JP3311881B2 - Power stabilizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power stabilizer for inputting a voltage adjustment signal as an auxiliary signal to an automatic voltage regulator for adjusting the amount of excitation so that the terminal voltage of a generator becomes a target value.

[0002]

2. Description of the Related Art Generally, an excitation control device of a generator is provided with an automatic voltage regulator (A) for keeping a terminal voltage of the generator constant at a target voltage.
VR) and a power stabilizing device (PSS) for stabilizing the operation of the generator by adjusting its target voltage. The power stabilizing device is designed to increase the braking force against the phase difference fluctuation caused by a disturbance applied to the generator.
A stabilizing signal such as ω or a change Δf in the system side frequency is detected and calculated, and is input as an auxiliary signal of the voltage adjusting signal of the automatic voltage adjusting device.

FIG. 6 is a block diagram showing a conventional example of a power stabilizing circuit (hereinafter, referred to as ΔP-PSS) of a type using an active power change ΔP. This power stabilizing circuit reduces the noise by passing the active power change ΔP, which is a stabilizing signal, through a signal reset function unit 7 including a reset filter, a lead / lag circuit, or a band elimination filter,
The configuration is such that the steady-state deviation of the voltage is eliminated, and the phase is corrected by the phase compensation function section 8 so as to be processed into an appropriate voltage adjustment signal and output.

A power stabilization circuit that is particularly frequently used is a ΔP of a type using a change ΔP in active power.
-PSS, that is, a power stabilizing circuit for an active power change. This is because this type ΔP-PSS is resistant to high-frequency noise and does not require much phase compensation, so that setting of a function is easier than other types.

Here, when the power stabilization circuit changes the field of the generator with a phase synchronized with the angular velocity change Δω, the power fluctuation can be suppressed most efficiently. On the other hand, the phase from the output of the power stabilization circuit to the strength of the field is about 90 Hz in the oscillation period of about 1 Hz due to the delay of the field circuit.
Delay. Therefore, in order to compensate for the delay of the field circuit, the power stabilizing circuit needs to calculate the angular velocity change Δω by 9%.
It is desirable to feed back an angular acceleration change Δa that is a signal advanced by 0 degrees and is in phase with the angular velocity change Δω, but it is difficult to detect the angular acceleration change Δa.

Therefore, instead of the angular acceleration change Δa,
ΔP-PSS, which is a method of feeding back the active power change ΔP almost in proportion thereto, is adopted.

[0007]

The power stabilizing circuit .DELTA.P-PSS using the change .DELTA.P in the active power is practical, but is susceptible to low-frequency disturbances represented by changes in the output of the generator. . Normally, the phase of the power stabilizing circuit ΔP-PSS for active power change is adjusted so as to dampen power fluctuation of about 1 Hz.
It is difficult to effectively suppress the slow power fluctuation below z. Conversely, if adjustment is made so as to dampen a slow power fluctuation of 0.3 Hz or less, it becomes difficult to dampen a power fluctuation that appears well at about 1 Hz.

As described above, when the oscillation period becomes as slow as about 0.3 Hz, the delay of the field circuit becomes smaller in phase, and the phase becomes too advanced in ΔP-PSS. The power stabilizing circuit Δω-PSS using the angular velocity change Δω is more appropriate. Δω
This is because -PSS can be adjusted so that damping is effectively performed from slow oscillation of 0.3 Hz to oscillation of 1 Hz by phase compensation.

However, since the phase compensation required for the angular velocity variation power stabilizing circuit Δω-PSS is a lead compensation, the transient gain becomes large at 1 Hz or more, and as a result, it is vulnerable to high frequency noise. As a result, there is a problem that it is difficult to effectively dampen a fluctuation having a relatively short frequency of about 2 Hz. Further, the frequency stabilizing power stabilizing circuit Δf-PSS has almost the same tendency as Δω-PSS and has the same problem.

It is an object of the present invention to obtain appropriate damping over a wide range of frequencies that can occur in a normal power system from a slow cycle of about 0.2 Hz to a fast cycle of about 3 Hz, and Another object of the present invention is to provide a power stabilizing device that is resistant to noise predicted at a high frequency.

[0011]

The power stabilizing device of the present invention is provided for each of a plurality of predetermined power fluctuation modes among the fluctuations included in the output power of the generator. Calculates at least one of the angular acceleration change estimated value, the angular velocity change estimated value, and the frequency change estimated value based on the stabilization signal change amount of the generator for each of the power fluctuation modes. A plurality of observers that are separated and output as a component, and based on at least one of an angular acceleration change estimated value, an angular velocity change estimated value, and a frequency change estimated value provided for the plurality of observers. A plurality of power stabilizing circuits for calculating respective voltage adjusting signals corresponding to a plurality of power fluctuation modes, and a voltage adjusting signal from the plurality of power stabilizing circuits. And an adder for inputting to the voltage regulator.

In this case, the change in the stabilizing signal is a change in the active power of the generator, a change in the angular velocity, and a change in the frequency.
The plurality of observers are a low frequency power fluctuation mode observer, a medium frequency power fluctuation mode observer, and a high frequency power fluctuation mode observer.

Here, the low frequency power fluctuation mode observer is a power fluctuation mode having a vibration frequency of 0.5 Hz or less, and the medium frequency power fluctuation mode observer is a power fluctuation mode having a vibration frequency of about 1 Hz. The high frequency power fluctuation mode observer uses a power fluctuation mode having a vibration frequency of 2 Hz or more.

The low frequency power fluctuation mode observer is a power fluctuation mode having a vibration frequency of 0.3 Hz.
The observer for the medium frequency power fluctuation mode is a power fluctuation mode with a vibration frequency of 1 Hz, and the observer for the high frequency power fluctuation mode uses a power fluctuation mode with a vibration frequency of 3 Hz.

The observer is configured to separate mechanical vibrations from fluctuations included in the output power of the generator and calculate at least one of an angular velocity change estimation value and a frequency change estimation value for the power fluctuations. And, specifically,
The observer is in a power fluctuation mode with a vibration frequency of 1 Hz, and calculates an estimated value of mechanical vibration of 5 Hz or more. The observer is in a power fluctuation mode with a vibration frequency of 3 Hz, and calculates mechanical vibration of 5 Hz or more.

On the other hand, the angular velocity change estimated value calculated by the observer is input to the angular velocity change power stabilization circuit, and the angular acceleration change estimated value is input to the active power change power stabilization circuit. In this case, specifically, the observer that calculates the estimated value of the angular velocity change is a power fluctuation mode with a vibration frequency of 1 Hz, and the observer that calculates the estimated value of the angular acceleration change is the power fluctuation mode with a vibration frequency of 3 Hz. It is.

In the present invention, if necessary, there is provided switching means for selecting an observer to be operated among a plurality of observers provided corresponding to the plurality of power fluctuation modes.

[0018]

According to the power stabilizing device of the present invention, each observer generates power for each of a plurality of predetermined power fluctuation modes among the fluctuations included in the output power of the generator. At least one of the angular acceleration change estimated value, the angular velocity change estimated value, and the frequency change estimated value is calculated based on the stabilization signal change of the machine. The calculated angular acceleration variation estimation value, angular velocity variation estimation value, and frequency variation estimation value are input to power stabilization circuits provided corresponding to the respective observers, and the voltages corresponding to the respective power fluctuation modes. Calculate the adjustment signal. The voltage adjustment signals from these power stabilization circuits are added by an adder and input to an automatic voltage adjustment device.

Therefore, 0.5 Hz of the power fluctuation
In the following low-frequency power fluctuation, a voltage adjustment signal is obtained by a low-frequency power fluctuation mode observer and a power stabilization circuit provided corresponding thereto. Similarly, a medium frequency power fluctuation of about 1 Hz The voltage regulation signal is obtained by the frequency power fluctuation mode observer and the power stabilization circuit provided corresponding thereto, and the high frequency power fluctuation of 2 Hz or more is obtained by the high frequency power fluctuation mode observer and the power provided corresponding thereto. A voltage adjustment signal is obtained by the stabilization circuit.

The observer separates mechanical vibrations from fluctuations included in the output power of the generator, and calculates at least one of an angular velocity variation estimation value and a frequency variation estimation value for the power fluctuations. Therefore, of the mechanical vibrations included in the power fluctuation, a mechanical vibration component to be removed can be separated as a mechanical vibration component. As a result, harmonic noise such as mechanical vibration, which is a problem in Δω-PSS and Δf-PSS, can be removed from the voltage adjustment signal output from the power stabilization circuit.

Further, in the present invention, if necessary, an observer to be operated among a plurality of observers provided corresponding to the plurality of power fluctuation modes is selected by the switching means. Thereby, a required observer can be selected.

[0022]

Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of a first embodiment of the present invention. The power stabilizing device of the present invention has a multi-mode observer 1 and a multi-mode power stabilizing circuit 2. The multi-mode observer 1 has a plurality of observers 1a to 1n, and the multi-mode power stabilization circuit 2 has a plurality of power stabilization circuits 2a to 2n.
n.

The plurality of observers 1a to 1n are provided for each of a plurality of predetermined power fluctuation modes among the fluctuations included in the output power of the generator. Then, based on the change in the stabilization signal of the generator for each of the power fluctuation modes, the estimated value of the angular acceleration change Δas1 to Δa1 to Δa1
sn, angular velocity change estimated values Δωs1 to Δωsn, and frequency change estimated values Δfs1 to Δfsn are calculated. As the stabilizing signal change, the active power change ΔP of the generator, the angular velocity change Δω,
Although the frequency change Δf is used, in the first embodiment shown in FIG. 1, the active power change ΔP and the angular velocity change Δ
An example using ω is shown.

The plurality of power stabilizing circuits 2a to 2n
It is provided corresponding to the plurality of observers 1a to 1n. Then, based on at least one of the angular acceleration change estimated values Δas1 to Δasn, the angular velocity change estimated values Δωs1 to Δωsn, and the frequency change estimated values Δfs1 to Δfsn from the plurality of power stabilizing circuits 2a to 2n. Thus, the respective voltage adjustment signals corresponding to the plurality of power fluctuation modes are calculated.

The plurality of power stabilizing circuits 2a to 2a
The voltage adjustment signal, which is an output signal from n, is added by the adder 3 and input to the automatic voltage adjustment device. by this,
The automatic voltage regulator uses the voltage regulation signal as an auxiliary signal,
The amount of excitation is adjusted so that the terminal voltage of the generator becomes the target value.

Here, the power stabilizing device of the present invention reproduces a plurality of power fluctuations with the multi-mode observer 1. That is, the multi-mode observer 1 calculates the active power change estimated value ΔPs, the angular velocity change estimated value Δωs, the frequency change estimated value Δfs, and the angular acceleration change estimated value Δas corresponding to each power fluctuation mode. The active power change estimated value ΔPs, the angular velocity change estimated value Δωs, or the frequency change estimated value Δfs, the actually measured active power change signal ΔP, the angular velocity change signal Δω, and the frequency change signal Δf And a function of feeding back a signal obtained by multiplying the deviation signal by a gain. Thereby, the plurality of power fluctuation modes are separated and detected without phase delay.

The multi-mode observer 1 includes an integrator that integrates each power fluctuation mode to calculate angular velocity by integrating angular acceleration, an integrator that integrates angular velocity to calculate a phase difference angle, and multiplies the angular velocity by a constant. And an adder for calculating the angular acceleration by subtracting the deceleration torque and the active power change signal.

Next, the principle by which the multi-mode observer 1 can separate and extract various power oscillation modes without phase delay will be described. As described above, the multimode observer 1 of the present invention has a function of reproducing several types of power fluctuation. Therefore, when the active power change ΔP due to the power fluctuation is detected, the expected power fluctuation is simulated.

In this case, if only a simulation is performed, the vibration frequency and the damping rate of the actual power fluctuation deviate slightly from those of the simulator, so that the prediction by the simulation and the actual observation value deviate with time. Therefore, the active power change ΔP, the angular velocity change Δω,
The deviation between the estimated value of the frequency change Δf by the simulator and the actually measured value is multiplied by an appropriate gain, and then returned to the simulator.

Thus, the phase and magnitude of the estimated value of the simulator can be corrected to be substantially equal to the actually measured value. This general theory has been established as an observer theory and a Kalman filter theory in the control theory.

Since such a power fluctuation reproducing function is difficult to operate in a power fluctuation mode other than the power fluctuation mode of the function, it is possible to accurately separate and extract components corresponding to each power fluctuation mode. Also, unlike a bandpass filter, there is almost no phase delay. Therefore, the multi-mode observer 1 including the main power fluctuation mode can take out each mode with high accuracy without being affected by other modes, and has a small phase delay.

Next, as the plurality of observers 1a to 1n, low frequency power oscillation mode observers 1a corresponding to the power oscillation mode having an oscillation frequency of 0.5 Hz or less,
And a high frequency power fluctuation mode observer 1c corresponding to a power fluctuation mode having a vibration frequency of 2 Hz or more. Correspondingly, a power stabilizing device including power stabilizing circuits 2a, 2b, 2c will be described.

Specifically, the low-frequency power fluctuation mode observer 1a is in the power fluctuation mode with a vibration frequency of 0.3 Hz, and the middle frequency power fluctuation mode observer 1b is 1H.
The power stabilizing device in the power fluctuation mode with the vibration frequency of z and the high frequency power fluctuation mode observer 1c in the power fluctuation mode with the vibration frequency of 3 Hz will be described.

That is, the power fluctuation mode to be separated,
The parameters K1, K2,... Of the DeMello / Concordia model for each of the three types of 0.3 Hz, 1 Hz and 3 Hz. . . K6 and the damping rate D are appropriately determined in accordance with the oscillation cycle. Usually, these parameters are expressed as a function of the system impedance, and the oscillation period is adjusted by appropriately determining the system impedance. Using this model, the following relational expression holds for one mode.

[Formula 1]

Next, the following equation is obtained by rearranging this equation into a state equation expression.

[Formula 2]

In this equation, x is the state quantity, y is the observed quantity, and u is the output of the PSS. A, B, and C are constant determinants determined by modes. The subscript i represents the mode type. In the above, a state equation was established for one mode. In the case of this embodiment, there are three types of power fluctuation modes of a vibration frequency of 0.3 Hz, a vibration frequency of 1 Hz, and a vibration frequency of 3 Hz. The state equation expressing the full power fluctuation mode to be used for No. 1 is as follows.

[Equation 3]

By expressing such a state equation, the multimode observer 1 is expressed by the following equation.

(Equation 4)

In this equation, the subscript s indicates an estimated value, and y is an observed value. L is a matrix of 9 rows and 2 columns, and is a field-back gain of the observer. This matrix can be calculated as a kalman filter, but it can also be determined so that the estimated value converges appropriately. In particular, when it is not easy to adjust all of the components in the 9 rows and 2 columns, in particular, L is set so that only the state of the generator, that is, the change in acceleration Δa and the change in angular velocity Δω is corrected. You may decide. In the electric power stabilizing device configured as described above, the multi-mode observer 1 estimates the change Δ 変 化
asi (i = 1, 2, 3) and angular velocity change estimated value Δωs
i (i = 1, 2, 3) is taken out and supplied to each of the power stabilizing circuits 2a, 2b, 2c optimally adjusted for each power fluctuation mode. The power stabilizing circuit 2a adjusted to the power fluctuation mode of 0.3 Hz operates almost according to the angular velocity change estimated value Δωs1. The other two power stabilizing circuits 2b and 2c almost output the estimated value Δ of the change in angular acceleration.
It operates according to as2 and Δas3. The reason for adjusting the power stabilizing circuits 2a, 2b, and 2c in this manner is as follows.

Considering the one-machine-to-infinite bus system, the output of the power stabilization circuit, that is, the transfer function from the PSS output to the electric torque change ΔTe has a delay as shown in FIG. 2 due to the delay of the field circuit. Existing. FIG. 2 is a Bode diagram showing the transfer characteristics of the field circuit. FIG. 2 (a) shows the gain characteristics, and FIG. 2 (b) shows the phase characteristics.
Since there is such a delay of the field circuit, a damping force against power fluctuation is obtained by compensating for this delay and changing the electric torque change ΔTe so as to be synchronized with the angular velocity change Δω.

Therefore, there is a different optimum phase compensation depending on the power fluctuation period. Also, large phase compensation is not preferable because it amplifies high frequency noise. Therefore, the amount of phase advance compensation is reduced by using an angular acceleration change Δa that is 90 degrees ahead of the angular velocity change Δω in advance in the power stabilizing circuits 2b and 2c requiring a large phase compensation. On the other hand, the angular velocity change Δω is used as it is in the power stabilizing circuit 2a which does not require a very large phase lead compensation. By adding the outputs of the three types of power stabilizing circuits 2a, 2b, and 2c by the adder 3, a final voltage adjustment signal is obtained. This allows optimal damping to be added to any possible power system perturbations.

Next, FIG. 3 shows a second embodiment of the present invention. The multi-mode observer 1 of the second embodiment includes an observer 1a for a power fluctuation mode for observing a power fluctuation mode, and an observer 1b for a mechanical vibration mode for monitoring a mechanical vibration of a generator. . That is, the active power change ΔP may include not only power fluctuation but also mechanical fluctuation. In that case, the mechanical fluctuation to be removed is separated as a mechanical vibration component. Thereby, Δω-PSS
It is possible to remove harmonic noise such as mechanical vibration, which was a problem with Δf-PSS, from the PSS output.

The multimode observer 1 separates the mechanical vibration from the fluctuation included in the output power of the generator by the observer 1b, calculates an estimated value Δωs of the angular velocity change with respect to the power fluctuation, and calculates the Δω of the multimode power stabilizing circuit 2. -PSS to output the angular velocity change estimation value Δωs. In this case, the vibration frequency of the power fluctuation in the observer 1a is, for example, a power fluctuation mode with a vibration frequency of 1 Hz,
Alternatively, the power oscillation mode is a vibration frequency of 3 Hz, and the vibration frequency of the observer 1b is set to a mechanical vibration of 5 Hz or more. Here, the transfer function of the mechanical vibration mode can be generally written as the following equation.

(Equation 5)

Therefore, in the same manner as in the first embodiment, the power fluctuation mode and the mechanical vibration mode are combined into one to obtain a state equation, and the multi-mode observer 1 is configured based on the equation. The multi-mode observer 1 estimates an angular velocity change estimated value Δωs of the power fluctuation mode, and obtains Δω−PSS
To supply. Since the multi-mode observer 1 can separate the mechanical vibration and the power fluctuation mode, it is possible to obtain the angular velocity change estimated value Δωs having an extremely small mechanical noise component.

Therefore, when a large lead compensation is made for the delay compensation of the field circuit, which has been a problem in the conventional Δω-PSS, mechanical noise included in the angular velocity change Δω is amplified to increase the shaft of the generator. Can solve the problem of shaking.

Although the second embodiment uses Δω-PSS as the power stabilizing circuit, the same applies to Δf-PSS using a frequency change. In general, the power fluctuation mode is often 1 Hz, but when the impedance between adjacent generators is small,
Vibrations of about 3 Hz may be a problem. In such a case, it is difficult to separate the power fluctuation mode and the mechanical vibration mode with the conventional power stabilizing device. Therefore, the separation of the power fluctuation mode and the mechanical vibration mode according to the second embodiment is particularly effective. Become.

FIG. 4 is a block diagram showing a third embodiment of the present invention. In the third embodiment, in order to effectively utilize the characteristics of the power stabilizing circuit for angular velocity change (Δω-PPS) and the characteristics of the power stabilizing circuit for active power change (ΔP-PSS), Δω -PPS is a power fluctuation mode with a vibration frequency of 1 Hz, and ΔP-PSS is a power fluctuation mode with a vibration frequency of 3 Hz. This is Δ
ω-PPS requires large phase lead compensation, and Δω−
This is because the short-period fluctuation of about 3 Hz, which was difficult to control in the PPS, is separated, and the separated short-period fluctuation of about 3 Hz uses the ΔP-PSS, which does not require much phase advance.

That is, the multimode observer 1 in the third embodiment is a power fluctuation mode observer 1a for observing power fluctuation having a fluctuation period of 1 Hz.
And a power fluctuation mode observer 1b for observing a power fluctuation having a fluctuation period of about 3 Hz.

The angular velocity change estimated value Δωs from the observer 1a is input to the angular velocity change power stabilizing circuit (Δω-PPS) 2a of the multi-mode power stabilizing circuit 2, and the angular acceleration change estimated from the observer 1b is estimated. The value Δas is input to a power stabilizing circuit (ΔP-PSS) 2b for an active power change.

As a result, only short-period fluctuations of about 3 Hz, which were difficult to control with Δω-PPS requiring large phase lead compensation, are separated,
By using -PSS, optimal phase compensation can always be realized.

FIG. 5 is a block diagram showing a fourth embodiment of the present invention. In the fourth embodiment, a switching means 9 for selecting an observer to be operated from a plurality of observers 1a to 1n provided corresponding to a plurality of power fluctuation modes in the multi-mode observer 1 is provided. Things.

During the operation of the generator, there may be cases where it is not always necessary to actually observe a large number of power fluctuation modes. In particular, incorporating a power fluctuation mode or a mechanical vibration mode, which does not actually exist, into the observer or incorporating the corresponding power stabilization circuits 2a to 2n complicate the calculation and has no benefit.

Therefore, such a disadvantage can be eliminated by preparing the switching means 9 for removing an unnecessary mode. Such switching means 9 can be easily realized by providing on / off switches in the power stabilizing circuits 2a to 2n corresponding to the respective oscillation modes of the observers 1a to 1n as shown in FIG. I can do it.

[0053]

As described above, according to the present invention, the power fluctuation mode is separated by using the multi-mode observer, and the optimum power stabilization circuit is set for each power fluctuation mode. Phase compensation can be realized. Also, the gain can be independently and optimally set.

Further, by configuring the multi-mode observer in the power fluctuation mode and the mechanical vibration mode, it is possible to separate them. As a result, mechanical noise included in the angular velocity change Δω signal in the power fluctuation mode, which has been conventionally difficult to handle, can be significantly reduced.
The same effect is obtained for the frequency change Δf signal.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a Bode diagram showing a transfer characteristic of a field circuit.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a configuration diagram showing a third embodiment of the present invention.

FIG. 5 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram showing a conventional ΔP-PSS.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multi-mode observer 2 Power stabilization circuit 3 Adder 7 Reset function 8 Phase compensation function 9 Switching means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-280714 (JP, A) JP-A-59-230431 (JP, A) JP-A-5-83859 (JP, A) 35975 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 3/00-5/00 H02P 9/14

Claims (11)

(57) [Claims] 1. A power stabilizing device for a generator for inputting a voltage adjustment signal as an auxiliary signal to an automatic voltage regulator for adjusting an excitation amount so that a terminal voltage of the generator becomes a target value. Is provided for each of a plurality of predetermined power fluctuation modes among the fluctuations included in the output power,
Calculating at least one of an angular acceleration change estimated value, an angular velocity change estimated value, and a frequency change estimated value based on the stabilization signal change of the generator for each of the power fluctuation modes. A plurality of observers that are separately output as components corresponding to the power fluctuation mode, and the angular acceleration change estimation value, the angular velocity change estimation value, and the frequency change estimation value that are provided corresponding to the plurality of observers. A plurality of power stabilization circuits for calculating respective voltage adjustment signals corresponding to the plurality of power fluctuation modes, based on at least one of the plurality of power oscillation modes, and An electric power stabilizing device, comprising: an adder for adding a voltage adjusting signal and inputting the same to the automatic voltage adjusting device. 2. The power stabilizing device according to claim 1, wherein the stabilizing signal change is a change in active power, a change in angular velocity, and a change in frequency of the generator. 3. The plurality of observers include a low frequency power fluctuation mode observer, a medium frequency power fluctuation mode observer, and a high frequency power fluctuation mode observer. Item 3. An electric power stabilizer according to Item 2. 4. The low frequency power fluctuation mode observer is a power fluctuation mode having a vibration frequency of 0.5 Hz or less, and the medium frequency power fluctuation mode observer is 1 Hz.
The power stabilizing device according to claim 3, wherein the power stabilization mode is a power oscillation mode having a vibration frequency of the order, and the high frequency power oscillation mode observer is a power oscillation mode having an oscillation frequency of 2 Hz or more. 5. The low frequency power fluctuation mode observer is a power fluctuation mode having a vibration frequency of 0.3 Hz.
5. The medium frequency power fluctuation mode observer is a power fluctuation mode with a vibration frequency of 1 Hz, and the high frequency power fluctuation mode observer is a power fluctuation mode with a vibration frequency of 3 Hz. 6. Power stabilizer. 6. The observer separates mechanical vibrations from fluctuations included in the output power of the generator, and calculates at least one of an angular velocity variation estimation value and a frequency variation estimation value for the power fluctuations. The power stabilizing device according to claim 1, wherein: 7. The power stabilizing device according to claim 6, wherein the observer is in a power fluctuation mode with a vibration frequency of 1 Hz and is a mechanical vibration of 5 Hz or more. 8. The power stabilizing device according to claim 6, wherein the observer is in a power oscillation mode with a vibration frequency of 3 Hz and is a mechanical vibration of 5 Hz or more. 9. The method according to claim 1, wherein the estimated value of the angular velocity change is input to a power stabilization circuit for angular velocity change, and the estimated value of the angular acceleration change is input to a power stabilization circuit for active power change. The power stabilizing device according to claim 1, wherein: 10. The observer for calculating the angular velocity change estimation value is a power oscillation mode with a vibration frequency of 1 Hz, and the observer for calculating the angular acceleration change estimation value is in a power oscillation mode with a vibration frequency of 3 Hz. The power stabilizing device according to claim 9, wherein: 11. The switching device according to claim 1, further comprising switching means for selecting an observer to be operated from among the plurality of observers provided corresponding to the plurality of power fluctuation modes. Power stabilizer.