CN103427426A - Phase-shifting transformer system and control method thereof - Google Patents

Abstract

The invention discloses a phase-shifting transformer system, which includes a series branch and a parallel branch. The series branch includes a seventh isolation switch, a sixth circuit breaker, a phase shifter body, a ninth circuit breaker and a sixth circuit breaker connected in series in sequence. Ten isolation switches, wherein the eighth grounding switch is installed between the sixth circuit breaker and the phase shifter body, and the eleventh grounding switch is installed between the phase shifter body and the ninth circuit breaker; the parallel branch The circuit includes the second isolating switch, the bypass circuit breaker and the fourth isolating switch in series in sequence, wherein the third grounding switch is installed between the second isolating switch and the bypass circuit breaker, and the fifth grounding switch is installed Between the bypass circuit breaker and the fourth isolation switch. This system can meet the needs of switching between different operation modes of the phase shifter system during normal operation, and ensure that the phase shifter can quickly exit the power system when it fails, but does not affect the normal operation of the line, ensuring the safety and reliability of the power system. The invention also discloses a control method of the phase-shifting transformer system.

Description

A phase-shifting transformer system and its control method

technical field

The invention belongs to the field of FACTS (Flexible AC Transmission Systems), and in particular relates to a phase shifter system structure.

Background technique

With the development of the economy, the power load continues to increase, which puts forward higher requirements on the transmission capacity of the power grid. However, the area of the load center at the receiving end is generally small, the line corridor resources are scarce, and the construction cost of the power grid is high. At the same time, the existing transmission network also has the problem of unbalanced line power flow, some lines are heavily loaded and some lines are lightly loaded, and the line utilization rate is insufficient. Therefore, while adding new transmission lines, it is also urgent to improve the utilization rate of existing lines and improve the transmission capacity of the power grid.

The phase shifter (phase-shifting transformer) is an effective means of controlling the power flow. It is installed at one end of the transmission line. It injects a compensation voltage into the line to change the phase angle difference between the voltages at both ends of the transmission line to realize the line flow. The adjustment can avoid the overload and underload of the transmission line or the main equipment of the transformer, improve the reliability of the power supply, and realize the rational distribution of the transmission power of the line, improve the efficiency of the transmission channel, and reduce the transmission cost.

Although there are many types of phase shifter body structures, all phase shifters are operated in series on the line. In order to meet the needs of different operating modes of the phase shifter system, the system structure needs to be equipped with circuit breakers, isolation switches, and grounding. Knife switch and other primary equipment.

Xiong Xinyin's "Electrical Parts of Power Plants" (China Electric Power Press, 2009-7-1) gives the circuit breaker and knife switch configuration scheme for conventional transformers connected to the power system. As shown in Figure 1, each transformer 1′ Only circuit breakers 2' and 3' are configured on the side. When an internal transformer fault occurs or the transformer 1' needs to be isolated from the system due to operational needs, the circuit breakers 2' and 3' on each side can only be tripped, and the line is also withdrawn from the power system. However, for systems with phase shifters installed, when the phase shifter is out of operation, the transmission line needs to maintain normal operation. Therefore, the circuit breakers and knife switches of the existing conventional transformer configuration are not comprehensive enough to meet the different operations of the phase shifter system. The needs of the method need to be improved.

Contents of the invention

The purpose of the present invention is to provide a phase-shifting transformer system and its control method, which can meet the needs of switching between different operating modes of the phase shifter system during normal operation, and ensure that the phase shifter can quickly withdraw from the power system when a fault occurs, but not Affect the normal operation of the line and ensure the safety and reliability of the power system.

In order to achieve the above object, the solution of the present invention is:

A phase-shifting transformer system comprising a series branch and a parallel branch, wherein the series branch is connected in series at one end of a transmission line in a power system, and the parallel branch is connected in parallel at both ends of the series branch;

The series branch includes the seventh isolating switch, the sixth circuit breaker, the phase shifter body, the ninth circuit breaker and the tenth isolating switch in series, and also includes the eighth and eleventh grounding switches, wherein the first The eighth grounding switch is installed between the sixth circuit breaker and the phase shifter body, and the eleventh grounding switch is installed between the phase shifter body and the ninth circuit breaker;

The parallel branch includes the second isolation switch, the bypass circuit breaker and the fourth isolation switch in series, and also includes the third and fifth grounding switches, wherein the third grounding switch is installed on the second isolation switch Between the bypass circuit breaker and the fifth grounding switch is installed between the bypass circuit breaker and the fourth isolation switch.

The above-mentioned phase shifter body is installed on the power transmitting side or the power receiving side of the transmission line.

A control method for a phase-shifting transformer system as described above, which defines the following five operating states:

(1) Running state: the isolation switch and circuit breaker in the series branch are in the closing position, the grounding switch is in the off position, the isolation switch in the parallel branch is in the closing position, and the grounding switch and the bypass circuit breaker are in the off position. bit;

(2) Bypass state: the isolation switch and circuit breaker in the series branch are in the close position, the ground switch is in the off position, the isolation switch and the bypass circuit breaker in the parallel branch are in the close position, and the ground switch is in the quantile;

(3) Isolation state: the isolation switch, circuit breaker and grounding switch in the series branch are all in the position, the isolation switch and the bypass circuit breaker in the parallel branch are in the close position, and the grounding switch is in the position;

(4) Inspection state: the isolation switch and circuit breaker in the series branch are in the off position, the grounding switch is in the closing position, the isolation switch and the bypass circuit breaker in the parallel branch are in the closing position, and the grounding switch is in the off position. bit;

(5) Circuit breaker inspection state: the isolation switch and circuit breaker in the series branch are in the closing position, the grounding switch is in the split position, the isolation switch and the bypass circuit breaker in the parallel branch are in the split position, and the grounding switch is in the split position. in place;

The control method includes the following:

(a) When the system is running normally without failure, control the system to work in the aforementioned operating state according to the operating requirements;

(b) When the system fails, if the fault is an internal fault of the phase shifter body, open the circuit breaker in the series branch and close the bypass circuit breaker in the parallel branch to completely isolate the phase shifter body from the transmission line If the fault is outside the phase shifter body, close the bypass circuit breaker in the parallel branch and put the phase shifter body in the bypass state. After the external fault is removed, whether to open the bypass circuit breaker will determine The phase shifter body is switched on again, and it is set by the control word in the control and protection system.

In the above control method (b), when the fault is an internal fault of the phase shifter body, if the system is working in the running state or the bypass state, close the bypass circuit breaker, open the circuit breaker and the isolation switch in the series branch Switch to the isolated state; if it is necessary to overhaul the equipment, continue to close the grounding switch in the series branch circuit and switch to the overhaul state.

After adopting the above scheme, the present invention has the following beneficial effects:

(1) When the system is in normal operation, the combination of circuit breaker and knife switch configured in the system structure can meet the needs of different operation modes of the phase shifter system and the switching between each operation mode;

(2) When the internal failure of the phase shifter, turn off the circuit breaker of the series part of the system and close the circuit breaker of the parallel part, completely isolate the phase shifter body from the transmission line, reduce the scope of the fault, and do not affect the normal operation of the transmission line run;

(3) When the phase shifter has an external failure, close the circuit breaker of the parallel part of the system, temporarily put the phase shifter in the hot standby state, open the circuit breaker of the parallel part after the external fault is removed, and put the re-phase shifter into operation. Reduce the impact of transient external faults on system operation.

Description of drawings

Figure 1 is a structural diagram of a conventional transformer connected to a power system;

Fig. 2 is a structural diagram of the present invention connected to the power system.

Detailed ways

The technical solutions and beneficial effects of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 2, the present invention provides a phase-shifting transformer system, including a series branch and a parallel branch, wherein the series branch is connected in series at one end of the transmission line (transmitting side or receiving side) in the power system, and The parallel branch is connected in parallel at both ends of the series branch, and X represents the line impedance, which will be introduced separately below.

The series branch includes an isolation switch 7, a circuit breaker 6, a phase shifter body 12, a circuit breaker 9 and an isolation switch 10 in series, and also includes a grounding switch 8, 11, wherein the grounding switch 8 is installed on Between the circuit breaker 6 and the phase shifter body 12 , the grounding switch 11 is installed between the phase shifter body 12 and the circuit breaker 9 .

The parallel branch includes an isolation switch 2, a bypass circuit breaker 1 and an isolation switch 4 connected in series, and also includes grounding switches 3 and 5, wherein the grounding switch 3 is installed between the isolation switch 2 and the bypass breaker. Between the circuit breaker 1, the grounding switch 5 is installed between the bypass circuit breaker 1 and the isolation switch 4, and the closing time of the bypass circuit breaker 1 is shorter than that of the conventional circuit breaker.

Based on the aforementioned phase-shifting transformer system, the present invention also provides a control method, specifically including the following:

(1) When the system is in normal operation without failure, the system is defined to include five operating states: operation, bypass, isolation, maintenance, and bypass circuit breaker maintenance. Realize the control to system running state, can combine as shown in table 1, and wherein, I represents to close, and ○ represents to divide;

Table 1

circuit breaker, knife switch run bypass isolation overhaul Bypass Breaker Overhaul 1 ○ I I I ○ 2 I I I I ○ 3 ○ ○ ○ ○ I 4 I I I I ○ 5 ○ ○ ○ ○ I 6 I I ○ ○ I 7 I I ○ ○ I 8 ○ ○ ○ I ○ 9 I I ○ ○ I 10 I I ○ ○ I 11 ○ ○ ○ I ○

(a) Running state: Bypass circuit breaker 1 and grounding switch 3, 5, 8, 11 are in position, circuit breaker 6, 9 and isolation switch 7, 10 are in close position; at this time, phase shifter body 12 is put into operation Operation, by controlling the compensation voltage generated by the phase shifter body 12 to change the voltage phase angle difference between the two ends of the transmission line, thereby adjusting the line flow;

(b) Bypass state: grounding switches 3, 5, 8, and 11 are in position, bypass circuit breaker 1, circuit breaker 6, 9 and isolation switches 2, 4, 7, and 10 are in close position; The phaser body 12 is in a hot standby state, does not affect the power system, and can be put into operation at any time;

(c) Isolation state: Bypass circuit breaker 1 and isolation switches 2 and 4 are in close position, grounding switches 3, 5, 8, 11, isolation switches 7 and 10 and circuit breakers 6 and 9 are in position; At this time, the phase shifter body exits the system operation, but the transmission line can still be put into operation normally;

(d) Inspection state: bypass circuit breaker 1, isolation switches 2 and 4 and grounding switches 8 and 11 are in close position, grounding switches 3 and 5, isolation switches 7 and 10 and circuit breakers 6 and 9 are in open position At this time, the phase shifter body 12 has exited the system, and the phase shifter body 12 and its control and protection system can be overhauled. The isolation switch 7 and 10 in the series branch provide obvious breakpoints for the maintenance personnel, and the grounding knife The gates 8 and 11 ensure reliable grounding of the phase shifter body 12;

(e) Inspection state of bypass circuit breaker: bypass circuit breaker 1, isolation switches 2 and 4, and grounding switches 8 and 11 are in position, grounding switches 3 and 5, isolation switches 7 and 10, and circuit breaker 6 , 9 are in the close position; at this time, the phase shifter body 12 is put into system operation, the isolation switch 2 and 5 in the parallel branch provide obvious breakpoints for the maintenance personnel, and the grounding switch 3 and 5 ensure the safety of the bypass circuit breaker 1 Reliable grounding.

(2) When the system fails, if the fault is an internal fault of the phase shifter body, such as inter-turn short circuit, gas fault, etc., disconnect the circuit breakers 6 and 9 in the series branch and close the bypass circuit breaker in the parallel branch 1. Completely isolate the phase shifter body 12 from the power transmission line to reduce the fault range without affecting the normal operation of the power transmission line; Circuit breaker 1, disconnect circuit breakers 6, 9 and isolation switch 7, 10 to switch to the isolation state; if it is necessary to overhaul the equipment, close the grounding switch 8, 11 again, and switch to the maintenance state;

If the fault is outside the phase shifter body, such as the line where the phase shifter body is installed fails, close the bypass circuit breaker 1 in the parallel branch, temporarily put the phase shifter body in the bypass hot standby state, and wait for After the external fault is removed, whether to disconnect the bypass circuit breaker 1 and reconnect the phase shifter body 12 can be set by the control word in the control and protection system.

Finally, it should be noted that: the combination of the above embodiments only illustrates the technical solution of the present invention rather than limiting it. Those of ordinary skill in the art should understand that: those skilled in the art can modify or equivalently replace the specific embodiments of the present invention, but these modifications or changes are all within the protection scope of the pending patent application.

Claims (4)

1. a phase shifting transformer system, it is characterized in that: comprise series arm and parallel branch, wherein, series arm is connected on an end of transmission line in electric power system, and parallel branch is connected in parallel on the two ends of series arm;

Described series arm comprises the 7th isolation switch, the 6th circuit breaker, phase shifter body, the 9th circuit breaker and the tenth isolation switch of series connection successively, also comprise the 8th, 11 grounding switchs, wherein, the 8th grounding switch is arranged between the 6th circuit breaker and phase shifter body, and the 11 grounding switch is arranged between phase shifter body and the 9th circuit breaker;

Described parallel branch comprises the second isolation switch, bypass breaker and the 4th isolation switch of series connection successively, also comprise the 3rd, five grounding switchs, wherein, the 3rd grounding switch is arranged between the second isolation switch and bypass breaker, and the 5th grounding switch is arranged between bypass breaker and the 4th isolation switch.

2. a kind of phase shifting transformer system as claimed in claim 1, it is characterized in that: described phase shifter body is arranged on transmission line power transmission side or power side.

3. the control method of a phase shifting transformer system as claimed in claim 1 is characterized in that: define following five kinds of running statuses:

(1) run mode: the isolation switch in series arm and circuit breaker are in co-bit, and grounding switch is in a minute position, and the isolation switch in parallel branch is in co-bit, and grounding switch and bypass breaker are in a minute position;

(2) bypass state: the isolation switch in series arm and circuit breaker are in co-bit, and grounding switch is in a minute position, and the isolation switch in parallel branch and bypass breaker are in co-bit, and grounding switch is in a minute position;

(3) isolated state: the isolation switch in series arm, circuit breaker and grounding switch are all in a minute position, and the isolation switch in parallel branch and bypass breaker are in co-bit, and grounding switch is in a minute position;

(4) maintenance state: the isolation switch in series arm and circuit breaker are in a minute position, and grounding switch is in co-bit, and the isolation switch in parallel branch and bypass breaker are in co-bit, and grounding switch is in a minute position;

(5) overhaul of line breaker state: the isolation switch in series arm and circuit breaker are in co-bit, and grounding switch is in a minute position, and the isolation switch in parallel branch and bypass breaker are in a minute position, and grounding switch is in co-bit;

Described control method comprises following content:

(a), during the system failure free operation, according to the operation demand control system, be operated in aforementioned running status;

(b), when system breaks down, if fault is phase shifter body interior fault, the circuit breaker in the disconnection series arm the bypass breaker in closed parallel branch isolate the phase shifter body fully from transmission line; If fault is this external fault of phase shifter; bypass breaker closure by parallel branch, be placed in the bypass state by the phase shifter body, after Removal of external faults; whether disconnect bypass breaker the phase shifter body is dropped into again, the control word in controlling protection system is adjusted.

4. the control method of a kind of phase shifting transformer system as claimed in claim 3, it is characterized in that: in described control method (b), when fault is phase shifter body interior fault, if system works is under run mode or bypass state, closed bypass breaker, the circuit breaker and the isolation switch that disconnect in series arm switch to isolated state; If need to be overhauled equipment, continue the grounding switch in closed series arm, switch to the maintenance state.

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