line voltage increases due to mass transmission, and insufficient supply and demand adjustment capacity due to excessive renewable energy power generation. This is because it can be entrusted to an electric power company. In such a case, the electric power company will install a static reactive power compensator (SVC) for voltage adjustment, a large power storage device for supply and demand adjustment, and reinforcement of distribution lines (20,000V distribution, low-voltage three-phase four-wire) It becomes necessary to perform etc.

  On the other hand, load leveling measures when a large amount of renewable energy power generation devices are introduced, called smart grids, are being studied. When there is too much power transmission from a renewable energy power generation device to a distribution line, it has been studied to issue a power generation suppression command from the outside such as a central command office (for example, Patent Document 1). However, when a dedicated line such as an optical fiber is installed in all the houses as a communication means from the outside and a power generation suppression command is transmitted to each power generation device, a huge amount of cost is required for infrastructure development.

The configuration of a renewable energy power generation device and a power storage device, such as a detached house, currently in practical use is as shown in FIG.
The solar power generation device 1 is controlled (MPPT control) so that the power generation amount is maximized by the power conditioner 4, and the variation in the sunlight intensity is directly reflected in the power transmission amount. The power conditioner 4 includes a DC-DC converter that adjusts the solar cell output voltage and a current control type inverter, and this inverter is normally operated at a power factor of 100% (there is no reactive power control function to be described later).

The wind turbine generator 2 is connected to the grid-connected inverter so that the output voltage becomes the rated voltage, and the power transmission amount reflects the wind intensity as it is (the power generation amount is proportional to the cube of the wind speed). In addition, a small wind power generator used in a detached house or the like generally uses a permanent magnet generator, and the output is an alternating current (about 100 Hz) whose frequency fluctuates. The The grid interconnection device 5 includes a DC-DC converter that adjusts the output voltage of the power generation device and a current control type inverter, and the inverter is normally operated at a power factor of 100% (there is no reactive power control function to be described later).
The power storage device 3 stores electric power at nighttime at night, and discharges it during a daytime or evening time when there is a large amount of power consumption. Charging / discharging of the power storage device 3 is controlled by the bidirectional inverter 7, and this inverter is normally operated at a power factor of 100% (there is no reactive power control function to be described later). In addition, since the power transmission from the storage battery charged with the system power is prohibited, the output is controlled to match the load at the same place.

  So far, the solar power generation device 1, the wind power generation device 2, and the power storage device 3 are operated independently, and coordinated operation control such as adjustment of the amount of power transmission using the power storage device 3 has not been performed. In the current renewable energy purchase system, it is more economically advantageous to transmit electricity as it is than to store electricity (the unit price of electricity sold is approximately twice as high as the unit price of electricity purchased). This is because cooperative control of the power storage device 3 is difficult. Therefore, the electricity that fluctuates greatly flows down the distribution line as it is, and the voltage also rises. However, as pointed out above, this type of operation can lead to voltage fluctuations in the distribution lines and insufficient supply and demand adjustment capacity of the power company (as already mentioned, large wind power plants exceed the supply and demand adjustment capacity of the power company). New introduction has become difficult.)

  An example of a conventionally known fluctuation suppression device for a solar power generation device is shown in FIG. 2 (see Patent Document 2). This device is intended to absorb fluctuations in the amount of photovoltaic power generation by the small power storage device 3, and controls the charge / discharge amount of the power storage device 3 in accordance with the amount of photovoltaic power generation. This is intended to absorb fast fluctuations on the order of seconds. However, this fluctuation suppression device absorbs fluctuations at a high speed and contributes to voltage fluctuation suppression, but does not contribute to voltage rise suppression or power generation amount suppression.

JP 2001-327080 A JP 2009-033802 A

  A complete review of the existing power infrastructure as the amount of renewable energy generated increases will force power companies to make excessive capital investments. May impose. An object of this invention is to provide the electrical storage system which can transmit the electric power derived from renewable energy stably using the existing power distribution infrastructure. More specifically, an object of the present invention is to provide a power storage system capable of sharing a countermeasure for leveling generated power derived from renewable energy on the power generation side (user side).

  In addition, it has been proposed to sell renewable energy generated power through relative transactions. However, in order to sell electricity, it is necessary to reliably transmit contracted power. It is not clear how to reliably transmit electricity using renewable energy power generation. It is also a problem to be solved by the present invention to enable relative trading of renewable energy generated power.

If the above-mentioned leveling measures for generated power derived from renewable energy can be done on the power generation side (user side) without spending so much, the cost of measures such as infrastructure investment can be greatly reduced. Can significantly reduce the cost of measures seen in.
In addition, if a power generator (user) can obtain an opportunity to sell electricity generated from renewable energy generated by a relative transaction, the merit is very large. As specific means for countermeasures on the power generation side (user side), for example, the following means can be considered.
・ Equalize fluctuations in the amount of power generated by renewable energy power generation devices using power storage devices.
• A voltage control function (reactive power control function) is provided in the grid interconnection device (inverter) of the renewable energy power generator. If the distribution line voltage deviates from the target value, the reactive power is adjusted and distributed by the grid interconnection device. Keep the wire voltage within the target range.
-When the voltage of the distribution line is abnormal or deviates from the transmission capacity, power transmission from the renewable energy power generation device to the distribution line is suppressed, and the surplus generated power is stored in the power storage device. When the chargeable amount of the power storage device decreases, the power generation amount is suppressed.
-The power company monitors the voltage of the distribution line and the amount of power transmission, sends a voltage adjustment and a power transmission suppression command, and the grid interconnection device adjusts the reactive power and power transmission amount according to the command.
-In order to support the operation of the power storage device, the power company predicts the amount of solar power generation and wind power generation, and transmits the forecast data. The control device for the power storage device adjusts the amount of power stored in the power storage device based on the predicted data and the power consumption prediction at the installation location.

By providing the above means, the following effects can be obtained.
-The power already stored in the power storage device can be stably transmitted at a constant output. Thereby, it becomes possible to sell the renewable energy generated power by a relative transaction. When power generation is performed during power transmission, the amount of power stored in the power storage device increases from the initially expected amount after the end of the power transmission process, and power can be transmitted in a further time. In this way, the power transmission amount in the previous time zone can be determined while looking at the amount of stored electricity.
-When selling power through a relative transaction, it is necessary to exchange bid information, so a communication line such as the Internet is required. On the other hand, if you only sell power to an electric power company, you only need to receive one-way commands such as voltage adjustment and power transmission amount adjustment from the electric power company (one-way communication). For example, it is sufficient to send a command by wireless data broadcasting and the communication infrastructure investment can be greatly reduced.

  Conventionally, since power storage devices are expensive, it is considered impossible to introduce them in large numbers in detached houses and the like, and they have not been studied in government-related agencies' smart grid studies. However, in recent years, electric vehicles are expected to be widely used, and secondary storage batteries used in electric vehicles will be used for power storage devices. Since it is possible to solve the problem of cost by having already been confirmed, it is possible to sufficiently construct a practical system by introducing a large amount of power storage devices.

  In the future, it may be possible to review the conditions for purchasing power generated by renewable energy. For example, there may be a situation where a value (price) difference is created depending on the quality of generated power from renewable energy. In this case, those who generate renewable energy have high power quality (stable output) and high power. If it can be sold at a price and the quality is low (fluctuation is large), there is no choice but to sell it at a low price. At this time, it is fair to reflect the distribution line voltage countermeasures and the power supply / demand adjustment countermeasures according to the contribution of the power generation side (user side) in the power selling price. Specifically, voltage fluctuation prevention by smoothing the amount of power transmission, SVC substitution by adding a reactive power control function of the grid interconnection device, cooperation for supply and demand operation by adjusting the amount of power transmission, etc. can be considered.

The present invention has been made based on such a background, and includes the following technical means.
A first invention includes a renewable energy power generation device, a power storage device that stores electric power derived from renewable energy, a DC-DC converter for a power generation device that converts output power from the renewable energy power generation device into a predetermined voltage, A grid connection having a DC bus to which a power storage device and a DC-DC converter for a power generator are connected, and an inverter that reversely converts DC power from the power storage device into AC power that can be linked to the power system and supplies the load to the power system Power storage system comprising a system device and a control device capable of receiving power generation amount prediction data, wherein the control device sets a target value for remaining charge based on power generation amount prediction data and power consumption prediction And a control system for changing the output of the grid interconnection device in a fixed time unit based on the target value and the actual value of the remaining charge amount. Is Temu.
According to a second invention, in the first invention, the means for detecting an abnormality of the power storage device and the power storage device are separated when the abnormality of the power storage device is detected, and the DC-DC converter for the power generator and the grid interconnection device are directly connected. And a switching mechanism.
According to a third invention, in the second invention, the DC-DC converter for a power generation device outputs a constant output current control function for maintaining an output current at a predetermined current, and an output when a DC bus becomes a predetermined voltage or higher. An output voltage limiting function for limiting is provided.
According to a fourth invention, in the second or third invention, the grid interconnection device includes an input current limiting function for narrowing down an output when the DC bus becomes a predetermined voltage or less.

According to a fifth invention, in any one of the first to fourth inventions, the control device receives the control command signal, and the transmission amount from the grid interconnection device to the power system based on the received control command signal. And means for controlling.
According to a sixth invention, in the fifth invention, the grid interconnection device has a function of adjusting the reactive power supplied to the power system, and the control device is configured to control the grid interconnection device based on the received control command signal. Means are provided for adjusting the reactive power supplied to the power system in a stepwise manner in units of a fixed time.
In a seventh aspect based on the sixth aspect, the grid interconnection device includes a single-phase inverter, and causes reactive power to be consumed by advancing the phase of the output current of the single-phase inverter from the distribution line voltage. It is characterized by adjusting.
According to an eighth invention, in any one of the fifth to seventh inventions, the control device has a transfer cut-off function for stopping supply from the grid interconnection device to the power system based on the received control command signal. And

A ninth invention is characterized in that, in any one of the first to eighth inventions, the means for receiving the control command signal is a means for receiving a control command signal by a broadcast radio wave.
According to a tenth invention, in any one of the first to ninth inventions, the control device includes means for performing bidirectional communication via a wired line.
An eleventh aspect of the present invention is the information processing apparatus according to any one of the first to tenth aspects, further comprising: means for transmitting power sale information derived from renewable energy to the power exchange via the communication network; and power via the communication network. It comprises: means for receiving successful bid information from an exchange; and means for transmitting a specified amount of power from a power storage device in a specified time zone based on the received successful bid information.

A twelfth aspect of the invention is a renewable energy power generator, a power storage device that stores power derived from renewable energy, a DC-DC converter for a power generator that converts output power from the renewable energy power generator into a predetermined voltage, A grid connection having a DC bus to which a power storage device and a DC-DC converter for a power generator are connected, and an inverter that reversely converts DC power from the power storage device into AC power that can be linked to the power system and supplies the load to the power system A power storage system comprising a system device and a control device, a means for transmitting power sale information of power derived from renewable energy to a power exchange via a communication network, and a power exchange via a communication network And means for receiving the successful bid information from the power storage device and means for transmitting the specified amount of power in the specified time zone from the power storage device based on the received successful bid information. It is a power storage system of renewable energy.
A thirteenth invention is characterized in that, in any one of the first to twelfth inventions, the renewable energy power generation device is a power generation device of solar power generation and / or wind power generation.

According to the present invention, fluctuations in the amount of power generated by renewable energy can be leveled using the power storage device, so that power derived from renewable energy can be transmitted while ensuring quality.
In addition, by providing a voltage control function in the grid interconnection device, when the distribution line voltage deviates from the target value, the reactive power is adjusted by the grid interconnection device, and the distribution line voltage can be kept within the target value range. Is possible.

In addition, it is possible to adjust the amount of power stored in the power storage device based on the received prediction data of the amount of solar power generation or wind power generation and the power consumption prediction at the installation location.
In addition, when the voltage of the distribution line is abnormal or deviates from the transmission capacity, it is possible to suppress the transmission of renewable energy generated power to the distribution line based on a command from an electric power company or the like.
Furthermore, it becomes possible to make a relative transaction for electric power derived from renewable energy.

It is a block diagram of the renewable energy electric power generating apparatus and electrical storage apparatuses, such as the conventional detached house. It is a block diagram of the fluctuation | variation suppression apparatus of the conventional solar power generation device. It is a block diagram which shows an example of the electrical storage system of the renewable energy which concerns on this invention. It is a figure which shows the output control example of a grid connection inverter. It is a figure which shows the example of operation control of the electrical storage apparatus which concerns on this invention. It is a figure which shows the example of control of the advance power factor driving | operation of the single phase inverter of the grid connection apparatus which concerns on this invention. It is a figure which shows the structural example of the installation for monitoring a distribution line. It is a figure which shows the example of the adjustment condition of a distribution line voltage. It is a figure which shows the example of the control method of the grid connection inverter at the time of distribution line abnormality. It is a figure which shows an example of a control signal. It is a figure which shows the operating method of each DC-DC converter at the time of electrical storage apparatus connection. It is a figure which shows the operating method of each DC-DC converter at the time of electrical storage apparatus disconnection. It is a figure for demonstrating the balance function of the electric power generation-power transmission at the time of electrical storage apparatus disconnection. It is a figure which shows the example of an electric power generation prediction. It is a figure which shows an example of a solar power generation characteristic. It is a figure which shows the example of electrical storage apparatus electrical storage residual amount (SOC) target value. (A) Clear to cloudy, no wind, (b) rain, no wind, (c) clear to cloudy → no rain, wind. It is a figure which shows the example of electrical storage apparatus electrical storage residual amount (SOC) target value. (A) Rain → Sunny to cloudy No wind, (b) Sunny to cloudy, weak wind, (c) Rain, wind weak. It is a figure which shows the example of electrical storage apparatus electrical storage residual amount (SOC) target value. (A) Sunny to cloudy → rain wind weak, (b) Rain → sunny to cloudy wind weak, (c) Sunny to cloudy wind to strong. It is a figure which shows the example of electrical storage apparatus electrical storage residual amount (SOC) target value. (A) rain in the wind to strong, (b) clear to cloudy → rain in the wind to strong, (c) rain → clear to cloudy in the wind to strong. It is a figure which shows the example of electrical storage apparatus electrical storage residual amount (SOC) target value. (A) No clear wind There is a transmission suppression forecast, (b) A mild wind is weak, a transmission suppression forecast is present, and (c) A strong wind is strong to a strong transmission suppression forecast. It is a figure which shows the example of electric power generation amount and electric power transmission amount. (A) No clear wind, (b) No cloudy wind, (c) Clear → No cloudy wind. It is a figure which shows the example of electric power generation amount and electric power transmission amount. (A) Sunny → Cloudy In the wind, (b) No sunny wind Daytime power transmission is suppressed. 6 is a configuration diagram of a power storage system according to Embodiment 2. FIG. 12 is a flowchart illustrating a bidding procedure in the power storage system according to the second embodiment. It is a figure which shows the change of the electric power generation amount, power transmission amount, and electrical storage amount when a relative transaction is made.

  An example of an embodiment of a renewable energy storage system according to the present invention will be described with reference to FIGS.

[1] The power storage system of the present invention described below includes one solar power generation device 1 and one wind power generation device 2 as renewable energy power generation devices. The solar power generation device 1 and the wind power generation device 2 are directly connected to the power storage device 3 by direct current after voltage adjustment by the DC-DC converters 11 and 21 (see FIG. 3). As a result, it has become possible to reduce the number of inverters that were required to be equal to or more than the number of conventional power generators. In addition, since fluctuations in the amount of power generated by renewable energy are absorbed by the power storage device 3, the number and combination of renewable energy power generation devices such as solar power generation devices and wind power generation devices can be freely set. is there.
The storage device 3 can use any storage battery such as a nickel / hydrogen storage battery, a nickel / cadmium storage battery, or a lithium ion storage battery, but it is cost effective to use a lithium ion secondary battery that has been used in an electric vehicle. Is preferred. The power storage device 3 stores only electric power derived from renewable energy and is not charged from system power.
The overall control device 10 performs monitoring control of the power storage device 3, the DC-DC converters 11, 21, the grid interconnection device 50, and the like, and receives control signals from the electric power company.
A watt-hour meter 17 for detecting the amount of electric power for power purchase / selling is provided at a connection site with the distribution line. In addition, in order to measure transmission / reception power (kW), the watt-hour meter shall be equipped with a pulse transmission device.

[2] The grid interconnection device 50 directly connected to the power storage device 3 is connected to the distribution line. Conventionally, a DC-DC converter is connected to the power storage device. However, in the present invention, by omitting the DC-DC converter, the responsiveness of the power storage device is increased, and fluctuations in power generation are absorbed. However, since the battery directly bears the charge / discharge load (there is no current limiting function of the DC-DC converter), it is necessary to use a relatively high performance battery.
The grid interconnection device 50 has a function of adjusting the output frequency and the output voltage so that grid interconnection is possible. Furthermore, the grid interconnection device 50 of the present invention is characterized in that its output is controlled such that the remaining charge (SOC) of the power storage device 3 is close to the target value. However, if normal feedback control is performed to achieve the target value, the output will hunt. Therefore, the target value of the remaining charge (SOC) is compared with the actual value at regular intervals (for example, every 10 minutes), and the deviation is calculated. Control is performed to change the inverter output of the grid interconnection device 50 in a staircase pattern according to the change rate of the remaining charge (see FIG. 4). As a result, the grid interconnection device 50 has a constant output for a certain period of time (for example, 10 minutes), and the fluctuation in the transmission amount of the renewable energy power generation is greatly reduced. In addition, the output of the grid interconnection device 50 can be set to a constant output for a longer time (for example, 30 minutes to 1 hour) according to the remaining charge of the power storage device 3, so that the stored power can be obtained through relative transactions. It is also possible to sell electricity. Power transmission from the power storage device charged from the grid power is prohibited, and the grid connection device 50 is not a bidirectional inverter but a general-purpose device because the power storage device 3 for grid power transmission cannot be charged from the grid power. Use an inverter.

  In addition, in order to monitor the operation status of the grid interconnection device 50, the inverter AC output active power, reactive power (may be a power factor), voltage, and current data are measured and taken into the overall control device 10. In order to reduce the cost, the sensor 16 shares a system interconnection device control sensor. Protective relay 53 is installed in accordance with national grid interconnection technical requirement guidelines (including isolated operation detection relay), operation status data is taken into the overall control device, and when the protective relay is activated, it is confirmed that an error has been restored. The grid interconnection device 50 does not operate until a reset operation is manually performed.

  In addition, when the amount of power generation is extremely large and the remaining charge (SOC) exceeds a predetermined value (for example, 75%), it is necessary to limit the charging current so that the charging voltage does not exceed the specified value. The power generation amount is suppressed by adjusting the outputs of the DC converters 11 and 21, and the power generation output is suppressed in a stepped manner up to a maximum of 0% according to the excess amount. Similarly, when the remaining amount of power storage falls below a predetermined value (for example, 30%), it becomes necessary to limit the discharge current so that the discharge voltage does not fall below a specified value. Therefore, the output of the grid interconnection device 50 is adjusted. Reduce power transmission to a maximum of 0% in a staircase pattern. Further, when the power storage device 3 is abnormal, it is disconnected, and the DC-DC converters 11 and 21 for generating renewable energy and the grid interconnection device 50 are directly connected. An example of such an operation control method for the power storage device is shown in FIG.

[3] The grid interconnection device 50 has a reactive power adjustment function.
When connected to the distribution line by three-phase AC, the inverter can independently control the active power and the reactive power according to the established p and q 2-axis theory. That is, the distribution line voltage can be adjusted by connecting the grid interconnection inverter 52 to the power system and supplying or consuming reactive power to the power system based on the reactive power command. When a large number of renewable energy power generation devices are installed, the distribution line voltage rises, and therefore, the reactive power adjustment only needs to consume reactive power (lower the distribution line voltage). An experiment of distribution line voltage adjustment by reactive power adjustment has already been carried out in a large-scale solar power plant using a three-phase inverter, and the same technique may be used in the present invention.
On the other hand, when connected to a distribution line by single-phase alternating current, the theory which controls independently the active power and reactive power of an inverter is not established. For this reason, there is no example in which reactive power adjustment is performed by a small power generator connected to a distribution line by a single-phase inverter. Therefore, in the present invention, the reactive power is consumed by advancing the phase of the output current of the grid interconnection inverter 52 from the distribution line voltage (see FIG. 6). Here, according to the national grid interconnection technical requirement guidelines, the power factor is 80% or more, so the advance angle is up to 37 °.
As described above, the power storage system of the present invention can cope with distribution line voltage adjustment when the grid interconnection inverter is either a three-phase AC output or a single-phase AC output.

  The reactive power control based on the output current phase adjustment cannot control only the reactive power, and the reactive power consumption is proportional to the active power output. Further, since the apparent current becomes large and the active power output is not stable, it causes a large voltage fluctuation. Therefore, it is essential that the active power output is stable. Also, if the inverter is advanced and power factor operation is enabled, the supplied current increases. Therefore, the current capacity of the inverter needs to be increased by 25% when performing 37 ° advanced operation (power factor 80%). The cost increase is small. In addition, if the single-phase inverter is not properly distributed and connected to the three phases, it will cause an unbalance between the phases.Especially when adjusting reactive power, the influence will increase due to the increase in apparent power. Care must be taken in the allocation.

The present invention is characterized in that the distribution line voltage is adjusted by simultaneously adjusting the reactive power of a number of grid interconnection devices 50 installed in a predetermined section. Since many small grid-connected inverters are connected to the distribution line, the individual adjustment capacity is slight, but reactive power is adjusted in the same way for all grid-connected inverters in the same section of the same distribution line. By doing so, a voltage adjustment effect can be obtained. That is, a voltage adjustment effect can be obtained by the control center that monitors the entire distribution line voltage controlling the grid interconnection device 50 of each house to the same advance power factor (for example, 10 °). Here, since it is not possible to finely adjust the distribution line voltage with each grid-connected inverter, the voltage adjustment is performed by transmitting a command for adjusting the reactive power in a stepped manner from the control center. That is, reactive power is adjusted step by step in a certain time unit, and when a desired voltage adjustment effect is obtained, the reactive power adjustment is terminated. Even when connected to the distribution line in three phases, the reactive power is changed in steps as in the case of the single phase.
The final fine voltage adjustment needs to be performed by a transformer tap adjustment or static reactive power compensator (SVC) of an electric power company as before. FIG. 7 shows a configuration example of equipment for monitoring the distribution line, and FIG. 8 shows an example of the adjustment state of the distribution line voltage.

[4] The remaining charge (SOC) target value of the power storage device 3 is determined based on the solar power generation / wind power generation prediction (see FIG. 14) of the day transmitted from the control center of the electric power company, and the consumption pattern at the site. A certain remaining charge (SOC) target value is selected. Although it is necessary to adjust the remaining charge target value according to the respective capacities of the solar power generation device, the wind power generation device, and the power storage device, the basic concept is as follows.
・ Refrain from power transmission as much as possible at night. Therefore, when the amount of wind power generation is large, power is stored at night.
・ Power transmission during the day. In order to flatten the amount of power transmission, electricity is stored after noon and discharged in the morning and evening.
・ If consumption is high in the morning and evening, store electricity during the day and increase the amount of discharge in the morning and evening.
・ If solar power generation is large and daytime power transmission is expected to be suppressed, reduce the amount of electricity stored in the morning and increase the amount of electricity stored in the daytime as much as possible.

[5] When distribution lines are abnormal, control commands are transmitted simultaneously from the control center of the power company to a number of overall control devices 10 in a predetermined section, and each of the grid interconnection devices 50 performs the following control. (See FIG. 9).

• When the distribution line voltage is high If the distribution line voltage is high, a reactive power consumption command is issued to the area where the voltage is high and the neighboring devices upstream. Upon receiving the command, the grid interconnection device 50 performs the phase advance operation from the normal 100% power factor operation. About 3 to 4 steps are prepared for the phase advance operation, and adjustment is performed at a cycle of about 1 minute, and steps are advanced when adjustment is not sufficient. Similarly, when the voltage has dropped, the step is returned in a cycle of about 1 minute.

-When a distribution line is separated due to a distribution line accident The individual grid interconnection device 50 is provided with an isolated operation prevention protective relay 53, which independently detects the isolated operation and stops the operation of the grid interconnection inverter. Here, when the power generation amount and consumption in the distribution line are balanced, there is almost no power supply from the substation, and there is a synchronous generator such as a diesel engine generator in the same distribution line, it is operated alone. It has been known that the detection sensitivity of the is deteriorated. Accordingly, when the distribution line is separated from the system, the control center immediately issues a transfer cutoff command, and reliably stops the grid interconnection device 50.

-When there is too much power transmission When the power generation output is too large and the distribution line capacity is exceeded, or when the frequency adjustment capability of the power company is exceeded, the output of the grid interconnection device 50 is suppressed. First, the grid interconnection inverter 52 is operated but not transmitted to the distribution line (balanced with the self-consumption), and when further tightened, the inverter 52 is stopped. The surplus power that cannot be transmitted is stored in the power storage device 3, and power generation is suppressed when the remaining charge amount of the power storage device 3 increases, and finally power generation is stopped when the power storage device 3 has no remaining charge capacity. .

[6] When selling electricity generated by renewable energy through a relative transaction, it is necessary to consign the power to the buyer using the distribution line of the power company. Under the current consignment rules, the amount of transmission up to several hours ahead is reported to the power company in units of 30 minutes, the power transmission side is obligated to stably transmit the amount of communication transmitted, and the power receiving side receives the amount of communication transmitted To do. If the reported amount of power transmission cannot be transmitted, the power transmission side must pay a penalty to the power company. For this reason, conventionally, electric power that fluctuates and has no fixed amount, such as solar power generation and wind power generation, cannot be consigned. In this regard, if the power storage device 3 is configured as in the present invention, power can be stably transmitted within the range of stored renewable energy power. Further, even when power is generated during power transmission, power can be stored in the power storage device 3, and the added power can be used for power transmission in a further time zone. If there is self-consumption, the output of the grid interconnection device 50 needs to be the power plus the amount of power transmission and the amount of self-consumption, and the output of the grid interconnection device 50 is adjusted so that the power transmission amount becomes a specified value. To do. In addition, the amount of stored electricity is secured for self-consumption.
As a method of relative trading of stored renewable energy power, it is conceivable that sellers and buyers participate in bidding and conclude sales contracts in the order in which prices are matched to determine the amount of power transmission. Details of the power storage system capable of relative transactions will be described in the second embodiment.

[7] It is of course possible to transmit a control command from the control center that monitors the entire distribution line voltage to the overall control device 10 of each door by laying a dedicated line in each door. However, since the one-way communication from the center to each grid interconnection device 50 is sufficient for the transmission of the control command, it is preferable to use a broadcasting system from the viewpoint of reducing equipment and operation costs. The broadcasting facility may use a dedicated low-power radio, or may use a character data area of digital general broadcasting (digitized AM broadcasting or FM broadcasting). Encryption is also necessary to prevent deliberate interference.
The distribution line name to which the grid interconnection device 50 is connected, the section name of the distribution line, and the control signal need only be identified, and the target distribution line data in a range in which broadcast can be received is repeatedly transmitted. By repeating, the probability of reception failure can be reduced. The receiving side registers its own wiring line name and section name, and extracts only necessary data. Moreover, the prediction for every 3 to 6 hours of solar power generation and wind power generation is also transmitted as a control signal. FIG. 10 shows an example of a control command signal to the grid interconnection device 50.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the following examples.

The renewable energy storage system according to the first embodiment has the configuration shown in FIG. 3 including one each of the solar power generation device 1 and the wind power generation device 2, and the contents already described will not be repeated here. Below, the control method and simulation result of the electrical storage system which concern on Example 1 are demonstrated.
[1] Operation control of the DC-DC converters 11 and 21 and the inverter 52 In the conventional grid interconnection device, the distribution line voltage is stable, so that the generated power such as solar power generation is a constant voltage using the DC-DC converter. It is boosted to AC, converted to alternating current by a grid-connected inverter, and transmitted to the distribution line. The grid-connected inverter matches the current phase with the distribution line voltage (power factor 100% operation), controls the output current of the grid-connected inverter, feeds back the output power, and performs constant output operation according to the power generation amount. (The output current fluctuates according to fluctuations in the distribution line voltage.)

On the other hand, the power storage system of Example 1 requires the following means.
Since the voltage of the DC bus fluctuates greatly (about 25%) depending on the remaining power (SOC) of the power storage device 3, the output voltage of the DC-DC converters 11 and 21 for the power generator can be made variable according to the power storage device voltage. .
-When the power storage device 3 fails, the power storage device 3 can be disconnected and the power generation devices 1 and 2 and the grid interconnection device 50 can be directly connected. At this time, it is possible to balance the outputs of the plurality of power generators 1 and 2 that vary greatly and the output of the grid interconnection device 50.

  In order to correspond to the above, the DC-DC converters 11 and 21 for power generators are made to be a constant output type with variable output voltage, and in order to prevent overvoltage charging of the power storage device 3, an output voltage that narrows the output abruptly above a predetermined voltage. Added a restriction function. In order to prevent overdischarge of the power storage device 3, an input current limiting function for abruptly reducing the output below a predetermined voltage is added to the grid interconnection DC-DC converter 51.

  As shown in FIG. 11, during normal operation, the operating point of the power generator DC-DC converters 11 and 21 is determined by the voltage of the power storage device 3 and the outputs of the solar power generator 1 and the wind power generator 2 at that time. The output of the grid-connected DC-DC converter 51 (equal to the output of the grid-connected inverter 52) can be arbitrarily determined within the limits, and the difference between the outputs of the power generators 1 and 2 and the inverter is the charge of the power storage device 3. Discharge amount.

  As shown in FIG. 12, when the power storage device 3 is disconnected due to a failure or the like, the output of the grid interconnection inverter 52 is controlled so that the voltage of the DC bus is constant. The DC-DC converters 11 and 21 for the power generator are operated at a constant output according to the power generation amount at that time.

FIG. 13 is an explanatory diagram of a power generation / power transmission balance function when the power storage device 3 is disconnected.
(1) During normal operation (when the amount of power generation and the amount of power transmission are balanced), the DC-DC converters 11 and 21 for power generators operate at a constant output according to the amount of power generation at that time (output current control type converter). The output power is measured and the output current is controlled so that the output power becomes the target value). The grid interconnection device 50 adjusts the output of the grid interconnection inverter 52 (equivalent to the output of the grid interconnection DC-DC converter 51) so that the DC bus voltage is constant, whereby the DC-DC converters 11 and 21 are adjusted. And the output of the grid interconnection inverter 52 are balanced.

(2) When the output of the grid interconnection inverter 52 is large (when the amount of power transmission increases with respect to the amount of power generation), in order to balance the input current of the grid interconnection DC-DC converter 51, the DC-DC for the power generator The output current of converters 11 and 21 increases, and the DC bus voltage decreases. Eventually, the bus voltage is applied to the input current limitation of the grid-connected DC-DC converter 51, the output of the DC-DC converter 51 is limited, and the power generation output and the output of the inverter 52 are balanced.

(3) When the output of the grid interconnection inverter 52 is small (when the amount of power transmission is small with respect to the amount of power generation), in order to balance the input current of the grid interconnection DC-DC converter 51, the DC-DC for the power generator The output current of converters 11 and 21 decreases and the DC bus voltage rises. Eventually, the bus voltage is applied to the output voltage limitation of the power generation DC-DC converters 11 and 21, the output of the DC-DC converters 11 and 21 is limited, and the power generation output and the output of the inverter 52 are balanced.
However, in this case, since the DC bus voltage hunts, it is preferable that this function be the final input / output balance function and that the output of the inverter 52 be adjusted before the voltage fluctuation becomes large so far. For this purpose, it is necessary to make the voltage fluctuation of the DC bus sufficiently slower than the control speed of the inverter 52. As a countermeasure, the capacitor installed on the input side of the grid interconnection DC-DC converter 51 is made larger than usual. When current imbalance occurs between the DC-DC converters 11 and 21, current is supplied or absorbed from this capacitor to achieve balance, but the DC bus voltage fluctuates. It is preferable to balance the power generation output and the inverter output by adjusting the output of the inverter 52 so as to cancel the fluctuation.

[2] Control of grid interconnection inverter 52 When the distribution line is abnormal, the grid interconnection device 50 performs the control shown in FIG. In FIG. 9, when the power generation side is separated from the power system and becomes a single system, there is a transfer cutoff function that stops the grid connection. Here, when the power generation and consumption in the distribution line are balanced, there is almost no power supply from the substation, and there is a synchronous generator such as a diesel engine generator that serves as a voltage source in the same distribution line. It has been known that the detection sensitivity of an isolated operation deteriorates, and it has been said that it is necessary to install a transfer interruption device in all inverters in order to reliably stop the grid interconnection inverter. According to the national grid connection technical requirement guidelines, the transfer interruption is transmitted through a dedicated line. For this reason, since a transfer cut-off signal sent by broadcasting is not officially recognized as a transfer cut-off signal, it is necessary to install a separate operation detection relay.

According to the combination of the transfer interruption by broadcasting and the isolated operation detection relay, the grid interconnection device 50 can be surely stopped. Even if the transfer cut-off command by broadcasting is not complete and some of the grid interconnection devices 50 do not stop, most of the grid interconnection devices 50 are stopped by the transfer cut-off command so that the amount of power generation and consumption in the distribution line can be reduced. Since the balance is greatly lost (consumption increases), the isolated operation detection relay operates reliably due to a sudden change in frequency or voltage, and all the grid interconnection devices 50 in which command leakage has occurred can be stopped. Thus, even if a formal transfer cut-off command using a costly dedicated line is not prepared, a necessary and sufficient function can be achieved with an incomplete transfer cut-off command by broadcasting.
Similarly, regarding the power transmission stop command and the voltage suppression command, the command by broadcasting is not complete, and it is expected that some command leakage will occur. However, even in this case, the amount of power transmission and voltage suppression per unit of the grid interconnection device 50 is very small, so even if a slight command leakage occurs, there is almost no effect on the whole and this is a practical problem. It is thought not to be.

[3] Method of controlling power transmission amount In this embodiment, the predicted power generation amount of solar power generation and wind power generation is not used, and the target value for remaining power storage device (SOC) is changed according to the predicted value. To control the amount of power transmission. The remaining charge target value is as stable as possible during normal daytime [normal case], and the self-consumption for morning and evening at home is provided as much as possible [morning and evening shift case]. Note that the remaining charge target value here does not assume a relative transaction, and is set for the purpose of stably transmitting power to the distribution line. The remaining charge target value is assumed to be 4kW class for solar power generation, 1kW class for wind power generation, 10kWh class for power storage devices (SOC operating range 30 to 75%), and 4kW class for grid interconnection inverter. If the capacity ratio does not change, it can be used as it is.

The basic concept of the remaining charge target value is as follows.
・ Electricity is stored near noon where there is a lot of solar power generation, and in the morning and evening, the amount of electricity transmitted is leveled by suppressing and discharging the amount of electricity stored.
・ In the morning and evening shift case, the morning electricity is discharged with a large amount of electricity stored at night. Also, increase the amount of electricity stored in the daytime as much as possible for the evening.
・ Wind power generation stores electricity as much as possible during the midnight hours to minimize power transmission during the midnight hours. In the daytime, the generated power is transmitted as it is.
-If the amount of solar power generation is large and daytime power transmission suppression (10:00 to 14:00) is expected, reduce the amount of electricity stored in the morning and increase the amount of electricity stored in the daytime as much as possible. If surplus occurs even if the electricity is stored, power generation is suppressed.
Examples of power storage device remaining power (SOC) target values based on the above concept are shown in FIGS. In the case where there is no wind power generator and only a solar power generator is used, the target value when no wind is used is used.

A simulation example of the power transmission amount control method according to the present embodiment will be described.
FIG. 14 is a specific example of prediction of solar power generation and wind power generation. Since solar power generation is affected by solar altitude and temperature, the ratio with the maximum power generation curve for the month is predicted. FIG. 15 shows a typical example of south-facing photovoltaic power generation.
As specific examples of the amount of power transmission, 4 kW for solar power generation, 1 kW for wind power generation, 10 kWh (SOC operation range 30 to 75%), a grid interconnection inverter output 4 kW, and a transmission efficiency 90% were set. 16 to 20 were used as the SOC target values, and the amount of power transmission was simulated using the methods shown in FIGS.

As simulation results, FIG. 21 shows an example of clear and no wind, FIG. 22 shows an example of cloudy and no wind, FIG. 23 shows an example of cloudy and no wind (with some power generation), and FIG. FIG. 27 shows an example in which there is considerable wind (medium wind) and FIG.
From the simulation results of FIGS. 23 to 27, power transmission control is performed in accordance with the concept of the remaining charge target value, and it is possible to stabilize high-quality photovoltaic power generation and wind power generation with large fluctuations, and to suppress power transmission. It was confirmed that the amount of power generation suppression can be reduced to some extent.

Example 2 is related with the electrical storage system for performing the relative transaction of the electric power derived from renewable energy.
A power storage system for performing a relative transaction includes a solar power generation device and / or a wind power generation device, a power storage device, and a grid interconnection device, and has a configuration shown in FIG. 3, for example. Since the power sale is targeted for the power stored in the power storage device, the power can be stably supplied for a short time (for example, several hours).

  Power traders, power sellers (generators), and power purchasers (customers) participate in mutual transactions, and power sellers and power purchasers wish to use the server for relative transactions provided by power traders. A person accesses via the Internet and exchanges information such as the contracted power transmission amount and contract amount (see FIG. 23). In other words, the power seller makes a bid for selling power by inputting the power sale information such as the amount of power provided and the amount of money provided to the server for power trading from the bidding device for the relative transaction, and the power receiver also receives the demand from the consumer terminal such as a PC. A power purchase bid is made by inputting power purchase information such as a desired power amount and a desired amount of money into a power trading server.

  The server for relative transaction includes means for acquiring power sale information from a bidding apparatus for relative transaction via a communication network, means for acquiring power purchase information from a consumer terminal via a communication network, and power purchase information for a successful bid. Means for determining, means for transmitting the successful bid information to the relative transaction bidding device and the consumer terminal via the communication network, and means for transmitting a consignment instruction to a power transmission network provider such as an electric power company. The server for relative transactions adjusts (matches) selling / buying based on each bid information stored in the storage device for a predetermined time period, determines the contracted power transmission amount and the contract amount for the predetermined time, and informs the seller buyer of the successful bid information. Is sent to the transmission network provider such as an electric power company. At the predetermined time, the power generator transmits the determined power transmission amount to the distribution line, and the consumer side receives the determined power reception amount.

FIG. 24 shows a procedure example of a relative transaction in the case where buying and selling is decided up to two hours ahead in units of 30 minutes. Here, the power selling bid exceeding the amount of power stored in the power storage device is excluded because there is a problem in terms of stable power supply. In addition, when power transmission regulations (transmission suppression) are imposed by power companies due to restrictions on distribution lines, power transmission is not possible and bids are not placed. In the present embodiment, the specification is such that bidding is performed up to two hours ahead and the amount of power transmission is determined, but how far ahead is allowed to be bid can be changed as appropriate.
Table 1 and FIG. 25 show examples of determining the amount of power transmission. Here, the power transmission efficiency is 90% and the self-consumption is not taken into consideration. In order to sell power stored in the power storage device, a simple method as shown in Table 1 causes a time lag between power generation and power sales. However, if the amount of power storage is increased, power sales in a wider range of time are possible. It is also possible to store electricity and to transmit power concentratedly during a time zone when the selling price is high.

  According to the power storage system of the present embodiment described above, since the power stored in the power storage device is used for grid connection, a relative transaction of renewable energy generated power (one-to-one transaction between a power seller and a power purchaser, (Consignment of electric power by an electric power company).

DESCRIPTION OF SYMBOLS 1 Solar power generation device 2 Wind power generation device 3 Power storage device 4 (For solar power generation device) System interconnection device 5 (For wind power generation device) System interconnection device 6 AC-DC converter 7 Bidirectional inverter 10 Overall control device 11 ( DC-DC converters 12 and 13 Ammeters 14 and 15 Voltmeter 16 Sensor 17 Energy meter 20 DC bus 21 (for wind power generator) DC-DC converter 22 (for wind power generator) Inverter 30 AC Bus 50 System interconnection device 51 (System interconnection) DC-DC converter 52 (System interconnection) Inverter 53 Protective relay

Claims (13)

Renewable energy power generation device, power storage device for storing electric power derived from renewable energy, DC-DC converter for power generation device for converting output power from renewable energy power generation device to predetermined voltage, power storage device and power generation device A grid interconnection device having a DC bus connected to the DC-DC converter, a grid interconnection device having an inverter that converts DC power from the power storage device into AC power that can be linked to the power grid, and supplies the load to the power grid; A storage device comprising a control device capable of receiving the predicted data of
The control device sets a target value for the remaining charge based on the predicted power generation amount data and the predicted power consumption, and changes the output of the grid interconnection device on a constant time basis based on the target remaining charge value and the actual value. A renewable energy storage system characterized by performing control.   The power storage device further includes means for detecting an abnormality of the power storage device, and a switching mechanism that separates the power storage device upon detection of the abnormality of the power storage device and directly connects the DC-DC converter for the power generation device and the grid interconnection device. The renewable energy storage system according to claim 1.   The DC-DC converter for a power generator includes a constant output current control function for maintaining an output current at a predetermined current, and an output voltage limiting function for limiting an output when the DC bus becomes a predetermined voltage or higher. The renewable energy storage system according to claim 2.   4. The renewable energy storage system according to claim 2, wherein the grid interconnection device includes an input current limiting function for narrowing down an output when the DC bus becomes a predetermined voltage or less. 5.   5. The control device according to claim 1, further comprising: means for receiving a control command signal; and means for controlling the amount of power transmitted from the grid interconnection device to the power system based on the received control command signal. Renewable energy storage system. The grid interconnection device has a function of adjusting reactive power supplied to the power grid,
The renewable energy of the renewable energy according to claim 5, wherein the control device comprises means for stepwise adjusting the reactive power supplied to the power system by the grid interconnection device based on the received control command signal in units of a fixed time. Power storage system.   7. The grid interconnection device according to claim 6, wherein the grid interconnection device includes a single-phase inverter, and adjusts the reactive power by causing the reactive current to be consumed by advancing the phase of the output current of the single-phase inverter from the distribution line voltage. Renewable energy storage system.   The renewable energy storage system according to any one of claims 5 to 7, wherein the control device includes a transfer cutoff function for stopping supply from the grid interconnection device to the power system based on the received control command signal. .   9. The renewable energy storage system according to claim 5, wherein the means for receiving the control command signal is a means for receiving a control command signal by broadcast radio waves.   10. The renewable energy storage system according to claim 1, wherein the control device includes means for performing bidirectional communication via a wired line.   Furthermore, based on the received successful bid information, means for transmitting power sale information derived from renewable energy to the power exchange via the communication network, means for receiving successful bid information from the power exchange via the communication network, and 11. The renewable energy storage system according to claim 1, further comprising means for transmitting a specified amount of power from a storage device in a specified time zone. Renewable energy power generation device, power storage device for storing electric power derived from renewable energy, DC-DC converter for power generation device for converting output power from renewable energy power generation device to predetermined voltage, power storage device and power generation device A grid interconnection device having a DC bus connected to the DC-DC converter, a grid interconnection device having an inverter that converts DC power from the power storage device into AC power that can be linked to the power grid, and supplies the load to the power grid, and a control device And a power storage system comprising:
Means for transmitting power sales information of power derived from renewable energy to a power exchange via a communication network;
Means for receiving successful bid information from the power exchange via the communication network;
A renewable energy storage system comprising: means for transmitting a specified amount of power from a storage device based on received successful bid information in a specified time zone.   The renewable energy power storage system according to any one of claims 1 to 12, wherein the renewable energy power generation device is a power generation device of solar power generation and / or wind power generation.