光伏机组虚拟惯量控制下电力系统频率特性分析

Analysis of frequency characteristics of power system under photovoltaic power plant with virtual inertia control

高比例可再生能源机组的接入和大量火电机组退出,导致电网系统的惯量支撑和一次调频能力下降,降低了系统的频率稳定性。文章首先考虑光伏机组的惯量支撑和一次调频能力,建立了计及新能源惯量支撑和一次调频能力的电力系统频率响应模型;其次,引入最大频率偏差、稳态频率偏差、最大频率变化率(Rate of Change of Frequency,RoCoF)幅值3个指标,对不同新能源渗透率场景下的频率特性进行量化评估。最后,基于DigSILIENT/PowerFac-tory15.1搭建含光伏机组的3机9节点系统仿真模型。仿真结果表明,尽管RoCoF幅值指标在不同渗透率场景下的数值均大于全同步机系统,但在惯性时间常数较大时,高渗透率场景下的最大频率偏差指标优于全同步机系统。

The integration of high proportion of new energy and the exit of a number of thermal power units will lead to the decrease of inertia support and primary frequency regulation capacity of power system,and then reduce the frequency stability of the system.In order to reveal the influence of high proportion of new energy units participating in frequency regulation on the frequency response characteristics of power system,this paper first considers the inertia support and primary frequency regulation ability of photovoltaic units,and establishes a power system frequency response model considering the inertia support and primary frequency regulation ability of new energy units.Secondly,the maximum frequency deviation,steady-state frequency deviation and frequency change rate amplitude are introduced to quantitatively evaluate the frequency characteristics of different new energy penetration scenarios.Finally,based on DIgSILENT/powerfactory15.1,a three-machine nine-node system simulation model with photovoltaic units is built.The simulation results are consistent with the theoretical analysis,which shows that the frequency response characteristics of new energy high penetration power system are significantly different from that of traditional power system.Although amplitude of maximum RoCoF index in different permeability scenarios is larger than that of full synchronous machine system,the maximum frequency deviation index in high permeability scenario is better than that of full synchronous machine system when inertia time constant is large.