The so-called auto reclosing circuit breaker is an automatic device which automatically puts the circuit breaker into operation according to the need after the breakdown. The use of auto reclosing device in power system greatly improves the reliability of power supply, reduces the loss of power outage, improves the transient stability level of power system, and enhances the capacity of transmission lines.
1. Classification of auto reclosing circuit breaker
1.1 According to the action of reclosure, it can be divided into electrical type and mechanical type.
1.2 According to the way that reclosure acts on circuit breaker, it can be divided into three kinds: three-phase common reclosure, single-phase reclosure and comprehensive reclosure.
1.3 According to the composition principle of reclosure, it can be divided into electromagnetic type, transistor type, integrated circuit type and digital (micro-computer) type.
1.4 According to the number of movements, it can be divided into one-time and multiple.
1.5 According to the operating conditions, it can be divided into single power supply reclosure and double power supply reclosure. Bilateral power supply reclosure can be divided into three types: verification of no-voltage reclosure, verification of the same period and non-verification.
2. Basic requirements for auto reclosing circuit breaker
2.1 In the following cases, auto reclosing circuit breaker should not be operated: manual tripping by operation attendants or remote control device tripping by unattended substations; automatic load shedding device operated at frequency or load control device operated when tripping; protection action tripping when manual power was sent to the fault line; bus differential protection or circuit breaker failure protection action; standby power supply. When the switching (or mutual switching) device trips or the circuit breaker is in an abnormal state and the reclosure is not allowed.
2.2 In addition to the above, after the circuit breaker trips due to relay protection action or other reasons, the reclosing device shall act to make the circuit breaker reclosed.
2.3 The reclosing device should be able to return automatically after the action and be ready for the next action, but the number of actions should be in accordance with the pre-set.
2.4 The reclosing device should be able to cooperate with relay protection to achieve pre-reclosing or post-reclosing acceleration.
2.5 In the line of bilateral power supply, the starting condition of reclosure should be limited by synchronous or non-voltage verification, and non-synchronous reclosure network should not be caused.
2.6 The start-up mode of reclosure generally adopts the non-corresponding start-up mode, and the protection start-up mode can also be used for the protection of microcomputers and integrated circuits.
2.7 reclosure operation should have delay function, and there should be more than two kinds of time to choose for power grid above 220 kv.
2.8 The charging time of auto reclosing circuit breaker should be 15-25s, and the faster the discharge, the better.
3. Selection Principle of reclosure Mode
3.1 Three-phase common primary reclosure mode
3.1.1 is suitable for 110 kV and below power grids, especially for dense ring grids in centralized power supply areas, which can operate stably without reclosing after line tripping.
3.1.2 is suitable for single-side power supply radiation circuit.
3.1.3 is not applicable at the outlet of large units.
3.2 Single Phase Reclosure and Comprehensive Reclosure
3.2.1 is suitable for 220 kV and above power grids. When single-phase grounding fault occurs, if three-phase reclosure can not guarantee the stability of the system, or the regional system will have a large area of blackouts, or will lead to important load blackouts, especially the high-voltage distribution lines of large units.
3.2.2 The use of three-phase reclosure circuit, when the use of single-phase reclosure system to restore power supply has a better effect.
3.3 Verify no voltage or verify synchronous reclosing mode
3.3.1 is applicable to the lines with power supply at both ends and the lines that do not allow non-synchronous closing.
3.3.2 The current on another double circuit line can be directly checked to determine the same period.
3.4 Non-synchronous reclosure mode
3.4.1 There should be three or more closely connected lines between power plants or power systems operating side by side.
3.4.2 The impulse current generated during non-synchronous reclosure does not exceed the allowable value.
3.4.3 After reclosure, the power system can quickly resume synchronous operation.
3.4.4 During the oscillation process caused by non-synchronous reclosure, the influence on important loads is small.
