Chain type STATCOM (Static Synchronous Compensator) chain unit bypass structure with mechanical switch

Abstract

The invention provides a chain type STATCOM (Static Synchronous Compensator) chain unit bypass structure with a mechanical switch, which is characterized in that a specially designed mechanical switch is selected as a bypass circuit of a chain unit to replace a power electronic device, and the circuit has the advantages of simple structure, small selected element amount and convenience for installation and operation and supplies reliable protection for the whole chain unit, thereby realizing the redundancy function of a chain, avoiding frequent quitting of an STATCOM device, caused by a chain fault, and solving the problems of difficult type selection of a large-capacity switch device, difficult acquisition of a control power supply of the switch device and the like.

Description

technical field [0001] The invention belongs to the technical field of dynamic reactive power compensation in electric power systems, and in particular relates to a chained STATCOM chain link unit bypass structure using a mechanical switch. Background technique [0002] STATCOM-Static Synchronous Compensator (Static Synchronous Compensator) for power transmission system is a new type of static var dynamic compensation device, which is composed of voltage source converters connected in parallel to the system, and the output capacitive or inductive reactive current is continuous , adjustable and independent of the voltage at the point of connection to the system. At present, the main circuit of STATCOM mainly includes three structures, namely multiple structure, multi-level structure and chain structure. [0003] The multiple structure takes the three-phase high-power voltage source converter as the core. The DC voltage on the capacitor is converted to generate a square wave ...

AI Technical Summary

Problems solved by technology

The disadvantages are: (1) The three phases share a DC voltage support, and phase separation control cannot be performed; (2) The series and parallel connection of turn-off devices is used to increase the voltage and capacity, resulting in voltage and current equalization problems; (3) Multiplexing Transformer has large loss and occupies a large area

This structure also has certain disadvantages: (1) It is difficult to realize the capacitor voltage balance control; (2) The switching frequency increases, the switching loss increases, and the efficiency decreases; (3) Multiple independent DC power supplies are required

When a fault occurs inside the chain link unit, the H-bridge circuit is blocked and the bypass IGBT is turned on at the same time. In the process, there will be inrush current and voltage. The ability of IGBT devices to withstand the impact is relatively weak, and it is easy to be damaged due to the impact current and voltage. , and the control power supply is not easy to obtain

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