An Algorithm of Power Flow for Distribution Networks based on Node Load Membership Grade Function with Incomplete Information

Xiaoming Li and N. Zhang (PRC)

Keywords

Modeling, simulation and Real-Time applications; Algorithm of power flow; load distribution; state estimation; pseudo-measuring data; membership grade function

Abstract

In practical operation of distribution networks, because of multi-node and severely lack of measuring nodes, load distribution method is usually adopted to obtain the pseudo-measuring data of multi-load nodes’ injection active powers with finite measuring data in distribution network, and then modify them to approximately obtain the data of non-measuring nodes. However, the specific value of power factor used in load distribution sort is different from the real value of each load, and the difference has fuzziness. An algorithm of power flow for distribution networks based on node load membership grade function with incomplete information is presented, which doesn’t adopt the algorithm of supposing the power factor of each node is 0.85 in traditional load distribution method, however, applies fuzzy control theory to construct the membership grade function of “big rated capacity distribution transformer” on basis of “country feed and consuming rule”, gets the corresponding load nodes’ power factors through calculating distribution transformer rated capacity membership grades of each load node, and obtains active and reactive powers of all load nodes through using load distribution method. Last, forward/backward sweep method is adopted for load flow. The algorithm in this paper makes the results more exact. Also, this algorithm is used in a 10kV distribution circuit of some city, of which the results testify the validity of it.

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