JP7365116B2 - Power system stabilizer - Google Patents

Description

The present invention relates to a power system stabilizing device.

BACKGROUND ART Regular private power generation equipment installed in factories and the like is known. Regular private power generation equipment is normally connected to an external power system such as a commercial power system, and performs grid-connected operation. If a failure such as a power outage occurs in the external power system, the private power generation equipment will be disconnected from the external power system and operate independently. When a plurality of loads are connected to the private power generation equipment, during self-sustaining operation, the private power generation equipment supplies power to some of the loads (important loads) among the plurality of loads.

For this reason, there is a risk that the load connected to the private power generation equipment may suddenly change when switching from grid-connected operation to standalone operation. If the required load power suddenly decreases due to a sudden change in load, the output of the private power generation equipment will suddenly decrease. If the private power generation equipment cannot follow sudden changes in load, the system frequency in the AC power system connected to the private power generation equipment will rise rapidly, and the generator of the private power generation equipment may stop (trip) due to overspeed.

For example, Patent Documents 1 and 2 below have been proposed as power stabilization systems that suppress fluctuations in voltage or frequency due to such load fluctuations.

Japanese Patent Application Publication No. 2007-236085 JP 2016-10252 Publication

In Patent Document 1, the load power is measured, and the load that decreases when the connection is disconnected is temporarily consumed by a load device or the like. However, in the method of measuring electric power, the method of calculating the load electric power becomes complicated when a plurality of load devices are installed together. Further, in Patent Document 1, load fluctuations are assumed during self-sustaining operation, but load fluctuations during switching from grid-connected operation to self-sustaining operation are not assumed. Even if the configuration of Patent Document 1 could be applied to grid-connected operation, it would be necessary to switch the load power measurement point and control method depending on the operating situation (depending on whether it is standalone operation or grid-connected operation). Is required. Therefore, it is not possible to cope with load fluctuations when switching from grid-connected operation to standalone operation.

Furthermore, in Patent Document 2, storage batteries can be used to stabilize the system, but since all the power output from the power generation equipment is converted into power by the power conversion device, the capacity of the power conversion device and storage battery is large. There is a problem with becoming.

The present invention solves the above-mentioned problems, and uses relatively small-capacity power storage equipment to enable switching from grid-connected operation to standalone operation without requiring switching of control mode according to operating conditions. An object of the present invention is to provide a power system stabilizing device that can suppress voltage or frequency fluctuations due to load fluctuations.

A power system stabilizing device according to one aspect of the present invention includes a generator, an AC wiring section to which the generator is connected, and a predetermined solution between a power system different from the generator and the AC wiring section. A power system stabilizing device for stabilizing the voltage or frequency in the AC wiring section in a power supply system comprising a circuit breaker provided at a row point and a power load connected to the AC wiring section. , a power storage facility including a power storage device, a first power converter connected between the AC wiring section and the power storage device, a resistor, and a first power converter connected between the AC wiring section and the resistor. a second power converter; a control device that controls the first power converter and the second power converter; and a frequency acquisition device that acquires the system frequency in the AC wiring section. , the control device calculates a received power target value for charging and discharging the electricity storage device according to a first deviation between the system frequency and a predetermined first frequency reference value, and calculates a received power target value for charging and discharging the electricity storage device based on the received power target value. a first drive signal calculation unit that generates a first drive signal for performing power conversion in the first power converter; and a second deviation between the system frequency and a predetermined second frequency reference value. a second drive signal calculation unit that calculates a power consumption target value to be consumed in the resistor according to the power consumption target value, and generates a second drive signal for performing power conversion in a second power converter based on the power consumption target value; , the second frequency reference value is set to a value larger than the first frequency reference value, and the first drive signal calculation unit is configured to set the first deviation to a value larger than the first frequency reference value. If the system frequency is equal to or higher than the first deviation, the charge/discharge target value is calculated by using the frequency threshold as the first deviation. The power consumption target value is calculated based on the second deviation when the frequency is equal to or higher than a frequency reference value.

According to the above configuration, fluctuations in voltage or frequency associated with load fluctuations that are expected in advance, such as those that occur during steady operation (grid-connected operation or standalone operation), are transferred to the storage battery via the first power converter. On the other hand, fluctuations in voltage or frequency caused by sudden load reduction that occur when switching from grid-connected operation to standalone operation are suppressed by charging and discharging power. It is absorbed by being exposed to water. Therefore, it is no longer necessary to set the capacity of the power storage device to a capacity that takes into account power fluctuations that occur during operation switching. Therefore, it is possible to suppress voltage or frequency fluctuations due to load fluctuations when switching from grid-connected operation to standalone operation using a relatively small-capacity power storage facility. Further, since the first power converter and the second power converter are independently controlled based on the system frequency, there is no need to change the control mode depending on the operating situation. Therefore, it is possible to suppress fluctuations in voltage or frequency due to load fluctuations when switching from grid-connected operation to standalone operation without requiring switching of control modes depending on the operating situation.

The frequency threshold may be set to an upper limit value of a frequency compensated by the power storage equipment, and the second frequency reference value may be set to a value equal to the frequency threshold.

The first drive signal calculation section may calculate the received power target value by performing proportional differential calculation processing on the first deviation. By adding a differential component to charge/discharge amount control, transient stability in charge/discharge amount control can be improved.

The second drive signal calculation section includes a power consumption target value calculation section that calculates the power consumption target value based on a value obtained by multiplying the second deviation by a predetermined proportional gain; a second drive signal generation section that generates a second drive signal, and the power consumption target value calculation section sets the power consumption target value to 0 when the system frequency is smaller than the second frequency reference value. In this case, when the system frequency is equal to or higher than the second frequency reference value, the power consumption target value may be set according to a value obtained by multiplying the second deviation by the predetermined proportional gain. This allows the resistor to appropriately consume surplus power of the generator due to a sudden load reduction due to grid disconnection using a simple control mode.

The power storage device may be a secondary battery. Alternatively, the electricity storage device may be an electric double layer capacitor.

The second power converter may include a rectifier circuit and a chopper circuit, and may be configured to perform AC-DC conversion between the AC wiring section and the resistor. Alternatively, the second power converter may include an AC power adjustment circuit and be configured to perform AC-AC conversion between the AC wiring section and the resistor. Alternatively, the second power converter may include a cycloconverter circuit and be configured to perform AC-AC conversion between the AC wiring section and the resistor. Alternatively, the second power converter may include a matrix converter circuit and be configured to perform AC-AC conversion between the AC wiring section and the resistor. The second power converter to which the resistor is connected only needs to adjust the amount of power supplied to the resistor (power consumed by the resistor), so it is necessary to adjust not only the amount of power supplied to the capacitor but also the AC wiring. The configuration can be simpler than that of the first power converter, which requires adjustment of the amount of power supplied to the parts.

According to the present invention, by using a relatively small-capacity power storage facility, voltage due to load fluctuations when switching from grid-connected operation to standalone operation is eliminated without requiring switching of control modes according to operating conditions. Alternatively, frequency fluctuations can be suppressed.

FIG. 1 is a block diagram showing a schematic configuration of a power supply system to which a power system stabilizing device according to an embodiment of the present invention is applied. FIG. 2 is a block diagram showing a schematic configuration of a control system in the power storage equipment shown in FIG. 1. FIG. 3 is a block diagram showing a schematic configuration of the frequency calculation section shown in FIG. 2. FIG. 4 is a diagram showing an example of a calculation mode in the received power target value calculation section shown in FIG. 2. FIG. 5 is a block diagram showing a schematic configuration of a control system in the resistance equipment shown in FIG. 1. FIG. 6 is a diagram showing an example of a calculation mode in the power consumption target value calculation section shown in FIG. 5. FIG. 7 is a diagram showing an example of a calculation mode in the second drive signal generation section shown in FIG. FIG. 8 is a diagram showing a graph of frequency fluctuations in power adjusted by the power storage equipment in this embodiment. FIG. 9 is a diagram showing a graph of frequency fluctuations in power adjusted by the resistance equipment in this embodiment. FIG. 10 is a diagram showing a graph of frequency fluctuations in power adjusted by the power system stabilizing device in this embodiment. FIG. 11 is a block diagram showing an example of a configuration for simulating a power supply system. FIG. 12 is a graph showing simulation results in Example 1. FIG. 13 is a graph showing simulation results in Example 1. FIG. 14 is a graph showing simulation results in Example 1. FIG. 15 is a graph showing simulation results in Example 1. FIG. 16 is a graph showing simulation results in Example 2. FIG. 17 is a graph showing simulation results in Example 2. FIG. 18 is a graph showing simulation results in Example 2. FIG. 19 is a graph showing simulation results in Example 2. FIG. 20 is a block diagram showing a schematic configuration of a control system in another example of the resistance equipment shown in FIG. 1.

Embodiments of the present invention will be described below with reference to the drawings. Note that, hereinafter, elements that are the same or have the same functions are designated by the same reference numerals throughout all the figures, and redundant explanation thereof will be omitted.

[System configuration]
Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing a schematic configuration of a power supply system to which a power system stabilizing device according to an embodiment of the present invention is applied. A power supply system 1 in this embodiment includes a generator 2, an AC wiring section 3 to which the generator 2 is connected, a power system (hereinafter referred to as an external power system) 4 that is separate from the generator 2, and AC wiring. A circuit breaker (GCB: Generator Circuit Breaker) 5 provided at a predetermined disconnection point We are prepared.

In this embodiment, the AC wiring section 3 includes a first AC wiring section 31 and a second AC wiring section 32, which are a three-phase three-wire AC system. In addition, in the drawings, the three-phase, three-wire systems in the AC system are shown as one line, except for some parts. The generator 2 is a generator known as a generator for private power generation equipment, such as a prime mover generator such as a gas turbine generator, a gas engine generator, or a steam turbine generator. The generator 2 is connected to the first AC wiring section 31 .

The external power system 4 is, for example, a commercial power system. The external power system 4 is connected to the second AC wiring section 32. Note that in this embodiment, the external power system 4 is connected to the second AC wiring section 32 via a transformer 41 and a circuit breaker 42. However, the transformer 41 and/or the circuit breaker 42 may not be provided. A circuit breaker 5 (line-breaking point X) is provided between the first AC wiring section 31 and the second AC wiring section 32.

The load 6 includes a load connected to the first AC wiring section 31 and a load connected to the second AC wiring section 32. The generator 2 is configured to maintain power supply to the load connected to the first AC wiring section 31 when power supply from the external power system 4 is stopped. Further, when the power supply from the external power system 4 is stopped, the first AC wiring section 31 is disconnected from the second AC wiring section 32 and the external power system 4 by the circuit breaker 5 . Therefore, when the power supply from the external power system 4 is stopped, no power is supplied to the load connected to the second AC wiring section 32. For this reason, hereinafter, the load connected to the first AC wiring section 31 will be referred to as an important load 61, and the load connected to the second AC wiring section 32 will be referred to as a general load 62.

The power system stabilizing device 10 in this embodiment suppresses fluctuations in the voltage or frequency of the first AC wiring section 31 and stabilizes the power in the first AC wiring section 31. connected to. The power system stabilizing device 10 includes a power storage facility 11 and a resistance facility 12.

Power storage equipment 11 includes a power storage device 13 and a first power converter 14 connected between first AC wiring section 31 and power storage device 13 . The resistance equipment 12 includes a resistor 15 and a second power converter 16 connected between the first AC wiring section 31 and the resistor 15. The first power converter 14 and the second power converter 16 are connected to the first AC wiring section 31 via the third AC wiring section 33. Hereinafter, the first AC wiring section 31 and the third AC wiring section 33 will be collectively referred to as a generator side AC wiring section 3A.

Furthermore, the power system stabilization device 10 includes a control device 17 that controls the first power converter 14 and the second power converter 16, and a frequency acquisition device 18 that acquires the system frequency f in the generator side AC wiring section 3A. , is equipped with. The control device 17 is composed of, for example, a computer such as a microcontroller, a memory, and/or an electronic circuit.

The control device 17 generates drive signals S1 and S2 based on the system frequency f acquired by the frequency acquisition device 18, and outputs them to the first power converter 14 and the second power converter 16. Each power converter 14, 16 connects the AC wiring section 3 (3A) and the first DC wiring section 71 (described later) connected to the capacitor 13 and the AC wiring section 3 based on each drive signal S1, S2. (3A) and a second DC wiring section 72 (described later) connected to the resistor 15, AC-DC power conversion is performed, respectively.

Note that, as described later, the first drive signal S1 output to the first power converter 14 and the second drive signal S2 output to the second power converter 16 are generated by independent calculations. Therefore, in FIG. 1, the control device 17 is shown as a common control device for the two power converters 14 and 16, but the control device 17 is a first control device that generates the first drive signal S1. 17a (see FIG. 2 described later) and a second control device 17b (see FIG. 5 described later) that generates the second drive signal S2 may be configured separately.

[Electricity storage equipment]
FIG. 2 is a block diagram showing a schematic configuration of a control system in power storage equipment 11 shown in FIG. 1. FIG. 2 shows only the control blocks necessary for functioning as the first control device 17a of the control device 17. In this embodiment, the first power converter 14 is configured by a power conversion circuit including switching elements (not shown) such as IGBTs. The first drive signal S1 generated by the first control device 17a is connected to the AC wiring section 3 (3A) by transmitting the first drive signal S1 for controlling on/off the switching element of the first power converter 14. This is a signal for controlling power conversion with the first DC wiring section 71.

In this embodiment, a transformer 141 is provided between the AC output end of the first power converter 14 and the generator side AC wiring section 3A. Thereby, the AC output voltage of the first power converter 14 can be suppressed lower than the AC voltage (system voltage) of the generator side AC wiring section 3A. Note that the transformer 141 may not be provided depending on the AC voltage of the generator side AC wiring section 3A.

Power storage device 13 is connected to first power converter 14 via first DC wiring section 71 . The power storage device 13 is composed of, for example, a secondary battery or an electric double layer capacitor. Electric power is supplied from the generator-side AC wiring section 3A to the first DC wiring section 71 in accordance with the first drive signal S1, so that the electricity storage device 13 is charged, and from the first DC wiring section 71 to the generator-side AC wiring section. By supplying power to 3A, the capacitor 13 is discharged.

The first control device 17a includes a first drive signal calculation section 19, a frequency calculation section 20, a current calculation section 21, and a voltage calculation section 22 as control blocks. Furthermore, the power storage equipment 11 includes an AC voltage measuring device 23 and an AC current measuring device 24 as a configuration for acquiring each value used for calculation by the first control device 17a.

The frequency calculating section 20 calculates the system frequency f of the generator side AC wiring section 3A from the AC voltage at the generator side AC wiring section 3A. Therefore, the AC voltage measuring device 23 detects instantaneous values _va , _vb , and _vc of voltages of each phase of the three-phase AC in the generator-side AC wiring section 3A. For example, a PT (Potential Transformer) is used as the AC voltage measuring device 23. The AC voltage measuring device 23 and the frequency calculation section 20 constitute the frequency acquisition device 18.

Furthermore, the first control device 17a controls the first power converter 14 using the alternating currents I _d and _Iq of the generator side alternating current wiring section 3A as control elements. Therefore, the alternating current measuring device 24 detects the instantaneous values i _a , i _b , and i _c of the currents of each phase of the three-phase alternating current in the generator side alternating current wiring section 3A. For example, a CT (Current Transformer) is used as the alternating current measuring device 24.

The first drive signal calculation unit 19 charges and discharges the capacitor 13 according to a first deviation Δf ₁ between the system frequency f acquired by the frequency acquisition unit 18 and a predetermined first frequency reference value f _ref1 . A received power target value calculation unit 191 that calculates a received power target value P _ref1 , and a first drive signal _S1 that generates a first drive signal S1 for performing power conversion in the first power converter 14 based on the received power target value P ref1. The driving signal generating section 192 is also provided.

[Frequency calculation section]
The frequency calculation section 20 calculates the system frequency f in the generator side AC wiring section 3A. FIG. 3 is a block diagram showing a schematic configuration of the frequency calculation section shown in FIG. 2. The instantaneous values va, _vb , _{and vc} of the alternating current voltage detected by the alternating current voltage measuring device 23 are input to the frequency calculation unit 20.

The frequency calculation unit 20 calculates the phase target value φ _ref of the generator side AC wiring unit 3A by a known PLL (Phase Lock Loop) calculation using the instantaneous values v _a , v _b , v _c of the input AC voltage. calculate. The frequency calculation unit 20 estimates the angular velocity ω from the deviation between the phase φ obtained from the voltage measurement and the phase target value φ _ref that is the output of the PLL calculation, and integrates the angular velocity ω to obtain the phase target value φ _ref. Determine. The frequency calculation unit 20 calculates the system frequency f by calculating f=ω/2π from the estimated angular velocity ω, and outputs the calculated system frequency f.

In this embodiment, the frequency calculation unit 20 includes an αβ conversion unit 701, a sine cosine calculation unit 702, a deviation calculation unit 703, a transfer function application unit 704, an integration unit 705, and a frequency conversion unit 706.

The αβ conversion unit 701 performs αβ conversion on the instantaneous values v _a , v _b , v _c of the AC wiring section voltages, and outputs two-phase AC voltages v _α , v _β . The sine cosine calculation unit 702 calculates the sine value sinφ and the cosine value cosφ of the phase φ of the generator side AC wiring unit 3A from the two-phase AC voltages v _α and v _β . These values are given by the following formulas.

The deviation calculation unit 703 calculates the deviation ε of the PLL from the sine value sinφ and cosine value cosφ of the phase φ, and the sine value sinφ _{ref and} cosine value cosφ _ref (feedback value) of the phase target value φ ref. The deviation ε is given by the following approximate expression.

The transfer function application unit 704 receives the deviation ε and calculates the angular velocity ω based on the transfer function G(s). For example, the transfer function G(s) is given by the following equation. Here, K _P represents the proportional gain and T _I represents the integral time constant.

Integrating section 705 integrates the angular velocity ω output from transfer function applying section 704 to calculate the phase target value φ _ref . As described above, the output phase target value φ _ref is fed back to the deviation calculation unit 703, and the PLL calculation is continued.

The frequency conversion unit 706 calculates the system frequency f=ω/2π from the angular velocity ω output from the transfer function application unit 704.

Note that the frequency calculation unit 20 is not limited to the above calculation mode, and may be configured to output the system frequency f measured by, for example, an FV (frequency/voltage) converter.

[Voltage calculation section]
The voltage calculation unit 22 calculates the rotational coordinate of the AC voltage using the following formula from the instantaneous values v _a , v _b , v _c of the voltage of each phase detected by the AC voltage measuring device 23 and the phase φ calculated by the frequency calculation unit 20. The voltages (d-axis voltage V _d , q-axis voltage V _q ) on each coordinate axis of the (dq-coordinate) system are calculated.

Further, the voltage calculation unit 22 calculates the AC voltage V _ac from the instantaneous values v _a , v _b , v _c of the voltages of each phase detected by the AC voltage measuring device 23 using the following equation.

Note that this AC voltage V _ac is used to generate a first drive signal S1, which will be described later. However, in order to ensure the stability of the system, the AC voltage V _ac may be set to a predetermined fixed value without using the voltage measurement value detected by the AC voltage measuring device 23 as described above.

[Current calculation section]
The current calculation unit 21 calculates the AC current using the following equation from the instantaneous values i _a , i _b , i _c of the current of each phase of the AC detected by the AC current measuring device 24 and the phase φ calculated by the frequency calculation unit 20. The currents (d-axis current I _d , q-axis current I _q ) in each coordinate axis of the rotating coordinate system are calculated.

[Received power target value calculation unit]
FIG. 4 is a diagram showing an example of a calculation mode in the received power target value calculation section shown in FIG. 2. The received power target value calculation unit 191 includes a subtracter 707, a proportional gain multiplier 708, a differential component application unit 709, an adder 710, and a limiter 711 as control blocks. The received power target value calculation unit 191 of the first drive signal calculation unit 19 calculates the received power target value P _ref1 by performing proportional differential (PD) calculation processing on the first deviation Δf ₁ . By adding a differential (D) component to charge/discharge amount control, transient stability in charge/discharge amount control can be improved.

More specifically, the subtractor 707 calculates the deviation (f _ref1 −f) between the system frequency f acquired by the frequency acquisition device 18 and a predetermined first frequency reference value f _ref1 . The output of the subtracter 707 becomes the first deviation Δf ₁ . A proportional gain multiplier 708 multiplies the first deviation Δf ₁ by a proportional gain K _p1 . In this embodiment, the proportional gain K _p1 is set to a negative value. Further, the differential component application unit 709 performs differential calculation processing on the output of the proportional gain multiplier 708. Adder 710 adds the output of proportional gain multiplier 708 and the output of differential component application section 709.

The output of adder 710 becomes a temporary received power target value. The temporary received power target value is input to the limiter 711. The limiter 711 limits the provisional received power target value between a predetermined upper limit value and a predetermined lower limit value, and outputs a received power target value P _ref1 . Limiting the received power target value P _ref1 to be outputted to a predetermined upper limit value or less by the limiter 711 is the same as limiting the first deviation Δf ₁ , which is the basis of PD calculation processing, to a predetermined frequency threshold value or less. It has technical significance.

That is, the first drive signal calculation unit 19 in this embodiment includes the limiter 711 in the received power target value calculation unit 191, so that the first deviation Δf ₁ is predetermined to be larger than the first frequency reference value f _ref1 . If the frequency is equal to or higher than the frequency threshold, the received power target value P _ref1 is calculated using the frequency threshold as the first deviation Δf ₁ .

For example, the upper limit value of the limiter 711 is set to the maximum power (1 PU) that the first power converter 14 can output to the first DC wiring section 71, and the lower limit value of the limiter 711 is set to the maximum power (1 PU) that the first power converter 14 can output to the first DC wiring section 71. The maximum power (-1 PU) that can be absorbed from the first DC wiring section 71 is set. Therefore, in the present embodiment, the predetermined frequency threshold is set to the upper limit of the frequency compensated by power storage equipment 11.

In this embodiment, the first frequency reference value f _ref1 is set to the rated frequency of the generator side AC wiring section 3A. Further, the frequency threshold value is set to a value equal to the second frequency reference value f _ref2 used in calculations in the second control device 17b. The details will be described later.

In the present embodiment, the received power target value calculation unit 191 calculates the received power target value P _ref1 by performing PD calculation processing. The received power target value P _ref1 may be calculated by performing only the process.

[First drive signal generation unit]
The first drive signal generation unit 192 receives input of AC currents I _d , I _q , AC voltages V _d , V _q , V _ac , phase φ, and received power target value P _ref1 of the generator side AC wiring unit 3A. . The first drive signal generation unit 192 calculates AC current target values I _{d_ref} and I _{q_ref} from the received power target value P _ref1 using the following formula.

Note that in this embodiment, the reactive power target value Q _ref1 is set to 0. That is, the q-axis current target value I _{q_ref} is zero. For this reason, 0 may be given to the first drive signal generation unit 192 in advance as the value of the q-axis current target value I _{q_ref} .

Further, the first drive signal generation section 192 obtains a first drive signal S1 such that the alternating currents I _d and I _q of the generator side AC wiring section 3A become the alternating current target values I _{d_ref} and I _{q_ref} , and generates the first drive signal S1. Output to power converter 14. Specifically, the first _{drive signal generation unit 192 calculates AC voltage target values V d_ref and V q_ref from} AC current target values I _{d_ref} and I _{q_ref} using the following equations. Here, K _d and K _q represent predetermined gains, and T _id and T _iq represent predetermined time constants.

The first drive signal generation unit 192 generates a target value V of each instantaneous voltage _{V a ,} V _b , V _c of the generator-side AC wiring unit 3A, which is a three-phase AC, from the AC voltage target values V d_ref and V _{q_ref} using the following formula. Calculate _{a_ref} , _{Vb_ref} , and _{Vc_ref} .

[Resistance equipment]
FIG. 5 is a block diagram showing a schematic configuration of a control system in the resistance equipment 12 shown in FIG. 1. FIG. 5 shows only the control blocks necessary for functioning as the second control device 17b of the control device 17.

Similarly to the power storage equipment 11, in the resistance equipment 12, a transformer 141 is also provided between the AC output end of the second power converter 16 and the generator side AC wiring section 3A. Thereby, the AC output voltage of the second power converter 16 can be suppressed lower than the AC voltage (system voltage) of the generator side AC wiring section 3A. Note that the transformer 141 may not be provided depending on the AC voltage of the generator side AC wiring section 3A. The resistor 15 is provided to consume surplus power of the generator-side AC wiring section 3A due to load fluctuations.

In this embodiment, second power converter 16 includes a rectifier circuit 28 and a chopper circuit 29. The rectifier circuit 28 and the chopper circuit 29 are connected via a second DC wiring section 72. The second power converter 16 is configured to perform AC-DC conversion between the generator-side AC wiring section 3A and the resistor 15.

For this purpose, the rectifier circuit 28 rectifies the AC power input from the generator side AC wiring section 3A to the second power converter 16 and converts it into DC. For example, the rectifier circuit 28 is constituted by a three-phase diode rectifier circuit in which two diodes are connected to each phase. The chopper circuit 29 includes a switching element that is controlled on/off based on the second drive signal S2, and steps down the DC power converted by the rectifier circuit 28 to power to be consumed by the resistor 15 and outputs the voltage. For example, the switching element is configured with a GTO thyristor or an IGBT, and the second drive signal S2 is configured as a signal that adjusts the conduction rate (roll-call angle) α of the GTO thyristor or IGBT.

The second power converter 16 to which the resistor 15 is connected only needs to adjust the amount of power supplied to the resistor 15 (power consumed by the resistor 15). Therefore, the configuration can be simpler than that of the first power converter 14, which requires adjusting not only the amount of power supplied to the power storage device 13 but also the amount of power supplied to the generator side AC wiring section 3A. .

The second control device 17b includes a second drive signal calculation section 27 and a frequency calculation section 20 as control blocks. Further, the resistance equipment 12 includes an AC voltage measuring device 23, a DC voltage measuring device 25, and a DC current measuring device 26 as a configuration for acquiring each value used for calculation by the second control device 17b. Note that the AC voltage measuring device 23, which has the same configuration as the power storage equipment 11, and the frequency calculation unit 20, which has the same control block as the first control device 17a, are provided separately for the power storage equipment 11 and the resistance equipment 12. However, it is also possible to have a common configuration for both.

Similarly to the power storage equipment 11, in the resistance equipment 12, the second control device 17b uses the system frequency f obtained by the frequency acquisition device 18 (consisting of the AC voltage measuring device 23 and the frequency calculation unit 20) to 2 drive signal S2 is generated. The second control device 17b also uses the DC voltage V _dc of the second DC wiring section 72 detected by the DC voltage measurement device 25 and the DC voltage V dc detected by the DC current measurement device 26 to generate the second drive signal S2. The DC current I _dc of the second DC wiring section 72 is obtained.

The second drive signal calculation unit 27 causes the resistor 15 to consume the signal according to a second deviation Δf ₂ between the system frequency f acquired by the frequency acquisition device 18 and a predetermined second frequency reference value f _ref2 . A power consumption target value calculation unit 271 that calculates a power consumption target value P _ref2 , and a second drive signal _S2 that generates a second drive signal S2 for performing power conversion in the second power converter 16 based on the power consumption target value P ref2. A drive signal generation section 272 is provided.

[Power consumption target value calculation unit]
FIG. 6 is a diagram showing an example of a calculation mode in the power consumption target value calculation section shown in FIG. 5. The power consumption target value calculation unit 271 includes a subtracter 712, a proportional gain multiplier 713, and a limiter 714 as control blocks. The power consumption target value calculation unit 271 of the second drive signal calculation unit 27 calculates the power consumption target value P _ref2 by performing proportional (P) calculation processing on the second deviation Δf ₂ .

More specifically, the subtracter 712 calculates the deviation (f _ref2 −f) between the system frequency f acquired by the frequency acquisition unit 18 and a predetermined second frequency reference value f _ref2 . The output of the subtracter 712 becomes the second deviation _Δf2 . The proportional gain multiplier 713 multiplies the second deviation Δf ₂ by the proportional gain K _p2 . In this embodiment, the proportional gain K _p2 is set to a negative value.

The output of the proportional gain multiplier 713 becomes a temporary power consumption target value. The temporary power consumption target value is input to the limiter 714. The limiter 714 limits the temporary power consumption target value between a predetermined upper limit value and 0, and outputs the power consumption target value P _ref2 . Limiting the output power consumption target value P _ref2 to 0 or more by the limiter 714 means that the power consumption target value P is limited based on the second deviation Δf ₂ when the system frequency f is equal to or higher than the second frequency reference value f _ref2 . It has the same technical significance as calculating _ref2 .

That is, the second drive signal calculation unit 27 in this embodiment includes the limiter 714 in the power consumption target value calculation unit 271, so that when the system frequency f is smaller than the second frequency reference value f _ref2 , the power consumption is reduced. When the power target value P _ref2 is set to 0 and the system frequency f is equal to or higher than the second frequency reference value f _ref2 , the power consumption target value P _ref2 corresponds to the value obtained by multiplying the second deviation Δf ₂ by the proportional gain K _p2 . is configured to calculate. This allows the resistor 15 to appropriately consume surplus power due to a sudden load reduction using a simple control mode.

For example, the upper limit value of the limiter 714 is set to the maximum power (1 PU) that the second power converter 16 can output to the second DC wiring section 72, and the lower limit value of the limiter 714 is set to zero.

In this embodiment, the second frequency reference value f _ref2 is set to a value larger than the first frequency reference value f _ref1 (that is, the rated frequency of the generator side AC wiring section 3A). For example, the second frequency reference value f _ref2 is set to 1.03 times the rated frequency (f _ref2 =1.03×f _ref1 ).

[Second drive signal generation section]
The second drive signal generation unit 272 generates the second drive signal S2 so that the power supplied to the resistor 15 reaches the power consumption target value P _ref2 . The power consumption target value P _ref2 calculated by the power consumption target value calculation unit 271 and the DC voltage V _dc and DC current I _dc in the second DC wiring unit 72 are input to the second drive signal generation unit 272. .

FIG. 7 is a diagram showing an example of a calculation mode in the second drive signal generation section shown in FIG. The second drive signal generation section 272 includes a divider 715, a subtracter 716, a PI calculation section 717, and a signal conversion section 718 as control blocks. The second drive signal generation unit 272 calculates the conduction rate α of the chopper circuit 29 based on the power consumption target value P _ref2 .

The divider 715 divides the power consumption target value P _ref2 by the DC voltage V _dc to calculate the current target value I _ref2 . The subtracter 716 outputs a value obtained by subtracting the DC current I _dc from the current target value I _ref2 . The PI calculation unit 717 performs a PI calculation using the output of the subtracter 716 as input. The transfer function G(s) of the PI calculation is the same as the above equation (3). The output of the PI calculation unit 717 becomes the conduction rate α. The signal conversion unit 718 generates the second drive signal S2 based on the conduction rate α calculated by the PI calculation unit 717. More specifically, the signal converter 718 generates the second drive signal S2 such that the voltage output period of the chopper circuit 29 follows the conduction rate α.

[Power stabilizing effect]
The following describes how the power system stabilizing device 10 according to the embodiment described above operates when the generator side AC wiring section 3A We show that it is possible to achieve power system stabilization in

FIG. 8 is a diagram showing a graph of frequency fluctuations in power adjusted by the power storage equipment in this embodiment. The horizontal axis in FIG. 8 shows the system frequency f, and the vertical axis shows the power P1 flowing into and out of the power storage equipment 11 (power storage equipment power). As shown in FIG. 8, when the grid frequency f increases from the first frequency reference value f _ref1 with respect to the first frequency reference value f _ref1 which is the rated frequency, the power storage unit 13 is charged with power (with a positive value). As a result, the power of the generator-side AC wiring section 3A is absorbed into the power storage equipment 11. Further, when the grid frequency f decreases below the first frequency reference value f _ref1 , power is discharged from the power storage device 13 (becomes a negative value), and power is released from the power storage equipment 11 to the generator side AC wiring section 3A. be done.

As described above, by providing the limiter 711 in the received power target value calculation unit 191, the first drive signal calculation unit 19 operates at a predetermined frequency where the first deviation Δf ₁ is larger than the first frequency reference value f _ref1 . If the frequency is equal to or higher than the threshold, the received power target value P _ref1 is calculated using the frequency threshold as the first deviation Δf ₁ . In this embodiment, the frequency threshold is set to the same value as the second frequency reference value f _ref2 . Therefore, even if the grid frequency f becomes equal to or higher than the second frequency reference value f _ref2 , the power charged in the electricity storage device 13 (power storage equipment power P1) is the value when the grid frequency f is the second frequency reference value f _ref2 . (upper limit). The same applies to the discharge side (the side where the electric power takes a negative value).

FIG. 9 is a diagram showing a graph of frequency fluctuations in power adjusted by the resistance equipment in this embodiment. The horizontal axis in FIG. 9 indicates the system frequency f, and the vertical axis indicates the power P2 flowing into and out of the resistance equipment 12 (resistance equipment power). As shown in FIG. 9, when the system frequency f increases more than the second frequency reference value f _ref2 based on the second frequency reference value f _ref2 which is larger than the first frequency reference value f _ref1 , power is consumed by the resistor 15. (becomes a positive value), the electric power of the generator side AC wiring section 3A is absorbed into the resistance equipment 12. On the other hand, when the system frequency f is less than or equal to the second frequency reference value f _ref2 , there is no fluctuation in the power of the resistor 15 (the resistance equipment power P2 becomes 0).

FIG. 10 is a diagram showing a graph of frequency fluctuations in power adjusted by the power system stabilizing device in this embodiment. The horizontal axis in FIG. 10 indicates the system frequency f, and the vertical axis indicates the power flowing into and out of the power system stabilizing device 10 (stabilizer power) Ps. As shown in FIG. 10, the power adjusted in the entire power system stabilizing device 10 is shown by a graph obtained by adding up the graphs in FIGS. 8 and 9 (Ps=P1+P2).

That is, when the system frequency f increases from the first frequency reference value f _ref1 with respect to the first frequency reference value f _ref1 which is the rated frequency, the electric power is charged to the power storage device 13, so that the generator side AC wiring section 3A of power is absorbed by the power system stabilizing device 10. Furthermore, when the grid frequency f increases and becomes equal to or higher than the second frequency reference value f _ref2 , the power storage device 13 does not absorb any more power, and the power is consumed by the resistor 15, so that the generator side AC wiring section 3A of power is absorbed by the power system stabilizing device 10.

According to the above configuration, voltage or frequency fluctuations due to load fluctuations that are assumed in advance, such as those that occur during steady operation (grid-connected operation or standalone operation), are handled via the first power converter 14. While being suppressed by charging and discharging the capacitor 13, fluctuations in voltage or frequency that occur when switching from grid-connected operation to standalone operation due to a sudden load reduction are suppressed by the resistor via the second power converter 16. It is absorbed by power consumption at 15. Therefore, it is no longer necessary to set the capacity of the power storage device 13 to a capacity that takes into account power fluctuations that occur during operation switching. Therefore, it is possible to suppress voltage or frequency fluctuations due to load fluctuations when switching from grid-connected operation to standalone operation using a relatively small-capacity power storage facility.

Moreover, since the first power converter 14 and the second power converter 16 are each independently controlled based on the system frequency f, there is no need to detect the open/close state of the circuit breaker 5 or to measure the load power. Furthermore, since the amount of power absorbed or released (received power target value and power consumption target value) is also determined according to fluctuations in the system frequency f, information such as the system configuration is not required. Therefore, there is no need to change the control mode depending on the driving situation. Therefore, it is possible to suppress fluctuations in voltage or frequency due to load fluctuations when switching from grid-connected operation to standalone operation without requiring switching of control modes depending on the operating situation.

[effect]
Below, the effects of applying the power system stabilizing device 10 in this embodiment to the power supply system 1 will be summarized.

(1) Prevention of overspeed trips that occur when the grid is disconnected Generally, in a factory equipped with in-house power generation equipment such as the generator 2 above, the load 6 is divided into an important load 61 and a general load 62, and the load 6 is divided into an important load 61 and a general load 62. If an accident such as an instantaneous voltage drop occurs, the generator-side AC wiring section 3A, including the important load 61 and the generator 2, is disconnected from external power by interrupting the predetermined circuit breaker 5 (disconnection point X). Separated from the system 4, the generator-side AC wiring section 3A continues to supply power only to the important load 61 by the generator 2 as an independent system. At this time, since the power generated by the generator 2 suddenly decreases, the rotational speed of the generator 2 increases, and an overspeed trip may occur in the generator 2, which has a slow ability to follow load fluctuations.

In contrast, by connecting the power system stabilizing device 10 according to the present embodiment to the generator side AC wiring section 3A, it is possible to react to the frequency increase caused by the load fluctuation due to grid disconnection, and to adjust the frequency according to the amount of frequency increase. Load absorption takes place. Thereby, an increase in the rotational speed of the generator 2 is suppressed, and an overspeed trip can be prevented from occurring.

(2) Ensuring stability of an independent system The power system stabilizing device 10 in this embodiment includes a power storage facility 11 and a resistance facility 12. During standalone operation by the generator 2, if the grid frequency f fluctuates due to expected load fluctuations in the important load 61, the power storage equipment 11 mainly absorbs the load fluctuations, thereby achieving stabilization control and increasing power output. Loss can be suppressed.

(3) Effects of frequency control Another method for preventing overspeed trips of the generator 2 due to load fluctuations that occur during grid disconnection is to measure the passing power at the disconnection point Therefore, it is possible to consider a method of lowering the power of the generator in advance for operation, or a method of consuming the power immediately before grid disconnection using resistance equipment, etc. However, these methods are only useful for preventing overspeed trips due to decoupling at decoupling point X.

In contrast, the power system stabilization device 10 in this embodiment uses only the system frequency f for power stabilization control. Therefore, it is possible to perform control regardless of the open/closed state of the circuit breaker 5 constituting the disconnection point X. Therefore, power stabilization control can be similarly performed, for example, even when a sudden load change occurs due to unexpected load shedding that occurs during self-sustaining operation. In addition, there is no need to measure the open/close state of the circuit breaker 5 constituting the parallel disconnection point X or the electric power passing through the parallel disconnection point X, and only the system frequency f measured by the power system stabilization device 10 itself is used. The power system stabilizing device 10 can be easily installed in the power supply system 1.

(4) Reduction of device cost The power system stabilizing device 10 in this embodiment uses relatively low-cost load equipment 12 to cope with the load reduction at the time of grid disconnection, and the power system stabilizer 10 according to the present embodiment uses a relatively low-cost load equipment 12 to cope with load fluctuations that are expected during self-sustaining operation. This is handled by the power storage equipment 11 that can handle both load increases and load decreases. Therefore, device cost can be reduced.

(5) Flexibility of equipment configuration As described above, the power system stabilizing device 10 according to the present embodiment is configured so that each equipment 11 and 12 performs stabilization control using only the system frequency f. It can be easily installed in conjunction with other applicable devices. Furthermore, when a plurality of generators 2 are connected to the power supply system 1, it is possible to flexibly respond to changes in the number of operating generators 2, such as stopping some of the generators 2 for maintenance or the like. can. In this way, the power system stabilizing device 10 according to the present embodiment can flexibly respond to changes in the equipment configuration, such as adding or adding equipment, changing the number of operating generators 2, etc.

[simulation result]
The simulation results for the power supply system 1 to which the power system stabilizing device 10 of the above embodiment is applied are shown below. FIG. 11 is a block diagram showing an example of a configuration for simulating a power supply system. In FIG. 11, the same components as in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Furthermore, the condition for the generator 2 to trip due to overspeed is when the frequency exceeds 64 Hz.

In this simulation, using each parameter shown in FIG. A simulation (Example 2) was performed in which a load change occurs in a state where the AC wiring section 3A is disconnected (during self-sustaining operation).

[Example 1]
12 to 15 are graphs showing simulation results in Example 1. FIG. 12 is a graph showing a temporal change in the system frequency f in the generator-side AC wiring section 3A, FIG. 13 is a graph showing a temporal change in voltage in the generator-side AC wiring section 3A, and FIG. is a graph showing temporal changes in active power output by the generator 2. Both graphs compare the transient response of load fluctuations when switching from grid-connected operation to standalone operation with a comparative example in which the power system stabilizer 10 is not connected (no stabilization control is performed). It shows. In each figure, the graph for Example 1 is shown by a solid line, and the graph for Comparative Example is shown by a broken line. FIG. 15 is a graph in which a graph of active power output by the power system stabilizing device is superimposed on the graph of Example 1 shown in FIG. 14.

As shown in FIG. 12, about 1 second after the start of the simulation, the generator side AC wiring section 3A is disconnected at the disconnection point X, and the frequency increases due to the accompanying load fluctuation. In the comparative example in which the power system stabilizing device 10 is not applied, the system frequency f exceeds the upper frequency limit (64 Hz), and the generator 2 trips. On the other hand, in Example 1 to which the power system stabilizing device 10 is applied, the system frequency f is suppressed to 63 Hz. From this, it can be understood that tripping of the generator 2 due to overspeed can be prevented.

Further, as shown in FIG. 13, the voltage at the generator-side AC wiring section 3A also fluctuates (increases) due to the sudden load reduction accompanying the disconnection of the generator-side AC wiring section 3A. In Example 1 in which the power system stabilizing device 10 is applied, the voltage fluctuation width is suppressed and converges earlier than in the comparative example in which the power system stabilizing device 10 is not applied. Although the power system stabilizing device 10 of the present invention focuses on suppressing frequency fluctuations, it can be understood that it is equally effective against voltage fluctuations.

Further, as shown in FIG. 14, the active power of the generator 2 rapidly decreases as the generator side AC wiring section 3A is disconnected. In FIG. 14, the fluctuation range of load fluctuation (the fluctuation range of active power) is approximately 3500 kW. In the comparative example in which the power system stabilizing device 10 is not applied, the active power of the generator 2 rapidly decreases when the system is disconnected.

On the other hand, also in the first embodiment in which the power system stabilizing device 10 is applied, the load fluctuation is once reduced. However, due to the accompanying frequency fluctuation, as shown in FIG. 15, the power system stabilization device 10 executes power stabilization processing and operates to absorb the active power corresponding to the load fluctuation. As a result, the active power of the generator 2 has recovered to about the load power before grid disconnection. Therefore, an increase in the system frequency f is suppressed. Thereafter, the system frequency f is reduced by governor control in the generator 2. Accordingly, the power absorbed by the power system stabilizing device 10 is also reduced.

As shown in FIG. 15, when load fluctuation occurs at the time of grid disconnection, the power storage equipment 11 first operates to absorb the active power output by the generator 2. Thereafter, when the active power absorbed by power storage equipment 11 reaches the rated value (1 MW), resistance equipment 12 operates to absorb active power output from generator 2. The active power absorbed by the power system stabilizing device 10 is the sum of the active power absorbed by the power storage equipment 11 and the active power absorbed by the resistance equipment 12.

In this way, the power system stabilizing device 10 operates to follow fluctuations in the active power of the generator 2 and absorb the active power. Therefore, the present simulation results show that the power system stabilizing device 10 can suppress voltage or frequency fluctuations due to load fluctuations when switching from grid-connected operation to standalone operation.

[Example 2]
16 to 19 are graphs showing simulation results in Example 2. FIG. 16 is a graph showing a temporal change in the system frequency f in the generator side AC wiring section 3A, FIG. 17 is a graph showing a temporal change in voltage in the generator side AC wiring section 3A, and FIG. is a graph showing temporal changes in active power output by the generator 2. Both graphs show the transient response of load fluctuation during self-sustaining operation in comparison with a comparative example in which the power system stabilizing device 10 is not connected (no stabilization control is performed). In each figure, the graph for Example 2 is shown by a solid line, and the graph for Comparative Example is shown by a broken line. FIG. 19 is a graph in which a graph of active power absorbed or released by the power system stabilizing device is superimposed on the graph of Example 2 shown in FIG. 18.

In this simulation, it is assumed that a load variation of 750 kW (that is, a load variation less than the rated value (1 MW) of the active power of the power storage equipment 11) occurs. As shown in FIG. 16, load fluctuation occurs about 1 second after the start of the simulation, and the grid frequency f decreases. In the second embodiment in which the power system stabilizing device 10 is applied, the range of frequency fluctuation is suppressed compared to the comparative example in which the power system stabilizing device 10 is not applied. Also, about 10 seconds after the start of the simulation, a load change occurs and the grid frequency f increases. In this case as well, in the second embodiment in which the power system stabilizing device 10 is applied, the range of frequency fluctuation is suppressed compared to the comparative example in which the power system stabilizing device 10 is not applied.

Further, as shown in FIG. 17, in the second embodiment in which the power system stabilizing device 10 is applied, the voltage at the generator side AC wiring section 3A is also applied when load fluctuation occurs. The range of voltage fluctuation is suppressed compared to the comparative example that does not. In addition, as shown in FIG. 18, when a load fluctuation occurs, the active power of the generator 2 is also reduced in the second embodiment in which the power system stabilizing device 10 is applied, compared to the case in which the power system stabilizing device 10 is not applied. The fluctuation range of active power is suppressed compared to the example.

At this time, as shown in FIG. 19, in the power system stabilizing device 10, the resistance equipment 12 does not absorb power, and only the power storage equipment 11 absorbs power (charging the power storage device 13) and discharging power (charging the power storage device 13). discharge). In FIG. 19, the graph of active power in power system stabilization device 10 matches the graph of active power in power storage equipment 11. As described above, according to FIG. 19, it can be understood that when a load fluctuation that is assumed in advance such that the system frequency f does not exceed the rated frequency occurs, power adjustment is performed only by the power storage equipment 11. Therefore, the present simulation results show that the power system stabilizing device 10 can suppress the load variation in the power supply system 1 while suppressing power loss when a predetermined load variation occurs. .

[Other embodiments]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various improvements, changes, and modifications can be made without departing from the spirit thereof.

For example, in the above embodiment, the second power converter 16 of the resistance equipment 12 includes a rectifier circuit and a chopper circuit, and performs AC-DC conversion between the generator side AC wiring section 3A and the resistor 15. Although the embodiment is illustrated, the configuration is not limited to this as long as the configuration is for absorbing the power of the generator side AC wiring section 3A and consuming it in the resistor 15.

For example, the second power converter 16 may be configured to perform AC-AC conversion between the generator-side AC wiring section 3A and the resistor 15. In this case, for example, the second power converter 16 may be an AC converter circuit such as an AC power adjustment circuit, a cycloconverter circuit, or a matrix converter circuit.

FIG. 20 is a block diagram showing a schematic configuration of a control system in another example of the resistance equipment shown in FIG. 1. Components similar to those in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. The second power converter 16B in this modification is configured to connect the generator side AC wiring section 3A and the resistor 15 with AC connection via the transformer 141. An AC wiring section closer to the second power converter 16B than the transformer 141 is referred to as a fourth AC wiring section 34.

The second power converter 16B includes an AC converter circuit 160 including a switching element such as a thyristor connected to each line of the fourth AC wiring section 34. The second power converter 16B includes a power converter AC voltage measuring device 161 that measures an AC voltage _VAC and an AC current _IAC input to the second power converter 16B (that is, of the fourth AC wiring section 34); A power converter AC current measuring device 162 is provided.

The second drive signal calculation unit 27B of the second control device 17b also includes a power consumption target value calculation unit 271 and a second drive signal generation unit 272B. The power consumption target value calculation unit 271 calculates the power consumption target value P _ref2 using the same calculation mode as in the above embodiment (FIG. 6). The power consumption target value P _ref2 and the AC voltage V _AC and AC current I _AC of the fourth AC wiring unit 34 are input to the second drive signal generation unit 272B.

The second drive signal generation unit 272B in this modification calculates the control delay angle α' of the AC converter circuit 160 based on the power consumption target value P _ref2 . However, the current conductivity α of the chopper circuit 29 and the control delay angle α' of the AC converter circuit 160 in the above embodiment are also values that determine the output period (duty ratio) of the voltage applied to the resistor 15. There is no.

Therefore, the second drive signal generation section 272B in this modification can also have the same configuration as the second drive signal generation section 272 (FIG. 7) in the above embodiment. However, the divider 715 receives an AC voltage V _AC instead of the DC voltage V _dc , and the subtracter 716 receives an AC current I _AC instead of the DC current I _dc . The output of the PI calculation unit 717 becomes the control delay angle α'. The signal converter 718 generates a second drive signal S2 such that the voltage output period of the AC converter circuit 160 follows the control delay angle α'. In this way, the second power converters 16, 16B for causing the resistor 15 to consume power can employ either an AC-DC conversion method or an AC-AC conversion method.

Further, in the above embodiment, a case has been described in which the AC wiring section 3 to which the power supply system is applied is a three-phase system, but the present invention is not limited to this. For example, even if the AC wiring section 3 is a single-phase two-wire system or a single-phase three-wire system, it is possible to construct a similar power supply system except that the various calculation methods differ depending on the system system. .

Further, in the above embodiment, an example in which one generator 2 is connected to one AC wiring section 3 (first AC wiring section 31) has been described, but two or more power generators are connected to one AC wiring section 3. Machine 2 may also be connected. Furthermore, when two or more generators 2 are connected to one AC wiring section 3, different types of generators may be connected. For example, a gas turbine generator and a gas engine generator may be connected to one AC wiring section 3.

Further, in the above embodiment, an example in which one power system stabilizing device 10 is connected to one AC wiring section 3 has been described, but two or more power system stabilizing devices 10 are connected to one AC wiring section 3. may be connected.

The present invention uses relatively small-capacity power storage equipment to eliminate the need to switch control modes depending on the operating situation, and to reduce the voltage or frequency associated with load fluctuations when switching from grid-connected operation to standalone operation. This is useful for suppressing fluctuations in

1 Power supply system 2 Generator 3A Generator side AC wiring section (AC wiring section)
4 External power system (another power system)
5 Breaker 10 Power system stabilization device 13 Condenser 14 First power converter 15 Resistor 16 Second power converter 17, 17a, 17b Control device 18 Frequency acquisition unit 19 First drive signal calculation unit 27 Second drive signal calculation Section 271 Power consumption target value calculation section 272 Second drive signal generation section

Claims (7)

A generator, an AC wiring section to which the generator is connected, a circuit breaker provided at a predetermined disconnection point between the AC wiring section and a power system different from the generator, and the AC wiring section. A power system stabilizing device for stabilizing the voltage or frequency in the AC wiring section in a power supply system comprising a power load connected to the
A power storage facility including a power storage device and a first power converter connected between the AC wiring section and the power storage device;
Resistance equipment including a resistor and a second power converter connected between the AC wiring section and the resistor;
a control device that controls the first power converter and the second power converter;
a frequency acquisition device that acquires the system frequency in the AC wiring section,
The control device includes:
A target value of received power to be charged and discharged to the electricity storage device is calculated according to a first deviation between the system frequency and a predetermined first frequency reference value, and the first power conversion is performed based on the target value of received power. a first drive signal calculation unit that generates a first drive signal for performing power conversion in the device;
A power consumption target value to be consumed in the resistor is calculated according to a second deviation between the system frequency and a predetermined second frequency reference value, and a second power converter is calculated based on the power consumption target value. a second drive signal calculation unit that generates a second drive signal for performing power conversion;
The second frequency reference value is set to a value larger than the first frequency reference value,
The first drive signal calculation unit calculates the received power using the frequency threshold as the first deviation when the first deviation is equal to or higher than a predetermined frequency threshold that is larger than the first frequency reference value. configured to calculate a target value ;
The second drive signal calculation unit includes a power consumption target value calculation unit that calculates the power consumption target value based on a value obtained by multiplying the second deviation by a predetermined proportional gain, and a power consumption target value calculation unit that calculates the power consumption target value based on the power consumption target value. a second drive signal generation section that generates a second drive signal;
The power consumption target value calculation unit sets the power consumption target value to 0 when the system frequency is smaller than the second frequency reference value, and sets the power consumption target value to 0 when the system frequency is equal to or higher than the second frequency reference value. , an electric power system stabilizing device, wherein the power consumption target value is set to a value obtained by multiplying the second deviation by the predetermined proportional gain. The power system according to claim 1, wherein the frequency threshold is set to an upper limit value of a frequency compensated by the power storage equipment, and the second frequency reference value is set to a value equal to the frequency threshold. Stabilizer. The power system stabilization device according to claim 1 or 2, wherein the first drive signal calculation unit calculates the received power target value by performing proportional differential calculation processing on the first deviation. The power system stabilizing device according to any one of claims 1 to 3, wherein the electricity storage device is a secondary battery. The power system stabilizing device according to any one of claims 1 to 3, wherein the electricity storage device is an electric double layer capacitor. The second power converter includes a rectifier circuit and a chopper circuit, and is configured to perform AC-DC conversion between the AC wiring section and the resistor. Power system stabilizer. The power according to any one of claims 1 to 5, wherein the second power converter includes an AC power adjustment circuit and is configured to perform AC-AC conversion between the AC wiring section and the resistor. Grid stabilizer.

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