JP2020182276A - Monitoring and controlling device and control method for photovoltaic power generation facility - Google Patents

Abstract

To provide a monitoring and controlling device and a control method for a photovoltaic power generation system capable of stabilizing the system voltage by keeping a power factor at a power receiving point of a facility above a predetermined value while suppressing reverse power flow.SOLUTION: A monitoring and controlling device for a photovoltaic power generation facility in a consumer 90 that feeds power to a load 50 from a bus bar connecting an AC system and the photovoltaic power generation facility 20 includes: a calculation portion 1 that detects a state quantity for calculating a power factor of an interconnection point 80 between the AC system and the consumer and calculates a reactive power outputted from an inverter required to make the power factor of the interconnection point between the AC system and the consumer equal to or higher than a predetermined power factor based on the state quantity; and an inverter control portion 10 that controls the inverter with the reactive power as a reactive power command.SELECTED DRAWING: Figure 1

Description

The present invention relates to a monitoring control device and a control method for a photovoltaic power generation facility installed in a customer, and in particular, a monitoring control device and a control method for the photovoltaic power generation facility linked to an AC system to supply power to an electric load in the consumer. Regarding.

In recent years, photovoltaic power generation systems have become widespread all over the world due to the fixed amount purchase system for electricity (hereinafter referred to as FIT) and tax incentives. Due to mass diffusion and the principle of market competition, the cost per kW of the photovoltaic power generation system is reduced, and in areas with good solar radiation conditions, the power generation cost by the photovoltaic power generation system is higher than the power generation cost by the conventional power generation system such as thermal power generation. The so-called grid parity, which is cheaper, has begun to be established.

On the other hand, due to the widespread use of photovoltaic power generation systems, the amount of electricity purchased at FIT has decreased or has been abolished depending on the region. In response to this, there are an increasing number of cases of introducing self-consumption type photovoltaic power generation systems in which the electricity generated by the photovoltaic power generation system is consumed by the equipment in the consumer, not for the purpose of selling electricity.

The amount of power-selling photovoltaic power generation facilities could be controlled to some extent by the grid operator by establishing an interconnection permit frame by the grid operator. However, in the case of self-consumed photovoltaic power generation that does not supply power to the grid, that is, does not reverse power flow, the power consumption only fluctuates when viewed from the grid. Therefore, it is not possible to control the introduction amount by the interconnection frame.

As a technique for establishing a self-consumption type photovoltaic power generation system, a photovoltaic power generation system having a rating of the minimum load or less is used, or as disclosed in Patent Document 1, a photovoltaic power generation system is used to prevent reverse power flow. There is a way to control.

JP-A-2018-182847

When introducing a self-consumption type photovoltaic power generation system, it is required that the system can be stabilized.

First, regarding the prevention of reverse power flow among the factors that inhibit stabilization, the power flow is maintained from the upper system to the lower system by adopting Patent Document 1 and the like. By maintaining the direction of the tidal current, the stable operation of the voltage stabilizer installed by the system operator can be maintained.

On the other hand, focusing on the inside of the self-consumption type photovoltaic power generation system, when the photovoltaic power generation system is operated at a power factor of 100%, only active power is supplied from the photovoltaic power generation system. In this case, the load in the consumer receives active power and reactive power from the grid regardless of the output of the photovoltaic power generation system, so the power receiving rate of the consumer who introduced the self-consumption photovoltaic power generation system is only the load. It will be lower than the connected situation. In particular, as the ratio of the rated value of the photovoltaic power generation system to the load power consumption increases, the effect of the above-mentioned decrease in power factor increases.

In this regard, the decrease in power factor in the photovoltaic power generation system is a factor that hinders the stabilization of the system. Most of the voltage stabilizing devices in the system estimate the voltage at the end of the feeder from the change in the active power flowing through the feeder, and control the voltage of the entire feeder within a predetermined range. Therefore, if the power factor of the received power fluctuates greatly, it becomes difficult to stably control the voltage of the system.

From the above, in the present invention, the monitoring and control device of the photovoltaic power generation equipment capable of stabilizing the system voltage by keeping the power factor at the power receiving point of the equipment above a predetermined value while suppressing the reverse power flow. The purpose is to provide a control method.

From the above, in the present invention, it is a monitoring control device for the photovoltaic power generation equipment in the consumer who supplies power to the load from the bus connecting the AC system and the photovoltaic power generation equipment, and the monitoring control device is the AC system and the consumer. The state quantity for calculating the power factor of the interconnection point of the AC system is detected, and the invalid power output by the inverter required to make the power factor of the interconnection point between the AC system and the consumer equal to or higher than the predetermined power factor is the state quantity. It is characterized in that it includes a calculation unit that calculates based on the above, and an inverter control unit that controls the inverter using the invalid power as an invalid power command.

Further, the present invention is a method of monitoring and controlling the photovoltaic power generation equipment in the consumer who supplies power to the load from the bus connecting the AC system and the photovoltaic power generation equipment, and determines the power factor of the interconnection point between the AC system and the consumer. The amount of state to be calculated is detected, the power factor output by the inverter required to make the power factor of the interconnection point between the AC system and the consumer equal to or higher than the predetermined power factor is calculated based on the amount of state, and the inverter is calculated. It is characterized by controlling.

According to the present invention, the power factor at the power receiving point of the equipment can be maintained at a predetermined value or higher while suppressing the reverse power flow, so that the system voltage can be easily stabilized.

The figure which shows the whole composition example of the consumer equipment including the monitoring control device of the photovoltaic power generation system which concerns on Example 1. FIG. The figure which shows the configuration example of the solar inverter system including the inverter control part 10 and the inverter INV. The figure which shows the schematic control logic of the control device 1. The figure which shows the control logic of the reactive power command value calculator 100. The figure which shows the control logic of the active power upper limit calculator 200. The figure which shows the operation map example of the inverter operation map table 201. The figure which shows the load operation example which does not perform reactive power control. The figure which shows the power factor fluctuation at the time of a load operation which does not perform reactive power control. The figure which shows the load operation example when the control which concerns on Example 1 of this invention is executed. The figure which shows the power factor fluctuation at the time of load operation which concerns on Example 1 of this invention. The figure which shows the load operation example which does not perform reactive power control. The figure which shows the power factor fluctuation at the time of a load operation which does not perform reactive power control. The figure which shows the load operation example which concerns on Example 1 of this invention which prevents reverse power flow. The figure which shows the power factor fluctuation at the time of a load operation which concerns on Example 1 of this invention which prevents reverse power flow. The figure which shows the whole composition example of the facility in a consumer including the monitoring control device of the photovoltaic power generation system which concerns on Example 2. FIG. The figure which shows the schematic control logic of the control device 1A. The figure which shows the control logic of the reactive power command value calculator 100A. The figure which shows the control logic of the active power upper limit calculator 200A. The figure which shows the whole composition example of the consumer equipment including the monitoring control device of the photovoltaic power generation system which concerns on Example 3. FIG. The figure which shows the schematic control logic of the control device 3. The figure which shows the whole composition example of the facility in a consumer including the monitoring control device of the photovoltaic power generation system which concerns on Example 4. FIG. The figure for demonstrating the structure and control logic of a storage battery system 70.

Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of the overall configuration of the consumer equipment including the monitoring and control device of the photovoltaic power generation system according to the first embodiment of the present invention.

In FIG. 1, the consumer 90 to which the control of the present invention is applied includes at least a load 50 and a solar panel 20, and the load 50 is supplied with power from the solar panel 20 and an AC system. The consumer 90 receives active power Ps and reactive power Qs from an AC system (not shown) via a power receiving point 80. The solar panel 20 is connected to the bus bus connected to the power receiving point 80 via the load 50 and the inverter INV. The load 50 receives the active power PL and the reactive power QL, which are power consumption, from the bus bus.

A solar panel 20 is connected to the DC circuit of the inverter INV, the power generated by the solar panel 20 is frequency-converted to AC, and the AC power Pgen and the ineffective power Qgen are output to the bus bus.

For the control of the above-mentioned equipment in the consumer 90, the monitoring control device of the photovoltaic power generation system according to the present invention includes the control device 1 and the inverter control unit 10. Of these, the control device 1 is connected to the current detector 30 for detecting the current at the power receiving point 80 and the voltage detector 31 for detecting the voltage of the bus bus in the first embodiment to determine the reactive power command value QRef. The reactive power command value Quref is input to the inverter control unit 10 via the communication line 40, and the inverter control unit 10 controls the inverter INV and outputs the reactive power Qge and the AC power Pgen according to the reactive power command value Quref.

Among the monitoring and control devices of the photovoltaic power generation system, the details of the inverter control unit 10 are illustrated in FIG. 2, and specific configuration examples of the control device 1 are illustrated in FIGS. 3, 4, and 5. The monitoring control device of the first embodiment shown in FIG. 1 is characterized on the control device 1 side. Therefore, for convenience of explanation, the control logic of the inverter control unit 10 will be described first with reference to FIG. The inverter control unit 10 and the inverter INV are often installed close to each other, and a solar inverter system is suitable for expressing this in a comprehensive manner.

FIG. 2 is a diagram showing a configuration example of a solar inverter system including an inverter control unit 10 and an inverter INV. In the solar inverter system of FIG. 2, the inverter INV is controlled according to the AC output voltage command value Vref calculated by the inverter control unit 10. The inverter INV is a self-excited inverter composed of an assembly composed of semiconductor switching elements and a harmonic filter circuit.

The inverter control unit 10 includes a communication interface 11, and inputs an active power upper limit value Plim and a reactive power command value Quref transmitted from the control device 1 via the communication line 40. Further, the DC input voltage Vdc, the DC input current Idc, the AC voltage Vac, and the AC output current Iac detected by the sensor in the inverter INV (not shown) are input.

The inverter control unit 10 executes MPPT (Maximum Power Point Tracking) with a limiter and reactive power control using these input values, determines the AC output voltage command value Vref, gives it to the inverter INV, and controls it. The reactive power Qgen and the active power Pgen defined by the inverter INV are transmitted to the control device 1 via the communication interface 17.

The specific control calculation will be further described. The DC input voltage Vdc and the DC input current Idc are input to the MPPT calculator 12 with a limiter. The MPPT calculator 12 with a limiter is a calculator that automatically searches for the point where the generated power becomes maximum by adjusting the DC input voltage Vdc, calculates the effective current command value for changing the DC input voltage Vdc, and calculates the effective current command value. Output to the current controller 16. Since the MPPT calculator 12 is a calculator that is frequently used in the field, detailed description thereof will be omitted.

The MPPT calculator 12 with a limiter inputs the active power upper limit value Plim input by the communication interface 11 as the upper limit value as the upper limit value. When the DC input power exceeds the active power upper limit value Plim, the MPPT calculator 12 limits the input power so that the input power becomes equal to or less than the active power upper limit value Plim by lowering and correcting the active current command value.

The reactive power control calculates the reactive current command value by the following arithmetic unit. First, the AC voltage Vac and the AC output current Iac are input to the active power / reactive power calculator 13. The active power / ineffective power calculator 13 calculates the active power Pgen and the ineffective power Qgen output from the AC output terminal of the inverter INV from the AC voltage Vac and the AC output current Iac. The calculated active power Pgen and reactive power Qgen are output to the communication interface 17 and appropriately used for processing on the control device 1 side. Further, the reactive power Qgen is input to the reactive power controller 14, and the reactive power Qgen calculates the difference between the reactive power command value Qreg and the measured reactive power Qgen, and outputs the difference to the reactive power controller 15.

The reactive power controller 15 is composed of a proportional integration controller, and calculates a reactive current command value output by the inverter INV so as to reduce the input difference.

The effective current command value calculated by the MPPT calculator 12, the invalid current command value calculated by the invalid power controller 15, and the AC output current Iac are input to the current controller 16, and the current controller 16 is AC. The AC output voltage command value Vref of the self-excited inverter INV is calculated so that the active component and the ineffective component of the current Iac follow the input command value, and is output to the inverter INV.

Next, the operation of improving the power receiving point power factor by the control device 1 will be described. First, the input / output of the control device 1 will be described with reference to the overall configuration diagram of FIG. In FIG. 1, the power receiving point 80 of the consumer 90 is provided with a current detector 30 for detecting the current at the power receiving point and a voltage detector 31 for detecting the bus voltage, and the output of these detectors is input to the control device 1. To. The output of the control device 1 is connected to the communication line 40 via the communication interface, and outputs the active power upper limit value Plim and the reactive power command value Quref to the inverter control unit 10.

The schematic control logic of the control device 1 is shown in FIG. To briefly describe its internal function, the control device 1 is composed of a reactive power command value calculator 100 and an active power upper limit value calculator 200.

The control device 1 includes a voltage detection value input interface 500 and a current detection value input interface 501, and inputs AC voltage Vs and AC current Is to be received at the power receiving point. The AC voltage Vs and the AC current Is are input to the reactive power command value calculator 100. The reactive power command value calculator 100 calculates the target value of the reactive power to be output from the inverter INV in order to make the power factor at the power receiving point 80 larger than a predetermined value as the reactive power command value Quref, and uses the communication interface 502. Output to the reactive power upper limit calculator 200.

In addition to the reactive power command value Quref, the reactive power command value calculator 100 calculates the active power calculation value Pscal received from the grid at the power receiving point 80 and outputs it to the reactive power upper limit value calculator 200. The active power upper limit value 200 calculates the active power upper limit value Plim for both preventing reverse power flow from the power receiving point 80 and stopping the overload of the solar inverter 10, and outputs it to the communication interface 502.

The control logic of the reactive power command value calculator 100 will be described with reference to FIG. The AC voltage Vs and the AC current Is are input to the active power / reactive power calculator 101. The active power / reactive power calculator 101 calculates the active power calculation value Pscal and the reactive power calculation value Qscal to be received at the power receiving point 80. The active power calculation value Pscal is output to the reactive power calculators 102 and 103 for power factor compliance and the active power upper limit calculator 200. The reactive power calculation value Qscal is output to the subtractor 106.

The subtractor 106 calculates the difference between the reactive power command value Qref (output of the low-pass filter 104) and the reactive power output estimated value (reactive power calculated value Qscal) output by the inverter INV, and estimates the reactive power consumed by the load 50. Calculate the value QLcal.

In calculating the reactive power estimated value QLcal, the reactive power command value Quref delays the reactive power command value Quref to be output to the inverter INV by the delay device 105, and the output is equal to the reactive power control response of the inverter INV. It is preferable to calculate by performing a low-pass filter operation having a constant with the low-pass filter 104.

The reactive power calculator 102 for power factor compliance inputs the delayed power factor limit value PFlag at the power receiving point 80, which is a predetermined value, in addition to the active power calculated value Pscal, and the power factor receives the delayed power factor limit value PFlag. The reactive power Qlimmag at the receiving point at the time is calculated according to the equation (1).

Similarly, the reactive power calculator 103 for power factor compliance inputs the active power calculation value Pscal and the leading power factor limit value PFlead at the power receiving point 80, which is a predetermined value, and the power factor is advanced, and the power factor limit value PFlead is input. The reactive power Qlimlead at the receiving point when becomes is calculated according to the equation (2).

Here, in this embodiment, the delay power factor limit value PFlag and the advance power factor limit value PFlead are set to predetermined values, but these values may be variable values by external communication.

The reactive power Qlimmag at the power receiving point when the power receiving rate reaches the delayed power factor limit value PFlag is sent to the subtractor 107, and the reactive power Qlimlead at the power receiving point when the power receiving rate advances and becomes the power factor limit value PFLad is the subtractor. The difference from the reactive power estimated value QLcal input to 109 and consumed by the load 50 is calculated.

The output of the subtractor 107 is output to the limiter 108, and the limiter 108 limits the output of the subtractor 107 to zero or more and Qmax or less, and outputs the limit value to the adder 1010.

Similarly, the output of the subtractor 109 is output to the limiter 111, and the limiter 111 limits the output of the subtractor 109 to −Qmax or more and zero or less, and outputs the limit value to the adder 110.

The adder 110 calculates the sum of the outputs of the limiter 108 and 111, and outputs the output to the communication interface 502 as the reactive power command value Quref to be output by the inverter INV.

According to the above configuration, if the reactive power estimated value QLcal is larger than the reactive power Qlimmag at the receiving point when the receiving power factor becomes the delayed power factor limit value PFlag, the excess reactive power is supplied from the inverter INV to receive power. The power factor of the points can be maintained above the delayed power factor limit value PFlag.

If the reactive power estimated value QLcal is smaller than the reactive power Qlimlead at the power receiving point when the power receiving rate advances and becomes the power factor limit value PFlead, the insufficient reactive power is absorbed by the inverter INV to reach the power receiving point. It is possible to advance the power factor and maintain the power factor limit value PFread or higher.

Next, the control logic of the active power upper limit calculator 200 will be described with reference to FIG. The active power upper limit calculator 200 inputs the invalid power command value Quref input from the invalid power command value calculator 100 and the active power calculated value Pscal received at the power receiving point 80, and the inverter INV outputs the invalid power and overloads. The active power upper limit value Plim for avoiding the operating state is calculated and output to the communication interface 502.

Specifically, the reactive power command value QRef is input to the inverter operation map table 201, and the active power upper limit value Pmax that can prevent the inverter from being overloaded is calculated.

FIG. 6 shows an example of an operation map of the inverter operation map table 201. The horizontal axis of FIG. 6 shows the reactive power Q that can be output, the vertical axis shows the active power P that can generate power, and the solid line in bold shows the operation map of the active power / reactive power showing the operable area of the inverter INV. In the region where the active power output is small, the reactive power can be output in the range of ± Qmax. On the other hand, in the region where the active power exceeds P1, the reactive power that can be supplied is limited within the range where the output apparent power does not exceed 1 pu. Conversely, in order to output reactive power, the reactive power that can be output can be increased by suppressing the active power to P1.

In the inverter operation map table 201 of FIG. 5, the maximum active power P1 capable of outputting the input reactive power command value QRef is calculated from the operation map shown in FIG. 6, and the calculated value Pmax is set as the upper limit value of the proportional integration controller. Output to 203. The inverter operation map table 201 may be stored in advance, or may be provided with an interface for inputting data from the outside.

Returning to FIG. 5, the explanation of the control logic of the active power upper limit calculator 200 will be continued. The proportional integration controller 203 inputs the calculated active power value Pscal, performs a proportional integration operation in which the upper limit value is Pmax and the lower limit is zero, and outputs the output to the communication interface 502 as the active power upper limit value Plim of the inverter INV.

When the calculated active power value Pscal at the receiving point is sufficiently large, the upper limit value Plim of the active power of the inverter INV becomes a large value, and the inverter INV can output a large amount of power. On the other hand, when the calculated active power value Pscal is less than zero, the upper limit value Plim of the active power of the inverter INV, which is the output of the proportional integration controller 203, becomes small, and the output of the inverter INV is suppressed.

By the above operation, the control device of the first embodiment can suppress the power factor of the consumer 90 at the power receiving point 80 within a predetermined range. Further, at this time, by limiting the power generation upper limit value in the inverter operation map table, it is possible to avoid the overload of the inverter INV and the reverse power flow at the power receiving point 80.

Next, the effect of the present invention will be described with specific illustration. First, FIGS. 7 (a) and 7 (b) assume a case where the inverter INV gives only the active power Pgen. Therefore, this case shows an example of operation by a consumer by self-consumed photovoltaic power generation in the prior art, in which the reactive power command is zero.

FIG. 7A is a diagram showing a load operation example in which reactive power control is not performed. The horizontal axis represents the time from 0:00 to 24:00 of the day, and the vertical axis represents the maximum active power consumption of the load 50 of 100. It shows the magnitude of electric power as%. First, the amount of power generated by self-consumed photovoltaic power generation is generated only during the daytime hours (for example, from 8:00 to 16:00) when the active power Pgen is generated. However, in the conventional method, since the inverter INV is operated at a power factor of 100%, the reactive power Qgen is always zero. On the other hand, the active power consumption PL and the reactive power consumption QL of the load 50 increase in accordance with the operation start time and decrease in the operation end time. However, the load power PL and QL are sufficiently larger than the solar power Pgen and Qgen, and it is not assumed that the solar power Pgen and Qgen exceed the load power PL and QL.

The power factor PF at the power receiving point 80 at this time is shown in FIG. 7 (b). The horizontal axis represents the time in the same time zone as in FIG. 7A, and the vertical axis represents the power receiving rate PF. According to this, the power receiving point power factor PF decreases with the start of power generation from the inverter INV. Although the power factor PF temporarily recovers due to the increase in the power PL and QL of the load, the power factor PF decreases again toward noon, and the power factor PF recovers as the generated power from the inverter INV decreases in the afternoon.

In this way, according to the conventional photovoltaic power generation method that does not generate reactive power based on the concept of constant power factor, the power receiving point power factor PF drops extremely during the daytime when it becomes a heavy load, which hinders the management of system voltage. There is a risk of causing it.

On the other hand, by applying the control device 1 of the first embodiment of the present invention, the power factor PF at the power receiving point is greatly improved. FIG. 8A shows the relationship between the electric power of each part when the control according to the first embodiment of the present invention is executed.

According to FIG. 8A, the active power consumption PL and the reactive power consumption QL of the load 50 are assumed to increase in accordance with the operation start time and decrease in the operation end time as in FIG. 7A. On the other hand, the reactive power Qgen due to sunlight, which was constant in FIG. 7A, is assumed to increase or decrease in proportion to the active power Pgen due to sunlight, for example. However, in the control according to the first embodiment of the present invention, the maximum value of the reactive power Qgen due to sunlight is limited to Qmax.

In the illustrated example, the reactive power Qgen increases slightly later than the increase in the generated power Pgen of the inverter INV. When the reactive power Qgen reaches the limit power Qmax, the generated active power Pgen is limited in order to keep the receiving power factor at or above the delay power factor limit value PFlag. Here, the maximum value Qmax of the reactive power Qgen is set to 30% of the maximum load power consumption.

The change in the power factor PF at the power receiving point 80 at this time is shown in FIG. 8 (b). Here, the delay power factor limit value PFlag is set to 0.9. According to FIG. 8B, before the inverter INV starts power generation, the power factor of the load 50, 0.92, is the power receiving point power factor. When the inverter INV starts power generation, the active power PL to be received decreases, while the reactive power QL does not change, so the power factor PF at the receiving point decreases.

When the power receiving point power factor PF drops to the delay power factor limit value PFlag, the control device 1 outputs a reactive power command QRef of zero or more to the inverter INV, and the reactive power Qs received from the system at the power receiving point 80 decreases. This keeps the power factor at 0.9.

In FIGS. 9 (a) and 9 (b) below, a load operation example for preventing reverse power flow without reactive power control and a power factor fluctuation will be described. The amounts shown in these figures are the same as those described so far. Here, it represents that the reverse power flow can occur in the period T. That is, in this state, the load 50 may be less than the amount of photovoltaic power generation.

FIG. 9A is a diagram showing an example of load operation for preventing reverse power flow without reactive power control. Comparing this figure with FIG. 7A, for example, the active power PL and the active power QL consumed by the load 50 are relatively smaller than those in FIG. 7A, for example, the active power Pgen which is the amount of photovoltaic power generation. It shows that reverse power flow is generated as a result of exceeding the active power PL consumed by the load at the timing of the rapid increase. In the conventional load operation example, the power factor of photovoltaic power generation is constantly controlled, and the reactive power Qgen due to photovoltaic power generation remains zero.

In the load operation example for preventing reverse power flow without such invalid power control, the amount of solar power generation is used to prevent reverse power flow when the active power PL consumed by the load 50 is lower than the rated power generation power Pgen of solar power. The active power Pgen is suppressed to be equal to or less than the active power PL consumed by the load. This prevents reverse power flow. In the figure, it is assumed that the active power PL is lower than the photovoltaic power generation power Pgen in the period T near noon.

FIG. 9B is a diagram showing a power factor fluctuation during load operation for preventing reverse power flow without reactive power control. Here, the power receiving point power factor PF can be expressed by Eq. (3).

As is clear from the change tendency of the active power PL and the ineffective power QL shown in the equation (3) and FIG. 9 (a), and the active power Pgen and the ineffective power Qgen (= 0) which are the amount of solar power generation, the active power PL The power receiving point power rate PF, which is determined according to the difference between the active power Pgen and the invalid power Qgen, decreases due to the occurrence of solar power generation, and does not have a mechanism for compensating for the invalid power from the solar power generation system. In the conventional example, the power receiving point power rate PF drops to zero in the period T near noon when the active power PL is lower than the generated power Pgen of solar power.

On the other hand, in the case of the present invention provided with a mechanism for compensating reactive power from the photovoltaic power generation system, load operation examples for preventing reverse power flow and power factor fluctuations are shown in FIGS. 10 (a) and 10 (b). ) Will be described.

First, FIG. 10A is a diagram showing a load operation example for preventing reverse power flow in the first embodiment of the present invention. In the first embodiment of the present invention, first, the allowable reactive power is calculated from the received power Ps [kW], and the amount of the reactive power QL of the load deviating from the allowable range of reactive power is compensated from the photovoltaic power generation system. In addition, the limit value of active power is calculated so that the inverter in the photovoltaic power generation system can output the reactive power for the compensation.

Therefore, the photovoltaic power generation system supplies the active power Pgen and the corresponding invalid power Qgen, and the occurrence of reverse power flow is suppressed. In this case, since the above limit value is smaller than the active power PL, PL ≠ Pgen near 12 o'clock.

Further, FIG. 10B is a diagram showing a power factor fluctuation during load operation for preventing reverse power flow in the first embodiment of the present invention. According to the first embodiment, for example, since the reactive power Qgen for keeping the power receiving point power factor PF at 0.9 or more is output from the photovoltaic power generation system, the power receiving point power factor PF is maintained at about 0.9 or more. .. The reactive power Qgen is controlled by the feedback system. At the timing when the fluctuation of the active power is large, the timing at which the power receiving point power factor PF becomes less than 0.9 occurs transiently.

As described above, according to the first embodiment of the present invention, the operation of a solar inverter that avoids reverse power flow and overload while keeping the power receiving point power factor larger than a predetermined value even when sunlight for self-consumption is introduced. Is possible. By keeping the power receiving rate higher than a predetermined value, the system voltage can be easily managed.

Example 2 of the present invention will be described with reference to FIGS. 11 to 14. The same elements as those in the first embodiment of the present invention are designated by the same reference numerals to avoid duplicate explanations.

First, FIG. 11 is a diagram showing an overall configuration example of in-customer equipment including a monitoring and control device for the photovoltaic power generation system according to the second embodiment. In FIG. 11, the difference between the second embodiment and the first embodiment is that the current detector 30 is provided on the bus bus that detects the load current IL. By directly detecting the load current IL instead of the current at the power receiving point 80, the active power PL and reactive power QL consumed by the load can be directly detected, so that the control logic provided in the control device of the present invention is simplified. Can be changed.

Further, the difference between the second embodiment and the first embodiment is that the processing contents of the control device 1 are partially changed in relation to the above changes. Therefore, the control device 1 in the second embodiment will be described and described as the control device 1A. In the monitoring control device of the photovoltaic power generation system of the second embodiment, the details of the inverter control unit 10 are not changed as illustrated in FIG. 2, and specific configuration examples of the control device 1A are shown in FIGS. 12 and 13. Illustrated in FIG.

In FIG. 11, the control device 1A receives the detected values of the current detector 30 and the voltage detector 31, and similarly to the first embodiment, the active power upper limit value Plim and the reactive power command value Quref of the inverter INV are transmitted via the communication line 40. Is transmitted to the inverter control unit 10.

The schematic control logic of the control device 1A is shown in FIG. To briefly describe its internal function, the control device 1A is composed of a reactive power command value calculator 100A and a reactive power upper limit value calculator 200A.

The invalid power command value calculator 100A of the control device 1A inputs the received voltage detection value Vs and the load current IL from the voltage detection value interface 500 and the current detection value interface 501, and inputs the generated power Pgen of the inverter INV from the communication interface 502. Input and calculate the invalid power command value QRef of the inverter INV and the active power calculation value PLcal consumed by the load 50. The active power upper limit value calculator 200A of the control device 1A calculates the active power upper limit value Plim for preventing reverse power flow and avoiding the overload of the photovoltaic inverter 10INV from the invalid power command value Queue and the active power calculation value PLcal. To do.

The reactive power command value Quref and the active power upper limit value Plim are transmitted to the inverter control unit 10 via the communication interface 502 and the communication line 40. Similar to the first embodiment of the present invention, the inverter control unit 10 executes, for example, the process of FIG. 2 to control the reactive power and reactive power output to the system according to the reactive power command value Quref and the active power upper limit value Plim.

The control logic of the reactive power command value calculator 100A will be described with reference to FIG. The difference from the reactive power command value calculator 100 of the first embodiment shown in FIG. 4 is that the active power calculation value PLcal consumed by the load 50 is calculated and the reactive power consumed by the load 50 is directly calculated. The difference is that the active power received at the power receiving point 80 is calculated from PLcal and Pgen. In addition, in FIGS. 11 to 14, the difference is clarified by adding "A" to the symbol to the portion where the processing functionally different between the first embodiment and the second embodiment is performed.

The receiving point voltage detection value Vs and the load current detection value IL are input to the active power / reactive power calculator 101A, and the active power calculation value PLcal and the reactive power calculation value QLcal consumed by the load 50 are calculated. By directly detecting the load current IL, it is possible to eliminate the logic for calculating the response of the inverter INV for the reactive power QLcal consumed by the load. In addition, the response speed of the control response changes when the system impedance expected from the inverter INV changes due to system switching or the like. Since it is not necessary to simulate the reactive power control response of the inverter INV in this embodiment, robustness can be improved for system operation including system switching as compared with Example 1 of the present invention.

The calculated active power PLcal consumed by the load 50 is output to the subtractor 112 and the active power upper limit calculator 250, and the reactive power QLcal is output to the subtractors 107 and 109.

The calculated active power PLcal consumed by the load 50 and the active power Pgen of the inverter INV are input to the subtractor 112, and the calculated active power Pscal received at the receiving point 80 is calculated. Since the calculation logic of the reactive power command value Quref using the calculated value Pscal of the active power received at the power receiving point 80 is the same as that in the first embodiment, duplicate description will be omitted.

The control logic of the active power upper limit value calculator 200A will be described with reference to FIG. The active power upper limit value calculator 200A inputs the reactive power consumption calculated value PLcal of the load 50 and the reactive power command value Quref calculated by the reactive power command value calculator 100A, and the active power output by the inverter INV from these inputs. The upper limit value Plim is calculated and output to the communication interface 502 of FIG.

In FIG. 14, the inverter operation map table 201 receives the reactive power command value Qref as the input, and can output the reactive power following the reactive power command value QRef while avoiding the overload of the inverter INV, as in the first embodiment. The upper limit value Pmax of is calculated by referring to the table, and the upper limit value is output to the minimum value calculator 202.

The upper limit value Pmax of the active power and the calculated active power consumption value PLcal are input to the minimum value calculator 202, and the smaller value is output to the communication interface 502 of FIG. 12 as the active power upper limit value Plim of the inverter INV.

From the above, by using the control device 1A of this embodiment, it is possible to avoid overload operation of the inverter INV while improving the power factor at the power receiving point 80 and preventing reverse power flow.

Further, by using the reactive power command value calculator 100A of this embodiment, the power factor at the power receiving point can be maintained at a desired value or higher while maintaining robustness against system operation.

Further, since the active power upper limit calculator 200A of this embodiment does not require a proportional integration controller, the calculation can be simplified as compared with the active power upper limit calculator 200 described in the first embodiment.

Example 3 of the present invention will be described with reference to FIGS. 15 and 16.

First, FIG. 15 is a diagram showing an overall configuration example of in-customer equipment including a monitoring control device for the photovoltaic power generation system according to the third embodiment. The difference between the third embodiment and the first and second embodiments constitutes a control device 3 having both the function of the control device 1 for controlling the power factor at the power receiving point 80 and the function of the inverter control unit 10, which is a solar inverter system. It was incorporated as part of. In other words, it can be said that the voltage and current information of the system is taken in as analog values and communication is excluded. Here, the power receiving point voltage detection value Vs and the load current detection value Is are received as analog signals, and the power receiving point power factor control, the active power upper limit calculation of the inverter INV, and the waveform control of the inverter INV are performed by the controller inside the control device 3. By performing batch calculation, delay due to communication can be avoided.

The control device 3 of this embodiment receives the output signals of the voltage detector 30 for detecting the receiving point voltage and the current detector 31 for measuring the load current.

A schematic control block of the control device 3 is shown in FIG. The control device 3 includes a voltage detection value interface 500 and a current detection value interface 501, and inputs a power receiving point voltage detection value Vs from the voltage detector 30 and a current detection value IL from the current detector 31. The same calculation as that of the control device 1A of FIG. 12 is performed by the reactive power command value calculator 100A and the active power upper limit value calculator 200A. The reactive power consumption calculated value PLcal of the load obtained by the reactive power command value calculator 100A is output to the active power upper limit value calculator 200A, and the reactive power command value Quref for maintaining the power factor at the power receiving point 80 is the subtractor 14. Is output to.

Since each function of FIG. 16 (MPPT12 with limiter, active power / reactive power calculator 13, subtractor 14, reactive power controller 15) performs the same calculation as in the first embodiment of the present invention, duplicate description will be omitted.

From the above, according to the present embodiment, since the control function shown in the second embodiment can be implemented without communication, delay due to communication can be avoided, and more accurate power factor control and active power control can be performed. Become.

Example 4 of the present invention will be described with reference to FIGS. 17 and 18.

The difference between the fourth embodiment and the first to third embodiments is that the photovoltaic inverter system for private consumption is provided with a storage battery system in addition to the photovoltaic inverter.

The control device 1 and the inverter INV may be positioned apart from each other, and the active power upper limit value Plim and the reactive power command value Quref may have to be transmitted by communication. Generally, communication takes several tens of ms to several hundred ms. On the other hand, when a large-capacity photovoltaic power generation facility for private consumption is introduced for the minimum load, the grid operator may request a reverse power flow prevention relay at the receiving point. Some reverse power flow prevention relays detect reverse power flow in about 100 ms and issue an opening command to the circuit breaker. Therefore, the reverse power flow prevention control by communication may not be in time transiently, and the reverse power flow prevention relay may operate to open the circuit breaker.

In this embodiment, in addition to suppressing the output of the inverter INV by communication, a storage battery system that detects the power at the receiving point with analog information is provided. With this storage battery system, the reverse power flow period due to communication delay is made shorter than the operating time of the reverse power flow prevention relay, thereby avoiding the opening of the circuit breaker and realizing a high-ratio self-consumption photovoltaic power generation system.

FIG. 17 shows an example of the overall configuration of the in-house equipment including the monitoring and control device of the photovoltaic power generation system according to the fourth embodiment of the present invention. The difference from the second embodiment is that a reverse power flow relay 35 is provided to detect the power at the power receiving point and open the breaker CB when a reverse power flow occurs, and the power flow at the power receiving point is an analog signal. The point is that the storage battery system 70, which is calculated based on the above and prevents reverse power flow for a short time, and the storage battery 25 connected to the storage battery system are provided. The AC terminal of the storage battery system 70 is connected to the same AC bus bus as the load 50 and the inverter INV. In FIG. 17, 32 is a current detector and 33 is a voltage detector.

The configuration and control logic of the storage battery system 70 will be described with reference to FIG. The storage battery system 70 includes a storage battery inverter waveform controller 70C and a storage battery inverter 70 INV. The storage battery inverter waveform controller 70C acquires the AC voltage detection value Vs and the AC current detection value Is at the power receiving point via the voltage detection value interface 700 and the current detection value interface 701, and detects the interconnection point voltage of the storage battery system 70 (not shown). Based on the value Vac2 and the interconnection point output current detection value Iac2, the voltage command value Vref2 of the storage battery inverter 70INV is calculated so as to output the active power that prevents the backflow in a short period of time.

The voltage detection value Vs and the current detection value Is are input to the active power / reactive power calculator 702, and the active power Pscal at the receiving point is calculated.

Pscal is input to the high-pass filter 703. The high-pass filter 703 extracts the reverse power flow of the high-frequency component from Pscal, which the output suppression of the solar inverter system 10 cannot keep up with due to the communication delay.

The output of the high-pass filter 703 is input to the limiter 704, and the limiter 704 limits the input value to zero or less and extracts the reverse power flow component which is a negative component of the received power. The output of the limiter 704 is input to the multiplier 705, and after the sign is inverted, the active power command value output by the storage battery system is calculated.

The active power command value, the voltage detection value Vac2, and the output current detection value Iac2 are input to the active power controller 706, and the output voltage of the storage battery inverter 70INV so that the active power output by the storage battery inverter 70INV follows the active power command value. The command value Vref2 is corrected and output to the inverter 70INV.

In this embodiment, an analog signal is used as a means for detecting the power at the receiving point, but the storage battery system 70 is provided by a control device having a communication rate higher than that of the communication between the solar inverter system 10 and the control device 1. You may control it.

From the above, according to the fourth embodiment of the present invention, it is possible to avoid an overload of the solar inverter while maintaining the power factor at the power receiving point at a desired value and preventing reverse power flow with high accuracy.

1, 1A, 3: Control device 20: Solar panel 25: Storage battery 30, 32: Current detector 31, 33: Voltage detector 35: Reverse power flow prevention relay 40: Communication line 50: Load 70: Storage battery Inverter system 80: Power receiving point 90: Consumer equipment 100, 100A: Invalid power command value calculator 200, 200A: Active power upper limit value calculator 500, 700: Voltage detection value input interface 501, 701: Current detection value input interface 502, 11, 17 : Communication interfaces 101, 101A, 702, 13: Active power Invalid power calculator 102, 103: Invalid power calculator for power factor compliance 104: Low pass filter 105: Delayer 106, 107, 109, 14: Subtractor 110: Addition Units 108, 111, 704: Limiter 201: Inverter operation map table 202: Minimum value calculator 203: Proportional integration controller 12: MPPT calculator with limiter 15: Invalid power controller 16, 706: Current controller INV: Sunlight Inverter 70: Storage battery system 70C: Storage battery inverter Wave controller 703: High-pass filter 705: Multiplier 70INV: Storage battery inverter

Claims (12)

It is a monitoring and control device for photovoltaic power generation equipment in consumers who supply power to the load from the bus that connects the AC system and the photovoltaic power generation equipment.
The monitoring and control device is necessary to detect the state quantity for calculating the power factor of the interconnection point between the AC system and the consumer, and to make the power factor of the interconnection point between the AC system and the consumer equal to or higher than the predetermined power factor. Monitoring control of a solar power generation facility including a calculation unit that calculates the reactive power output from the inverter based on the state quantity, and an inverter control unit that controls the inverter using the reactive power as a reactive power command. apparatus. The monitoring and control device for the photovoltaic power generation facility according to claim 1.
A photovoltaic power generation facility characterized in that the state quantity for calculating the power factor of the interconnection point is the amount of electricity that can calculate the active power and reactive power consumed by the load provided in the customer. Monitoring and control device. The monitoring and control device for the photovoltaic power generation facility according to any one of claims 1 to 2.
The amount of state for calculating the power factor of the interconnection point is the amount of electricity that can calculate the active power and the ineffective power of the interconnection point, and the active power output by the photovoltaic power generation facility. A monitoring and control device for photovoltaic power generation equipment, which is characterized by including the amount of electricity that can be produced. The monitoring and control device for the photovoltaic power generation facility according to any one of claims 1 to 3.
The calculation unit calculates the active power output by the inverter and supplies it to the inverter control unit to control the inverter, and the active power output by the inverter is equal to or less than the active power consumed by the load provided in the consumer. A monitoring and control device for photovoltaic power generation equipment, which is characterized by being limited to. The monitoring and control device for the photovoltaic power generation facility according to any one of claims 1 to 4.
The calculation unit calculates the active power output by the inverter and supplies it to the inverter control unit to control the inverter, and limits the active power to an upper limit value set from the reactive power. Monitoring and control device for photovoltaic power generation equipment. The sun according to any one of claims 1 to 5, wherein a circuit breaker is installed at the interconnection point between the AC system and the consumer to open the circuit breaker by reverse power flow at the interconnection point. It is a monitoring and control device for photovoltaic power generation equipment.
Solar power is characterized in that a storage battery is connected to a bus via a second inverter, charge / discharge of the storage battery is controlled prior to reverse power flow at the interconnection point, and reverse power flow at the interconnection point is prevented. Monitoring and control device for power generation equipment. The monitoring and control device for the photovoltaic power generation facility according to any one of claims 1 to 6.
A monitoring and control device for photovoltaic power generation equipment, wherein the calculation unit and the inverter control unit are connected by a communication means. The monitoring and control device for the photovoltaic power generation facility according to any one of claims 1 to 7.
The calculation unit calculates the active power output by the inverter and supplies it to the inverter control unit to control the inverter, and the active power is equal to or less than the active power consumed by the load provided in the customer. A first means for limiting the upper limit value of the active power and a second means for limiting the active power to the second upper limit value set from the invalid power are provided, and the active power is set to the smaller upper limit value of the active power. A monitoring and control device for solar power generation equipment, which is characterized by being controlled. The monitoring and control device for the photovoltaic power generation facility according to any one of claims 1 to 8.
An inverter operation map table that defines the operable range of the inverter is obtained via the interface, and the calculation unit is required to refer to the inverter operation map table and set the power factor of the interconnection point to a predetermined power factor or more. A monitoring and control device for photovoltaic power generation equipment, characterized in that the reactive power output by the inverter is calculated. It is a monitoring and control method for photovoltaic power generation equipment in consumers who supply power to the load from the bus that connects the AC system and the photovoltaic power generation equipment.
Detects the state quantity for calculating the power factor of the interconnection point between the AC system and the consumer, and outputs the inverter required to make the power factor of the interconnection point between the AC system and the consumer equal to or higher than the predetermined power factor. A monitoring and control method for photovoltaic power generation equipment, which comprises calculating reactive power based on the state quantity and controlling the inverter. The method for monitoring and controlling a photovoltaic power generation facility according to claim 10.
Photovoltaic power generation characterized in that the active power output by the inverter is calculated to control the inverter, and the active power is limited to an upper limit value equal to or less than the active power consumed by the load provided in the customer. Equipment monitoring and control method. The method for monitoring and controlling a photovoltaic power generation facility according to claim 10 or 11.
The active power output by the inverter is calculated to control the inverter, and the active power is set from the first upper limit value which is equal to or less than the active power consumed by the load provided in the customer and the reactive power. A monitoring and control method for solar power generation equipment, wherein the active power is controlled by the smaller upper limit of the active power among the second upper limit values.

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