Static state synchronization reactive compensator connected through capacitance impedance and control method (thereof)

Abstract

The invention relates to a static synchronous reactive compensation device in an electric power system and a control method thereof. The compensation device comprises a voltage-type inverter and a connection inverter which are based on a full-controlled power electronic device, as well as a capacitive impedor and a control device of the electric power system. The capacitive impedor comprises a capacitor provided for the reactive compensation and an inductor added for suppressing the current fluctuation. The device adopts capacitive impedor connection, which greatly reduces the voltage of a DCpart of the inverter, reduces the cost of the reactive compensation and the switching loss. The control method comprises the following steps: three-phase instantaneous reactive power is firstly computed, and the reactive compensation current required by each phase is computed according to the instantaneous reactive power; a fundamental voltage that the inverter needs to output to compensate the reactive power of fundamental frequency is computed according to an effective value of the fundamental frequency of the compensation current and capacitive impedance, and the reactive power is compensated dynamically. As the reactive power of each phase is independently computed, the static synchronous reactive compensation device realizes the dynamic asymmetrical reactive compensation and is suitable for three-phase three-wire systems and three-phase four-wire systems.

Description

technical field [0001] The invention relates to a static synchronous reactive power compensation device and a control method in an electric power system, and belongs to the technical field of current conversion in electrical engineering. Background technique [0002] The traditional means of reactive power compensation include mechanical input shunt capacitors, and condensers. But they all have some problems, such as the most common shunt capacitors are inconvenient to operate, and cannot effectively provide reactive power support when the system voltage is reduced. Although the dynamic performance of the condenser is better and the operating range is wider, but because it contains rotating parts, its equipment and operating costs are relatively high. [0003] The emergence of flexible alternating current transmission (FACTS) technology has brought new control technology and application means to power system. Static Var Compensator (SVC) and Static Synchronous Compensator ...

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Problems solved by technology

[0005] The existing reactive power compensation device connects the three-phase voltage inverter in parallel to the power system through a transformer or an inductance, but there is a problem of DC bias when the transformer is running. In the patent "reactive power compensation device" (Japanese Patent Office, published Date: August 13, 1996, publication number: JP Special Kaiping 8-207626A), the DC bias of the transformer in the reactive power compensation device is reduced by series capacitors, and the series capacitors in this system are equivalent to DC filters However, the equivalent total impedance of the fundamental frequency between the series connected inverter and the power system is still inductive, and the capacitor cannot be used for reactive power compensation to reduce the DC side voltage of the inverter, thereby reducing the inverter capacity

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