Study On Probabilistic Model Of Random Harmonics

With rapid development of the modern industry, more and more non-linear power loads, such as massive rectifier, have been joined power system, and there are increasing the flexibility of power systems and HVDC; they are bring the present power system more and more harmonics which can seriously damage the system components and operation. The power harmonics are time-varying because it is unfixed and non-deterministic to operate the system loads, linear loads or non-linear loads. So, it will be reasonable and effective to analyze power harmonics with the probabilistic method. Many international standards advised to use an evaluation as a limit to the level of harmonics. For example, the IEC has taken 95% probabilistic value of a day or maximum value of a week as the limit standards.Taking into account the nature of power system network, it is necessary to establish the harmonics probabilistic model of network, and then studying effective probabilistic analyzing method, the probabilistic values can be assessed. On the other hand, among a large of nodes of network, based on known harmonic source node, usually it is need to assess harmonics of other unknown nodes, so it have to solve the summation of several random vectors. The traditional solving methods need a mass of calculation or localize its applying area so that they bring biggish error.This paper used Laguerre orthogonal polynomials expansion to approach the probability density functions (pdf) of power random harmonics and assessed the 95%...