Power conversion system based on energy storage of lithium battery and control method thereof

Abstract

The invention relates to a power conversion system based on energy storage of a lithium battery and a control method of the power conversion system, wherein a lithium battery system is connected to a direct-current end of a converter and is formed by the serial and parallel connection of lithium battery single bodies, and the voltage of the lithium battery system formed by serial and parallel connection is not lower than 1.633 times of a voltage level of a grid system. In the invention, an LCL (inductance capacitance inductance) filter formed by tree groups of series inductors and three capacitors is adopted, every two inductors are connected in series into one inductor group, one end of the each three inductor groups is connected to a three-phase alternating-current output terminal of the converter, respectively, and the other end of the each three inductor groups is respectively connected to a power grid; one ends of the three capacitors are connected with one another to form a common terminal, and the other ends of the three capacitors are respectively connected to the common terminal of the three groups of series inductors. The system and the method carry out SOC (state of charge) monitoring on the battery of the lithium battery system, adopts a current feedback type compensation method to compensate a dead zone, and adopts an SVPWM (space vector pulse width modulation) technology to control the converter. The maximal value of the fundamental wave of the voltage of the output wire of the converter is the voltage of the direct-current side, and is higher than an output voltage of common SPWM converters by 15%.

Description

Technical field [0001] The invention relates to a power conversion system based on lithium battery energy storage and a control method thereof. Background technique [0002] In view of the unpredictability and intermittent problems of electricity generated by most renewable energy power generation devices, domestic and foreign countries have begun to try to solve the bottleneck problem by means of grid transformation, wind power forecasting technology, reserve capacity and large-scale energy storage. Among them, the large-scale energy storage system has the characteristics of good dynamic response characteristics, long life, high reliability, etc., and has attracted attention at home and abroad in the field of improving the capacity of wind power in the grid. At the same time, in recent years, large-capacity battery energy storage technology has been rapidly developed and applied, and the corresponding technical route has gradually become clear. Some typical energy storage batter...

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the shortcomings of the existing power conversion system such as complex equipment, low bidirectional power conversion efficiency, neglect of energy storage battery system protection, poor grid-connected harmonic filtering effect, lack of dead zone compensation, etc., and propose a new Power conversion system with hardware structure and its control method

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