JP6032365B2 - Power stabilization system and control device - Google Patents

Description

  The present invention relates to a power stabilization system and a control device.

  In recent years, the interconnection of a distributed power source such as a wind power generator or a solar battery using natural energy such as wind power or solar power to a commercial power system is increasing. However, since the output of a distributed power source using natural energy fluctuates from moment to moment depending on natural conditions such as wind speed and weather, fluctuations in the grid frequency occur especially in weak power systems such as remote areas and remote islands. It may be a problem above. Further, even in a strong power system, there is a concern that the system frequency may fluctuate greatly due to the output fluctuation of the distributed power source as the amount of introduced natural energy increases.

  For fluctuations in the system frequency due to natural energy as described above, for example, an increase in frequency adjustment capacity by governor-free control can be suppressed by adding a rotating machine and increasing the frequency adjustment capacity. However, in this case, the power generation efficiency is reduced by the amount of operation of the generator at an output lower than the rated output for frequency adjustment by the governor-free control. In addition, the reduction effect of carbon dioxide emissions due to the introduction of natural energy is offset by that amount.

  Thus, for example, Patent Document 1 discloses a control device that compensates for fluctuations in power generation output by absorbing or discharging power using a power storage system such as a secondary battery. For example, if the power generation output of a distributed power source (such as a wind power generator or a solar cell) increases, it can be connected to the power grid by reducing the power released by the power storage system or increasing the power absorption. Frequency fluctuations at the system point can be suppressed. On the other hand, when the power generation output of the distributed power supply decreases, the frequency fluctuation at the connection point to the power system is suppressed by decreasing the absorption of power by the power storage system or increasing the discharge of power. Can do.

Japanese Patent Laid-Open No. 11-262186

  In the control device of the power storage system of Patent Document 1, the output power of the wind power generator is detected using a current sensor and a voltage sensor, and the compensation amount is obtained according to the variation. However, when the compensation amount is obtained in accordance with the fluctuation of the power flow by one distributed power source in this way, the system frequency may deviate from the target range. For example, even if the power flow detected by the control device changes due to the output fluctuation of a certain distributed power supply, the system frequency may hardly change depending on the output fluctuation of the distributed power supply at another location. In this case, when the compensation amount is obtained according to the fluctuation of the power flow detected by the control device, actually unnecessary compensation is performed, and the system frequency may deviate from the target range.

  The main present invention that solves the above-described problems is a power stabilization system that suppresses fluctuations in the active power of an AC power system, and stores power and absorbs or releases power with the AC power system. A storage device; a power converter that mutually converts power absorbed or released between the AC power system and the power storage device; and the power converter is controlled in accordance with an active power fluctuation of the AC power system A control device that detects a system frequency of the AC power system as a frequency measurement value, and a power flow detection that detects a power flow of the AC power system as a power flow measurement value. A frequency control unit that obtains, as a frequency compensation amount, an amount of power that compensates for fluctuations in the system frequency based on the frequency measurement value, the power flow measurement value, and the frequency compensation A power flow control unit for obtaining a power flow compensation amount as a power flow compensation amount based on the power flow, and a power converter for controlling the power converter according to the frequency compensation amount and the power flow compensation amount And a control unit.

  Other features of the present invention will become apparent from the accompanying drawings and the description of this specification.

  ADVANTAGE OF THE INVENTION According to this invention, the unnecessary compensation control according to the fluctuation | variation of electric power flow can be suppressed, and the deviation from the target range of a system frequency can be prevented.

It is a block diagram which shows the structure of the electric power stabilization system provided with the control apparatus in the 1st thru | or 3rd embodiment of this invention. It is a block diagram which shows an example of the specific connection state of an alternating current power system and a power stabilization system. It is a block diagram which shows the outline of a structure of the control apparatus in the 1st thru | or 3rd Embodiment of this invention. It is a block diagram which shows the structure of the control apparatus in 1st Embodiment of this invention. It is a block diagram which shows the structure of the control apparatus in which a frequency control part and a power flow control part each obtain | require a frequency compensation amount and a power flow compensation amount independently. It is a schematic diagram which shows an example of the suppression operation of a frequency fluctuation by the control apparatus shown in FIG. It is a schematic diagram which shows an example of the suppression operation of a frequency fluctuation by the control apparatus shown in FIG. It is a schematic diagram which shows an example of the suppression operation of the frequency variation by the control apparatus in 1st Embodiment of this invention. It is a block diagram which shows the structure of the control apparatus in 2nd Embodiment of this invention. It is a block diagram which shows the structure of the control apparatus in 3rd Embodiment of this invention. It is a block diagram which shows the structure of the upper / lower limit setting part in 3rd Embodiment of this invention. It is a schematic diagram which shows an example of the suppression operation of the frequency variation by the control apparatus in 3rd Embodiment of this invention. It is a schematic diagram which shows an example of the suppression operation of the frequency variation by the control apparatus in 3rd Embodiment of this invention.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings.

=== Configuration of Power Stabilization System ===
Hereinafter, with reference to FIGS. 1 to 3, a configuration of a power stabilization system including a control device in first to third embodiments to be described later will be described. In FIG. 1 to FIG. 3, the power line is indicated by a solid line and the signal line is indicated by a broken line.

  The power stabilization system 1 shown in FIG. 1 is a system for suppressing fluctuations in active power of the AC power system 9, particularly fluctuations in the system frequency. In the AC power system 9, as a distributed power source using natural energy, for example, a solar cell module 50 installed in the solar power plant 5 and a wind power generator 60 installed in the wind power plant 6 are respectively power converters. Interconnected via 51 and 61. In addition, a generator (not shown) of another power plant 7 is also connected to the AC power system 9. Here, the other power plants 7 may include thermal power plants, nuclear power plants, hydroelectric power plants and the like that are not accompanied by output fluctuations due to natural conditions such as wind speed and weather. Further, a consumer load 8 is connected to the AC power system 9.

  The power stabilization system 1 includes a control device 10, an instrument transformer 15, a power storage device 20, and a power converter 21.

  The power storage device 20 is linked to the AC power system 9 via a power converter 21. Here, the power storage device 20 has the capability of storing power and absorbing or discharging power with the AC power system 9 regardless of the type, such as a flywheel generator motor or a secondary battery. Just do it. In addition, the power converter 21 has a function of mutually converting power absorbed / released between the AC power system 9 and the power storage device 20.

  The control device 10 is connected to the AC power system 9 via an instrument transformer 15. In addition, system information indicating the state of the AC power system 9 is input to the control device 10. And the control apparatus 10 suppresses the active power fluctuation | variation (fluctuation | variation of a system frequency) of the alternating current power system 9 according to the state of the alternating current power system 9 obtained by the instrument transformer 15 or obtained as system information. The power converter 21 is controlled accordingly.

  FIG. 2 shows an example of specific connection states of the AC power system 9 and the power stabilization system 1.

  In FIG. 2, solar cell modules 50a and 50b are shown as an example of a distributed power source using natural energy. The solar cell module 50a is connected to the AC power system 9 via a power converter 51a and a (for power) transformer 52a, and the solar cell module 50b is connected to the AC power system via a power converter 51b and a transformer 52b. 9 linked. Further, as an example of other generators of the power plant 7, diesel generator groups 70a and 70b including a plurality of small-capacity diesel generators are shown. The diesel generator group 70a is linked to the AC power system 9 via the transformer 72a, and the diesel generator group 70b is linked to the AC power system 9 via the transformer 72b. Further, the customer load 8a is connected to the AC power system 9 via the transformer 82a, and the customer load 8b is connected to the AC power system 9 via the transformer 82b.

  In FIG. 2, a storage battery is shown as an example of the power storage device 20, and the storage battery 20 is linked to the AC power system 9 via a power converter 21 and a transformer 22. Further, in order to detect the power flow PL1 of the node close to the solar cell module 50a, the diesel generator group 70a, and the consumer load 8a, the control device 10 detects voltage / current data of each node or Power flow data is input. Note that voltage / current data and power flow data for detecting the power flow PL2 of the node close to the solar cell module 50b, the diesel generator group 70b, and the customer load 8b are not input to the control device 10.

  FIG. 3 shows an outline of the configuration of the control device 10. The control device 10 shown in FIG. 3 includes a frequency detection unit 111, a frequency control unit 113, a power flow detection unit 121, a power flow control unit 123, a command value generation unit 134, and a power converter control unit 135. It is configured.

  The frequency detection unit 111 is connected to the AC power system 9 via the instrument transformer 15. And the frequency detection part 111 detects the system frequency of the alternating current power system 9 as the frequency measurement value f1 based on the voltage waveform of the alternating current power system 9 obtained by the transformer 15 for instruments. Further, the frequency controller 113 receives a frequency deviation Δf between the frequency target value f0 and the frequency measurement value f1. The frequency control unit 113 outputs a frequency compensation amount Wf corresponding to the amount of power that compensates for fluctuations in the system frequency.

  System information of the AC power system 9 is input to the power flow detection unit 121. The power flow detection unit 121 detects the power flow of the AC power system 9 as a power flow measurement value PL1 based on the input system information. For example, voltage / current data of each node is input as system information, and a voltage value, a phase angle, active power, reactive power, and the like are obtained from these data. Note that the power flow detection unit 121 may directly input power flow data of each node. Further, the power flow control unit 123 is input with the power flow measurement value PL1 or the power flow deviation Δp between the power flow target value PL0 and the power flow measurement value PL1. Furthermore, the frequency compensation amount Wf is also input to the power flow control unit 123. The power flow control unit 123 outputs a power flow compensation amount Wp corresponding to the power amount that compensates for fluctuations in the power flow.

  The command value generator 134 receives the frequency compensation amount Wf and the power flow compensation amount Wp. Further, the control command value W 0 is input from the command value generation unit 134 to the power converter control unit 135. And from the power converter control part 135, the control signal C0 of the power converter 21 is output.

<First Embodiment>
=== Configuration of Control Device ===
Hereinafter, the configuration of the control device according to the first embodiment will be described with reference to FIG.

のように、一次遅れ要素で表すことができる。ここで、ｓはラプラス変換子であり、Ｔ₁は時定数である。なお、制御指令値Ｗ０には、加算器９３において電力潮流ＰＬ１の変動分が外乱ｄ１として加算され、その加算結果が制御対象９１に入力されている。In FIG. 4, 91 indicates a control object (plant) having the control command value W0 as the manipulated variable and the power flow PL1 as the controlled variable. If this transfer function is P1,

As shown in FIG. Here, s is a Laplace transformer, and T ₁ is a time constant. The control command value W0 is added with the fluctuation of the power flow PL1 as the disturbance d1 in the adder 93, and the addition result is input to the control object 91.

のように、積分要素で表すことができる。ここで、Ｍは発電機の単位慣性定数である。なお、電力潮流ＰＬ１には、加算器９４において電力潮流ＰＬ２の変動分が外乱ｄ２として加算され、その加算結果が制御対象９２に入力されている。In FIG. 4, reference numeral 92 denotes a control target having the power flow PL1 as an operation amount and the system frequency f1 as a control amount. If this transfer function is P2,

As shown in FIG. Here, M is a unit inertia constant of the generator. The power flow PL1 is added with the fluctuation of the power flow PL2 as disturbance d2 in the adder 94, and the addition result is input to the control object 92.

  The control device 10a shown in FIG. 4 includes a frequency detection unit 111, an adder 112, a frequency control unit 113, a power flow detection unit 121, a power flow control unit 123, and a command value generation unit 134. Yes. In FIG. 4, the command value generation unit 134 shown in FIG. 3 is configured as an adder, and the power converter control unit 135 is omitted.

  The adder 112 receives the frequency target value f0 and the frequency measurement value f1 detected by the frequency detection unit 111. The frequency deviation Δf (= f0−f1) is input from the adder 112 to the frequency control unit 113. The frequency controller 113 outputs a frequency compensation amount Wf.

のように、制御対象９１の伝達関数Ｐ１と同様に、一次遅れ要素で表される。The power flow control unit 123 includes a power flow model unit 1231, an adder 1232, and a first proportional gain 1233. Here, the value of the first proportional gain 1233 is L1. The power flow model unit 1231 models a change in the power flow PL1 due to the frequency compensation amount Wf, and corresponds to a nominal plant for the control target 91. Therefore, if this transfer function is P1 _n ,

Like this, like the transfer function P1 of the control object 91, it is represented by a first-order lag element.

  The power flow model unit 1231 receives the frequency compensation amount Wf, and the power flow model unit 1231 outputs the power flow estimated value PLe. The adder 1232 is supplied with the power flow estimated value PLe and the power flow measurement value PL1 detected by the power flow detection unit 121. Further, the difference Δp ′ (= PLe−PL1) between the power flow estimated value PLe and the power flow measured value PL1 is input from the adder 1232 to the first proportional gain 1233. Then, from the first proportional gain 1233, the power flow compensation amount Wp is output.

  The command value generator (adder) 134 receives the frequency compensation amount Wf and the power flow compensation amount Wp. The command value generation unit 134 outputs a control command value W0 (= Wf + Wp).

=== Operation of Control Device ===
Next, the operation of the control device in this embodiment will be described.

と表される。The frequency control unit 113 obtains the frequency compensation amount Wf based on the frequency deviation Δf. For example, the frequency control unit 113 can be configured as a PI (Proportional-Integral) controller. Further, for example, the frequency control unit 113 extracts a system frequency fluctuation component from the frequency deviation Δf by a high-pass filter or the like, multiplies the extracted fluctuation component by a proportional gain, and performs phase compensation (phase advance compensation or phase delay compensation). For example, the frequency compensation amount Wf may be obtained. When the transfer function of the frequency control unit 113 is K, the frequency compensation amount Wf output from the frequency control unit 113 is

It is expressed.

と表される。The power flow control unit 123 obtains a power flow compensation amount Wp based on the power flow measurement value PL1 and the frequency compensation amount Wf. Specifically, first, based on the frequency compensation amount Wf, the power flow model unit 1231 estimates a change in power flow due to control of the power converter according to the frequency compensation amount Wf as the power flow estimated value PLe. Then, the power flow compensation amount Wp is obtained by multiplying the difference Δp ′ between the power flow estimated value PLe and the power flow measurement value PL1 by the first proportional gain L1. Therefore, the power flow compensation amount Wp output from the power flow control unit 123 is

It is expressed.

  The command value generator 134 adds the frequency compensation amount Wf and the power flow compensation amount Wp to obtain the control command value W0. And the power converter control part 135 shown in FIG. 3 outputs the control signal C0 according to the control command value W0, and controls the power conversion operation | movement of the power converter 21. FIG.

=== Specific Example of Frequency Variation Suppression Operation ===
Hereinafter, specific examples of the frequency fluctuation suppressing operation performed by the control device according to this embodiment will be described with reference to FIGS. 5 to 8 as appropriate.

  First, as a comparative example, a configuration of a control device in which the frequency compensation amount Wf is not input to the power flow control unit, and the frequency control unit and the power flow control unit independently obtain the frequency compensation amount and the power flow compensation amount as shown in FIG. Shown in The control device 10d shown in FIG. 5 includes a power flow control unit 153 instead of the power flow control unit 123, and further includes an adder 122 with respect to the control device 10a of the present embodiment. . The power flow controller 153 includes a high-pass filter 1531 and a fourth proportional gain 1532. Here, the value of the fourth proportional gain 1532 is L4.

と表され、電力潮流制御部１５３から出力される電力潮流補償量Ｗｐは、

と表される。The power flow target value PL0 and the power flow measurement value PL1 are input to the adder 122, and the power flow deviation Δp (= PL0−PL1) is output from the adder 122. Then, the power flow control unit 153 extracts the power flow fluctuation component Δp ″ from the power flow deviation Δp by the high-pass filter 1531 and multiplies the extracted fluctuation component Δp ″ by the fourth proportional gain L4 to A compensation amount Wp is obtained. If the transfer function of the high-pass filter 1531 is H,

The power flow compensation amount Wp output from the power flow control unit 153 is

It is expressed.

  Here, FIG. 6 shows an example of the operation of suppressing the frequency fluctuation by the control device 10d shown in FIG. In FIG. 6, as an example, in the AC power system 9 shown in FIG. 2, 6% of the total capacity of the operating generators of the diesel generator groups 70 a and 70 b in the period from time t1 to t2 is 6%. Is shown when the solar cell module 50a causes the output fluctuation (see the photovoltaic power generation output 1). In this case, when the power converter 21 is controlled in accordance with the control command value W0 output from the control device 10d shown in FIG. 5, for example, as shown in FIG. 6, charging / discharging (absorption / release of power) by the storage battery 20 is performed. ) And the frequency variation can be kept within the target range.

  On the other hand, FIG. 7 shows a case where an output fluctuation having a polarity opposite to the output fluctuation of the solar cell module 50a occurs in the solar cell module 50b (see the photovoltaic power generation output 2). In this case, if there is no compensation control by the control device 10d, output fluctuations of the solar cell modules 50a and 50b cancel each other, and the system frequency does not change.

However, the control device 10d calculates the power flow compensation amount Wp based on the power flow measurement value PL1 of the node close to the solar cell module 50a, and thereby charges the storage battery 20 in order to suppress the output fluctuation of the solar cell module 50a. To reduce the system frequency. Thereafter, the control device 10d obtains the frequency compensation amount Wf based on the reduced frequency measurement value f1, thereby causing the storage battery 20 to perform a discharging operation to increase the system frequency, but the system frequency temporarily falls within the target range. In the control device 10a of the present embodiment that deviates, the power flow control unit 123 estimates the power flow estimated value PLe based on the frequency compensation amount Wf input from the frequency control unit 113, and the power flow estimated value PLe The power flow compensation amount Wp is obtained by multiplying the difference Δp ′ from the power flow measurement value PL1 by the first proportional gain L1. Then, the power converter 21 is controlled according to the control command value W0 obtained by adding the frequency compensation amount Wf and the power flow compensation amount Wp. As a result, for example, as shown in FIG. 8, even in the case where output fluctuations with opposite polarities canceling each other occur in the solar cell modules 50a and 50b, unnecessary compensation control is suppressed, and the frequency fluctuation is kept within the target range. Can fit.

Second Embodiment
=== Configuration of Control Device ===
Hereinafter, the configuration of the control device according to the second embodiment will be described with reference to FIG. 9.

のように、制御対象９２の伝達関数Ｐ２と同様に、積分要素で表される。The control device 10b shown in FIG. 9 further includes a disturbance feedback unit 143 and an adder 144 with respect to the control device 10a of the first embodiment. The disturbance feedback unit 143 includes system frequency model units 1431 and 1432, an adder 1433, and a second proportional gain 1434. Here, the value of the second proportional gain 1434 is L2. System frequency model units 1431 and 1432 model changes in system frequency f1 due to frequency compensation amount Wf, and correspond to nominal plants for control objects 91 and 92, respectively. Therefore, the transfer function of the system frequency model unit 1431 is the same as the transfer function P1 _n of the power flow model unit 1231, and the transfer function of the system frequency model unit 1432 is P2 _n .

Like the transfer function P2 of the control object 92, it is expressed by an integral element.

  System frequency model units 1431 and 1432 are connected in series, frequency compensation amount Wf is input to system frequency model unit 1431, and frequency estimation value fe is output from system frequency model unit 1432. The adder 1433 receives the frequency estimation value fe and the frequency measurement value f1. Further, the difference Δf ′ (= fe−f1) between the frequency estimation value fe and the frequency measurement value f1 is input from the adder 1433 to the second proportional gain 1434. A frequency disturbance compensation amount Wd is output from the second proportional gain 1434.

  The adder 144 receives the frequency compensation amount Wf and the frequency disturbance compensation amount Wd. The adder 134 receives the output value of the adder 144 and the power flow compensation amount Wp. The adder 134 outputs a control command value W0 (= Wf + Wp + Wd). In the present embodiment, the adders 134 and 144 correspond to a command value generation unit.

=== Operation of Control Device ===
Next, the operation of the control device in this embodiment will be described.

と表される。The disturbance feedback unit 143 obtains the frequency disturbance compensation amount Wd based on the frequency measurement value f1 and the frequency compensation amount Wf. Specifically, first, system frequency model units 1431 and 1432 estimate, as frequency estimated value fe, a change in system frequency by control of the power converter according to frequency compensation amount Wf, based on frequency compensation amount Wf. . Then, the frequency disturbance compensation amount Wd is obtained by multiplying the difference Δf ′ between the frequency estimation value fe and the frequency measurement value f1 by the second proportional gain L2. Therefore, the frequency disturbance compensation amount Wd output from the disturbance feedback unit 143 is

It is expressed.

  The command value generation unit (adders 134 and 144) obtains the control command value W0 by adding the frequency compensation amount Wf, the power flow compensation amount Wp, and the frequency disturbance compensation amount Wd. The power converter control unit 135 shown in FIG. 3 outputs a control signal C0 according to the control command value W0, and controls the power conversion operation of the power converter 21.

  In the control device 10b of the present embodiment, the disturbance feedback unit 143 estimates the frequency estimation value fe based on the frequency compensation amount Wf input from the frequency control unit 113, and the difference between the frequency estimation value fe and the frequency measurement value f1. A frequency disturbance compensation amount Wd is obtained by multiplying Δf ′ by the second proportional gain L2. Then, the power converter 21 is controlled according to a control command value W0 obtained by adding the frequency compensation amount Wf, the power flow compensation amount Wp, and the frequency disturbance compensation amount Wd. As a result, for example, as shown in FIG. 8, even in the case where output fluctuations with opposite polarities canceling each other occur in the solar cell modules 50a and 50b, unnecessary compensation control is suppressed, and frequency fluctuations are kept within the target range. Can fit in.

<Third Embodiment>
=== Configuration of Control Device ===
Hereinafter, the configuration of the control device according to the third embodiment will be described with reference to FIGS. 10 and 11.

  The control device 10c illustrated in FIG. 10 includes a power flow control unit 133 instead of the power flow control unit 123, and includes an adder 122 and an upper and lower limit setting unit 132, as compared with the control device 10a of the first embodiment. Furthermore, it is comprised. The power flow control unit 133 includes a high-pass filter 1331, an adder 1332, a limiter unit 1333, and a third proportional gain 1334. Here, the value of the third proportional gain 1334 is L3.

  The power flow deviation Δp is input from the adder 122 to the high-pass filter 1331, and the power flow fluctuation component Δp ″ is output from the high-pass filter 1331. The power flow fluctuation component is output to the adder 1332. Δp ″ and the frequency compensation amount Wf are input. Further, the difference between the power flow fluctuation component Δp ″ and the frequency compensation amount Wf is input from the adder 1332 to the limiter unit 1333. The output value of the limiter unit 1333 is input to the third proportional gain 1334. Is input, and the power flow compensation amount Wp is output from the third proportional gain 1334.

  FIG. 11 shows the configuration of the upper and lower limit setting unit 132 in the present embodiment. The upper / lower limit setting unit 132 illustrated in FIG. 11 includes a high-pass filter 1321, determination units 1322 and 1325, selection units 1323 and 1326, and first-order lag elements 1324 and 1327. Of the upper and lower limit setting units 132, the determination unit 1322, the selection unit 1323, and the first-order lag element 1324 correspond to an upper limit value setting unit, and the determination unit 1325, the selection unit 1326, and the first-order lag element 1327 are lower limit value setting units. It corresponds to.

  A frequency deviation Δf is input to the high pass filter 1321. The system frequency fluctuation component Δf ″ output from the high-pass filter 1321 is input to the determination units 1322 and 1325.

  The selectors 1323 and 1326 are configured as a 2-input 1-output multiplexer. An output value of the determination unit 1322 is input to the selection control input of the selection unit 1323, and an upper limit set value MAX is input to a data input corresponding to the case where the output value of the determination unit 1322 is 1, and the determination unit 1322 The value “0” is input to the data input corresponding to the case where the output value is 0. On the other hand, the output value of the determination unit 1325 is input to the selection control input of the selection unit 1326, and the lower limit set value MIN is input to the data input corresponding to the case where the output value of the determination unit 1325 is 1, and the determination unit The value “0” is input to the data input corresponding to the case where the output value of 1325 is 0.

  The output value of the selection unit 1323 is input to the first-order lag element 1324, and the upper limit value Pmax is output from the first-order lag element 1324. On the other hand, the output value of the selection unit 1326 is input to the primary delay element 1327, and the lower limit value Pmin is output from the primary delay element 1327.

=== Operation of Control Device ===
Next, the operation of the control device in this embodiment will be described.

  The power flow control unit 133 obtains a power flow compensation amount Wp based on the power flow deviation Δp and the frequency compensation amount Wf. Specifically, the power flow control unit 133 first extracts the power flow fluctuation component Δp ″ from the power flow deviation Δp by the high-pass filter 1331. Then, the extracted fluctuation component Δp ″ and the frequency compensation amount Wf are extracted. The difference (Δp ″ −Wf) is limited by the limiter unit 1333 with the upper limit value Pmax or the lower limit value Pmin, and multiplied by the third proportional gain L3 to obtain the power flow compensation amount Wp.

  Here, the upper / lower limit setting unit 132 extracts the fluctuation component Δf ″ of the system frequency from the frequency deviation Δf by the high-pass filter 1321, and the upper limit value Pmax of the limiter unit 1333 according to the magnitude of the extracted fluctuation component Δf ″. And the lower limit value Pmin is switched.

  Specifically, the determination unit 1322 starts to output a value “1” when the fluctuation component Δf ″ is equal to or less than a predetermined first threshold value Set (<0), whereby the limiter unit 1333 outputs an upper limit value. Output of an output value limited by Pmax (= MAX) is started. In addition, after the output from the limiter unit 1333 is started, when the fluctuation component Δf ″ becomes equal to or greater than the predetermined third threshold value Arst (> Aset), the determination unit 1322 starts outputting the value “0” and sets the upper limit. By setting the value Pmax = 0, the output of the limiter unit 1333 is stopped. Here, as an example, the third threshold value Arst = 0. Then, the determination unit 1322 holds the output state while Set <Δf ”<Arst. The first-order lag element 1324 changes the value“ 0 ”to the upper limit set value MAX when the upper limit value Pmax is switched. The change or the change from the upper limit set value MAX to the value “0” is moderated.

  On the other hand, the determination unit 1325 starts to output the value “1” when the fluctuation component Δf ″ is equal to or greater than the predetermined second threshold value Bset (> 0), whereby the limiter unit 1333 outputs the lower limit value Pmin (= The output of the output value limited by MIN) is started. Further, after the output from the limiter unit 1333 is started, when the fluctuation component Δf ″ becomes equal to or less than the predetermined fourth threshold value Brst (<Bset), the determination unit 1325 starts outputting the value “0” and sets the lower limit By setting the value Pmin = 0, the output of the limiter unit 1333 is stopped. Here, as an example, the fourth threshold value Brst = 0. Then, the determination unit 1325 holds the output state while Brst <Δf ″ <Bset. The first-order lag element 1327 changes from the value “0” to the lower limit set value MIN when the lower limit value Pmin is switched. The change or the change from the lower limit set value MIN to the value “0” is moderated.

  In the control device 10c of the present embodiment, the power flow control unit 133 extracts the power flow fluctuation component Δp ″ from the power flow deviation Δp, and the upper and lower limit setting unit 132 uses the frequency deviation Δf to change the system frequency fluctuation component Δf ″. Is extracted. Only when the absolute value of the fluctuation component Δf ″ is large to some extent, output from the limiter unit 1333 is started, and the output value is multiplied by the third proportional gain L3 to obtain the power flow compensation amount Wp. Then, the power converter 21 is controlled according to the control command value W0 obtained by adding the frequency compensation amount Wf and the power flow compensation amount Wp.

  Thereby, as shown in FIG. 12, for example, when output fluctuations of opposite polarities canceling each other occur in the solar cell modules 50a and 50b, the system frequency does not change and the fluctuation component Δf ″ = 0. Pmax = Pmin = 0 and the power flow compensation amount Wp is 0. Therefore, unnecessary compensation control according to the fluctuation component Δp ″ is suppressed, and deviation of the system frequency from the target range can be prevented. In this case, the frequency compensation amount Wf is also zero. On the other hand, as shown in FIG. 13, for example, when the output fluctuation occurs only in the solar cell module 50a, the power flow compensation amount according to the difference between the fluctuation component Δp ″ and the frequency compensation amount Wf from the power flow control unit 133. Wp is output, and the frequency variation can be kept within the target range.

  As described above, in the power stabilization system including the control device 10 shown in FIG. 3, the power amount for compensating for the fluctuation of the system frequency of the AC power system 9 is set based on the frequency measurement value f1 (frequency deviation Δf). The corresponding frequency compensation amount Wf is obtained, and based on the power flow measurement value PL1 (power flow deviation Δp) and the frequency compensation amount Wf, the power flow compensation amount Wp corresponding to the power amount that compensates for fluctuations in the power flow is obtained. By controlling the power conversion operation between the AC power system 9 and the power storage device 20 by the power converter 21 in accordance with the control command value W0 to which the power is added, unnecessary compensation control according to fluctuations in the power flow Can be suppressed, and deviation of the system frequency from the target range can be prevented.

  Further, in the power stabilization system including the control device 10a shown in FIG. 4, a change in the power flow due to the control of the power converter according to the frequency compensation amount Wf is estimated as the power flow estimated value PLe, and the power flow estimated value By calculating the power flow compensation amount Wp by multiplying the difference Δp ′ between PLe and the measured power flow value PL1 by the first proportional gain L1, output fluctuations of opposite polarities canceling each other occur in a plurality of distributed power sources. Even in this case, the frequency variation can be kept within the target range.

  Further, in the power stabilization system provided with the control device 10b shown in FIG. 9, the change of the system frequency due to the control of the power converter according to the frequency compensation amount Wf is estimated as the frequency estimated value fe, and the frequency estimated value fe The frequency disturbance compensation amount Wd is further obtained by multiplying the difference Δf ′ from the frequency measurement value f1 by the second proportional gain L2, thereby adding the frequency compensation amount Wf, the power flow compensation amount Wp, and the frequency disturbance compensation amount Wd. In response to the control command value W0, the power conversion operation of the power converter 21 is controlled, and even when output fluctuations with opposite polarities canceling each other occur in a plurality of distributed power sources, the frequency fluctuation is within the target range. Can fit in.

  Further, in the power stabilization system including the control device 10c shown in FIG. 10, when the fluctuation component Δf ″ of the system frequency is extracted and Δf ″ ≦ Aset (<0), the limiter unit 1333 outputs the upper limit value. When the output of the output value limited by Pmax (= MAX) is started and Δf ″ ≧ Aset (> 0) is satisfied, the output of the output value limited by the lower limit value Pmin (= MIN) is output from the limiter unit 1333. And the output value is multiplied by the third proportional gain L3 to obtain the power flow compensation amount Wp, so that the power flow compensation amount Wp is output only when the absolute value of the fluctuation component Δf ″ is large to some extent. Therefore, unnecessary compensation control according to the fluctuation component Δp ″ of the power flow can be suppressed, and deviation of the system frequency from the target range can be prevented.

  Further, when Δf ″ ≧ Arst (> Aset) or Δf ″ ≦ Brst (<Bset) is satisfied after the output from the limiter unit 1333 is started, the output of the limiter unit 1333 is stopped to thereby change the fluctuation component. The frequent switching of the upper limit value Pmax when Δf ″ is in the vicinity of the first threshold value Aset and the frequent switching of the lower limit value Pmin when the fluctuation component Δf ″ is in the vicinity of the second threshold value Bset are suppressed. Can be prevented from vibrating.

  In the first to third embodiments, for example, the control constants such as the first proportional gain L1, the second proportional gain L2, and the third proportional gain L3 use a general control system design technique. Can be obtained. For example, it can be obtained experimentally by performing an actual operation test in the AC power system 9 that is a target for suppressing frequency fluctuations or an operation simulation using a model of the AC power system 9.

  In the second embodiment, it is preferable that the first proportional gain L1 and the second proportional gain L2 are determined first in the first proportional gain L1. In this case, for example, the first proportional gain L1 is first determined by setting the second proportional gain L2 to 0, and then the second proportional gain L2 is determined using the determined first proportional gain L1.

  In the third embodiment, the threshold values of the first threshold value Aset, the second threshold value Bset, the third threshold value Arst, and the fourth threshold value Brst are determined based on the characteristics of the AC power system 9 and the target range of the system frequency. It can be obtained experimentally as in the case of the control constant. Similarly, the first-order lag elements 1324 and 1327 can also be obtained experimentally from the characteristics of the AC power system 9 and the like.

  In addition, the said embodiment is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

DESCRIPTION OF SYMBOLS 1 Electric power stabilization system 5 Solar power plant 6 Wind power plant 7 Power plant 8 (8a, 8b) Customer load 9 AC power system 10 (10a-10d) Control device 15 Instrument transformer 20 Power storage device (storage battery)
21, 51 (51a, 51b), 61 Power converter 22, 52a, 52b, 72a, 72b, 82a, 82b (For power) Transformer 50 (50a, 50b) Solar cell module 60 Wind power generator 70a, 70b Diesel power generation Machine group 91, 92 Control target 93, 94 Adder 111 Frequency detection unit 112, 122, 144 Adder 113 Frequency control unit 121 Power flow detection unit 123, 133, 153 Power flow control unit 132 Upper / lower limit setting unit 134 Command value generation Part (adder)
135 Power converter control unit 143 Disturbance feedback unit 1231 Power flow model unit 1232, 1332, 1433 Adder 1233, 1334, 1434, 1532 Proportional gain 1321, 1331, 1531 High-pass filter 1322, 1325 Judgment unit 1323, 1326 Selection unit 1324, 1327 Primary delay element 1333 Limiter part 1431, 1432 System frequency model part

Claims (6)

A power stabilization system that suppresses fluctuations in the active power of an AC power system,
A power storage device that stores power and absorbs or discharges power with the AC power system; and
A power converter that mutually converts power absorbed or released between the AC power system and the power storage device;
A control device for controlling the power converter in accordance with an active power fluctuation of the AC power system;
With
The control device includes:
A frequency detection unit for detecting a system frequency of the AC power system as a frequency measurement value;
A power flow detector for detecting the power flow of the AC power system as a power flow measurement value;
Based on the frequency measurement value, a frequency control unit that obtains an amount of power that compensates for fluctuations in the system frequency as a frequency compensation amount;
A power flow control unit for obtaining a power flow compensation amount as a power flow compensation amount based on the power flow measurement value and the frequency compensation amount;
A power converter controller that controls the power converter according to the frequency compensation amount and the power flow compensation amount;
A power stabilization system comprising: The power stabilization system according to claim 1,
The power flow controller is
A power flow model unit that estimates a change in the power flow by the control of the power converter according to the frequency compensation amount as a power flow estimation value;
A power stabilization system for obtaining the power flow compensation amount by multiplying a difference between the power flow estimated value and the power flow measurement value by a first proportional gain. The power stabilization system according to claim 2,
A system frequency model unit that estimates a change in the system frequency as controlled by the power converter according to the frequency compensation amount as a frequency estimated value; and a second proportional to the difference between the frequency estimated value and the frequency measured value A disturbance feedback unit for multiplying the gain to obtain a frequency disturbance compensation amount;
The power converter control unit controls the power converter in accordance with the frequency compensation amount, the power flow compensation amount, and the frequency disturbance compensation amount. The power stabilization system according to claim 1,
The power flow controller is
A difference between the fluctuation component of the power flow and the frequency compensation amount is input, and includes a limiter unit that outputs an upper limit value or a lower limit value,
The power flow compensation amount is obtained by multiplying the output value of the limiter unit by a third proportional gain,
The limiter unit is
Only when the fluctuation component of the system frequency is equal to or less than a predetermined negative first threshold, starts outputting the output value limited by the upper limit value,
The power stabilization system starts output of the output value limited by the lower limit value only when the fluctuation component of the system frequency becomes equal to or greater than a predetermined positive second threshold value. The power stabilization system according to claim 4,
The limiter unit is
When the output value limited by the upper limit value is output, if the fluctuation component of the system frequency becomes equal to or greater than a predetermined third threshold value greater than the first threshold value, the output value limited by the upper limit value Stop the output of
When outputting the output value limited by the lower limit value, if the fluctuation component of the system frequency becomes equal to or less than a predetermined fourth threshold value smaller than the second threshold value, the output value limited by the lower limit value Power stabilization system characterized by stopping the output of A power storage device that stores power and absorbs or discharges power to and from the AC power system;
A power converter that mutually converts power absorbed or released between the AC power system and the power storage device;
A control device that is used together to control the power converter to suppress fluctuations in the active power of the AC power system,
A frequency detection unit for detecting a system frequency of the AC power system as a frequency measurement value;
A power flow detector for detecting the power flow of the AC power system as a power flow measurement value;
Based on the frequency measurement value, a frequency control unit that obtains an amount of power that compensates for fluctuations in the system frequency as a frequency compensation amount;
A power flow control unit for obtaining a power flow compensation amount as a power flow compensation amount based on the power flow measurement value and the frequency compensation amount;
A power converter controller that controls the power converter according to the frequency compensation amount and the power flow compensation amount;
A control device comprising:

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