JP2011024386A - Power stabilizer and controller thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain frequency stability by coping with fluctuation in a band lower than or equal to a governor control range, particularly that of several tens of milliseconds or less. <P>SOLUTION: A power stabilizer 10 includes a power storage device 14 and a control device 11 which generates and outputs an effective power command Ps for the power storage device 14. The control device 11 includes an effective current fluctuation compensation part 12 which generates and outputs a compensation signal corresponding to a fluctuation of an effective current based on a compensation object current Io, and an effective power fluctuation compensation part 13 which extracts and outputs an effective power fluctuation amount based on the compensation object current Io, compensation object voltage Vo, and frequency fo. The compensation signal added with the effective power fluctuation amount is outputted as the effective power command Ps. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a system in which power generation equipment using natural energy is linked to a power system.

  In an electric power system, frequency fluctuations occur when the balance between generated power and consumed power is lost. Therefore, the output increase / decrease adjustment of the generator of the internal combustion power generation facility is carried out so as to always balance the power consumption and the generated power which change every moment by various frequency control according to the fluctuation cycle of the load.

  Conventionally, with respect to load fluctuations whose fluctuation cycle band is several tens of seconds to several minutes (for example, about 30 seconds to 5 minutes), control is performed by governor-free operation of the rotational speed of the generator. In addition, for load fluctuations in which the bandwidth is from several minutes to several tens of minutes (for example, about 5 to 20 minutes), control for performing load distribution in consideration of economics of the generator is performed by economic operation control (EDC).

  In recent years, the development of microgrid systems using renewable energy (natural energy) such as sunlight and wind power is increasing. Since power generation facilities that use renewable energy such as solar and wind power fluctuate momentarily according to natural conditions such as solar radiation and wind speed, especially in weak power systems such as remote areas and remote islands, the frequency of the system It is assumed that there will be a problem with fluctuations in voltage and voltage.

Here, for example, there is a conventional technique described in Patent Document 1.
As described in Patent Document 1, in a power generation facility that uses natural energy, since the natural energy varies, the power generation output varies. For this reason, in such a system in which such power generation facilities are connected to the electric power system, fluctuations in the system frequency and voltage due to the influence of fluctuations in natural energy become a problem. In view of this, a method has been proposed in which a fluctuation in the power generation output is compensated by absorbing or releasing power using a power storage system such as a secondary battery.

  And as described in Patent Document 1, fluctuations in a plurality of cycles may be mixed in fluctuations in the power generation output of natural energy. For example, in the case of wind power generation, there may be a mixture of a fluctuation of a period of 0.5 to 2 seconds accompanying the rotation of the wings and a fluctuation of a period of 10 seconds or more accompanied by a change in wind strength.

  In the invention of Patent Document 1, in correspondence with the above-described fluctuations in the power generation output of natural energy, a short period fluctuation compensator corresponding to a fluctuation of 0.5 to 2 seconds and a length corresponding to a fluctuation of a period of 10 seconds or more. And a periodic fluctuation compensator.

Japanese Patent Laid-Open No. 11-262186

As described above, the governor-free operation is generally performed for load fluctuations as described above, but the control range of the governor for adjusting the speed of the internal combustion power generation facility ranges from several tens of seconds to several minutes. In weak AC power such as islands and remote islands, the range in which the frequency stability can be secured only by the generator of the internal combustion power generation facility has been limited. That is, in a system in which the power generation facility using the natural energy is connected to the power system, the power generation output fluctuation of the natural energy, that is, the fluctuation of the period of 0.5 to 2 seconds or the period of about 10 seconds occurs. It cannot be handled by governor control in which the control range is from several tens of seconds to several minutes.

  On the other hand, the invention of Patent Document 1 can partially cope with a band that cannot be handled by the governor control. It is possible to deal with fluctuations in the period of 0.5 to 2 seconds or a period of 10 seconds or more.

  However, in a system in which the power generation facility using natural energy is linked to a power system, fluctuations in an extremely short period of several tens of milliseconds or less may occur, for example, the output of the natural energy power generation facility is cut off. Of course, the fluctuation of the band of several seconds to 10 seconds or more is also mixed.

  For this reason, by controlling the power storage device corresponding to a wide band including the band below the governor control range, that is, the band of several tens of seconds or less, especially the band of several tens of milliseconds or less, the frequency variation It is desired to suppress the noise and stabilize the frequency.

  The problem of the present invention is that when the power generation facility using natural energy is connected to a weak power system such as a remote place or a remote island, it is a wide band including a band below the governor control range, particularly a band of several tens of milliseconds or less. An object of the present invention is to provide a power stabilization device capable of maintaining frequency stability by performing compensation in response to fluctuations in a band, a control device thereof, and the like.

  The power stabilization device of the present invention is a power stabilization device in an AC power system that supplies power generated by an internal combustion power generation facility and a natural energy power generation facility to a load in remote areas or remote islands, and stores the power, Based on a power storage device that absorbs power in the power system or discharges power to the power system, a measuring device that measures a compensation target current, a compensation target voltage, and a frequency in the power system, and a measurement result by the measuring device A control device that controls the power storage device to absorb or release the power, and the control device obtains an effective current based on the compensation target current and copes with a change in the effective current. Active current fluctuation compensating means for generating and outputting a first compensation signal to be generated, and active power is obtained based on the current to be compensated and the voltage to be compensated to cope with the fluctuation of the active power Active power fluctuation compensation means for generating and outputting a second compensation signal, and outputting an active power command signal obtained by adding the second compensation signal to the first compensation signal to the power storage device To do.

  In the power stabilizing device having the above configuration, the fluctuation of the band below the governor control range is basically dealt with by the active power fluctuation compensating means. However, since there is a band that cannot be handled by the active power fluctuation compensation means (for example, a band of several tens of milliseconds or less), this band can be dealt with by the active current fluctuation compensation means, and as a whole, a wide band that is less than the governor control range. It is possible to compensate for fluctuations in the frequency and maintain frequency stability in weak power systems such as remote areas and remote islands.

  In the power stabilizing device having the above configuration, for example, the effective current fluctuation compensating unit includes an effective current calculating unit that obtains the effective current based on the compensation target current, and a ramp function that obtains a ramp function output of the effective current. A first subtracting signal obtained by subtracting the ramp function output from the effective current.

Alternatively, in the power stabilizing device having the above configuration, for example, the active power fluctuation compensating unit includes an active power calculating unit that obtains the active power based on the compensation target current and the compensation target voltage, and the measured frequency. The frequency correction means for multiplying the difference between the frequency and the rated frequency by a predetermined speed arbitration rate, the addition means for adding the output of the frequency correction means to the active power, and the output of the addition means It has active power fluctuation amount extraction means for generating the second compensation signal by extracting the fluctuation amount.

  According to the power stabilization device of the present invention, its control device, etc., when a power generation facility using natural energy is linked to a weak power system such as a remote place or a remote island, it is in a band below the governor control range, in particular. Compensation can be performed in response to fluctuations in a wide band including a band of several tens of milliseconds or less, and frequency stability can be maintained.

1 is an overall configuration diagram of a power stabilization system including a power stabilization device of the present example. It is a functional block diagram of a control apparatus. It is a block diagram of an effective current fluctuation compensation part. It is a figure which shows the calculation method of the effective current Id by an effective current calculation function part. It is a timing chart figure of operation of an effective current variation compensation part. It is a functional block diagram of an active power fluctuation compensation part. It is a figure which shows the calculation method of the active power P in an active power calculation function part. It is a block diagram of a frequency correction function part. It is a figure for demonstrating an active power fluctuation amount extraction function part. (A), (b) is a figure which shows the frequency fluctuation suppression effect by the control apparatus of this example. It is a figure which shows the control range by the control apparatus of this example. (A)-(c) is a figure for demonstrating and showing a specific example regarding a frequency correction function part.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an overall configuration diagram of a power stabilization system including a power stabilization apparatus according to the present embodiment.

  In the illustrated power stabilization system, the internal combustion power generation facilities 1 to 3 supply AC power to an arbitrary load 4 via the distribution line 7. In addition, a solar power generation device 5 and a wind power generation facility 6 which are natural energy power generation facilities are connected to the power system including the distribution line 7, and the power generated by the solar power generation device 5 and the wind power generation facility 6 is connected. Is also supplied to the load 4. The illustrated power stabilization system is, for example, a power system provided on a remote island (not connected to another power system).

Further, a current to be compensated Io is measured by a CT (Current Transformer) 18 provided on the distribution line 7, and a voltage to be compensated Vo and a frequency fo are measured from a VT (Voltage Transformer) 17. . These measure the current and voltage of power supplied from the internal combustion power generation facilities 1 to 3 to the load 4 and measure the frequency of the power system. In other words, the current to be compensated in the power system that supplies the power generated by the internal combustion power generation facilities 1 to 3 to the load 4 and also supplies the power generated by the natural energy power generation facility to the load 4 by connecting the natural energy power generation facilities. The compensation target voltage and frequency are measured.

  These measured values fluctuate due to load fluctuations of the load 4, output fluctuations of the solar power generation device 5 and the wind power generation equipment 6, and the power stabilization device 10 of this example particularly suppresses frequency fluctuations. Control.

  The illustrated power stabilization system is, for example, installed on a remote island, and is not connected to another power system but is operated. For example, not only the internal combustion power generation facilities 1 to 3 that are small-scale thermal power generation facilities but also a solar power generation device 5 and a wind power generation facility 6 that are natural energy power generation facilities are provided, and the power demand (load 4) in the remote islands is provided. ).

  As already mentioned, in such a weak power system such as remote areas and remote islands, if natural energy power generation facilities are also provided, fluctuations in the system frequency, etc. may occur due to the effects of natural energy fluctuations, which may be a problem. The

  In particular, it is difficult to cope with governor-free operation or EDC, that is, a band that is less than the governor control range (for example, a band that is several tens of seconds or less), especially a wide band including a band that is several tens of milliseconds or less. Therefore, it is desired that the frequency fluctuation can be suppressed by performing compensation. This makes it possible to cover a very wide band together with the governor control and maintain the frequency stability of the system. For this purpose, the system includes a power stabilization device 10.

  The power stabilization device 10 includes a power storage device 14 and a control device 11. The control device 11 inputs the measurement results (compensation target current Io, compensation target voltage Vo, frequency fo), and controls the power storage device 14 based on the measurement results. That is, the control device 11 includes an active current fluctuation compensation unit 12 and an active power fluctuation compensation unit 13, and the two fluctuation compensation units 12 and 13 send the power storage device 14 based on the measurement result. The active power command Ps is calculated, and the active power command Ps is output to the power storage device 14.

  The control device 11 is, for example, an arithmetic processing unit such as a DSP (digital signal processor) or PLC (programmable logic controller), a storage device such as a memory, or an input / output for inputting the measurement result or outputting the active power command Ps. Has an interface. A predetermined application program is stored in the storage device in advance, and the arithmetic processing unit reads out and executes this application program to thereby function the active current fluctuation compensator 12 and the active power fluctuation compensator 13 (in detail). (To be described later). The functions of the active current fluctuation compensator 12 and the active power fluctuation compensator 13 are not limited to this example, and can be realized by a dedicated analog circuit.

The power storage device 14 is connected to the distribution line 7 and is, for example, a secondary battery or the like that absorbs or discharges power from the power system in accordance with the active power command Ps.
As shown in FIG. 2 and the like, the active power command Ps is obtained by adding the output of the active power fluctuation compensation unit 13 to the output of the active current fluctuation compensation unit 12.

As already described in the related art and problems, the generator rotation speed is governed by a free-running operation for load fluctuations with a fluctuation period band of several tens of seconds to several minutes (for example, about 30 seconds to 5 minutes). Control. That is, in FIG. 1, the internal combustion power generation facilities 1 to 3 can be governed to cope with fluctuations of several tens of seconds to several minutes, and the configuration and the like are not particularly shown or described. Similarly, for the fluctuation of the band from several minutes to several tens of minutes (for example, about 5 minutes to 20 minutes), the load distribution considering the economy of the generator is performed by economic operation control (EDC). This is not particularly described.

  As described in the prior art and problems, in particular, in a power system in which natural energy power generation facilities (in this example, the solar power generation device 5 and the wind power generation facility 6) are connected to an AC power system, In addition to fluctuations (demand fluctuations), fluctuations in the power generation output of natural energy power generation facilities due to fluctuations in natural energy occur, and the fluctuations on the AC power system caused by this fluctuations are, for example, short-cycle bands that include bands of tens of milliseconds or less Fluctuations may be included. That is, there is a case where the fluctuation of the band is less than the governor control range (for example, several tens of seconds or less). Therefore, such fluctuations cannot be handled by governor-free operation of the internal combustion power generation facilities 1 to 3.

  On the other hand, according to the power stabilizing device 10, the frequency stabilization corresponds to a wide band that is below the governor control range (here, several tens of seconds or less) and particularly includes a band of several tens of milliseconds or less. Sex can be maintained. Basically, the active current fluctuation compensator 12 handles a band of several tens of milliseconds or less, and the active power fluctuation compensator 13 handles a band of several tens of milliseconds to several tens of seconds. It is not a limit. These fluctuation compensators 12 and 13 will be described in detail later.

  As described above, according to the present configuration shown in FIG. 1, the power stabilizer / compensator 10 compensates for power fluctuations / demand fluctuations caused by the solar power generation device 5, the wind power generation facility 6, or the load 4, thereby It is possible to suppress the fluctuation of the frequency and to operate economically.

FIG. 2 is a functional configuration diagram of the control device 11.
As described with reference to FIG. 1, the control device 11 includes the active current fluctuation compensator 12 and the active power fluctuation compensator 13, which will be described in more detail with reference to FIG. 2.

  As shown in FIG. 2, the active power command Ps is obtained by adding the output 'm' from the active current fluctuation compensator 12 and the output 'n' from the active power fluctuation compensator 13 by the adder 15 (Ps = m + n ).

The input to the effective current fluctuation compensation unit 12 is the compensation target current Io. The input to the active power fluctuation compensation unit 13 is a compensation target current Io, a compensation target voltage Vo, and a frequency fo.
Hereinafter, the configuration and operation of the active current fluctuation compensating unit 12 will be described with reference to FIGS.

  The effective current fluctuation compensation unit 12 generates and outputs the output ‘m’, which is a compensation signal corresponding to the fluctuation of the compensation target current Io in the AC power system. Specifically, for example, an effective current is obtained based on the current to be compensated Io, and a compensation signal necessary for the fluctuation of the effective current is generated and output.

FIG. 3 is a configuration diagram of the active current fluctuation compensator 12.
The active current fluctuation compensation unit 12 includes an active current calculation function unit 21, a ramp function calculation function unit 22, and an adder / subtractor 23.

  The effective current calculation function unit 21 inputs the compensation target current Io, and calculates and outputs the effective current Id. The ramp function calculation function unit 22 inputs the effective current Id that is the output of the active current calculation function unit 21 and outputs the ramp function output q. Then, by inputting these two outputs to the adder / subtractor 23, the difference (Id−q) between the effective current Id and the ramp function output q becomes the output m from the effective current fluctuation compensation unit 12.

FIG. 4 shows a method for calculating the effective current Id by the effective current calculation function unit 21.
Note that the effective current Id calculation method itself is an existing technology and will be briefly described here.
Here, the active current calculation function unit 21 will be described as having an αβ conversion unit 24 and a dp axis conversion unit 25.

First, the three-phase instantaneous currents of the compensated current Io _{I R,} I S, and _{I T.} αβ conversion unit 24, the three-phase instantaneous current _{I R,} I S, the αβ conversion from _{I T} alpha current I _alpha, obtaining the beta current I _beta. The calculation formula (1) for the α current and β current is as follows.

Next, the dp axis conversion unit 25 obtains the d axis current Id and the q axis current Iq by dq axis conversion from the α current I _α and β current I _β . This d-axis current Id = the effective current Id. The calculation formula (2) for the d-axis current and the q-axis current is as follows.

In the above calculation formula, ω represents the angular frequency [rad / s] of the system.
As described above, the effective current Id calculation method itself is an existing technology and will not be described in further detail. However, in general, when the input current is three phases, the three phases are transformed into an orthogonal coordinate system by αβ conversion. Then, the orthogonal coordinate system is converted into the rotating coordinate system by dp conversion. Thereby, phase information or the like can be detected as a direct current amount. That is, the compensation target current Io, which is an AC amount, is converted into a DC amount.

FIG. 5 shows a timing chart of the operation of the active current fluctuation compensator 12.
That is, a timing chart of the effective current Id, the ramp function output q, and the output m of the effective current fluctuation compensator 12 obtained by adding and subtracting them is shown.

For example, the effective current Id fluctuated in a step function as shown in FIG. 5 due to fluctuations in the current Io to be compensated due to fluctuations in the output of the solar power generation device 5 and the wind power generation facility 6 and load fluctuations of the load 4. And The ramp function output q fluctuates as shown in accordance with the fluctuation of the effective current Id. Ramp function itself, which is well-known that, although not described in particular detail is easy if explained ramp function is a function that varies (increases or decreases) in ² predetermined desired slope Thus, the ramp function output q changes to a trapezoidal shape according to the step change of the effective current Id shown in the figure.

Then, due to the adder / subtractor 23, the output m of the active current fluctuation compensator 12 becomes the difference between the ramp function output q and the active current Id as shown in FIG. As a result, the effective current fluctuation compensator 12 compensates for the increase in the effective current Id (however, subtracting the amount of the ramp function output q; that is, the amount of Id−q) during the period of t1 to t2 shown in the figure. In addition, the power storage device 14 is discharged according to the output m within the period, and control is performed so that the output change rate of the internal combustion power generation facilities 1 to 3 is kept constant. Thereafter, when the outputs of the internal combustion power generation facilities 1 to 3 are stabilized at the time t2 shown in the figure, the discharge of the power storage device 14 is stopped during the period t2 to t3 shown in the figure. Thereafter, the power storage device 14 is charged according to the output m within the period so that the decrease of the effective current Id (however, as in the above, the amount of Id-q) is compensated for the period of t3 to t4 shown in the figure. The control is performed so that the output change rate of the internal combustion power generation facilities 1 to 3 is kept constant.

  Note that the control itself so as to perform the compensation for the “Id-q” using the ramp function described above is disclosed in, for example, the disclosure relating to FIGS. 2 and 3 of Reference 1 (Japanese Patent Laid-Open No. 2008-301545). As it is, it is an existing technology. Therefore, although not described in detail, if briefly described, compensation for fluctuations in the active current is not performed only by the power storage device 14, but is also performed by the internal combustion power generation facilities 1 to 3. Yes (preliminarily set so as to correspond to the ramp function output q), so that compensation for fluctuations in the effective current Id is performed by “compensation by the internal combustion power generation facilities 1 to 3 + compensation by the power storage device 14”. I have control. The ramp function output q means the target value of the outputs of the internal combustion power generation facilities 1 to 3.

  Here, in general, a functional unit that involves a calculation process of active power such as the active power fluctuation compensation unit 13 takes a relatively long calculation time (cannot be processed in one cycle, for example, requires about 10 cycles), and therefore, several tens of times. It has been found that fluctuations of less than a millisecond cannot be accommodated. On the other hand, it has been found that a functional unit that does not involve an active power calculation process, such as the active current fluctuation compensation unit 12, requires a relatively short calculation time and can cope with fluctuations of several tens of milliseconds or less. Of course, it is possible to cope with fluctuations of several tens of milliseconds or more. However, since the active power fluctuation compensator 13 only needs to cope with this band, here, the active current fluctuation compensator 12 has a band of several tens of milliseconds or less. Correspondingly, the fluctuation of the active current is compensated to suppress the fluctuation of the frequency.

  As described above, the effective current fluctuation compensator 12 maintains frequency stability in weak power systems such as remote areas and remote islands by compensating for fluctuations in current to be compensated in a band of several tens of milliseconds or less.

Next, the configuration and operation of the active power fluctuation compensator 13 will be described below with reference to FIGS.
The active power fluctuation compensation unit 13 generates and outputs a compensation signal (n above) corresponding to the fluctuation of the active power based on the compensation target current Io, the compensation target voltage Vo, and the frequency fo in the AC power system.

FIG. 6 is a functional configuration diagram of the active power fluctuation compensation unit 13.
The active power fluctuation compensation unit 13 includes an active power calculation function unit 30, a frequency correction function unit 31, and an active power fluctuation amount extraction function unit 32.

  The active power calculation function unit 30 inputs the compensation target current Io and the compensation target voltage Vo, and calculates and outputs the active power P. The frequency correction function unit 31 inputs the frequency fo, and calculates and outputs Δf · c. Δf · c will be described later.

  The output of the active power calculation function unit 30 (active power P) and the output of the frequency correction function unit 31 (Δf · c) are added by the adder 33, and the output (P + Δf · c) of the adder 33 is the active power. This is input to the fluctuation amount extraction function unit 32. The output of the active power fluctuation amount extraction function unit 32 becomes the output n of the active power fluctuation compensation unit 13.

The active power fluctuation amount extraction function unit 32 basically extracts the fluctuation amount of the active power P. The effective power fluctuation is corrected by adding the output (Δf · c) of the frequency correction function unit 31. In this case, it may be considered that the fluctuation amount of the active power P is extracted.

The inputs to the active power calculation function unit 30 are the compensation target current Io and the compensation target voltage Vo. The input to the frequency correction function unit 31 is the frequency fo.
Hereinafter, the active power calculation function unit 30 will be described in detail with reference to FIG.

FIG. 7 is a diagram illustrating a method for calculating the active power P in the active power calculation function unit 30.
The active power calculation function unit 30 includes an αβ conversion unit 35, an αβ conversion unit 36, and an active power calculation unit 37.

The αβ conversion unit 35 is the same as the αβ conversion unit 24. That is, the three-phase instantaneous currents of the compensated current Io _{I R,} I S, and _{I T.} αβ conversion unit 35, the three-phase instantaneous current _{I R,} I S, the αβ conversion from _{I T} alpha current I _alpha, obtaining the beta current I _beta. The calculation formulas for α current and β current are the calculation formula (1) already shown.

The αβ converter 36 is basically the same as the αβ converter 35 although there is a difference between current and voltage. That is, the three-phase instantaneous voltage of the compensation target voltage Vo is set to V _R , V _S , and V _T. The αβ conversion unit 36 obtains an α voltage V _α and a β voltage V _β by αβ conversion from the three-phase instantaneous voltage.

  The calculation formula (3) for the α voltage and β voltage is as follows.

The outputs of the αβ conversion unit 35 and the αβ conversion unit 36, that is, the α current I _α and β current I _β , the α voltage V _α , and the β voltage V _β are input to the active power calculation unit 37.
The active power calculation unit 37 calculates and outputs the active power P according to the following calculation formula (4) according to this input.

P = V _α I _α + V _β I _β (4) Next, the frequency correction function unit 31 will be described below with reference to FIG.
FIG. 8 shows a configuration example of the frequency correction function unit 31.

The frequency correction function unit 31 includes a noise removal filter 40, a speed adjustment unit 41, and an adder / subtractor 42.
The frequency fo and the predetermined reference frequency fa are input to the adder / subtractor 42, and a frequency difference Δf = (fa−fo) is output. The reference frequency fa is a rated frequency and is either 50 Hz or 60 Hz in Japan. That is, Δf (Δω) indicates how much the frequency on the power system is deviated from the rated frequency.

The frequency difference Δf is input to the noise removal filter 40, and after noise is removed, the frequency difference Δf is input to the speed adjustment unit 41.
The noise removal filter 40 is, for example, a primary low-pass filter or the like, and has an existing general noise removal filter function (for example, a filter that cleans the waveform by taking a moving average or the like). Is represented by, for example, “1 / (1 + sT)”. Here, the output of the noise removal filter 40 is also expressed by the frequency difference Δf.

  The speed adjustment unit 41 multiplies the frequency difference Δf by a speed adjustment rate and outputs the result. The speed regulation rate is a constant (here, c), and generally c = 1 / δ = 0.03 to 0.05 (3% to 5%). The speed adjustment unit 41 calculates and outputs the above “Δf · c” by multiplying the frequency difference Δf by the speed adjustment rate c. The output of the speed adjustment unit 41 becomes the output of the frequency correction function unit 31.

  The frequency correction function unit 31 is provided in order to keep the frequency stable by reducing the sensitivity to frequency fluctuations. In other words, if the frequency correction function unit 31 is not provided, the control is based only on the output of the active power calculation function unit 30, so that the sensitivity to the frequency fluctuation may be too good, and the frequency is not stable. There is a possibility of (fluttering). For this reason, it is desirable to provide the frequency correction function unit 31 in an actual apparatus. This is a story related to the so-called “Droop characteristic”, and is a general one. In addition, by actually providing the frequency correction function unit 31 by simulation by the present inventor, the frequency correction function unit 31 is It has been confirmed that the frequency can be kept stable as compared with the case where there is no device.

  Therefore, it will not be described in further detail here (however, it will be described later with reference to FIG. 12). As is well known, in the governor control in the internal combustion power generation facilities 1 to 3 and the like, the same control using the speed regulation rate (sensitivity to frequency fluctuation) is performed. Therefore, the effect of keeping the frequency stable can also be obtained by governor control. However, there may be a situation where the frequency fluctuates temporarily temporarily. In this case, there is a possibility that the governor control cannot cope with it, and it is desirable to provide the frequency correction function unit 31.

  However, the frequency correction function unit 31 is not an essential component of the present invention. The main feature of the present invention is that it is possible to cope with fluctuations in a wide band including a band below the governor control range, particularly a band of several tens of milliseconds, and a frequency correction function for realizing this feature. Part 31 is not absolutely necessary. However, as described above, when the frequency correction function unit 31 is provided, an effect of maintaining the above-described frequency stably can be obtained.

In addition, when the frequency correction function part 31 is provided, the following merits are also obtained.
That is, although not shown in FIG. 1, there may be a case where a load other than the load 4 exists in another system. However, in the configuration of FIG. 1, the current to be compensated and the voltage to be compensated for the load 4 can be detected, and the current to be compensated and the voltage to be compensated for the load of another system cannot be detected as they are. However, since the frequency fo is common to other systems, it can be handled to some extent by compensation by the frequency correction function unit 31.

Next, the active power fluctuation amount extraction function unit 32 will be described below with reference to FIG.
As described above, the output (P + Δf · c) of the adder 33 is input to the active power fluctuation amount extraction function unit 32, and fluctuation components (mainly fluctuation components of active power) are extracted and output from this input signal. To do. The output of the active power fluctuation amount extraction function unit 32 is the output n.

The active power fluctuation amount extraction function unit 32 receives, as an input, an added value (P + Δf · c) of the output of the active power calculation function unit 30 and the output of the frequency correction function unit 31, for example, a time constant Tf as shown in FIG. High pass filter configuration. This is, for example, a high-pass filter that allows fluctuations in a band of several tens of milliseconds or more to pass. This configuration itself is an existing configuration as shown in FIG. 4 in Reference Document 2 (Japanese Patent Laid-Open No. 2007-129803), for example. As disclosed in Reference Document 2, this configuration uses the illustrated “1 / (1 + sTf)” low-pass filter 51 to achieve the same characteristics as the high-pass filter as a whole. That is, a component in the low frequency region is extracted by the low-pass filter 51, and the output of the low-pass filter 51 is subtracted from the original signal (input to the active power fluctuation amount extraction function unit 32) in the adder / subtractor 52, thereby That is, the fluctuation component can be extracted.

  Since the active power fluctuation amount extraction function unit 32 is a high-pass filter for extracting fluctuation components, it is not limited to the configuration using the low-pass filter 51, and may be a normal high-pass filter configuration (for example, The configuration shown in FIG.

The time constant Tf can be made variable according to the value of the active power command Ps (by the same function as the filter time constant setting unit described in Reference 2).
As already described, the active power fluctuation compensator 13 cannot cope with the fluctuation of the band of several tens of milliseconds or less due to the calculation processing time, but can cope with the fluctuation of the band of several tens of milliseconds or more. However, since it is possible to cope with fluctuations in the band of several tens of seconds or more by governor control, it is only necessary to cope with governor control. Therefore, in this example, the active power fluctuation compensating unit 13 is adapted to cope with a band fluctuation of several tens of milliseconds to several tens of seconds.

  As described above, the active power fluctuation compensator 13 maintains frequency stability in a weak power system such as a remote place or a remote island to compensate for fluctuations in active power in a band of several tens of milliseconds to several tens of seconds.

  Note that “several tens of milliseconds” and “several tens of seconds” are one guideline and are not limited to this example. In this method, a band that cannot be handled by the governor control is basically handled by the active power fluctuation compensation unit 13, and a band that cannot be handled by the active power fluctuation compensation unit 13 is further handled by the active current fluctuation compensation unit 12. Thus, it is possible to cope with fluctuations in a wide band. In this example, it is set to several tens of seconds or less as one guideline of the band that cannot be handled by the governor control. Similarly, in this example, it is set to several tens of milliseconds or less as one guideline of the band that cannot be handled by the active power fluctuation compensation unit 13.

  In this method, by using both the active current fluctuation compensator 12 and the active power fluctuation compensator 13, a band that cannot be handled by the governor control, particularly a wide band including a band of “several tens of milliseconds” or less. In response to the above, it is possible to compensate for fluctuations on the AC power system due to load fluctuations, output fluctuations of natural energy power generation facilities, etc., using the power storage device 14 to suppress frequency fluctuations on the AC power system. it can.

FIGS. 10A and 10B are diagrams showing the effect of suppressing frequency fluctuations by the control device 11 of this example.
The examples shown in FIGS. 10A and 10B show actual simulation results.

FIG. 10A shows frequency fluctuations when there is no control by the control device 11 of this example. On the other hand, FIG. 10B shows frequency fluctuations when there is control by the control device 11 of this example.
That is, FIG. 10A shows frequency fluctuations on the distribution line 7 (on the power system) due to various fluctuations such as output fluctuations of the solar power generation device 5 and the wind power generation equipment 6 and load fluctuations of the load 4. Yes. On the other hand, FIG. 10B shows frequency fluctuations on the distribution line 7 (on the power system) when there is control by the control device 11 of this example.

As shown in the figure, it can be seen that FIG. 10B has a smaller frequency fluctuation with respect to the reference frequency than FIG. 10A.
Here, the frequency fluctuation shown in FIG. 10A is a mixture of a relatively short-period fluctuation (for example, several tens of milliseconds or less) and a long-period fluctuation (for example, about several seconds). . FIG.
As can be seen by referring to 0 (b), the control by the control device 11 of this example performs the control so that the frequency fluctuation is small for both the relatively short period fluctuation and the relatively long period fluctuation. I understand that

  The suppression of frequency fluctuations in a relatively short cycle (for example, a band of several tens of milliseconds or less) is an effect of effective current fluctuation compensation in a band of several tens of milliseconds or less by the active current fluctuation compensating unit 12. In addition, a relatively long period frequency fluctuation (here, a band of about several seconds, but is not limited to this example, for example, a band of several tens of milliseconds to several tens of seconds, in other words, a band of a governor control range or less, In other words, regarding suppression of a band of several tens of seconds or less, it is an effect of active power fluctuation compensation by the active power fluctuation compensator 13.

The effects described above will be further described with reference to FIG.
FIG. 11 is a diagram illustrating a control range by the control device 11 of the present example.
As shown in FIG. 11, a band of several tens of milliseconds or less is used as a control region of the active current fluctuation compensator 12, and a band of several tens of milliseconds to several tens of seconds is used as a control area of the active power fluctuation compensator 13. The frequency stability can be maintained by compensating frequency fluctuations in a wide band that is less than the governor control range and includes several tens of milliseconds or less by using the two compensation units 12 and 13.

  As already described, governor-free operation and economic operation control (EDC) are also performed in this method. In the illustrated example, the band corresponding to several tens of seconds to several minutes is handled by governor control. A few tens of bands can be handled by economic operation control.

In this way, when governor-free operation and economic operation control (EDC) are combined, there is almost no band that cannot compensate for fluctuations.
As described above, according to the power stabilization device 10 of the present example, the discharge / storage control of the power storage device 14 by the control device 11 (the active current variation compensating unit 12 and the active power variation compensating unit 13) of the present example. Maintains frequency stability in weak power systems such as remote areas and remote islands in response to a wide band that is below the governor control range (for example, several tens of seconds or less), especially including several tens of milliseconds or less. It becomes possible to do.

Lastly, the acquisition of the frequency correction function unit 31 will be described with reference to FIG.
FIG. 12A shows an example of the output (active power P) of the active power calculation function unit 30.
In this example, the active power P is approximately 100 kW, and it is assumed that fluctuations as shown in the figure occur.

FIG. 12B shows a waveform obtained by extracting the variation of the active power P shown in FIG.
As shown in the figure, the waveform is based on 0 kw, and only the fluctuation component is extracted from the waveform of FIG. This is the output of the active power fluctuation amount extraction function unit 32, which is output as the active power command Ps. There may be no problem with this, but there may be a problem (for example, excessive compensation) when the frequency is greatly disturbed instantaneously, which corresponds to the above-mentioned “sensitivity is too good”.

  On the other hand, when the frequency correction function unit 31 is provided, the active power command Ps has a waveform indicated by a dotted line in FIG. 12B, for example (not excessive compensation). This corresponds to the above-mentioned “decrease sensitivity”.

In this example, the power storage unit 14 is configured to discharge power when the value of the active power command Ps is positive, and to absorb power when the value of the active power command Ps is negative. Has been. Therefore, if only the output m shown on the upper and lower sides of FIG. 5 is the active power command Ps, the period from t1 to t2 is a positive value, so that the power is discharged and the period from t3 to t4 is negative. Therefore, power absorption is performed. That is, the extracted effective current fluctuation becomes a compensation signal corresponding to the effective current fluctuation as it is. The same applies to the active power fluctuation. For example, as shown in FIG. 12B, the extracted active power fluctuation becomes the compensation signal corresponding to the active power fluctuation as it is.

  However, the present invention is not limited to this example. Contrary to the above example, the power storage unit 14 discharges power when the value of the active power command Ps is negative, and absorbs power when the value of the active power command Ps is positive. In the case of the configuration, the active power command Ps is obtained by inverting the waveform shown in FIG. 12B (for example, as shown in FIG. 12C). In the case of this example, a configuration for inverting the outputs m and n is necessary, but this is not particularly shown or described.

1, 2, 3 Internal combustion power generation facility 4 Load 5 Solar power generation device 6 Wind power generation facility 7 Distribution line 10 Power stabilization device 11 Control device 12 Effective current variation compensation unit 13 Effective power variation compensation unit 14 Power storage device 15 Adder 21 active current calculation function unit 22 ramp function calculation function unit 23 adder / subtractor 24 αβ conversion unit 25 dp axis conversion unit 30 active power calculation function unit 31 frequency correction function unit 32 active power fluctuation amount extraction function unit 33 adder 35 αβ conversion unit 36 αβ conversion unit 37 active power calculation unit 40 noise removal filter 41 speed adjustment unit 42 adder / subtractor 51 low pass filter 52 adder / subtractor

Claims (4)

A power stabilization device in an AC power system that supplies power generated by an internal combustion power generation facility and a natural energy generation facility to a load in remote areas or remote islands,
A power storage device that stores power and absorbs power of the power system or discharges power to the power system;
A measuring device for measuring current to be compensated, voltage to be compensated, frequency in the power system;
A control device that controls the power storage device to absorb or release the power based on a measurement result by the measurement device;
The control device
Effective current fluctuation compensation means for obtaining an effective current based on the current to be compensated, and generating and outputting a first compensation signal corresponding to the fluctuation of the active current;
Active power fluctuation compensation means for obtaining active power based on the compensation target current and compensation target voltage, and generating and outputting a second compensation signal corresponding to the fluctuation of the active power;
An active power command signal obtained by adding the second compensation signal to the first compensation signal is output to the power storage device.   The effective current fluctuation compensating means includes effective current calculating means for obtaining the effective current based on the compensation target current, and ramp function calculating means for obtaining a ramp function output of the effective current, and from the effective current, the lamp The power stabilization apparatus according to claim 1, wherein a function output subtracted is output as the first compensation signal. The active power fluctuation compensating means includes an active power calculating means for obtaining the active power based on the compensation target current and the compensation target voltage, and a predetermined speed arbitration for the difference between the measured frequency and the rated frequency. A frequency correction unit that multiplies the output by an output; an addition unit that adds the output of the frequency correction unit to the active power; An active power fluctuation amount extracting means for generating a compensation signal;
The power stabilizing device according to claim 1, wherein the power stabilizing device includes: A power stabilization device in an AC power system that supplies power generated by an internal combustion power generation facility and a natural energy power generation facility to a load in remote areas or remote islands, storing power and absorbing the power of the AC power system or A control device in the power stabilization device having a power storage device for discharging power to an AC power system,
In the control device that controls the power storage device to absorb or release the power based on a measurement result by a measurement device that measures a compensation target current, a compensation target voltage, and a frequency in the power system,
Effective current fluctuation compensation means for obtaining an effective current based on the current to be compensated, and generating and outputting a first compensation signal corresponding to the fluctuation of the active current;
Active power fluctuation compensation means for obtaining active power based on the compensation target current and compensation target voltage, and generating and outputting a second compensation signal corresponding to the fluctuation of the active power;
A control device for a power stabilizer, wherein an active power command signal obtained by adding the second compensation signal to the first compensation signal is output to the power storage device.