可变速抽水蓄能发电技术的应用与进展

 可变速抽水蓄能可成为电网负荷频率控制、平衡可再生能源发电出力波动的有效手段。论文在介绍可变速抽水蓄能整体结构的基础上,重点介绍了交交方式和交直交方式变频励磁单元的拓扑和构成。说明了交交方式具有器件少、可靠性高、易于大容量化等优点,但存在频率只能整数倍减小、无法实现大范围连续调节、响应速度较慢等缺点。而交直交方式具有频率可大范围连续调节、响应速度较快等特点,其性价比呈快速上升趋势。分析了机组在发电方式和电动方式时运行的变速原理和调节过程。通过发电出力与转速的关系曲线说明通过转速控制实现最佳出力的过程。通过泵类负荷输入功率与转速的关系,描述了电动方式下调节转速对电网功率调节的作用。综合考虑能量平衡、波动负荷与可再生能源发电出力跟踪控制及电压稳定控制的需求,形成参考功率。在此基础上,采用d-q解耦方法实现可变速机组有功与无功功率的控制。最后,通过电网功率调节、电压波动控制及风电功率波动抑制示例,阐述了可变速机组对电网运行的控制作用。

Progress in the Power Generation Technology with Variable Speed Pump Storage and Its Applications

Variable speed pump storage is very likely become the effective measure for the control of power grid load frequency and for balancing fluctuation caused by renewable energy resources. Based on the principle introduction of variable frequency pump storage, the topology and configuration of frequency conversion and field excitation unit of typical converters used for variable speed pump storage are mainly described. Analysis indicates that the AC-AC cycle-converter has few devices and high reliability, however with limited range of frequency change and low response speed. Meanwhile the AC-DC-AC converter possesses the large range of frequency adjustment and high response speed, its cost performance rapidly raising, and would become the leading topology in the future development. The speed change principle and adjustment process are analyzed for the generator set operating in both generator mode and pump mode. Based on the characteristic curve of electric output power and rotating speed in generator mode, the optimum output power is able to be achieved by speed control. According to the relationship between the input power and speed in pump mode, the power extracting from electric grid is able to be controlled through speed control. The reference power could be calculated by combining the energy balance with fluctuating load, tracing power output generated by renewable energy resources, and the voltage stability control. By adopting a d-q decoupling strategy, the control of active power and reactive power for variable speed unit is able to be realized. Finally, by taking electric fence power adjustment, voltage fluctuation control, and wind generation power balance as example, the control function of variable speed unit to electric fence operation is addressed.