A Micro/Off-Grid Compressed Air Energy Storage System Based on Free Piston Expansion/Compressor-Linear Motor

Abstract

The invention discloses a free piston expander / compressor-linear motor-based miniature / off-grid compressed-air energy storage system. The system comprises free piston expanders / compressors, a linear motor, pressure regulating air tanks, heat exchangers, a shell-and-tube air storage tank, water pumps, a water storage and energy storage tank, a water storage pool and corresponding connecting pipelines; a control system comprises a control module, pressure sensors, a displacement sensor, electric valves, switching relays, an electrical storage device, electromagnetic three-way valves, electromagnetic valves and corresponding connecting lines. The energy storage system can separately act as the compressors and the expanders during energy storage and power generation, so that a structure of the compressed-air energy storage system is greatly simplified, and cost is reduced; meanwhile, by adopting the shell-and-tube air storage tank and regulating an expansion / compression ratio, drastic fluctuation of pressure and temperature of compressed air in the air storage device can be reduced by the system, optimal utilization on energy of an air compression and expansion link is realized, and efficiency of the compressed-air energy storage system is increased.

Description

technical field [0001] The invention relates to the field of energy storage power generation, in particular to a micro / off-grid compressed air energy storage system. Background technique [0002] Compressed air energy storage system (CAES) is an electric energy storage system that can realize large-capacity and long-term electric energy storage. It stores excess electrical energy by compressing air, and releases high-pressure air to generate power through an expander during peak power consumption. Among them, the compressor and expander are the core components of the compressed air energy storage system, and their performance has a decisive impact on the performance of the entire system. At the same time, due to the small flow rate of the system, traditional compressed air energy storage systems mostly use single-stage or multi-stage reciprocating compressors and turbine units, the compression / expansion ratio cannot be adjusted, the system structure is relatively complex, t...

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Problems solved by technology

At the same time, due to the small flow rate of the system, traditional compressed air energy storage systems mostly use single-stage or multi-stage reciprocating compressors and turbine units, the compression / expansion ratio cannot be adjusted, the system structure is relatively complex, the cost is high, and the reliability is high. poor

At the same time, in the process of compressing energy storage, the pressure in the gas storage device gradually increases, resulting in a decrease in energy storage efficiency, and in the process of deflated power generation, the pressure of compressed air in the gas storage device gradually decreases, which in turn leads to a decrease in power generation efficiency

In addition, the compressed air energy storage system will generate a large amount of low-grade heat energy during operation, which is wasted without utilization

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