直流和新能源高渗透型电网惯性水平多维度评估

随着密集型大容量直流输电工程的推进以及规模化新能源的开发,我国已有部分清洁能源富集地区发展成为典型的直流输电线路和新能源高渗透型电网。多直流异步送出格局下,大量风电和光伏持续替代同步发电机组,系统惯性水平大幅下降,削弱了电网抵御大容量功率扰动的频率响应能力。同时,系统惯性的时空分布特性渐显,使得惯性响应机理更加复杂,亟待针对此类低惯性电力系统的惯性水平评估开展研究。文章基于运行机组旋转动能、惯性变化率和惯性分布指数三个量化指标,提出一种考虑惯性时空分布特性的电网惯性水平多维度评估方法,从总体大小、时间维度、空间维度分别对系统惯性特性进行评估分析,并基于云南电网运行方式数据展开算例分析,测试结果验证了所提出的惯性水平评估方法的有效性。

Multi-Dimensional Assessment of the Inertia Level of Power Systems with High Penetration of HVDCs and Renewables

With the development of HVDC and renewable-energy power generation， many typical power grids with high penetration of HVDCs and renewables are forming where there are of abundant clean energy in China. Under asynchronous transmission mode with multiple HVDCs， the inertia level of these systems have considerably decreased as a great amount of wind and photovoltaic power replaces the synchronous units， which impairs the frequency response performance for resisting dangerous faults. Meanwhile， the spatial and temporal distribution of mechanical inertia becomes more obvious than ever before， which makes the inertia response mechanism of the power system more complex to be detected. Thus， it is critical and essential to carry out inertia assessment of these low-inertia systems. This paper proposes a multi-dimensional framework for assessing the inertia level from three aspects: the overall size， the time-varying characteristics and the geographical distribution based on three quantitative indices， i.e.， the kinetic energy of units， the change rate of inertia and the inertia distribution index. Case study and application are carried out on Yunnan Power Grid， and the simulation results verify the effectiveness of the proposed method for assessing inertia level of power systems.