多电源梯级调频方案及风电场级调频时序优化策略

目前，大规模风电接入电力系统面临的主要问题之一是系统的频率稳定性。文中提出一种风电场级一次调频时序优化的工程实用策略，并对风光水火参与系统调频的次序提出了梯级调频方案。首先以云南电网为例，讨论了风光水火不同电源接入电网时的梯级调频方案，在电网发生频率扰动情况下对不同电源参与调频的顺序进行了研究，并提出了风电和光伏机组参与调频的需求。然后分析了调频时间尺度内风电场的功率变化及风电机组层面调频时的有功控制策略。在此基础上，在风电场层面给出了场内风电机组一次调频的投入与退出策略，通过读取风电场内各台风电机组的实时状态与计算系统的调频需求，得出风电场在调频期间需要投入的最小的风电机组台数，在风电场结束一次调频时通过时序依次退出风电机组的一次调频，降低风电场退出一次调频可能会造成的频率二次跌落。最后通过仿真验证了所提出的策略。

Multi-source Cascaded Frequency Modulation Scheme and Time-sequence Optimization Strategy of Frequency Modulation at Level of Wind Farm

One of the major problems of large-scale wind power integration is the frequency stability of the power system at present. This paper puts forward an engineering practical strategy for the time-sequence optimization of wind-farm-level primary frequency modulation, and a cascaded frequency modulation scheme for the order of wind, photovoltaic, hydraulic, thermal power participating in the system frequency modulation. Firstly, by taking the Yunnan power grid as an example, the cascaded frequency modulation scheme is discussed when different power sources of wind, photovoltaic, hydraulic, thermal power are connected to the power grid, the order of different power sources participating in the frequency modulation is studied with the frequency disturbance of the power grid, and the requirement of wind and photovoltaic power units participating in the frequency modulation is put forward. Then the active power variation of wind farm within the time scale of frequency modulation is analyzed, and the active power control strategy of wind turbines during the frequency modulation is discussed. Based on this, the input and exit strategies of primary frequency modulation of wind turbines at the wind farm level are given, and the minimum number of wind turbines that the wind farm needs to input during the frequency modulation is obtained by reading the real-time status of each wind turbine in the wind farm and computing the frequency modulation requirement of the power system. In order to reduce the probability of secondary frequency drop when the wind farm withdraws the primary frequency modulation, the wind turbines withdraw the primary frequency modulation orderly by the time sequence at the end of frequency modulation of the wind farm. Finally, the proposed strategy is verified by the simulation.