JPS6029122B2 - Tap switching control method in AC/DC conversion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transformer for phase modifier equipment in a power system including DC power transmission, and a tap switching control method during load for a transformer parallel to the phase modifier equipment.

Generally, a DC power transmission system is provided with a phase adjustment facility to adjust reactive power, and the reactive power is maintained within an appropriate range by automatically operating this equipment.

This is to absorb the reactive power generated by the operation of the AC/DC converter using the main phase equipment, to reduce power loss due to the power transmission load, and to prevent normal operation of the AC/DC converter due to a drop in AC voltage. This is to prevent this. This phase modifier equipment is generally connected to the grid via a phase modifier transformer. Here, rather than being used exclusively for phase adjusting equipment, this phase adjusting transformer is often placed in parallel with the phase adjusting equipment and drawing the station's power supply therefrom. In a system in which a station transformer is connected in parallel with such phase modifier equipment, the primary voltage of the station transformer fluctuates due to the operation of the phase modifier equipment, resulting in fluctuations in the station power supply.

In particular, when it comes to automatic operations such as adjusting the reactive power generated by the AC/DC converter, this voltage fluctuation becomes quite large since reactive power is generated that is 50 to 60% of the power converted by the AC/DC converter. Normally, this voltage fluctuation is absorbed by the AVR control of the phase modifier transformer and the station transformer, but if the voltage fluctuation is quite large and the control time is quite long, the station transformer in between and the connection Over-excitation or voltage drop of the equipment being used becomes a problem.

In order to solve this problem, the present invention provides a bypass circuit in the AVR control circuit of the phase modifier transformer or the in-station transformer, and drives this bypass circuit according to the control command of the phase modifier equipment to switch the taps of the corresponding transformer during load. The purpose of this study is to obtain a tap switching control system for AC/DC conversion equipment that forces the machine to perform rapid switching control.

In order to achieve the above object, the present invention performs control to continuously switch the number of switching taps that can compensate for voltage fluctuations calculated in advance based on system conditions using a phase adjustment control command, and thereby Similarly, there is no integration time, and the tap switching control time is significantly shortened because it is controlled only by the switching time of the tap switching mechanism.

Of course, once the preset number of taps have been switched, the control rules can be applied to conventional AVR control.
centre. By returning , the voltage can be adjusted. Next, Fig. 1 shows an example of the system configuration of AC/DC conversion equipment.

The AC/DC converter 7 is connected to the AC bus 13 and the AC power source 12 via the converting transformer 5 and the breaker 1, and the phase modifier transformer 6 is connected to 13 via the breaker 2. Also, phase modifier transformer 6
Static capacitors (stacon or shunt capacitors) 9,
A shunt reactor 10 is connected, and a station transformer 8 is further connected to the secondary side of 6. PTI I is connected to the secondary side of the station transformer 8. Here, reactive power control is performed by opening/closing switches 3 and 4. Next, an embodiment of the tap switching control system according to the present invention will be explained with reference to FIG. In the figure, 8 and 11 are the same as 8 and ]1 in Figure 1, and 90 is an automatic voltage regulator (abbreviated as AVR), A,,A,',n,A3'
AND circuits 02 and 02' are OR circuits, and N5 and N5' are NOT circuits. Also, FF4 and FF4' are flip-flop circuits, and a signal comes to the set terminal S and is set, Q = 1.
, Q=0, and when a signal comes to the reset terminal R, it is set, and Q=0 and Q=1. 100 and 100' are effective tap number setting circuits that preset the number of taps to be switched in the method according to the present invention;
102 and 102' are switching tap number detection circuits for counting the number of taps switched by the method according to the present invention, and 101
, 101' is a comparison circuit that compares the tap numbers of 100 and 102, and 100' and 102', and outputs an output when there is a difference.

AVR90 is connected to the output of PTI I, and its output is A,,A,', which is ANDed with the Q output of FF4, FF4', and the outputs of A,,A,' are 02, 02', respectively.
It is ORed with A3' and becomes a tap switching command. F
The Q outputs of F4 and FF4' are respectively connected to comparison circuit 1 at A3'.
After ANDing with the output of 01,101'○R02,0
2' is added. Furthermore, the Q outputs are given as activation inputs of the functional tap number detection circuits 102 and 102', respectively. The outputs of the switching tap number detection circuits 102, 102' and the switching tap number setting circuits 100, 100' are input to the comparison circuits 101, 101', respectively.
The output 101' passes through NOT circuits A3, N' and N5, N5', respectively, and becomes the R (reset) side input of FF4, FF4'. The phase adjustment control command becomes the B (set) side input of FF4 and FF4'. Next, the operation of the circuit shown in FIG. 2 will be explained.

The SC9 on, S pulse 10 off command is the switch 3 on or 4 off command in Figure 1, the SC9 off, ShRI O on command is 3
It means the input command of 4.

Also, switching tap number setting circuits 100, 100', switching tap number detection circuits 102, 102', and comparison circuits 101, 101'.
100 and 100' respectively are the number of taps that should absorb the voltage that fluctuates during phase adjustment equipment control, which is calculated in advance based on the system configuration, etc., and 102 and 102' are the number of taps switched by this control method by the phase adjustment control command. Output circuit, 1
01 and 101' are circuits for comparing the tap number outputs of the above two circuits. The operation for turning on the phase control command SC9 and turning off ShRIO will be explained.

Normally, the tap cutting sliding door is controlled by the output of the automatic voltage regulator (AVR) 90 as in the past, but when a phase control command is received, flip-flop circuit FF4 (the phase control command is considered as a one-shot) is set. and AVR90
The output is locked at 1 and the switching tap number detection circuit 102 is driven.

Here, since there is a difference between the outputs of the switching tap number setting circuits 100 and 102, the output of the comparison circuit 101 becomes "1", and a tap switching command is output through 02. When tap cutting is performed, the output of 102 changes, and further, in 101, the outputs of 100 and 102 are compared. In this way, the taps are sequentially switched up to the number of taps set by the sequential switching tap number setting circuit 100. When tap switching is performed by the number of taps set in 100, the output of 101 becomes 0, and 4 is reset.

When FF4 is reset, the 90 output lock at A is released and evening switching is controlled by normal 90 automatic control. The same operation occurs when the SC9 is turned off and the ShRIO is turned on. In this embodiment, the preset number of switching taps and the number of switched taps are compared, but in addition, the input voltage of the automatic voltage regulator 90 and the preset upper limit of allowable voltage fluctuation are compared. Tap switching can be similarly controlled by comparing the level with the voltage that provides the lower limit.

According to the present invention, tap switching control is performed promptly after opening/closing control of phase modulating equipment, and voltage fluctuations caused by controlling phase competing equipment in AC/DC converter equipment can be quickly suppressed. .

This makes it an effective means for countering overexcitation and voltage drop in each device connected to the phase adjustment equipment.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the configuration of AC/DC conversion equipment, and FIG. 2 is a diagram showing an example of the configuration of the LRT tap switching control system according to the present invention. A,,A,,A3,A3...AND circuit, 02
, 02...OR circuit, FF4, FF4...
Flip-flop circuit, N5, N5...NOT
Circuit, 8... Load tap-off transformer, 9...
... Shunt capacitor, 10... Shunt reactor, 11... PT or PD, 90...
・Automatic voltage regulator, 100, 100... Functional tap number setting circuit, 101, 101... Comparison circuit, 1
02,102... Cutting fusuma tap number detection circuit. Figure 1 Figure 2

Claims (1)

[Claims] 1 Control commands for the taps of an in-house transformer connected in parallel with the phase modulating equipment of an AC/DC converter station, which is used for supplying power within the station, or a phase modulating transformer connected in series with the phase modulating equipment, to the said phase modulating equipment. and a command from an automatic voltage regulator for controlling the secondary voltage of the in-station transformer to a constant value to perform switching control, and when the reactive power deviates from the scheduled range, the output is output. A switching tap number setting circuit that is controlled according to a phase modulation equipment control command and rapidly outputs an output signal corresponding to a predetermined number of taps, and a circuit that detects the actual number of taps of the phase modulation transformer or the station transformer. A switching tap number detection circuit, a comparison circuit that inputs the output of this switching tap number setting circuit and the output of the switching tap number detection circuit, and generates an output until both input amounts match if the magnitudes of both input amounts do not match. , a logic circuit that outputs a tap switching command from the output of the comparison circuit and a signal based on the phase modifier control command, and invalidates the command from the automatic voltage regulator while this tap switching command is issued. Tap switching control system for AC/DC conversion equipment consisting of