JP2015208130A - Output control method for power generation system, power conditioner, and power generation system - Google Patents

Abstract

An output control method for a power generation system capable of setting a voltage at a regulation point to be equal to or lower than a regulation voltage regardless of output power of a power generation facility. An output control method for a power generation system that reversely flows into a power system through grid interconnection, and a wiring between a control point and a power generation system that require a voltage value not to deviate from a predetermined range A voltage value at the regulation point based on the step of setting the impedance of the power generation system (S1), the step of acquiring the output current of the power generation system and the output voltage of the power generation system (S2, S3), And a step (S6, S7, S8) of controlling the output of the power generation system based on the calculated voltage value of the regulation point. [Selection] Figure 2

Description

  The present invention relates to a power generation system output control method, a power conditioner, and a power generation system.

  The solar power generation facility supplies the generated power to the power system by a technique called grid connection that supplies the generated power by connecting to the power line of the power company. At this time, when the load of the facility that uses power (hereinafter referred to as “demand facility”) is small, a reverse power flow is performed to supply surplus power to the electric power company out of the generated power.

  When reverse power flow is performed, the generated power flows from the power generation facility to the electric power company, so that a voltage rise corresponding to the impedance of the wiring occurs. The voltage of the power system is required to be a value that does not deviate from the range of 101 ± 6 V when the supply voltage is 100 V according to the Enforcement Rules of the Electricity Business Law. When the generated power of the power generation facility is large, the power system voltage may increase due to reverse power flow and exceed the regulation voltage.

  For this reason, the power generation facility has a function of lowering the supply voltage below the regulation voltage by means such as reducing the output of the power generation facility when the regulation voltage is exceeded. Non-Patent Document 1 discloses details of examples of specific means for this function. With this function, the voltage at the output end of the power generation facility is measured, and if the voltage exceeds a preset voltage, an operation to reduce the power generation output is performed.

  Further, the operating voltage range of a general demand facility is 100 ± 10 V, and it is necessary to prevent the allowable voltage of the demand facility from being exceeded due to the above-described voltage increase.

Japan Electrical Association Electrical Engineering Regulations System Integration Edition System Integration Regulations JEAC 9701-2012 Pages 106-121

  In the conventional method for suppressing the voltage increase of the power generation facility, the voltage at the output end of the power generation facility is a value obtained by adding the regulation voltage to the voltage increase value calculated in advance from the maximum output current of the power generation facility and the impedance of the wiring (hereinafter referred to as “settling value” ) Control the output power so that: However, in this method, when the output power is small, the actual voltage rise is smaller than that in the case of the maximum output current, and thus the regulation voltage may be exceeded. For this reason, since the set value is set with a margin, there is a problem that the power generation facility suppresses the output before reaching the regulation voltage.

  The present invention has been made in view of the above, and an output control method for a power generation system, a power conditioner, and a power generation system capable of setting a voltage at a restriction point to be equal to or lower than a restriction voltage regardless of the output power of the power generation equipment. The purpose is to obtain.

  In order to solve the above-described problems and achieve the object, the present invention is an output control method for a power generation system that reversely flows into a power system through grid interconnection, and the voltage value does not deviate from a predetermined range. A first step of maintaining a wiring impedance between a required regulation point and the power generation system; a second step of acquiring an output current of the power generation system and an output voltage of the power generation system; And a third step of calculating a voltage value of the restriction point based on the output current and the output voltage, and an output of the power generation system based on the voltage value of the restriction point calculated in the third step. And a fourth step of controlling.

  According to the present invention, there is an effect that the voltage at the regulation point can be made equal to or less than the regulation voltage regardless of the output power of the power generation equipment.

FIG. 1 is a diagram illustrating a configuration example of a power generation system according to the first embodiment. FIG. 2 is a flowchart illustrating an example of an output control procedure in the power generation system of the first embodiment. FIG. 3 is a diagram illustrating a configuration example of the power generation system according to the second embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments of a power generation system output control method, a power conditioner, and a power generation system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a power generation system according to the present invention. The power generation system according to the present embodiment is installed in the consumer 2 and includes a power conditioner 5 (voltage control unit) and a solar cell module 6 (power generation module). The power generation system of the present embodiment flows backward to the power system through grid interconnection.

  When electric power for housing is supplied from an electric power company, a consumer 2 that installs a power generation system from a pole transformer 1 installed on a utility pole via a lead-in pillar 10 and an adjacent consumer 3- adjacent to the consumer 2 Electric power is supplied to 1, 3-2. However, there is a case where the lead-in pillar 10 is omitted, and the customer 2 is directly supplied from the pole transformer 1. Further, when power is supplied to the adjacent customer 3-2 via the power receiving point 11 of the customer 2 (generally, the first support point where the wiring is first supported in the premises of the customer 2) (such a form) There is also "connected pull-in". In FIG. 1, the structural example which supplies electric power to the adjacent consumer 3-2 via the receiving point 11 is shown. The configuration of FIG. 1 is an example, and the form of power supply to the customer 2 in which the power generation system of the present embodiment is installed (whether it is routed through the pull-in column 10 or whether it is a connected pull-in configuration) Etc.) and is not limited to the configuration of FIG.

  A distribution board 4 is installed in the customer 2. Further, between the power receiving point 11 and the distribution board 4, a watt hour meter (not shown) for measuring the supply and demand of power and a reverse power flow (not shown), an inlet switch (not shown), and the like are installed. These are connected to the distribution board 4. Electric power is supplied from the distribution board 4 to the load 7 in the customer 2 by indoor wiring.

  The power conditioner 5 of the power generation system in the customer 2 converts the DC power generated in the solar cell module 6 into AC power. The solar cell module 6 is connected to the DC side of the power conditioner 5 through a connection box (not shown) for enabling connection of a plurality of solar cell modules 6. The solar cell module 6 of the power generation system in the customer 2 is a module configured to connect a large number of solar cells in series and parallel to obtain a power generation output. For example, it arrange | positions on the roof of the consumer's 2 house.

  Here, the resistance value of the wiring from the lead-in column 10 to the power receiving point 11 is Rs, the resistance value of the wiring from the power receiving point 11 to the distribution board 4 is Ra, and the wiring from the distribution board 4 to the power conditioner 5 Let Rb be the resistance value. In addition, although inductance exists in these wirings, it is not considered here because it is a negligible level in low-voltage wiring. In addition, a current output from the power generation system by power generation (that is, output from the power conditioner 5) is Ig, and a current at the power receiving point 11 is Ia.

  Hereinafter, an example in which the restriction point is the power receiving point 11 will be described. In order to input the current value of the power receiving point 11, a current sensor may be installed at the power receiving point 11. In this embodiment, an example in which this current sensor is not used will be described. According to the Electricity Business Law Enforcement Regulations, the voltage supplied by the electric power company to the customer 2 is required to be a regulated value (101 ± 6 V), and the voltage rising by the power generation system of the customer 2 is outside the regulated range. . However, the customer 2 having the power generation system is required to set the supplied voltage to the regulation value (101 ± 6 V) by the adjacent customer 3-2 in which the power generation facility is not installed. For this reason, in the case of connection drawing, the consumer 2 needs to make the voltage of the power receiving point 11 into the range of the regulation value. Control may be performed so that the voltage at the power receiving point 11 is Va and the upper limit of the voltage is 107 V or less.

  At this time, in order to set the voltage Va at the power receiving point 11 to 107 V or less, Va may be measured, but it is generally difficult to measure Va. For this reason, the voltage Vg at the output terminal of the power conditioner 5 is measured, and Va is estimated by subtracting the voltage increase value (Vg−Va) up to the power receiving point 11 from this Vg. Assuming that the power of the load 7 is zero, this voltage increase value can be calculated if the wiring impedance (Ra and Rb) and the output current Ig of the power generation system are known.

  The impedance of the wiring is known because it is determined by the wiring diameter and the wiring length at the time of construction. Further, the output current Ig is also a value output by the power conditioner 5 itself. Generally, the power conditioner 5 can grasp this current by a built-in current sensor. Therefore, the voltage Va of the power receiving point 11 that is a restriction point can be accurately estimated by setting the impedance (Ra and Rb) of the wiring in the power conditioner 5 from the outside in advance.

  Next, a specific operation of the power generation system according to the present embodiment will be described. FIG. 2 is a flowchart showing an example of an output control procedure in the power generation system of the present embodiment. Of the processes according to the following output control procedure, processes other than the measurement of current and voltage are performed by, for example, the output control unit in the power conditioner 5. This output control unit may be implemented as hardware or software.

  First, the impedance of the wiring is set in the power conditioner 5, and the power conditioner 5 holds the set impedance (step S1). This setting is input by an administrator or the like by an input means (not shown) such as a switch or a button based on a display prompting the setting displayed on a display device (not shown) provided in the power conditioner 5, for example. To implement. Alternatively, another device may be connected to the power conditioner 5 and the impedance of the wiring may be set using a display device and input means included in the device. As the impedance of the wiring to be set, if only the voltage at the power receiving point 11 is controlled, the total value (Ra + Rb) of the impedance of the wiring may be set. This setting is generally performed at the start of operation of the power generation system, but thereafter, the impedance of the wiring may be updated when the installation position is changed.

  Then, the power conditioner 5 measures the voltage Vg at its output terminal (step S2). Since the power conditioner 5 measures the voltage Vg at the output end, this measured value is used. The processing after step S2 is periodically performed, for example, once per second. Here, when the period of the process for performing this process is T and the measurement in step S2 is performed, the measurement of T is also started. For example, a timer that expires at T starts counting.

  Next, the power conditioner 5 measures the output current Ig of the power generation system (step S3). Since the power conditioner 5 generally includes a current sensor for controlling the generated current, the current value measured by this current sensor can be used. The measurement period of Vg and Ig may be the same as T, but may be shorter than T. The power conditioner 5 holds the measured values of Vg and Ig for a certain period. The current sensor incorporated in the power conditioner 5 and the means for measuring the voltage Vg at the output terminal of the power conditioner 5 are combined to form a measuring unit.

  Next, the power conditioner 5 performs an averaging process on the output terminal voltage Vg and current Ig so that the operation is stabilized (step S4). For this averaging process, for example, a simple filter process or the like can be used, and a time constant of, for example, about 3 seconds or more is selected.

Next, the power conditioner 5 calculates the voltage Va of the power receiving point 11 which is a regulation point by the following formula (1) (step S5). The values averaged in step S4 are used for Vg and Ig.
Va = Vg−Ig · (Ra + Rb) (1)

  Next, the power conditioner 5 compares the upper limit (107V) of the regulation voltage with the voltage Va at the power receiving point 11 obtained by the calculation in step S5, and determines whether Va is higher than the upper limit of the regulation voltage. (Step S6). If it is determined that Va is higher than the upper limit of the regulation voltage (Yes in step S6), the output current of the power conditioner 5 is suppressed (reduced) (step S7), and the process proceeds to step S9. When it is determined that Va is equal to or lower than the upper limit of the regulation voltage (No in step S6), the output current of the power conditioner 5 is increased (step S8), and the process proceeds to step S9. In step S8, for example, when Va is lower than the upper limit of the regulation voltage by a certain value or more, the output current is increased, and when Va is less than the certain value, the output current is not increased. May be.

  Then, the power conditioner 5 determines whether or not T has elapsed from the start of step S2 (step S9), and when it has not elapsed (No in step S9), repeats step S9. If it has elapsed (Yes in step S9), the process returns to step S2. By carrying out the above operation, the voltage Va at the power receiving point 11 can be made lower than the upper limit (107 V) of the regulation voltage.

  Moreover, the operating voltage range of general demand equipment is 100 ± 10V. For this reason, it may be necessary to set the voltage Vb at the output end of the distribution board 4 to an upper limit value of 110 V or less. Since the operation in this case is similar to the above-described example (example in which the voltage Va at the power receiving point 11 is equal to or lower than the upper limit (107V) of the regulation voltage), the flowchart in FIG. Explained.

  In this case, in addition to setting the upper limit of the voltage Va at the power receiving point 11 to 107 V, the upper limit of the output voltage Vb of the distribution board 4 must be limited to 110 V as the regulation voltage in this case. That is, the power receiving point 11 is set as the first restriction point, the output of the distribution board 4 is set as the second restriction point, and control is performed so that the voltage does not exceed the upper limit determined for the two restriction points. In this case, Ra and Rb are individually set as the impedance of the wiring set in step S1. As a setting means in step S1, a simple display device, a switch and the like (not shown) can be used as in the above example.

Since the operation from step S2 to step S4 is the same as that in the above-described example, the description thereof is omitted. In step S5, Va and Vb are calculated using Ra and Rb set in step S1 and Vg and Ig averaged in step S4. Note that the formula for calculating Va is the same as described above, and is omitted. About Vb, it calculates with the following formula | equation (2).
Vb = Vg−Ig · Rb (2)

In step S6, it is determined whether or not either of the following (a) and (b) is established, and when any of (a) and (b) is established (Yes in step S6), the process proceeds to step S7. . If neither (a) nor (b) is established (No in step S6), the process proceeds to step S8. Steps S7 to S9 are the same as in the above example.
(A) Upper limit of regulation voltage at receiving point 107V <Va
(B) Upper limit of distribution board input voltage 110V <Vb

  By performing the above operation, the voltage Va at the power receiving point 11 can be kept below the upper limit (107V) of the regulation voltage, and the output voltage Vb of the distribution board 4 can be made below the upper limit (110V) of the regulation voltage. Become. In the above description, two examples of restriction points are shown. However, when there are three or more restriction points, similarly, when any of a plurality of restriction points exceeds a predetermined upper limit, Control which suppresses the output of the conditioner 5 can be performed.

In the above description, since the current of the load 7 is unknown, the control is performed assuming that the power consumption of the load 7 is zero. On the other hand, by installing a current sensor at the power receiving point 11, Va can be estimated with higher accuracy by calculating Va using the following formula (3) using the measured current Ia at the power receiving point 11.
Va = Vg−Ig · Rb−Ia · Ra (3)

  The measurement result of the current sensor at the power receiving point 11 is input to the power conditioner 5, and in step S3, in addition to Ig, Ia is also measured, and in step S4, Ia is also averaged. In step S6, Va is calculated using the above equation (3) instead of equation (1). In addition, when the current sensor at the power receiving point 11 and the power conditioner 5 are physically separated, the current of the current sensor is temporarily measured by a measuring device (not shown), and the data is communicated by wired or wireless communication. You may transmit to the inverter 5 using a technique.

  Moreover, the output voltage Vb of the distribution board 4 may be measurable with a voltage sensor (not shown). In this case, the same can be realized by controlling the output voltage Vb of the distribution board 4 using a voltage value measured instead of the value calculated by the above equation (2). Further, the voltage Va at the power receiving point 11 can be controlled in the same manner even if the measured value is used.

  In the above description, there is a case where there is an adjacent consumer 3-2 that performs connection drawing at the power receiving point 11. However, when there is no adjacent customer 3-2 that performs connection drawing, the voltage supplied by the electric power company The restriction point can be the pull-in column 10. In this case, voltage control at the restriction point can be similarly realized by replacing Ra described above with (Ra + Rs) and the voltage Va at the restriction point with the voltage Vs of the pull-in column 10.

  In the above description, the method of suppressing the power generation output is shown as means for suppressing the voltage rise. However, the voltage control of the restriction point can be similarly realized by controlling the power factor of the power generation system. In the above description, the example in which the power generation system of the present embodiment is a solar power generation system has been described. There may be. In a case other than a solar power generation system, a power generation module corresponding to a power generation method such as a fuel cell is connected instead of the solar cell module 6.

  As described above, in the present embodiment, in the consumer 2 having the power generation system, the power conditioner 5 of the power generation system is based on the impedance of the wiring, the voltage at the output end of the power generation system, and the output current. The output current of the power generation system is controlled based on the calculated value. For this reason, the voltage of a regulation point can be made below into regulation voltage irrespective of the output electric power of a power generation system.

Embodiment 2. FIG.
FIG. 3 is a diagram illustrating a configuration example of a second embodiment of the power generation system according to the present invention. In the present embodiment, in the customer 2, a power generation system including the first power conditioner 5-1 and the solar cell module 6-1, the second power conditioner 5-2 and the solar cell module 6. -2 power generation systems are set.

  In FIG. 3, the configuration from the pole transformer 1 to the distribution board 4 is the same as that of the first embodiment. Components having the same functions as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and redundant description is omitted. Hereinafter, differences from the first embodiment will be described.

  The outputs of the first power conditioner 5-1 and the second power conditioner 5-2 are collected at the power conditioner connection point 12 by wirings having impedances Rb1 and Rb2, respectively. The power conditioner connection point 12 is connected to the distribution board 4 by a wiring having an impedance of Rb0.

  Next, the operation of the power generation system of the present embodiment will be described. Since the operation of the present embodiment is similar to that of the first embodiment, the difference from the first embodiment will be mainly described using the flowchart of FIG. Here, the operation of the first power conditioner 5-1 will be described.

  First, in the wiring impedance setting in step S1, if only the voltage at the power receiving point 11 is controlled, the total impedance value (Ra + Rb0) and Rb1 of the wiring from the power receiving point 11 to the power conditioner connection point 12 are obtained. You only have to set it.

  Since the operation from step S2 to step S4 is the same as that of the first embodiment, the description thereof is omitted. However, the first power conditioner 5-1 can measure the output current Ig1 of the first power conditioner 5-1, as in the first embodiment, but the second power conditioner 5-2. Output current Ig2 cannot be measured. For this reason, the first power conditioner 5-1 and the second power conditioner 5-2 transmit the output current to the other power conditioner through communication by wired or wireless means. Thereby, in step S3, the first power conditioner 5-1 acquires the output current Ig2 of the second power conditioner 5-2, and the output current Ig1 of itself and the second power conditioner 5-2. The generated current Ig0 of the entire power conditioner that is the sum of the output current Ig2 and the output current Ig2 is measured. Further, even if a current sensor (not shown) is installed at the power conditioner connection point 12, the generated current Ig0 can be similarly measured. In step S2, the voltage Vg1 at the output terminal of the first power conditioner 5-1 is measured. In step S4, Vg1, Ig0, and Ig1 are averaged.

In step S5, Va is calculated by the following equation (4) using (Ra + Rb0) and Rb1 set in step S1 and Vg1, Ig0, and Ig1 averaged in step S4.
Va = Vg1-Ig1.Rb1-Ig0. (Ra + Rb0) (4)

  Steps S6 to S9 are the same as those in the first embodiment. In addition, in the case where a current sensor is installed at the power receiving point 11 in order to measure the current of the load 7, or when the restriction point is the pull-in column 11, control can be realized as in the first embodiment.

  In the second power conditioner 5-2, the control of the voltage at the regulation point can be similarly realized by replacing Vg1, Ig1, and Ig2 with Vg2, Ig2, and Ig1, respectively, in the above example. Furthermore, even when the number of inverters installed is 3 or more, it is possible to control the voltage at the regulation point by the same processing.

  As described above, in the present embodiment, in the customer 2 including a plurality of power generation systems, the power conditioner is based on the impedance of the wiring, the voltage at its output terminal, and the sum of the output currents of the plurality of power generation systems. The voltage at the specified point was calculated, and the output current of the power generation system was controlled based on the calculated value. For this reason, even when a plurality of power conditioners are provided, the voltage at the regulation point can be made equal to or less than the regulation voltage regardless of the output power of the power generation system.

  As described above, the output control method, the power conditioner, and the power generation system of the power generation system according to the present invention are useful for a solar power generation system, and are particularly suitable for a power generation system in a consumer who performs connection pull-in.

  1 pole transformer, 2 customers, 3-1 and 3-2 adjacent customers, 4 distribution board, 5 power conditioner, 5-1 first power conditioner, 5-2 second power conditioner, 6,6-1,6-2 Solar cell module, 7 load, 10 lead-in column, 11 power receiving point, 12 power conditioner connection point.

Claims (13)

An output control method for a power generation system that reversely flows into a power system by grid connection,
A first step of maintaining the impedance of the wiring between the regulation point and the power generation system, the voltage value of which is required not to deviate from a predetermined range;
A second step of obtaining an output current of the power generation system and an output voltage of the power generation system;
A third step of calculating a voltage value of the restriction point based on the impedance, the output current, and the output voltage;
A fourth step of controlling the output of the power generation system based on the voltage value of the restriction point calculated in the third step;
An output control method for a power generation system, comprising:   The said 4th step WHEREIN: When the voltage value of the said restriction | limiting point calculated at the said 3rd step exceeds the upper limit of the said defined range, the output of the said electric power generation system is suppressed. An output control method for the described power generation system. The regulation point includes a first regulation point and a second regulation point located between the first regulation point and the power generation system, and the voltage value of the first regulation point is from the first range. It is required not to deviate, and the voltage value of the second regulation point is required not to deviate from the second range;
In the first step, a first impedance which is an impedance of a wiring between the first restriction point and the second restriction point, and a wiring between the second restriction point and the power generation system And a second impedance that is the impedance of
In the third step, a voltage value of the first restriction point is calculated based on the first impedance, the second impedance, the output current, and the output voltage, and the second impedance and the Calculating the voltage value of the second restriction point based on the output current and the output voltage;
In the fourth step, the voltage value of the first restriction point calculated in the third step exceeds the upper limit value of the first range, or the second value calculated in the third step. 3. The output control method for a power generation system according to claim 1, wherein an output of the power generation system is suppressed when a voltage value of a regulation point exceeds an upper limit value of the second range.   4. The power generation system output control method according to claim 3, wherein the second restriction point is a distribution board.   When power is supplied to an adjacent consumer that is adjacent to the consumer and does not have a power generation system via a power reception point of the consumer having the power generation system, the power reception point is used as the restriction point. The output control method of the power generation system according to any one of claims 1 to 4.   6. The output control method for a power generation system according to claim 5, wherein, in the third step, the voltage value of the restriction point is calculated by setting the load in the consumer to zero. A fifth step of acquiring a current measurement result of the power receiving point;
Further including
6. The power generation system output control method according to claim 5, wherein in the third step, a voltage value of the restriction point is further calculated based on the measurement result obtained in the fifth step.   The control point is a pull-in column to which the consumer is connected when there is no adjacent consumer to which power is supplied via a power receiving point of the consumer having the power generation system. The output control method of the electric power generation system as described in 1, 2 or 3. A plurality of the power generation systems, a plurality of the power generation systems are added to the output current of the plurality of power generation systems at a connection point,
9. The voltage value at the restriction point is calculated based on the total value of the output currents of the plurality of power generation systems connected to the connection point in the third step. The output control method of the electric power generation system as described in one.   The power generation system output control method according to claim 9, wherein the power generation system transmits its output current to another power generation system.   10. The power generation system output control according to claim 9, wherein a measurement current value is obtained by measuring a current at the connection point, and a total value of output currents of a plurality of the power generation systems is set as the measurement current value. Method. A power conditioner that controls power generated by a power generation module in a power generation system that reversely flows into a power system through grid interconnection,
A measuring unit for measuring the output current of the power conditioner and the output voltage of the power conditioner;
Maintaining the impedance of the wiring between the control point and the power conditioner that is required not to deviate from the voltage range, the control point based on the impedance, the output current and the output voltage An output control unit that controls the output of the power generation system based on the calculated voltage value of the regulation point;
A power conditioner comprising: A power generation system that reversely flows into the power system through grid interconnection,
A power generation module for generating power;
A power conditioner for controlling the power generated by the power generation module;
With
The inverter is
A measuring unit for measuring the output current of the power conditioner and the output voltage of the power conditioner;
Maintaining the impedance of the wiring between the control point and the power conditioner that is required not to deviate from the voltage range, the control point based on the impedance, the output current and the output voltage An output control unit that controls the output of the power generation system based on the calculated voltage value of the regulation point;
A power generation system comprising:

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