Chained battery energy storage system integrated with active power filter

Abstract

The invention relates to a chained battery energy storage system integrated with an active power filter. The chained battery energy storage system comprises a three-phase main convertor, a three-phase auxiliary convertor, three connection electric reactors and three breakers. In terms of each phase of the battery energy storage system, one ends of alternating current sides of the main convertor are in cascade connection with one ends of alternating current sides of the auxiliary convertor. The other ends of the alternating current sides of the main convertor are connected with one ends of the connection electric reactors respectively. The main convertor is used for achieving active power or reactive power regulation of a power grid dispatching order fundamental wave; the other ends of the alternating current sides of the three-phase auxiliary convertor are connected to form a neutral point of the battery energy storage system. The auxiliary convertor plays a role of active power filtering. The other ends of the connection electric reactors are connected with one ends of the breakers. The other ends of the breakers are connected into a three-phase power grid. According to the chained battery energy storage system integrated with the active power filter, the energy storage technology is combined with the active power filtering technology, the more flexible and diverse electric energy quality adjusting functions are achieved, the system efficiency is high and the cycle life of a battery is long.

Description

Technical field [0001] The invention relates to the field of energy storage in medium and high voltage power systems, in particular to a chain battery energy storage system integrating active power filters. Background technique [0002] As an important part of the six major links of "collection-generation-transmission-distribution-use-storage" in the grid operation process, energy storage technology can solve the impact of intermittent renewable energy generation directly on the grid, and can also be used Peak clipping and valley filling balance the peak-valley difference of power supply in the power grid. In addition, it can also be applied to reactive power supplementation, frequency modulation, black start, isolated grid operation and accident backup. Battery energy storage systems have significant advantages in terms of capacity, power / energy density, lifespan, operating efficiency and maintenance, and have gradually become research hotspots and development directions. [0003...

AI Technical Summary

Problems solved by technology

[0004] A chain-type battery energy storage system in the prior art has the following defects: the H-bridge converter in each cascaded unit is directly connected in parallel with the energy storage battery pack through the filter capacitor, which is mainly used for the fundamental wave of the grid dispatching command The adjustment of active / reactive power has no compensation function for load-side harmonics and reactive power, and the function is relatively single; the series number of battery packs depends on the DC bus voltage level of cascaded units, and too high series number will reduce System reliability; the device needs to adopt a relatively high switching frequency to obtain better system output harmonic characteristics, and the system loss is large; when the device is running, the DC side will generate 2 pulse power, and when the reactive power is adjusted, the battery The battery pack will be in a state of frequent charging / discharging, which will affect the cycle life of the battery. In addition, the secondary pulsating power on the DC side will also affect the quality of the system output waveform

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