Three-phase unbalance factor probability assessment method based on state estimation

Abstract

The invention discloses a three-phase unbalance factor probability assessment method based on state estimation. The method comprises the steps that A, a network node three-phase admittance matrix of an actual electric system is calculated; B, an injection active power expression and a reactive power expression of a phase p of a node i in the electric system are calculated; C, the error between the measured quantity and the true physical quantity of the system is calculated through a state estimation method; D, a sampling process expression of a load power and n distributed power output powers is obtained; E, a state quantity estimated value is solved; F, a voltage unbalance factor is solved; G, a three-phase unbalance factor probability assessment is carried out. By the adoption of the three-phase unbalance degree probability assessment method based on state estimation, three-phase unbalance probability distribution and change characteristics of voltages of a power distribution system which a distributed power supply is connected into can be analyzed objectively and reasonably; the method has positive significance in reasonably utilizing renewable energy to generate electricity in a conventional power distribution system.

Description

technical field [0001] The invention relates to the field of power quality of distributed power generation in a distribution network of a power system, in particular to a method for evaluating the probability of three-phase unbalance degree based on state estimation. Background technique [0002] Energy is an important material basis for human survival and development. In recent decades, human consumption of energy, especially electric energy, has reached an unprecedented level. The traditional large-scale centralized power supply model is gradually unable to meet people's needs. As a power generation technology based on renewable energy, distributed power generation is clean and pollution-free, and can fully and efficiently utilize decentralized resources, so it has broad application prospects. In 2011, my country's grid-connected new energy power generation capacity was 93.355 billion kWh, accounting for about 2% of the total power generation. [0003] With the rapid deve...

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Problems solved by technology

The probability method for voltage unbalance calculation includes: according to whether the network structure is symmetrical, it is normal distribution and Rayleigh distribution respectively, and the improved Bessel equation is used for analysis; and the improved Bessel equation used in the above method , the solution is too complicated and inconvenient to calculate, and this method assumes that the phase angles always keep a mutual difference of 120 degrees during the analysis process, which is also somewhat different from the actual analysis problem

In other literatures on VUF evaluation, Monte Carlo simulation is often used for analysis, which requires a large number of repeated sampling and calculation of three-phase power flow, which makes the entire calculation process very cumbersome and complicated

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