In order to accommodate high-penetration wind & PV power sources with strong fluctuation and randomness, the access of renewables and planning of transmission grids not only need to consider the balance of electricity, but also the balance of flexibility capacity. On this occasion, the conventional method of transmission expansion cannot economically realize the above-said objectives, thus joint expansion planning of energy storage and transmission becomes the new solution. A joint expansion planning method for energy storage and transmission based on quantitative assessment of flexibility is established. Firstly, from the perspective of flexibility, we qualitatively analyze the technical characteristics and advantages of the joint ‘storage-transmission’ planning in power balance and flexible adjustment capacity. Then, a joint storage-transmission planning model considering flexibility is established, and the solution method is given with combination of heuristic and mathematical programming. Finally, the feasibility of the proposed method is verified based on the modified Garver-6 system. The results show that under the scenario of high-penetration of renewable energy sources, the joint ‘storage-transmission’ planning has better economy. The energy storage can effectively improve the system’s up-regulation flexibility, but the cost is an important factor for restricting its planning capacity.

为应对大量新能源并网给电力系统惯量、频率所带来的不利影响,提出了一种基于模块化多电平换流器的虚拟同步机,并研究了其控制技术.该虚拟同步机使用一种能提供虚拟惯量的d由外环控制器代替传统MMC的外环功率控制器,从而为电力系统提供暂态频率支撑.同时,采用了一种基于两相静止坐标的锁相环,代替常用的同步坐标锁相环,以更好地适应虚拟同步控制对参考相位的要求.基于实时数字仿真器的仿真结果表明,该虚拟同步机能模拟出同步机的惯性和调速器特性,其并网运行可以减小系统的暂态有功缺额,降低频率偏差,阻尼区域间振荡.