随着分布式能源和储能容量的增加以及电动汽车的普及，配电网的功率流动由单向转变为双向，且网络拓扑由径向转变为复杂的网状结构。为了高效应对网状配电网的潮流(power flow，PF)分析和最优潮流(optimal power flow，OPF)问题，以及进一步提升现有线性化模型的近似精度、完善对网络损耗等元素的线性近似，该文构建迭代隐式线性化潮流(iterative implicit linearization power flow，IIL-PF)模型及其最优潮流模型(IIL-OPF)。该模型将非线性潮流流形M(Manifold)视为节点电压和节点注入功率之间的隐式代数关系，之后利用切平面对M进行局部近似，并迭代更新线性化点以提高线性模型的近似精度。此外，所提模型充分考虑了支路始/末端潮流、支路潮流平方、支路损耗等因素，并对其进行明确的线性化推导。最后，基于修改的IEEE 33系统，分别在径向和网状运行方式下，验证所提模型可快速收敛，并具有较高的近似精度。其中IIL-PF计算结果、IIL-OPF的目标函数和发电机出力等优化结果与 MATPOWER 的非线性模型相比，误差均在1％以内，因此所提模型可以满足工程规划或日前运行模拟等应用要求。
Iterative Implicit Linearization Based Power Flow Calculation and Optimal Power Flow Model for Meshed Distribution Networks
With the increase of distributed energy and energy storage capacity and the popularization of electric vehicles,the power flow in the distribution network has changed from unidirectional to bidirectional,and the network topology has changed from a radial structure to a complex meshed structure.In order to efficiently deal with the power flow(PF)analysis and optimal PF(OPF)problems of meshed distribution networks,as well as to further improve the approximation accuracy of the existing linearization models and to refine the linear approximation of network losses,this paper constructs an iterative implicit linearization PF model(IIL-PF)and its optimal PF model(IIL-OPF).The proposed model considers the nonlinear PF manifold M as an implicit algebraic relationship between the node voltages and the nodal power injections,after which M is locally approximated using the tangent plane,and the linearization points are iteratively updated to improve the approximation accuracy of the linear model.In addition,the proposed model considers the branch start/end PF,the squared PF,and the line losses,and derives an explicit linearization for them.Finally,based on the modified IEEE 33 system in radial and meshed operation modes,respectively,it is verified that the proposed model can converge quickly and has high approximation accuracy.The results of IIL-PF,objective function of IIL-OPF and generator power are within 1％error compared with MATPOWER's nonlinear models,so the proposed model can meet the requirements of engineering planning or day-ahead operation simulation.
distribution networkmeshed topologypower flow calculationoptimal power flowimplicit linearization
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