JP2017017792A - Distribution type power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distribution type power supply device, executing parallel operation with a plurality of PCSs, capable of preventing a power system from becoming unstable.SOLUTION: The distribution type power supply device includes a plurality of PCSs 21 connected in parallel. Each of the PCSs 21 includes a power inversion part 30, a calculation part 40 and a control part 50. The calculation part 40 calculates a first peak-cut power command value and determines a second peak-cut power command value allotted for each of the PCSs 21. The control part 50 determines a targeted output power value on the basis of the determined second peak-cut power command value and a system power value pout and generates such control signals s1, s2 that an error between an output power value po of each of the PCSs 21 and the targeted output power value reduces. The power inversion part 30 inverts DC power into AC power on the basis of the control signals s1, s2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a distributed power supply apparatus in which a plurality of power conditioners (hereinafter referred to as “PCS”), which are power converters, are connected in parallel to perform parallel operation.

  As described in Patent Documents 1 to 5 and the like, the conventional PCS implements a system power sensor and a PCS, a peak cut power command value as a set value, etc. in order to realize peak cut control of the system power at the power receiving point. And is composed of.

  Specifically, the grid power value measured (detected) by the grid power sensor is input to the PCS, compared with the peak cut power command value, and the grid power value does not exceed the peak cut power command value. PCS supplies insufficient power to the load. Thereby, the maximum value (upper limit value) of the system power can be suppressed, and the power system can be leveled.

  When a distributed power supply apparatus using a plurality of PCSs is configured by such a conventional method, for example, the circuit configuration is as shown in FIG.

FIG. 2 is a schematic configuration diagram showing a conventional distributed power supply apparatus.
This distributed power supply apparatus includes a plurality of PCSs 10 (= 10-1 to 10-n) connected to a plurality of DC power supplies 1 (= 1-1 to 1-n), respectively. Each PCS 10 is a device that converts DC power supplied from each DC power source 1 into AC power, and is parallel to the wiring 13 between the power receiving point 16 that receives the system power from the power system 17 and the load 14. It is connected to the. The power receiving point 16 is provided with a system power sensor 15 that detects the system power value pout. The system power value pout is given to each PCS 10.

  Each PCS 10 is a device that converts DC power supplied from each DC power source 1 into AC power, and includes a power converter 11 and a controller 12. The power conversion unit 11 converts DC power supplied from the DC power supply 1 into AC power based on a control signal given from the control unit 12. The control unit 12 obtains an output power target value based on the system power value pout and the upper limit peak cut power command value pcut1 of the system power, outputs the output power value detected from the output power of each PCS 10, and outputs A control signal that reduces an error from the power target value is generated and supplied to the power conversion unit 11.

  In this type of distributed power supply apparatus, the load power Pz supplied from the power system 17 to the load 14 exceeds the peak cut power command value pcut1 (for example, 50 kW) as the upper limit of the system power received from the power system 17. At this time, output power Pc (= Pc1 to Pcn) is supplied from the plurality of PCSs 10 to the load 14. As a result, the upper limit value of the system power is suppressed, and the power system 17 can be leveled (that is, stabilized).

JP-A-8-223816 JP 2005-295707 A JP 2008-43184 A JP 2010-55974 A JP 2012-33547 A

However, the conventional distributed power supply device has the following problems.
In the conventional distributed power supply device, the system power value pout is detected by the system power sensor 15 provided at the power receiving point 16 of the power system 17, and this system power value pout is given to a plurality of PCSs 10. Each PCS 10 shares one system power value pout and tries to control the system power value pout to the same peak cut power command value pcut1, so that the system power varies depending on the detection error and control response of each PCS 10. It becomes impossible to control such as vibration of the load, and it becomes impossible to manage the load sharing.

  A distributed power supply apparatus according to the present invention includes a plurality of PCSs connected in parallel to a wiring between a power receiving point for receiving system power from a power system and a load, and respectively converting DC power into AC power, An apparatus for supplying power from the plurality of PCSs to the load when load power supplied from the system to the load exceeds a first peak cut power command value of an upper limit of the system power received from the power system It is.

  Each of the PCSs calculates a first peak cut power command value and obtains a second peak cut power command value to be shared for each PCS; and the second peak cut power obtained by the calculation unit An output power target value is obtained based on the command value and the system power value detected from the system power, and an error between the output power value detected from the output power of each PCS and the output power target value And a power converter that converts the DC power into the AC power based on the control signal.

  The calculation unit includes a rank setting value for setting a rank of load sharing in the power supplied to the load, a rank changing element for changing the rank of the load sharing in order to drive all of the plurality of PCSs, and a predetermined value. An adjustment value is obtained based on the load sharing power, and the second peak cut power command value is calculated by subtracting the adjustment value from the first peak cut power command value.

  According to the distributed power supply device of the present invention, each PCS is provided with a calculation unit, and the calculation unit calculates an adjustment value based on the rank setting value, the rank changing element, and the load sharing power, and the first peak cut power command Since the second peak cut power command value is calculated by subtracting the adjustment value from the value, a difference is generated in the second peak cut power command value that is the control target value of each PCS. This difference eliminates the influence of detection errors and control response variations of individual PCSs, so that the upper limit value of the system power can be accurately suppressed and the power system can be leveled (ie, stabilized). .

FIG. 1 is a schematic configuration diagram illustrating a distributed power supply device according to a first embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing a conventional distributed power supply apparatus. FIG. 3 is a schematic functional block diagram showing the configuration of the PCS 21 in FIG. FIG. 4 is an explanatory diagram showing the operation of FIG.

  Modes for carrying out the present invention will become apparent from the following description of the preferred embodiments when read in light of the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

  As shown in FIG. 2 of the related art, when performing parallel operation by connecting a plurality of PCSs 10 (= 10-1 to 10-n) in parallel to the same power system 17, they are provided at a power receiving point 16 for system power. Since the system power value pout is detected by the system power sensor 15 and control is performed based on the system power value pout, the load sharing varies depending on the detection error, and management becomes impossible. In order to improve this situation, the distributed power supply device according to the first embodiment has the following configuration.

(Configuration of Example 1)
FIG. 1 is a schematic configuration diagram illustrating a distributed power supply device according to a first embodiment of the present invention.

  This distributed power supply apparatus includes a plurality of PCSs 21 (= 21-1 to 21-n, for example, n) respectively connected to a plurality of DC power sources 20 (= 20-1 to 20-n, for example, n = 5). = 5). Each DC power source 20 is a distributed DC power source such as a storage battery, a solar cell, or a fuel cell. The plurality of PCSs 21 are devices that convert DC power supplied from each DC power supply 20 into AC power, respectively, and a wiring 54 between a power receiving point 57 that receives system power from the power system 58 and the load 55. Connected in parallel. The power receiving point 57 is provided with a system power sensor 56 that detects the system power value pout.

  The system power sensor 56 is configured by a power meter, or by an ammeter and a voltmeter. The system power value pout detected by the system power sensor 56 is sent to the first PCS 21-1, and is sequentially distributed from the first PCS 21-1 to the next second PCS 21-2, the third PCS 21-3,.

  Each PCS 21 includes a power conversion unit 30, a power sensor 36, a calculation unit 40, and a control unit 50.

  The power conversion unit 30 converts DC power supplied from the DC power source 20 into AC power based on a plurality of control signals s1 and s2 given from the control unit 50. The power sensor 36 detects the output power Pc (= Pc1 to Pcn) of the power conversion unit 30 and supplies the output power value po to the control unit 50. The power sensor 36 is configured by a wattmeter, or an ammeter and a voltmeter. It is comprised by.

The calculating unit 40 calculates a first peak cut power command value pcut2 (for example, 50 kW) given from the outside to obtain a second peak cut power command value pcut2 to be shared for each PCS 21, and this second peak cut power command value is calculated. It has a function of giving the value pcut2 to the control unit 50. The control unit 50 generates a plurality of control signals s1 and s2 based on the second peak cut power command value pcut2 given from the calculation unit 40 and the system power value pout detected from the system power, and the power conversion unit 30.
Note that Pz in FIG. 1 is system load power supplied to the load 55.

FIG. 3 is a schematic functional block diagram showing the configuration of the PCS 21 in FIG.
In each PCS 21, the power conversion unit 30 includes, for example, an input switching circuit 31, a transformer (hereinafter referred to as “transformer”), a rectifier circuit 33, a filter circuit 34, and an output switching circuit 35. .

  The switching circuit 31 for input is a circuit that inputs DC power output from the DC power supply 20, switches the input DC power to convert it into high-frequency AC power, and outputs this AC power to the transformer 32. , And a plurality of switching elements that are turned on / off by a plurality of control signals s1. The transformer 32 insulates the input side and the output side of the power converter 30, and a rectifier circuit 33 is connected to the output side of the transformer 32.

  The rectifier circuit 33 is a circuit that converts AC power output from the transformer 32 into DC power, and is configured by a diode bridge circuit or the like. A filter circuit 34 is connected to the output side. The filter circuit 34 is a circuit that removes and smoothes high-frequency components contained in the output voltage of the rectifier circuit 33. The filter circuit 34 is composed of an LC circuit or the like, and an output switching circuit 35 is connected to the output side.

  The switching circuit 35 is a circuit that converts DC power output from the filter circuit 34 into low-frequency AC power having the same frequency as that of the power system 58, and a plurality of on / off operations performed by a plurality of control signals s2. A switching element is used, and the output side is connected to the wiring 54. A power sensor 36 is provided in the wiring 54.

  The computing unit 40 includes a rank setting value for setting the rank of load sharing in the power supplied to the load 55, a rank changing element for changing the rank of load sharing in order to drive all the PCSs 21, and a predetermined load sharing. An adjustment value AV is obtained based on the power d, and the second peak cut power command value pcut2 is calculated by subtracting the adjustment value AV from the first peak cut power command value pcut1.

  In the calculation unit 40, the order setting value is a value set based on the machine number a corresponding to each of the plurality of PCSs 21 and the number of operating units b of the plurality of PCSs 21. The rank changing element is clock information c including any one of year, month, day, hour, minute, and second at the time of system power detection, or a combination thereof. Further, the predetermined load sharing power d is a power value for absorbing a detection error of each PCS 21 and providing a difference in the first peak cut power command value pcut1.

The adjustment value AV is obtained according to the following equation (1), for example.
Adjustment value AV = {(unit number a + clock information c)% number of operating units b} × load sharing power d
However, “%” means obtaining a remainder.
... (1)

  As described above, in the first embodiment, the machine number “a”, the number of operating units “b”, and the load sharing power “d” are provided as set values, and the current time that is the clock information “c” is used. A difference is provided in the second peak cut power command value pcut2. That is, according to the calculation of the equation (1), the second peak cut power command value pcut2 for each PCS 21 has a difference in load sharing power d and all have different values.

  The calculation unit 40 according to the first embodiment includes, for example, a clock 41, a remainder calculation unit 42, a multiplication unit 43, and a subtraction unit 44.

  The clock 41 measures clock information c, and a remainder calculating means 42 is connected to the output side. The remainder calculating means 42 adds the machine number a and the clock information c, and divides the number of operating units b by the added value to calculate the remainder of the division result. Is connected. The multiplication means 43 multiplies the remainder calculated by the remainder calculation means 42 and the load sharing power d to calculate the adjustment value AV, and the subtraction means 44 is connected to the output side. The subtracting means 44 subtracts the adjustment value AV from the first peak cut power command value pcut1 to calculate the second peak cut power command value pcut2, and the control unit 50 is connected to the output side.

  The control unit 50 includes a target value calculation unit 51, an error calculation unit 52, and a control signal generation unit 53.

  The target value calculation means 51 calculates the output power target value e by subtracting the system power value pout from the second peak cut power command value pcut2, and an error calculation means 52 is connected to this output side. . The error calculation means 52 calculates an error f between the output power value po and the output power target value e by calculation, and a control signal generation means 53 is connected to the output side. The control signal generation unit 53 generates a plurality of control signals s1 and s2 having a duty ratio so that the error f is reduced, and the plurality of control signals s1 and s2 are supplied to the switching circuits 31 and 35 in the power conversion unit 30. For example, it is constituted by pulse width modulation means (PWM means), drive means, and the like.

  The calculation unit 40 and the control unit 50 are configured by a processor, an individual circuit, or the like.

(Overall operation of the first embodiment)
1 and 3, when the first peak cut power command value pcut1 that is the upper limit of the system power is supplied from the outside, the first peak cut power command value pcut1 is calculated in each PCS 21. To part 40. The system power of the power system 58 is supplied to the load 55 via the power receiving point 57 and the wiring 54.

  The system power value pout detected by the system power sensor 56 is given to each PCS 21. In the example of FIG. 1, the same value is distributed to the second PCS 21-2, the third PCS 21-3, the fourth PCS 21-4, and the fifth PCS 21-5 in order via the first PCS 21-1.

  Due to the fluctuation of the grid load power Pz supplied to the load 55, the grid power value pout detected by the grid power sensor 56 increases, and when this grid power value pout tries to exceed the first peak cut power command value pcut1, A plurality of PCSs 21 operate as follows.

  In the calculation unit 40 in each PCS 21, the remainder calculating means 42 adds the machine number a and the clock information c, and divides the number of operating units b by the added value to calculate the remainder of the division result. The result is given to multiplication means 43. The multiplying unit 43 multiplies the residue calculated by the residue calculating unit 42 and the load sharing power d to obtain the adjustment value AV of the equation (1), and gives it to the subtracting unit 44. The subtracting means 44 subtracts the adjustment value AV from the first peak cut power command value pcut 1 to calculate the second peak cut power command value pcut 2 and gives it to the target value calculating means 51 in each control unit 50.

  The target value calculation means 51 in each control unit 50 subtracts the grid power value pout detected by the grid power sensor 56 from the second peak cut power command value pcut2 given from the calculation unit 40, and outputs power target A value e is calculated and given to the error calculation means 52. The error calculation means 52 calculates an error f between the output power value po detected by the power sensor 36 and the output power target value e, and gives it to the control signal generation means 53. As a result, the control signal generation unit 53 generates a plurality of control signals s1 and s2 having a duty ratio that reduces the error f and supplies the control signals s1 and s2 to the power conversion unit 30.

  In each power conversion unit 30, the input switching circuit 31 switches the DC power output from the DC power source 20 and converts it into high-frequency AC power based on a plurality of control signals s 1 given from the control unit 50. . The converted AC power is converted into DC power by the rectifier circuit 33 via the transformer 32, high-frequency components are removed and smoothed by the filter circuit 34, and sent to the output switching circuit 35.

  The switching circuit 35 converts the DC power output from the filter circuit 34 into low-frequency AC power having the same frequency as that of the power system 58, based on the plurality of control signals s2 given from the control unit 50. The converted output power Pc is detected by the power sensor 36, and this output power value po is given to the control unit 50.

  The controller 50 is controlled so that the system power value pout detected by the system power sensor 56 does not exceed the second peak cut power command value pcut2, and a plurality of PCSs 21 operate based on the control signals s1 and s2. Insufficient power is supplied to the load 55. Thereby, the upper limit of the system power is suppressed, and the power system 58 is leveled.

(Load sharing operation of PCS of Example 1)
4A to 4C are explanatory diagrams showing the operation of the distributed power supply device of FIG.

  4A to 4C, FIG. 4A shows a load sharing characteristic diagram of the conventional PCS 10 without the parallel operation function, and FIG. 4B shows the PCS 21 of the first embodiment with the parallel operation function. FIG. 4C is a diagram showing a calculation example of the second peak cut power command value pcut2 for each PCS 21 of the first embodiment having a parallel operation function.

  When the power control is individually performed so that the output power Pc (= Pc1 to Pc5) of each PCS 10 (= 10-1 to 10-5) becomes the same target value as in the conventional case illustrated in FIG. Due to the variation in detection error, one of the PCSs 10 performs an operation of carrying the entire load power Pz. In the first embodiment, control is performed based on the machine number “a”, the number of operating units “b”, the load sharing power “d”, and the current time in each PCS 21 in order to accurately manage load sharing, not errors.

  In the present Example 1, the operation image at the time of peak cut supply driving | operation is shown by FIG.4 (b). For example, in a plurality of PCSs 21 (= 21-1 to 21-5), the system load power Pz is sequentially shared by the plurality of output powers Pc (= Pc1 to Pc5).

  In order to realize the operation of FIG. 4B, the calculation unit 40 obtains the second peak cut power command value pcut2 for each PCS 21 based on the equation (1). As a result, since the second peak cut power command value pcut2 of each PCS 21 has a difference, load sharing is sequentially controlled.

  FIG. 4C shows a calculation example in the case where, for example, the first peak cut power command value pcut1 is 50 kW, the number of operating units b is 5, the load sharing power d is 0.3 kW, and the day is adopted as the current time. Has been.

  In FIG. 4 (c), on the 4th of May, when the grid power load 55 increases and the grid power value pout which is grid input power exceeds 48.8 kW, the PCS 21-5 starts output. When the PCS rating exceeds 10 kW, the PCS 21-5 alone cannot be controlled, and the system power value pout exceeds 48.8 kW. After that, 49.1 kW is reached and the PCS 21-4 performs output. Thereafter, similarly, the PCS 21-3, 21-2, and 21-1 sequentially output.

Since there is a date in the calculation formula, on the next 5th day, the calculation result of PCS 21-4 is the lowest, 48.8 kW, and it is responsible for load power Pz first. Thereafter, similarly, the PCS 21-3, 21-2, 21-1, 21-5 are responsible for the load power Pz in order.
With this operation, load sharing is managed.

  On the other hand, even when each DC power source 20 is combined with electric power originating from wind power generation or hydroelectric power generation in addition to storage batteries and solar cells, system power can be controlled by this method. In the case of the month 4 in FIG. 4C, a storage battery is connected to the DC power source 20-1 and the DC power sources 20-2, 20-3, and a solar cell is connected to the DC power source 20-4 and the DC power source 20-5. When the grid power load 55 increases and the grid power value pout exceeds 48.8 kW, the PCS 21-5 attempts to start output. However, if the generated power of the solar cell is insufficient due to factors such as bad weather, Power cannot be supplied, and the system power value pout exceeds 48.8 kW. After that, 49.1 kW is reached and the PCS 21-4 performs output. However, for the same reason, when the supply power of the solar cell is insufficient and the system power value pout exceeds 49.4 kW, the PCS 21-3 starts outputting. The system power value pout is controlled.

(Effect of Example 1)
According to the distributed power supply device of the first embodiment, each PCS 21 is provided with a calculation unit 40, and by this calculation unit 40, the load sharing rank setting value consisting of the machine number a and the number of operating units b and the clock information c are included. An adjustment value AV is obtained based on the load sharing rank changing element and the load sharing power d, and the adjustment value AV is subtracted from the first peak cut power command value pcut1, to obtain the second peak cut power command value pcut2. Since the calculation is performed, a difference is generated in the second peak cut power command value pcut2, which is the control target value of each PCS 21. This difference eliminates the influence of the detection error and control response variation of each PCS 21, so that the grid power can be accurately suppressed to the upper limit of the first peak cut power command value pcut 1 or less. Leveling can be achieved.

(Modification)
The present invention is not limited to the first embodiment, and various usage forms and modifications are possible. For example, there are the following forms (I) and (II) as usage forms and modifications.

  (I) The PCS 21 shown in FIG. 3 is not limited to the illustrated configuration. For example, the calculation unit 40 may obtain the adjustment value AV using a mathematical expression other than the expression (1). The calculation unit 40 may be provided in the control unit 50. Further, instead of the clock 41 provided in each calculation unit 40, a single clock that can be shared by a plurality of calculation units 40 is provided, and the clock information c of this clock may be provided to each calculation unit 40. Thereby, a structure can be simplified.

  (II) The distributed power supply device shown in FIGS. 1 and 3 is not limited to the illustrated configuration. For example, the power conversion unit 30 may be configured by a circuit other than that illustrated.

20, 20-1 to 20-n DC power supply 21, 21-1 to 21-n PCS (power converter)
DESCRIPTION OF SYMBOLS 30 Power conversion part 36 Power sensor 40 Calculation part 41 Clock 42 Remainder calculation means 43 Multiplication means 44 Subtraction means 50 Control part 51 Target value calculation means 52 Error calculation means 53 Control signal generation means 55 Load 56 System power sensor 57 Power reception of system power Point 58 Power system

Claims (9)

It is connected in parallel to the wiring between the power receiving point and the load that receives system power from the power system, and includes a plurality of power conversion devices that respectively convert DC power into AC power,
When load power supplied from the power system to the load exceeds a first peak cut power command value that is an upper limit of the system power received from the power system, power from the plurality of power converters to the load A distributed power supply for supplying
Each of the power conversion devices
A calculation unit that calculates the first peak cut power command value and obtains a second peak cut power command value to be shared for each power converter;
An output power target value is obtained based on the second peak cut power command value obtained by the arithmetic unit and the system power value detected from the system power, and is detected from the output power of each power converter. A control unit that generates a control signal that reduces an error between the output power value and the output power target value;
A power converter that converts the DC power into the AC power based on the control signal;
Have
The computing unit is
A rank setting value for setting a rank of load sharing in the power supplied to the load, a rank changing element for changing the rank of the load sharing in order to drive all the plurality of power converters, and a predetermined load sharing A distributed power supply apparatus that calculates an adjustment value based on power and subtracts the adjustment value from the first peak cut power command value to calculate the second peak cut power command value. The rank setting value is a value set based on the number of the machine corresponding to each of the plurality of power converters, and the number of operating units of the plurality of power converters,
The rank changing element is clock information consisting of any one of year, month, day, hour, minute, second at the time of system power detection, or a combination thereof,
The predetermined load sharing power is a power value for absorbing a detection error of each power converter and providing a difference in the first peak cut power command value.
The distributed power supply apparatus according to claim 1. The adjustment value is
3. The distributed power supply apparatus according to claim 2, wherein the power distribution is determined according to the following equation.
Adjustment value = {(unit number + clock information)% number of operating units} x load sharing power
However, “%” means obtaining a remainder. The computing unit is
A remainder calculating means for adding the number of the machine and the clock information, and dividing the number of operating units with respect to the added value to calculate a remainder of the division result;
Multiplication means for calculating the adjustment value by multiplying the remainder calculated by the remainder calculation means and the load sharing power;
Subtracting means for calculating the second peak cut power command value by subtracting the adjustment value from the first peak cut power command value;
The distributed power supply device according to claim 3, further comprising:   The distributed power supply apparatus according to claim 1, wherein the system power value and the output power value are detected by two power sensors, respectively.   The distributed power supply device according to claim 2, wherein the clock information is measured by a clock. The controller is
Target value calculating means for calculating the output power target value by subtracting the grid power value from the second peak cut power command value;
Error calculation means for calculating an error between the output power value and the output power target value by calculation;
Control signal generating means for generating the control signal having a duty ratio such that the error is reduced;
The distributed power supply device according to any one of claims 1 to 6, wherein:   The distributed power supply apparatus according to claim 1, wherein the arithmetic unit and the control unit are configured by a processor or an individual circuit. The DC power input to each power converter is
The distributed power supply device according to any one of claims 1 to 8, wherein the distributed power supply is supplied from a distributed direct current power source including a storage battery, a solar battery, and a fuel cell.

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