JPS6158500A - Digital control system of generator - Google Patents

Abstract

PURPOSE:To detect a load interruption including a remote terminal interruption without time delay by performing the prescribed logical calculation from 3-phase voltages, effective power, reactive power and internal phase difference angle of a generator. CONSTITUTION:A digital controller 11 executes an excitation, a governor calculating program, and a load interruption detecting program according to a generator terminal voltage, a rotating speed, an effective power, a reactive power and an internal phase difference angle. The excitation and the governor calculating program are started at the prescribed period of T1+T2, and a control command is output at the end time of T1. The load detecting program is repeatedly executed at the T2 time after the program is finished. Then, after the load interruption is detected, an emergency start command is applied immediately to the excitation and the governor calculating program, and the newly updated prescribed control command is output after the time T1.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention detects load interruption including far-end interruption using various physical quantities obtained by detection or calculation on the generator side, and immediately starts excitation of the generator. This invention relates to a digital control system for a generator that issues predetermined control commands to a system and a governor system.

[Prior art and its problems]

Conventionally, as a control method during load shedding, a predetermined relay, a so-called overfrequency relay, is installed outside the generator's excitation system or governor system layer digital control device to detect a rise in frequency due to load shedding, or An auxiliary contact indicating the open/closed state of the generator breaker is incorporated into the control device to detect load interruption, and a predetermined control command is issued at regular intervals based on this detection signal.

However, in the former method of detecting load interruption using an overfrequency relay, there is a time delay from when a load interruption occurs until the frequency increases. It will be later. For this reason, by the time the overfrequency relay operates, various quantities on the generator side have already changed significantly and cannot be dealt with, resulting in the disadvantage that appropriate and quick control cannot be performed. On the other hand, with the latter method of incorporating the auxiliary contact of the generator breaker, it is possible to reliably detect load interruption due to the opening of the generator breaker, but if a load interruption occurs at the far end of the generator m, this will be detected. The problem was that I couldn't do it.

[Purpose of the invention]

This invention was made under these circumstances, and provides a control system that is capable of detecting far-end shutoffs other than load shutoffs caused by opening of a generator breaker without time delay and quickly updating control commands. The purpose is to provide a method.

[Key points of the invention]

By performing predetermined logical operations from the generator's three-phase voltage, active power, reactive power, internal phase difference angle, etc., load interruptions including far-end interruptions are detected without time delay, and the generator excitation and governor are immediately activated. A predetermined control command is issued to the system.

[Implementation sequence of the invention] Fig. 1 is a diagram showing an implementation sequence of the present invention, 1A [J is a schematic diagram showing a specific example of the detection calculation unit shown in Fig. 1, and Fig. 2 is a schematic diagram showing a specific example of the detection calculation unit shown in Fig. 1. 3 is a time chart for explaining the operation of the digital control device shown in FIG. In Figure 1, 1 is a generator, 2 is a prime mover, 3 is a field filter, 4,
6 is a transformer, 5 is a control thyristor, 7 is a current transformer, 8 is a pickup coil, 9 is a rotation speed detector, 10 is a detection calculation unit, 11 is a digital control device, and 12 is a generator breaker.

The generator 1 is driven by a prime mover 2 to rotate. A predetermined voltage is applied to the field coil 3 of the generator 10 from the generator terminal 5 via the transformer 4 and the control thyristor 5, thereby generating a generator terminal voltage. The terminal voltage, armature current, field flux and rotation speed of the generator are determined by the transformer 6. Current transformer 7, pickup coil 8 and detector 9
is detected by and provided to the detection calculation unit 10.

The detection calculation unit 10 calculates, from various detected physical quantities,
The active power P, reactive power Q, and internal phase difference angle δ of the generator are calculated using a well-known method, and load interruption is detected as follows based on these calculations and the physical scenery. Here, an example of the detection method will be described with reference to FIG. 1A. In other words, this method produces 1 output when the load is cut off! This method takes advantage of the fact that the active power P, reactive power Q, and internal phase difference angle δ of the machine are each approximately zero. Therefore, the conditions that δ is O, and the conditions that P is o and Q is 0 are input to the AND gates AN1 and As2 in the figure, respectively. However, it is possible that the above conditions are met even though the load is not cut off, so the generator terminal voltage V, which is the characteristic of the generator immediately after the load cutoff,
t is greater than a predetermined value (ε) (Vt>ε), and the generator terminal voltage is in a three-phase balanced state (Vu+■v
By adding +■0 in w as an AND condition, interlocking is performed to prevent a false determination that load is not cut off or that O is load cut off. In the figure, OR is an OR gate, and the output (2) from the AND gate AN 1 p As2, J>
Load interruption is detected based on at least one of the following.

The active power of the generator calculated by the unit 10.

Reactive power, internal phase difference angle, etc. are controlled by digital control device 1.
1, the control device 11 uses this information to control the generator's excitation system (here, the control thyristor 5 is arranged) and the governor system (here, The peeling is the prime mover 2
), while another program (load cutoff detection program) checks whether a load cutoff detection signal is being output from the unit 10.

The relationship between these two programs will be explained with reference to FIG.

In the steady state before the load is changed as shown in the figure, the excitation and governor calculation program n-gram is activated at regular intervals of T1 and T2, and the control command is output at the end of this program (see ■). , the output interval is also TI+T2. For 72 hours after the end of this program, the load shedding detection program for determining whether or not load shedding has occurred is repeatedly executed several to ten-odd times, so that load shedding is monitored almost constantly. Here, for example, ■
Assuming that a load cutoff occurs as shown in Figure 1, and this is detected 13 hours after the load cutoff program issues the control command, an emergency start command is immediately given to the excitation and governor calculation program at this point, and from time point After time T1, a newly updated predetermined control command is output. At this time, since T2)T3, the control command is output earlier than in the steady state by 'r2-'r3 time, so the control can be faster than the conventional one by this time. . In this way, high-speed control is possible even for load interruptions other than load interruptions due to opening of the generator breaker.

〔Effect of the invention〕

According to this invention, in a device that digitally controls the excitation system and governor system of a generator, load shedding including far-end shedding is performed by utilizing the generator's active and reactive power, internal phase difference angle, etc. Since it is detected quickly and the excitation and governor calculation programs are started urgently,
This provides the effect of quickly suppressing steep fluctuations in various quantities during load cutoff.

[Brief explanation of drawings]

FIG. 1 is a layout diagram showing an embodiment of the present invention, FIG. 1A is a schematic diagram showing a specific example of the detection calculation unit shown in FIG. 1, and FIG. It is a time chart for explaining the operation. Code explanation 1... Generator, 2... Prime mover, 3...
...Field coil, 4,6...Transformer, 5.
...Control thyristor, 7...Current transformer,
8...Pickup coil, 9...Rotation speed detector, 10...Detection calculation unit, 11
...Digital control device, 12 ... Generator breaker, ANI, AN2 ... Song and gate, O
Lu...or gate. Figure 1 Figure 1A

Claims (1)

[Claims] The far end is calculated by calculating at least the active power, reactive power, and internal phase difference angle of the generator from various physical quantities detected on the generator side, and performing a predetermined logical operation from the calculated amounts and the three-phase voltage of the generator. a detection means for detecting load failures including power failures; and a digital device that calculates control commands for the excitation system and governor system of the generator from the calculated amount and various physical quantities, updates the control commands at predetermined intervals, and outputs the control commands. 1. A digital control system for a generator, comprising: a control means, the control means immediately issuing a control command when a load interruption is detected.