JPH0638718B2 - Synchronous machine excitation controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excitation control device for a synchronous machine, and more particularly to an excitation control device for a synchronous machine suitable for improving the steady stability of a multi-machine power system.

[Conventional technology]

As described in Japanese Patent Laid-Open No. 61-15599, a conventional device attempts to realize optimum characteristics by selecting blocks according to the system configuration and load state, but the parameters are stepwise. However, there is a problem in that the optimum control characteristics cannot always be obtained because of changes, and that control becomes unstable when the system configuration or operating state exceeds expectations.

[Problems to be Solved by the Invention]

The above-mentioned conventional technology only improves the steady-state stability by the open loop control using the fixed gain and phase constants set for the system configuration assumed in advance.
If it is not possible to perform optimal control for the operating state of the actual system that changes moment by moment, and if the operating state of the actual system deviates significantly from the assumed system state, the steady state stability is lost and control becomes unstable. In addition, there is a problem in that effective stabilization control cannot be performed for all different frequency components of the actual multi-machine system.

An object of the present invention is to provide a circuit that generates an ideal control target value Pref of active power P for improving steady-state stability in order to always perform optimum stability improvement according to changes in the system state. Provided is an excitation control device that improves the steady-state stability effective for all various fluctuation frequency components without depending on the operating state of the actual system by performing closed-loop feedback control in which the active power P follows the control target value Pref. To do.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention determines a field amount of the synchronous machine corresponding to a deviation signal between a terminal voltage and a set terminal voltage of the synchronous machine connected to a power system, and a terminal for controlling the terminal voltage. In a synchronous machine excitation control device including a constant voltage control device, a power system fluctuation signal detecting means for detecting a fluctuation signal of the power system, an internal phase difference angle component and an internal phase difference angle from an output of the power system fluctuation signal detecting means. The effective power output from the synchronous machine from the value obtained by calculating the time differential value of the component and multiplying the internal phase difference angle component by the synchronizing force coefficient and the value obtained by multiplying the time differential value of the internal phase difference angle component by the braking force coefficient Active power target value generation means for generating a target value, active power detection means for detecting active power output by the synchronous machine, and a deviation between the active power target value and the detected value of the active power, Correction signal corresponding to It was a synchronous machine excitation control device, characterized in that it comprises a correcting means for adding product to the deviation signal between the terminal voltage and the set terminal voltage of the synchronous machine the correction signal.

In addition, at least one of the terminal voltage of the synchronous machine, the armature current, the field voltage, the field current, the frequency, the rotor shaft position, and the shaft speed is the power system fluctuation signal detected by the power system fluctuation signal detection means. Good.

[Action]

With this configuration, the above-described object can be achieved according to the present invention by the following actions.

In the synchronous machine excitation control device configured as described above,
First, at least one of the signals detected by the power system fluctuation signal detecting means, the terminal voltage and the armature current, the field voltage and the field current, the rotor shaft position and the shaft speed, and the terminal voltage and the rotor shaft position is at least 1. If the set is used, the internal phase difference angle component is calculated.

If the internal phase difference angle component of the active power target value is differentiated with respect to time, the time differential value is obtained. The component proportional to the internal phase difference angle is the synchronizing force component, and the component proportional to the time differential value is the braking force component.The ratio of these components can be arbitrarily changed by changing the gains of the synchronizing force coefficient and the braking force coefficient. Since it can be set, it can be determined according to the specifications for system stabilization required for the synchronous machine.

Since the correction means forms a correction signal corresponding to the deviation between the active power target value and the active power output by the synchronous machine, the closed loop tracking control is added to the deviation signal for controlling the field amount. It can be controlled to match the actual active power of the synchronous machine. As a result, it is possible to always ensure the system stability of the synchronous machine having the specified specifications regardless of the operating state, the change of the system configuration, and the type of the exciter.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a diagram showing the overall configuration of a static exciter using a thyristor in an embodiment of the present invention. In FIG. 1, the static exciter includes a voltage Vg obtained by stepping down the terminal voltage of the synchronous machine 1 by an instrument transformer PT6 and a voltage setter (90R) 12 of an automatic voltage regulator (terminal voltage constant controller).
Deviation ε ₁ from the voltage setting value Vref from
₁ is amplified by the amplifier 13, and the automatic pulse phase shifter A
A pulse for cycle control is generated at pps14, and the exciting power source obtained through the exciting power source transformer EXTR2 is controlled by the thyristor 3 to keep the field voltage Vf of the synchronous machine 1 and the synchronous device terminal voltage Vg constant. It is a device to control.

Further, in order to improve the system stability, an active power target value generation circuit (active power target generation means) 15, which inputs the output voltage and current of the synchronous machine 1 via the instrument transformer PT6 and the instrument current transformer CT5, Active power detection circuit (active power detection means) 1
At 9, the active power target value Pref and the active power P are detected.
The gain and phase of this signal are properly corrected, and the power deviation ΔP =
The output Vpss whose gain and phase are adjusted so that Pref-P becomes zero is given as an auxiliary signal to the signal adding circuit to the automatic voltage adjusting device.

The synchronous machine 1 is connected to a power transmission line 10 via a main transformer 7, a main circuit breaker 8, and a system circuit breaker 9.

Similarly, a power system network 11 including a plurality of synchronous machines
Are connected to form a multi-machine power system.

First, the active power target value generation circuit 15 uses the current transformer CT for meters.
5. An internal induced voltage detection circuit 16 for inputting current and voltage from the instrument transformer PT6 to detect an internal phase difference angle δ of the internal induced voltage Eq, and synchronization for setting a synchronization force coefficient Kδ to the internal phase difference angle δ. The weighting factor of the following equation, which includes a force coefficient setting circuit 17 and a braking force coefficient setting circuit 18 that differentiates the internal phase difference angle δ with respect to time and sets the braking force coefficient K _ω to the time differential signal ω = Active power P
The active power target value Pref is generated.

Pref = K _δ δ + K _ω ω (1) Of the active power target value Pref, the component proportional to the internal phase difference angle δ is the synchronizing force component, and the component proportional to the time differential signal ω is the braking force component. The ratio of these components is the synchronization force coefficient K
Since it can be set arbitrarily by changing the gains of _δ and the braking force coefficient K _ω , the active power target value Pref according to the specifications required for system stabilization from the plant, that is, the ideal control target of the active power P. The value can be easily determined.

The active power target value Pref determined in this manner is an optimum signal for controlling the sway between the synchronous machine 1 and the power system 11 connected to the synchronous machine 1.

Next, using this active power target value Pref as a reference signal, a deviation ΔP = Pref−P from the active power output P is obtained. This ΔP
In the phase adjustment circuit 20, the signal Vpss obtained by gain / phase adjustment so that ΔP becomes zero is given to the signal addition circuit of the automatic voltage adjustment device. The output Vpss changes the synchronous machine field voltage Vf and the terminal voltage Vg via the amplifier 13, the automatic pulse phase shifter 14, the thyristor 3, and the field breaker 4, so that the synchronous machine active power P becomes the active power target value Pref. Closed loop control is performed so that By matching the active power P with the active power target value Pref, the synchronization component and the braking force component included in the active power P can be controlled so as to match the design target values K _δ and K _ω , so that the design target is always met. It is possible to improve system stability.

Next, the operation of this embodiment will be described with reference to FIG. Second
The figure is a detailed block diagram of FIG.

In FIG. 2, the active power target value generation circuit 15 calculates and detects the internal induced voltage q in the internal induced voltage detection circuit 16a from the terminal voltage g and the current I _G of the synchronous machine 1.

Here the internal induced voltage q is _{q =} G + jxq G j: complex number xq: a synchronous machine q-axis synchronous reactance, the phase of the internal induced voltage g is equivalent to δ internal phase angle of the synchronous machine 1.

Next, the internal phase difference angle δ of the internal induced voltage q is determined by the phase detection circuit 1
6b, and the time differential value of the internal phase difference angle δ. Is detected by the differentiating circuit 18a. These δ and ω are gain-adjusted by the coefficient setting circuits 17 and 18b, respectively, and added to obtain an active power target value Pref. Further, the active power P of the synchronous machine 1 is detected by the power converter 19 using the terminal voltage g and the current g. A deviation signal Δ between the active power target value Pref and the active power P is obtained, and the exciter transfer function G _AVR (S) 27 is calculated by the ΔP phase adjusting circuit (correction means) 20.
And output Vpss corrected for the field delay of the synchronous machine 1
To the exciter signal adder circuit. Here, the phase adjustment circuit 20 includes a DC component removal circuit 24, a gain and phase adjustment circuit 2
5, output limiter circuit 26. First, the DC component removing circuit 24 is provided to remove the signal required for system stabilization because it is the time change of ΔP and the DC component is unnecessary. Next, the gain / phase adjusting circuit 25 corrects the time delay of the exciter and the synchronous machine field circuit, and the active power target value generating circuit 15, the active power detection circuit 19, the gain phase adjusting circuit 25, the exciter transfer function G. _This is for stabilizing the closed loop control system including the _AVR (S) 27 and the synchronous machine 1.

The output Vpss of the phase adjustment circuit 20 changes the synchronous machine field voltage Vf and the terminal voltage V current I through the signal addition circuit of the exciter to change the active power P to the active power target value Pref.
Closed loop tracking control is performed so that As a result, the synchronization force and the braking force included in the active power P are designated as K _δ ,
Since the control can be performed so as to become K _ω , the fluctuation of the synchronous machine 1 can be quickly converged and the system stability can be improved.

FIG. 3 shows active power P detected by the active power detection circuit 19.
Of the internal phase difference angle component δp and the time differential value component ωp of the internal phase difference angle component, which are separately detected by the circuits 21 and 22, and the deviation with respect to each component generated by the active power target value generation circuit 15 is detected. 3 is a block diagram of a phase adjustment circuit 20 in which circuits 20a and 20b for adjusting gain and phase are provided.

The output Vpss of the phase adjustment circuit 20 changes the synchronous machine field voltage Vf, the terminal voltage g, and the current g through the signal adder circuit of the exciter in the same manner as described above, and the synchronization force included in the active power P, By performing the closed-loop follow-up control so that the braking force matches that included in the active power target value Pref,
It is possible to further improve system stability.

Next, the effect of controlling the active power P as P = K _δ δ + K _ω ω is as follows. The equation of motion of the synchronous machine 1 is However, M: Penetration constant Pm: Turbine output and secondary vibration system Substituting Becomes When the eigenvalue α of this equation is calculated And the real part of the eigenvalue α is Can always be negative and can always be stable. Further, the natural frequency of the system can always be made constant by _{keeping the} synchronizing force K _δ constant.

The above functions are shown in block diagrams in FIGS. 4 and 5.
FIG. 4 shows a simplified block diagram of the actual system. The active power P shown here becomes an output through a complicated transfer function Ge (s) of the power system, the synchronous machine, the exciter, etc., and the synchronizing force / braking force is not a controlled value. Makes it unstable. On the other hand, the fifth embodiment is applied.
According to the figure, the active power P is a value that is controlled so that P = K _δ · δ + K _ω ω, so it is always constant K _δ and K _ω regardless of the operating state and system configuration of the synchronous machine. The system stability can be improved.

In the present embodiment, the internal phase difference angle ω is obtained from the internal electromotive force q, but other than this, signals indicating the actual rotor shaft position and shaft speed and the operating state of the direct synchronous machine may be used. In addition, the internal phase difference angle δ depends on the other factors, such as the synchronous machine field voltage Vf and the field current If.
Using However, Rf: synchronous machine field resistance Tdz ': synchronous machine load time field time constant xd: synchronous machine direct axis synchronous reactance xd': synchronous machine direct axis transient reactance, which may be used.

〔The invention's effect〕

Since the present invention is configured as described above, it has the effects described below.

Since it is possible to control the actual active power P of the synchronous machine to match the active power target value Pref generated so as to have the designated braking torque component / synchronization torque component, the operating state of the synchronous machine, the change in the system configuration, and the use Regardless of the type of exciter being used, it is possible to always ensure system stability with the specified specifications.

Furthermore, since the closed-loop follow-up control is performed so that the active power P matches the active power target value Pref, the influence of external factors such as the operating state of the synchronous machine and the change in the system configuration can be hardly affected. It becomes simple and the adjustment during the trial run becomes extremely easy.

Further, both the active power target value Pref and the active power P include the signal equivalent to the influence of the mechanical output Pm of the turbine output, and the difference signal Pref-P between them.
Is used for the control signal, it is not affected by Pm.
Therefore, turbine high speed valve control (EVA: Early Valve)
Turbine output P when a system accident occurs, such as Actuation)
Even when the control that greatly changes m is also used, stable stabilization control can always be performed without being affected by the turbine output Pm.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a synchronous machine excitation control device of one embodiment of the present invention, FIG. 2 is a detailed block diagram of FIG. 1, and FIG. 3 is a block diagram of a phase adjustment circuit according to another embodiment. FIG. 4 is a block diagram showing a synchronous machine as a secondary vibration system, and FIG. 5 is a block diagram in which a control block of an embodiment according to the present invention is added to FIG. 1 ... Synchronous machine, 11 ... Power system network, 15 ...
... Active power target value generation circuit, 16 ... Internal induced voltage detection circuit, 17 ... Synchronization force coefficient setting circuit, 18 ... Braking force coefficient setting circuit, 19 ... Active power detection circuit, 20 ... Phase adjustment circuit .

Claims (2)

[Claims] 1. A terminal voltage constant control device for determining a field amount of the synchronous machine according to a deviation signal between a terminal voltage and a set terminal voltage of the synchronous machine connected to an electric power system and controlling the terminal voltage. In the synchronous machine excitation control device, a power system fluctuation signal detecting means for detecting a fluctuation signal of the power system, and an internal phase difference angle component and a time differential value of the internal phase difference angle component from the output of the power system fluctuation signal detecting means. Active power output from the synchronous machine from a value calculated by multiplying the internal phase difference angle component by the set synchronization force coefficient and a value obtained by multiplying the time differential value of the internal phase difference angle component by the set braking force coefficient Active power target value generation means for generating a target value, active power detection means for detecting active power output by the synchronous machine, and a deviation between the active power target value and the detected value of the active power, Correction signal corresponding to Generating and synchronous machine excitation control device, characterized in that it comprises a correcting means for adding the deviation signal. 2. The power system fluctuation signal detected by the power system fluctuation signal detecting means is smaller among the terminal voltage of the synchronous machine, the armature current, the field voltage, the field current, the frequency, the rotor shaft position and the shaft speed. 2. The synchronous machine excitation control device according to claim 1, wherein the number is one.