光伏调节电网频率技术研究现状与展望

Research Status and Prospect of Photovoltaic Power Grid Frequency Regulation Technology

太阳能光伏发电将是未来以新能源为主的"新型电力系统"中最具前景的发电形式,然而光伏出力的随机波动和元件本身的零惯性特征将严重冲击系统的频率稳定。为此,针对前人所作综述研究的不足,分别基于功频静特性方程和转子运动方程详细分析了光伏接入对微网和主网频率稳定性的影响机理,并针对性总结下垂控制和虚拟惯量控制两种策略的本质特征:前者模拟传统机组一次调频特性以弥补系统频率偏差,后者模拟传统机组转子运动特性以抵抗系统频率变化。随后对三种光伏调节电网频率的技术手段——减载运行、附加储能、虚拟同步发电机分别开展综述研究,并揭示了三者的共有本质:光伏阵列/储能装置结合下垂惯量两种控制策略,模拟传统机组调频特性,及时调整光伏/光储系统的出力大小以应对电网频率变化。此外,储能装置也可以通过平滑光伏出力的方式,从源头上抑制系统频率波动。最后,从源、网、荷多角度切入提出了5个方面的下一步侧重研究建议。

Solar photovoltaic power generation will be the most promising form of power generation in the new energy-based"new power system"in the future.However,the random fluctuation of photovoltaic power output and the zero-inertia characteristics of the components themselves will seriously affect the frequency stability of the system.In this regard,focusing on the PV response to grid frequency change,we analyze the impact mechanism of PV access on the frequency stability of micro-grid and main grid based on the powerfrequency static characteristic equation and rotor motion equation,respectively,and summarize the essential features of two strategies,namely sag control and virtual inertia control:the former simulates the primary frequency regulation characteristics of traditional units to compensate for the system frequency deviation,and the latter simulates the primary frequency regulation characteristics of traditional units to compensate for the sys-tem frequency deviation.The latter simulates the rotor motion characteristics of conventional units to resist sys-tem frequency variations.Subsequently,a review of three technical means of PV frequency regulation-load shedding operation,additional energy storage,and virtual synchronous generator-was conducted and revealed the common nature of the three:PV arrays/energy storage devices combined with two control strategies of sag inertia to simulate the frequency regulation characteristics of conventional units and adjust the output power of PV/photovoltaic storage systems in time to cope with grid frequency changes.The PV array/storage device combines two control strategies of sagging inertia to simulate the frequency regulation characteristics of a conventional unit and adjust the power output of the PV/photovoltaic storage system in time to respond to grid frequency changes.In addition,the energy storage device can also suppress the system frequency fluctuation from the source by smoothing the PV power output.Finally,the next five research recommendations are proposed from the source,network and load perspectives.