学校地址:湖南省 长沙市 雨花区 车站南路红花坡路口 |
学校地址:湖南省 长沙市 雨花区 车站南路红花坡路口 |
基于神经网络的电力系统状态估计①
韩富春 王娟娟
(太原理工大学电气与动力工程学院 太原 030024)
摘 要 本文以Tank和Hopfield神经网络为基础,建立了一种由主从网络构成的电力系统状态估计神经网络模型。理论分析和实例模拟结果表明:该网络是稳定的,该方法是可行有效的。
关键词 状态估计 电力系统 神经网络
1 INTRODUCTION
Among the current state estimators,due togood estimation qualities and astringency,weightedleast estimator is a classical algorithm and an aca-demic basis.Butit also has some shortcomingssuchas the calculation of matrices.The paper applies aneural network modelto solve the real-time leastsquares(RLS)problem.Theoretical analysis andsimulations prove that this network is very suitableto solve this kind of problem and has greatly im-proved on the traditionalpower state estimation al-gorithm.
2 A MODEL OF WEIGHTED LEAST SQUARESALOGORITHM
The observation equation ofpower systemstate estimation is nonlinear and can be linear as:
z=Hx+v (1)
where x isan dimension state vector;z isa mdimen-sion measurement vector;v is a measurement errorvector,which is normalized as:H is a m×n dimension observation matrix.Rank[H]=n.Its elements are decided by the structureof power system and the configuration of meteringsystem.In general case,H can act as constant be-cause its change is minute in every iteration.
The observation function applying weightedleastsquares algorithmis:
where R-1 is weight,Δz is the difference betweenthe measurementand the value ofthe correspondingmeasurementfunction.Eq.(2)is expressed in a vec-
tor form:
3 THEREALIZATION OFRLSALGO-RITHM USINGANEURALNETWORK
According to the reference[3]that a energy function was used to research the stability of a feed-back neuralnetwork and simulation electroniccircuitcould realize its circuitmodel.In reference[1],thereis a network that comprised of a main and a sub-sidiary network,showed as the Figure 1.The paperapplies the network to power system state estima-tion successfully.The main and the subsidiary neu-rons are connected with each other.The left mainnetwork has n neurons,every neuron is modeled asan amplifier,and the relation ofitsinput and outputis nonlinear.It has input capacitance Ci and resis-tance Ri.vi(t)and ui(t)are the i-th neuron output and input voltage.g(u)is a degressive function.
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