JPH04165999A - Exciter for synchronous machine - Google Patents

Abstract

PURPOSE:To ensure safety regardless of operational state change of a system by additionally providing a device for identifying the operational state of a power system and employing the output from the device as an input signal to an exciter for synchronous machine thereby regulating the setting parameters of the exciter dynamically and optimally. CONSTITUTION:An automatic voltage regulator AVR steps down the terminal voltage V1 of a synchronous machine through an instrument transformer PT3 to produce a signal which is then compared with a set value in a voltage setter Vref. Field current If of the synchronous machine is controlled through an exciter so that the stepped down terminal voltage coincides with the set value thus controlling the terminal voltage V1. of generator to coincide with the voltage set value Vref. According to the invention, a power system identifying unit 9 provides input signals to an automatic voltage regulator and a power system stabilizing unit constituting an exciter for synchronous machine thus realizing stabilization of power system robust against large scale modification of constitution or load variation of power system.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method of adding a power system identification device to an excitation device for a synchronous machine and optimally controlling the control parameters of the excitation device using the output of this device. be.

[Conventional technology]

In the conventional technology, the optimum value of the excitation system constant is set for a fixed power system that is set in advance assuming the worst power flow condition, and the change in stability is calculated based on the system reactance xe viewed from the generator end. I had decided on constant settings that would result in low sensitivity. Alternatively, adaptive optimization has been performed focusing only on the phase and gain relationship between the generator output P and the exciter output V.

For this reason, the conventional technology is completely powerless against large changes in system operating conditions.

[Problem to be solved by the invention] The conventional technology does not take into account dynamically optimally changing the setting values or parameters of the excitation device in response to changes in the operating status of the power system, and When there is a large change in the system operation status, such as a sudden change in power consumption or a sudden change in power consumption, there is a problem that stability is lost and self-excitation diverges.

The purpose of the present invention is to add a new device to identify the operating state of the power system, and dynamically change the setting values or parameters of the synchronous machine exciter according to the output of this device, thereby improving the power system's operation status. The goal is to achieve stable synchronous machine operation even in the face of changes.

[Means to solve the problem]

In order to achieve the above objectives, a new device has been installed to identify the operating status of the power system, and the output of this circuit is used as an input signal to the excitation device for synchronous machines to dynamically optimally adjust the setting parameters of the excitation device to operate the system. This ensures stability regardless of state changes.

In addition, the power system identification and stabilization device has the following functions to stabilize the power system.

(1) A circuit for identifying actance xe when looking at the system side from the generator terminal based on the ratio of changes in the values obtained by dividing the synchronous machine active power P and reactive power Q by the square of the synchronous machine terminal voltage.

(2) System voltage, active current, and
Reactive current flow is taken in as an input signal, system reactance and local load amount are determined from these values, and the optimum excitation constant is set for the determined power system constant.

(3) Store the model system related to the relevant synchronous machine, and perform power flow calculations using the voltages, active currents, reactive currents at main points of the system, and opening/closing information of system breakers as initial conditions. Using this identified power flow state as an input signal, the excitation device constants are optimized.

[Effect]

The power system identification device operates to identify the operational state of the power system of the connected synchronous machines and inputs 1) power system impedance, 2) estimated power flow, and 3) opening/closing of each system breaker to the excitation device. Therefore, even if there is a change in the configuration, load amount, load point, or interconnection system in the actual power system, the necessary information can be sent to the excitation system, so that the synchronous machine can always be operated stably.

〔Example〕

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

The automatic voltage regulator (AVR) steps down the terminal voltage v1 of the synchronous machine via the instrument transformer PT3, and compares this signal with the voltage setter Vref (90R) so that these values match (i.e., the deviation is By controlling the field current of the synchronous machine via the exciter so that ε becomes zero, the generator terminal voltage is controlled to match the voltage setting value (V r e i). .

The present invention eliminates major configuration changes in the power system by newly using the power system identification device 9 as an input signal to the AVR (automatic voltage regulator) and PSS (power system stabilization device) that constitute the synchronous machine excitation device. It is possible to stabilize the power system robustly against load changes, etc. The signal interface between the power system operating state identification device 9 and the AVR and PSS includes a method of dynamically changing the setting constants of the AVR and PSS based on the output signal of the identification device 9, and a method of directly controlling the analog output of the identification device M9. good.

Next, an embodiment of the power system identification device will be described using FIGS. 2 to 4.

If the system can be regarded as infinite in one machine as shown in FIG. 2, the system reactance xe can be identified using the active power P and reactive power Q of only the synchronous machine as input signals. In the same figure, V I V 2 p 1 = −s j nδ xe e holds true, so by canceling δ from these, Pl, Ql
By finding the change in , -Q is found. Therefore, xe can be identified by determining the system reactance xe from the above equation by measuring ΔQ/ΔP.

Next, in the case of a power system with large local loads (PL, QL) that cannot be considered as a single machine infinite system as shown in Fig. 3, it can be reduced to line resistance Rc q and line reactance xeq as shown in Fig. 4. You can think about it.

In FIG. 4, since the following holds true, it is determined by measuring aPlaQx aV12 aVzz, and the system reactance Ze can be identified. Here, z=, /'iτ75 璽``3self=1- α
= eq As described above, the systems shown in Figures 2 to 4 can cover most of the actual system, but if more advanced identification is required for a multi-machine system, it is possible to cover the system near the target generator. By incorporating this into the identification circuit 9, the system status can be similarly identified.

〔Effect of the invention〕

According to the present invention, stable operation can be maintained at all times by dynamically controlling the setting parameters of the excitation device by identifying large changes in the operating status of the power system. can significantly improve stability.

In addition, since it is possible to identify a wide range of system operating conditions using only the operating information of synchronous machines and power plants using the power system operating state change detection circuit, it is possible to identify the stability of the power system even if power system information cannot be obtained from the power grid side. It is also possible to omit the installation of a new transmission line between the grids.

Note that the present invention is based on the SMES (Supe
r Magnetic Energy Storage
It is also applicable to superconducting synchronous machines (System) and superconducting synchronous machines.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIGS. 2, 3, and 4 are diagrams showing embodiments of a power system identification device. 9. Power system identification device, 11... Exciter.

Claims (1)

[Claims] 1. Power system operation using as an input signal any one or a combination of the output signal of the relevant synchronous machine, the output signal of the relevant internal and external synchronous machine, and the power system operating status signal. An excitation device for a synchronous machine, characterized in that it is provided with a state identification device and dynamically changes excitation device constant parameters of the synchronous machine using this circuit output signal. 2. In the system operation state identification device according to claim 1, the system operation state is characterized in that the system side is viewed from the generator terminal, which is one of the system operation states, from the respective changes in the active power P and the reactive power Q. Identification device. 3. A power system operating state identification device characterized by capturing system voltage, active power, and reactive power flow at important points in the power system, and identifying system reactance xe and local load size from these values. 4. In the power system connected to the synchronous machine, store the part that is particularly strongly related to the machine as a model system, and use it based on the voltage, active power, reactive power, closing/opening signal of the system breaker, etc. of important points in the system. A power system operating state identification device characterized by determining power flow conditions of a model system and estimating actual operation. 5. An excitation device for a synchronous machine, characterized in that when there is an operation mode in which the synchronous machine is connected to different types of power systems, the setting constant is switched depending on the type of power system to be connected to ensure stability. 6. For synchronous machines characterized by installing an operating status monitoring device at important points in the power system, and switching the excitation constant setting constant using the system output information from this device to each linked power plant to ensure stability. Excitation device. 7. Detect the rate of change of active power P and reactive power Q with respect to synchronous machine terminal voltage V, ∂P/∂V, ∂Q/∂V, and estimate the system reactance xe and local load R of the power system from these values. A power system operating state identification device characterized by: