含分布式光伏的多级变压交直流混合配电网经济性评估

Economic Evaluation of Multi-voltage Hybrid AC/DC Distribution Networks With High Penetration of Photovoltaics

交直流混合配电系统可以提高电网的灵活性和可再生能源消纳,提出了在高渗透率分布式光伏场景下基于电力电子变压器(power electronic transformer,PET)的交直流配电网运行优化和经济性评估方法。通过计算包含交直流变换环节损耗和电网可靠性约束等条件的运行成本,分析交直流配电系统相比传统交流配网在提高优化调度水平和降低功率损耗方面的优势。将PET和PV并网变流器作为调控对象,提出PET配置与运行综合优化调度方法,在确定PET最优位置与容量设置的条件下进行有功和无功功率调节,最小化运行成本与计及多级变换器运行效率的总功率损耗。为求解包含整数变量的多目标优化问题,提出两阶段优化算法,优化配置与功率调节两个阶段迭代求解。最后在含分布式光伏和PET的改造33节点配电网进行仿真,验证交直流配电在促进光伏消纳和提高运行经济性的效果。

Hybrid AC/DC power distribution improves flexibility of power system and accommodation of renewables.This paper develops a method for optimal operation and cost-effectiveness evaluation of the hybrid distribution network based on power electronic transformer(PET)with high penetration of photovoltaics(PV).The power loss in AC-DC conversion is included in calculation of operating cost with the constraints of power system reliability.The advantages of hybrid distribution network in terms of improving optimal operation and reducing power losses are analyzed by comparing with traditional distribution network.A combined optimization of PET configuration and operation of power networks is formulated by adjusting PET and PV power converter.Active and reactive powers are regulated with fixed location and capacity of PETs for minimizing the operating cost and power losses considering the operational efficiency of multi-voltage converters.A two-stage optimal algorithm is proposed to solve the multi-objective mixed integer optimization problem,where the optimal configuration and operation of mixed network are solved iteratively.A 33-bus test system with distributed PVs and PETs is simulated and the results show the merits of hybrid AC/DC network in terms of economic operation and PV integration.