JPH04308425A - System stabilizing method - Google Patents

Abstract

PURPOSE:To realize stable power supply by detecting a change in the internal phase angle of a generator from the rotor phase of the generator and voltage phase on a system side and controlling the internal phase angle of a synchronous phase modifier by means of a high-speed phase shifter so that excessive power can be absorbed by the synchronous phase modifier. CONSTITUTION:An RC internal phase angle change detecting means 7 detects the phase difference between the inside of an RC and system and supplies the detected phase difference to a firing angle control means 8 as deltaR. On the other hand, a generator internal phase angle change detecting means 9 supplies the variation deltaC of an internal phase angle when a system accident occurs to the control means 8. The deltaC is the phase angle of a generator corresponding to the power which becomes excessive when one transmission line circuit is cut off by the accident. Then the control means 8 finds the power to be supplied to the RC from the deltaC and deltaR and controls the firing angle of a generator by outputting the control angle alpha corresponding to the value to a phase shifter. Therefore, the fluctuation of the system can be suppressed when the system accident occurs.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power system stabilization system for suppressing power fluctuations caused by load interruption in the event of a power transmission line fault.

0002

2. Description of the Related Art FIG. 4 shows a power system in which a generator 1 is connected to a bus bar 2, and two parallel power transmission lines 3 are connected via this bus bar. Note that 4 is an infinite bus bar, and a synchronous phase modifier 5 is usually installed on the power transmission line to maintain voltage stability. In FIG. 4, line reactance per line of the power transmission line is shown as X.

0003

Problems to be Solved by the Invention In the above configuration, generator oscillation in the event of a single transmission line fault will be explained with reference to FIG. First, the generator is operating at a constant internal phase difference angle commensurate with the output until the accident point (■). The accident in this case is considered to be a 3φ accident. Because one transmission line circuit is cut off, the line reactance increases and the generator internal phase difference angle decreases (point ■).

[0004] The excessive mechanical input due to the sudden decrease in generated power increases the internal phase difference angle of the generator (section 2 indicated by the arrow). Since the transmission line is reclosed at (3), the line reactance decreases and the internal phase difference angle of the generator increases. In case (2), a synchronizing force acts to correct the internal phase difference angle that has expanded too much due to inertia, but the inertia causes an overrun and the generator thereafter oscillates periodically. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a system stabilization system capable of suppressing power fluctuations and stably supplying power.

[0005]

[Means and operations for solving the problems] In order to achieve the above object, the present invention provides a power system in which a synchronous phase modifier is installed at the center of a long-distance power transmission line to adjust the voltage. The change in the internal phase difference angle of the generator is detected from the system voltage phase, and the internal phase difference angle of the synchronous phase modulator is controlled by a high-speed phase shifter so that the synchronous phase modulator absorbs excess power. Therefore, system fluctuation can be suppressed.

[0006]

[Embodiment] An embodiment will be described below with reference to the drawings. Figure 1
FIG. 1 is a configuration diagram of an embodiment of the grid stabilization system according to the present invention. In FIG. 1, the same parts as those in FIG. 4 are given the same reference numerals, and the description thereof will be omitted. A phase shifter 6 is provided between the system and a synchronous phase adjuster (hereinafter referred to as RC). 7 is an RC internal phase difference angle change detection means that detects the system phase difference angle and R.
The difference with the internal phase difference angle of C is detected. Reference numeral 8 denotes an ignition angle control means which uses the output of the RC internal phase difference angle change detection means 7 and the output of the generator internal phase difference angle change detection means 9, which will be described later, to be used as a phase shifter 6.
Derive the control output to. The generator internal phase difference angle change detecting means 9 detects changes in the generator's internal phase difference angle from the generator rotor phase and grid side voltage phase.

The basic concept of the present invention is that when one line is cut off due to a power transmission line fault, the internal phase difference of the RC is adjusted using a high-speed phase shifter so that the RC is actively used and the excess power is absorbed by the RC. It controls the angle. In short, it is a system that stores surplus power as RC inertial energy and releases it slowly to suppress system fluctuations.

Therefore, the RC internal phase difference angle change detection means 7 detects the phase difference between the inside of the RC and the system, and provides this to the firing angle control means 8 as ΔδR. On the other hand, the generator internal phase difference angle change detection means 9 provides the internal phase difference angle change amount ΔδG at the time of a system fault to the firing angle control means 8. Here, Δ
δG is the phase angle of the generator corresponding to the surplus power as a result of one transmission line being cut off due to an accident. Therefore, the firing angle control means 8 derives the electric power that should flow into the RC from ΔδG and ΔδR, and outputs a control angle α corresponding to this value to the phase shifter for control.

FIG. 2 is a diagram illustrating the contents of the calculation. First, the adder 10 calculates the system rotation angle (commercial frequency) ωR and R
The difference ΔδR is calculated from the C rotor speed ωN, and the power change amount ΔPR calculating means 20 calculates the corresponding power change amount and outputs it as ΔPR. On the other hand, the adding device 30 calculates the difference ΔδG from the system rotation angle (commercial frequency) ωR and the G rotor speed ωN, and the power change amount ΔPG calculating means 40 calculates the corresponding power change amount, and calculates the corresponding power change amount as ΔPG. Output. The firing angle control means 50
is input, and the corresponding control amount α is output.

FIG. 3 is a diagram illustrating the above effect. Until the accident occurrence point (■), the generator and RC are operated with a constant internal phase difference angle and a phase difference angle of 0. Due to the accident in (2), one line of the power transmission line was cut off and opened. As a result, the line reactance increases and the generator internal phase difference angle decreases. RC has an internal phase difference angle because the system phase angle of the VR point changes (point ■). The corresponding synchronizing force acts to return to the 0 phase, but by applying a larger phase change (the control angle shown by the solid line) using the phase shifter, the RC maintains a constant internal phase difference angle (■ (dotted line corresponding to the position) where power is supplied.

That is, the phase shifter is controlled so that the RC absorbs an amount of power commensurate with the internal phase difference angle of the generator. In (2), the line is reclosed, the line reactance decreases, and the generator internal phase difference angle increases. This change in the phase difference angle inside the generator is detected, and the phase shifter is controlled to alleviate the output fluctuation of the generator. In (2), the high-speed phase shifter is controlled so as to slowly take out the energy stored in RC.

0012

[Effects of the Invention] As explained above, according to the present invention, changes in the internal phase difference angle of the generator are detected and excess power is absorbed by the RC, so that oscillations in the event of a system fault can be reduced. It can be suppressed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of a grid stabilization system according to the present invention.

FIG. 2 is a diagram showing calculation states in chronological order.

FIG. 3 is a diagram illustrating the effects of the present invention.

FIG. 4 is a diagram illustrating stabilization of a conventional system.

FIG. 5 is a diagram showing power fluctuations when an accident occurs.

[Explanation of symbols]

1 Generator 2 Bus line 3 Power transmission line 4 Infinity bus 5 Rotary capacitor 6 Phase shifter 7 RC internal phase difference angle change detection means 8 Control means 9 Generator internal phase difference angle change detection means

Claims (1)

[Claims] [Claim 1] In a power system in which voltage is adjusted by installing a synchronous phase modifier at the center of a long-distance transmission line, changes in the internal phase difference angle of the generator are detected from the rotor phase of the generator and the voltage phase on the grid side. A grid stabilization system characterized by controlling the internal phase difference angle of a synchronous phase modifier using a high-speed phase shifter so that excess power is absorbed by the synchronous phase modifier.