JPS58212328A - Controller for thyristor reactive power compensating device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] In a silisk-type reactive power compensator installed for the purpose of stabilizing voltage in a power transmission system or distribution system, constant voltage control is usually used, and this method does not Does not respond to voltage changes. Therefore, the present invention attempts to improve the response characteristics of the above control by detecting a steep change in the reactive power of the load.

First, control of this conventional thyristor type reactive power compensator will be explained.

FIG. 1 shows an example of a conventional constant voltage control method in a thyristor type reactive power compensator.

In the figure, numeral 1 is a thyristor-type reactive power compensator connected to, for example, a substation busbar, and is made up of a series circuit of a reactor and a thyristor connected in antiparallel.

A voltage transformer (PT) 2 is connected to the mother aβ, and this PT2
Difference △Vsk between the detected bus voltage value v5 obtained by rectifying the output of by the rectifier Rf and the average value ■s passed through the low-pass filter (LPF) 3, low-pass filter (LPF, ) 4
The reactor current of the reactive power compensator 1 is controlled by a thyristor through the Fanokunyong circuit and the pulse generating circuit 5.

FIG. 2 shows an example of steep voltage variation control of a reactive power compensator used to prevent flicker in a conventional arc furnace.

Current in a variable load 7 such as an arc furnace 1. Based on the bus power *5, find the instantaneous reactive power Q5 with the reactive power detector 6,
Throughout the function circuit and the Noculus generating circuit 5, the reactor current of the reactive power compensator is increased or decreased by a thyristor according to the reactive power of the load, thereby suppressing linkage in the system.

Of the above explanations, the former, as mentioned above, compensates for reactive power by comparatively amplifying it with LPF4 so that the difference △■5 between the mother IT pressure ■5 and the average value ■5 due to LPF3 falls within an appropriate range. The reactor current of the device 1 is controlled.

In this case, the time constants τl and τ2 of LPFB and LPF4 are τ
1) τ2 is selected, and voltage fluctuations in the time domain determined by τl can be suppressed.

This range is usually in the range of about 0.1 seconds to several seconds to several tens of seconds, and if a faster response than this is attempted, the reactive power compensator becomes unstable.

``Also, as mentioned above, the latter detects the instantaneous reactive power QS of the load, controls the reactor current in accordance with this ?5, and suppresses the fringe of the grid power □.

This method has the effect of suppressing even fast fluctuations of about 0.001 seconds, but since it is open loop control, very high precision control cannot be expected.

In view of the actual situation in the control of the reactive power compensator as described above, the present invention calculates reactive power compensation by adding the difference between the instantaneous reactive power Qs and its average value, the difference between the bus voltage (■), and its average value (■). It is used as a control signal for the device to suppress steep voltage fluctuations in the former and relatively slow fluctuations in the latter, thereby stabilizing voltage changes i1J' in the power transmission system or distribution system.

Examples of the present invention will be described below.

In the block diagram of FIG. 3, A is a constant voltage control system signal detection block, and B is a reactive power control system signal detection block. In block A, the instantaneous voltage ? Signals vs and L obtained by inputting s and applying current to it
Add the difference in the voltage average value ■s through PF3, . This difference signal 1 ΔV5 is compared and amplified by the LPF 4 and output. This signal Δ■5 is similar to that of the conventional example shown in FIG. 1, and has a slow constant voltage control function.

In block B, the variable load current 1s obtained by the means already explained and the above! pressure'
Using the instantaneous reactive power QS obtained by inputting Js to the reactive power detector 6 as input, the adder 8 outputs the difference △Qs between this QS and the reactive power compensator S passed through the LPF 9.
Ru. This corresponds to the sudden change part of Δqs&i.

This ΔgsiqLPF4 output Δ■5 is added by an adder 8, and the reactor current of the reactive power compensator using a thyristor is controlled through a function circuit and a pulse generation circuit 5.

In this case, the time constant 73 of the LPF 9 is appropriately selected,
△Qs compensates for fluctuations as fast as 0.1 seconds, which are compensated by the constant voltage control system signal V5, and changes as slow as 0.1 seconds, which can be compensated for by the constant voltage control system, etc. For Δ
Ensure that Q5 is sufficiently damped.

FIG. 4 shows the response speed according to the present invention when the system voltage changes in a Ste-knob pattern. In response to sudden fluctuations in bus voltage, the reactive power compensator is activated immediately by △QS, and when the bus voltage remains at the fluctuated level, △
(5) indicates that the reactive power compensator operates.

As explained above, according to the present invention, it is possible to compensate to a certain extent even for steep voltage fluctuations in the order of io, ol to old seconds, which cannot be compensated for in the conventional example shown in FIG.
It is possible to stabilize the system voltage with high precision even for fluctuations of several seconds to several tens of seconds rather than 0.1 seconds.

Note that the fluctuations are detected using low-pass filters LPF9 and LPF3k for the flocks A and B of the embodiment in FIG. 3, and 1-□=□]+Sτ]
+ Sτ may be connected to the o-panu filter by only the crab, no-inno-ζ filter.

[Brief explanation of drawings]

1 and 2 show electronic control of a conventional thyristor reactive power compensator, and FIG. 3 shows an embodiment of the present invention. FIG. 4 shows the response speed # of the system voltage fluctuation of the control device of the present invention.

Claims (1)

[Claims] (1) In a silisk-type reactive power compensator installed for the purpose of voltage stabilization in a power transmission system or distribution system,
In addition to using constant voltage control, in order to improve the response speed, the reactive power generated by the load is detected, and the difference signal between the reactive power and the average value of the reactive power obtained by passing this reactive power through a low-pass filter, or the reactive power A control device for a silisk-type reactive power compensator, characterized in that a signal obtained through a bypass filter is used.