1.浙江大学大学电气工程学院，浙江省杭州市 310027;2.国家电网公司华北分部，北京市 100053;3.华北电力科学研究院有限责任公司，北京市 100045
1.College of Electrical Engineering, Zhejiang University, Hangzhou 310027;2.North China Branch of State Grid Corporation of China, Beijing 100053, China;3.North China Electric Power Research Institute Co., Ltd., Beijing 100045
With the connection of large-scale renewable energy sources, the rotational inertia of modern power system is reduced, and the dynamic characteristics of frequency are deteriorating. In order to support the system frequency, the power generation devices of renewable energy sources are usually required to have additional control functions, such as inertial simulation or primary frequency regulation. However, there is little research on the optimal frequency support of renewable energy sources. Based on the optimal control theory, this paper preliminarily discusses the optimal power support trajectory and approximate optimal control structure of power electronic devices as grid-connected interfaces, when there are energy constraints on the renewable energy sources participating in frequency regulation. Firstly, the common mode component of frequency of multi-machine system is deduced, and it is pointed out that this component dominates the frequency drop characteristics of power grid. Secondly, based on the Gauss pseudospectral method, this paper studies the optimal support trajectory of power electronic devices with energy constraints when the system frequency drops. Thirdly, the optimal feedback control structure for grid-connected power electronic devices supporting power grid frequency is studied. It is pointed out that the control structure combined with virtual inertia control and droop control is close to the optimal control structure, and the virtual inertia control is better than the droop control when the available energy is small. Finally, the simulations verify the rationality of the theoretical analysis and the discussed optimal control structure.
GAO Huisheng, ZI Peng, HUANG Linbin, et al. Optimal Frequency Control of Grid-connected Power Electronic Devices with Energy Constraints[J/OL]. Automation of Electric Power Systems, http://doi. org/10.7500/AEPS20191022007.