Cheng Haozhong

Multiobjective planning of open-loop mv distribution networks using ComGIS network analysis and MOGA

In this paper, an advanced method for the planning of open-loop medium voltage (MV) distribution network is proposed. The multiobjective planning model is constructed, and a special multiobjective genetic algorithm (MOGA) is designed based on the network dataset built by component geographical information systems (ComGIS). The network analysis function of the ComGIS is embedded in the overall optimization process to find single-loop optimal paths. Crossover and mutation operator are designed according to characteristics of the coding. The evolutionary orientation is directed by the fitness function based on Pareto order of individuals. The Pareto optimal set (POS) including several candidate planning schemes is gotten through MOGA, from which the recommended scheme is selected. The method has been applied to real life power distribution networks, showing its potential in practical applications.

Reliability and economy evaluation of MicroGrid based distribution network connection mode

Because of the mature of MicroGrid technology in China, more and more power users tend to use the new MicroGrid to improve its power reliability. Whether the traditional connection mode of distribution network is able to suit the actual needs of MicroGrid users has become a real problem which can not be avoided in network planning. First of all, some typical connection modes which are representative in current distribution network have been analyzed and described. After that, an automated distribution network planning has been conducted in this paper. Then, a evaluation of various connection modes which include or exclude MicroGrid based on the previous distribution network planning has been conducted. In the evaluation, two factors which represent the reliability and economy have been considered. They are: Average Service Availability Index (ASAI) and Annual Fee per Load Unit. Finally, a comprehensive comparison has been executed in order to analyze the advantage and disadvantage of various distribution network connection modes which include or exclude MicroGrid.

A Novel Simplified Approach to Estimate a Closest Voltage Collapse Margin

Abstract This paper proposes a novel simplified approach to estimate a closest voltage collapse margin. The proposed approach has two stages of computations. The first stage is to compute an approximated closest voltage collapse point. This computation includes a pair of multiple load flow solutions. The left and right eigenvectors corresponding to the zero eigenvalue of load flow Jacobian are also approximated. Most of the computation time at this stage is taken to calculate the multiple load flow solution pair. Additional computation time is less than that of an ordinary load flow. The second stage is to refine the approximated solutions that are obtained in first stage, and this may be carried out only when the exact solution is needed. Equations to be solved at stage 2 is of dimension 2n+l, for n-dimensional load flow equations.