CN106026008A

CN106026008A - Transverter self-removing type flexible DC power transmission system fault reclosing method

Info

Publication number: CN106026008A
Application number: CN201610330634.2A
Authority: CN
Inventors: 李斌; 李晔; 何佳伟
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2016-05-18
Filing date: 2016-05-18
Publication date: 2016-10-12

Abstract

The invention discloses a transverter self-removing type flexible DC power transmission system fault reclosing method, and the method comprises the steps: removing a DC fault current through locking TLSM-MMC, and completing the deionization; enabling all TLSM submodules to enter a TLSM half-bridge-like locking mode; achieving a TLSM-MMC no-control rectification bridge operation mode through employing the TLSM half-bridge-like locking mode; judging that a fault disappears if a DC line does not has a current, entering a system restart operation mode, and restoring the normal operation under a restart control strategy; judging that the fault still exists if the DC line has the current again, judging that the fault is a permanent fault, and instantly locking a transverter. Compared with the prior art, the method can achieve the reclosing judgment through judging whether the current exists or not. When the fault is judged to be the permanent fault, the method can quickly lock the transverter under the condition of a very small line circuit, effectively prevents reclosing from causing secondary overcurrent impact on a system, and is low in current danger.

Description

A kind of inverter self-cleaning type flexible direct current power transmission system fault reclosing method

Technical field

The present invention relates to protecting electrical power system control field, particularly relate to a kind of flexible direct current power transmission system DC Line Fault weight Closing switch method.

Background technology

The flexible DC power transmission utilizing overhead transmission line to transmit electricity is one of efficient implementation of following high-capacity direct current transmission of electricity.Frame In the case of empty multi-line power transmission, DC Line Fault rate is greatly improved, utilize three level submodules (three-level sub-module, TLSM) formula MMC (TLSM-MMC) replaces traditional semibridge system MMC to be capable of the most clear of fault current Remove.Additionally, overhead transmission line transient fault probability is relatively big, therefore need to design suitable fault reclosing strategy.Existing Reclosing strategy is mainly after system in a period of time goes free process, unlocks current conversion station under zero energy pattern, logical Cross and judge whether that can set up DC voltage realizes the judgement to fault presence or absence.But, this method is with Voltage Establishment Whether as criterion, if the permanent fault of coinciding with, quick owing to electric capacity discharges can cross stream, cause secondary to endanger system Evil.For this problem, it is necessary to be designed to effectively reduce secondary system and cross the reclosing method of stream harm.

Summary of the invention

Electric current secondary can be caused to cross the problem of stream harm for current flexible direct current system fault reclosing strategy, the present invention carries It has a kind of inverter self-cleaning type flexible direct current power transmission system fault reclosing method, it is achieved that for TLSM-MMC Type flexible direct current power transmission system, have low current harm DC Line Fault reclosing method.

A kind of inverter self-cleaning type flexible direct current power transmission system fault reclosing method of the present invention, the method includes following Step:

Step 1, utilize TLSM inverter to remove direct fault current, and complete to dissociate；

Step 2, all TLSM inverters are put into TLSM class half-bridge non-blocking mode；

Step 3, TLSM class half-bridge non-blocking mode is utilized to realize the TLSM-MMC uncontrollable rectifier bridge method of operation；

Step 4, judge that DC line occurs that electric current carrys out failure judgement and yet suffers from or disappeared the most again；

If electric current no longer occurs in step 5 DC line, then show that fault has disappeared, then enter system reboot and run Pattern, recovers properly functioning under restarting control strategy；

If step 6 DC line occurs electric current again, then show that fault yet suffers from, it is determined that for permanent fault, stand I.e. locking TLSM-MMC.

TLSM class half-bridge non-blocking mode in described step 2 includes three kinds of implementations: implementation one, accordingly TLSM class half-bridge non-blocking mode one turns on IGBT T5, T6, T1～T4 keeps blocking, and now fault current is through continuous Stream diode D2, D3 and IGBT T5, T6 circulation；Implementation two, corresponding TLSM class half-bridge non-blocking mode Two conducting IGBT T1, T6, T2～T5 keeps blocking, and now fault current is through sustained diode 3, D8 and IGBT T1, T6 circulate；Implementation three, corresponding TLSM class half-bridge non-blocking mode three turns on IGBT T4, T5, T1～T3 And T6 keeps blocking, now fault current is through sustained diode 2, D7 and IGBT T4, T5 circulation.

The described TLSM-MMC uncontrollable rectifier bridge method of operation includes three kinds of realizations of three kinds of TLSM class half-bridge non-blocking mode The three-phase commutation bridge respectively constituted.

Directly unlock with tradition inverter based on compared with Voltage Establishment whether reclosing strategy, the present invention is coinciding with forever Electric capacity electric discharge is avoided for a long time during property fault, and owing to electric current presence or absence only need to be judged, therefore can be at the least circuit Under current conditions, quick locking inverter the most again, is not result in that the secondary of system crosses stream, effectively prevent reclosing to system The secondary caused crosses stream impact.

Accompanying drawing explanation

Fig. 1 is TLSM class half-bridge non-blocking mode circuit diagram, (a), implementation one；(b), implementation two； (c), implementation three；

Fig. 2 is TLSM-MMC uncontrollable rectifier method of operation schematic diagram, (a), based on class half-bridge non-blocking mode realize The TLSM-MMC uncontrollable rectifier method of operation one that mode one is constituted；(b), based on class half-bridge non-blocking mode realization side Formula two constitutes the TLSM-MMC uncontrollable rectifier method of operation two；(c), based on class half-bridge non-blocking mode implementation three Constitute the TLSM-MMC uncontrollable rectifier method of operation three.

Fig. 3 is a kind of DC Line Fault reclosing method for TLSM-MMC type flexible direct current power transmission system of the present invention Overall flow figure.

Detailed description of the invention

For TLSM construction features, present invention design proposes a kind of novel submodule operational mode and corresponding respectively The inverter uncontrollable rectifier method of operation, and devise accordingly a kind of have low current harm fault reclosing strategy, tool Internal appearance includes:

For TLSM topological structure feature, proposing corresponding novel submodule operational mode, the present invention is by this operational mode It is referred to as class half-bridge non-blocking mode.As Fig. 1 (a) show class half-bridge non-blocking mode implementation one, in conducting Fig. 1 (a) IGBT T5, T6, T1～T4 keeps blocking, and now fault current is only possible to through sustained diode 2, D3 and IGBT T5, T6 circulate, and it is identical that its physical characteristic touches block with half-bridge under blocking, the most named class half-bridge locking mould Formula；As Fig. 1 (b) show class half-bridge non-blocking mode implementation two, turn on IGBT T1, T6 in Fig. 1 (b), T2～T5 keeps blocking, and now fault current is only possible to through sustained diode 3, D8 and IGBT T1, T6 stream Logical, it is identical that physical characteristic also touches block with half-bridge under blocking；As Fig. 1 (c) show class half-bridge non-blocking mode in fact Existing mode three, IGBT T4, the T5 in conducting Fig. 1 (c), T1～T3 and T6 keep blocking, now fault current Be only possible to through sustained diode 2, D7 and IGBT T4, T5 circulation, physical characteristic also with the half-bridge under blocking It is identical that son touches block.

According to TLSM three kinds of implementations of class half-bridge non-blocking mode, respective design as shown in Figure 2 three kinds The TLSM-MMC uncontrollable rectifier method of operation.Under this method of operation, inverter is equivalent to a uncontrollable rectifier bridge.

As it is shown on figure 3, be a kind of DC Line Fault weight for TLSM-MMC type flexible direct current power transmission system of the present invention The overall flow of closing switch method, comprises the following steps:

Utilize TLSM inverter to remove direct fault current, and complete free process, step 1；By all TLSM Submodule puts into class half-bridge non-blocking mode, step 2；Class half-bridge non-blocking mode realizes TLSM-MMC uncontrollable rectifier bridge The method of operation, step 3；By judging that DC line occurs that electric current carrys out failure judgement and yet suffers from or the most again Disappear, step 4；If electric current I_dc=0, show that electric current no longer occurs in DC line, then fault has disappeared, and enters system Restart operational mode, under restarting control strategy, recover properly functioning, step 5；Otherwise, if electric current I_dC ≠ 0, then table Bright DC line occurs electric current again, then fault yet suffers from, it is determined that for permanent fault, immediately locking inverter, step Rapid 6.

Claims

1. an inverter self-cleaning type flexible direct current power transmission system fault reclosing method, it is characterised in that the method Comprise the following steps:

Step (1), utilize TLSM inverter to remove direct fault current, and complete to dissociate；

Step (2), all TLSM inverters are put into TLSM class half-bridge non-blocking mode；

Step (3), TLSM class half-bridge non-blocking mode is utilized to realize the TLSM-MMC uncontrollable rectifier bridge method of operation；

Step (4), judge that DC line occurs that electric current carrys out failure judgement and yet suffers from or disappeared the most again；

Step (5) if electric current no longer occurs in DC line, then shows that fault has disappeared, then enter system reboot Operational mode, recovers properly functioning under restarting control strategy；

Step (6) if DC line occurs electric current again, then shows that fault yet suffers from, it is determined that for permanent fault, Locking full-bridge submodule inverter immediately.

2. inverter self-cleaning type flexible direct current power transmission system fault reclosing method as claimed in claim 1, it is special Levying and be, the TLSM class half-bridge non-blocking mode in described step (2) includes three kinds of implementations: implementation one, Corresponding TLSM class half-bridge non-blocking mode one turns on IGBT T5, T6, T1～T4 keeps blocking, now fault electricity Flow through sustained diode 2, D3 and IGBT T5, T6 circulation；Implementation two, corresponding TLSM class half-bridge closes Latching mode two turns on IGBT T1, T6, T2～T5 keeps blocking, now fault current through sustained diode 3, D8 and IGBT T1, T6 circulate；Implementation three, corresponding TLSM class half-bridge non-blocking mode three turn on IGBT T4, T5, T1～T3 and T6 keep blocking, and now fault current is through sustained diode 2, D7 and IGBT T4, T5 Circulation.

3. inverter self-cleaning type flexible direct current power transmission system fault reclosing method as claimed in claim 1, it is special Levying and be, the described TLSM-MMC uncontrollable rectifier bridge method of operation includes that three kinds of TLSM class half-bridge non-blocking mode are real respectively The three-phase commutation bridge that existing mode respectively constitutes.