Chained static synchronous compensator with active power adjusting capacity and cascading unit thereof

Abstract

The invention provides a chained static synchronous compensator with an active power adjusting capacity. The chained static synchronous compensator with the active power adjusting capacity comprises three phases of cascading chain links, connection reactors and breakers. Each phase of the cascading chain link comprises n cascading units which are connected in series at the alternating current side. One ends of the three phases of the cascading units are connected to form a neutral point of the static synchronous compensator, and the other ends of the three phases of the cascading units are connected into a three-phase grid through the corresponding connection reactors and the corresponding breakers. The invention further provides a corresponding cascading unit. An STATCOM and a BESS are combined, the capacity of controlling active power and reactive power at the same time is achieved, grid connection of medium voltage and high voltage is achieved in a manner of cascading multiple cascading units, a power switch device which is low in voltage resistance is used for achieving energy conversion of high voltage levels, modularization and redundancy design are easy to achieve, the function of balancing a battery is achieved, meanwhile, a bidirectional DC/DC converter is introduced at the direct current side, and ensuring the cycle life of the battery is facilitated.

Description

technical field [0001] The invention relates to the field of reactive power compensation of medium and high voltage power systems, in particular to a chain-type static synchronous compensator (STATCOM) with power adjustment capability and cascaded units thereof. Background technique [0002] As the most advanced power quality adjustment device at home and abroad, STATCOM can comprehensively solve power quality problems such as power grid reactive power shortage, voltage fluctuation and flicker, current distortion, and three-phase imbalance. , Good harmonic characteristics and so on. However, STATCOM needs to absorb a certain amount of active power to compensate its own loss during operation to maintain the stability of the DC side voltage, and it does not have the ability to adjust active power. [0003] The battery energy storage system (BESS) has a strong ability to regulate active power, which can solve the impact of intermittent renewable energy power generation directl...

AI Technical Summary

Problems solved by technology

[0010] Its disadvantages are: the operating range of the system is limited: it is not combined with BESS, the DC side needs to absorb a certain amount of active power to maintain the voltage stability of the DC side, it does not have the function of active power adjustment, and it cannot operate in 4 quadrants

[0014] Its disadvantages are: topological structure: it needs to be connected to the medium and high voltage power grid through a step-up transformer, which greatly increases the volume, floor area, cost and system loss of the system

[0022] Its disadvantages are: 1. DC side structure: when the system is running, the DC side of the cascaded unit will generate 2 times of pulsating power, which will affect the cycle life of the battery

This problem can be solved by adding a bidirectional DC / DC converter; 2. Hybrid cascaded topology: there is a cascaded unit in each phase bridge arm of the system to improve the system output voltage characteristics, and the remaining units are used for the active / active power of the fundamental wave Reactive power regulation, the overall topology design and control strategy are relatively complex

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