UFLS Online Optimization Setting Based On Multi-Generator System

The main characteristics of modern power system is large generator units, extra high voltage lines and large-scale long distance network connection. The power system operation condition becomes more complicated with the development of network and the appearance of power market recently. Meanwhile the network's security and stability should be improved.UFLS is the last defense that guarantees the electric power network's safety and reliability. In order to improve accuracy of UFLS installment fixed value computation, to minimize over shedding and under shedding, and to optimize amount of reduced load of UFLS in optimum system. UFLS optimization setting is a mixed nonlinear optimization problem with a large number of variables and constrains, the optimization becomes very complex. As a kind of search algorithm based on the mechanics of natural selection and genetics, genetic algorithm is fairly fit for solution to the problem of UFLS in power system.This paper establishes the basic mathematical model, studies the flow of solution to UFLS optimization with applied genetic algorithm, and improves the solution of UFLS based genetic algorithm on base of utilizing features of UFLS, presents project based improved genetic algorithm with including code mode, crossover operator, mutation operator and termination conditions,discusses the meaning and methods of UFLS online optimization setting based on multi-generator system.For the example of Liao Ning electric power network, this work optimized sets the UFLS installments, analyzes the influence of UFLS parameters on frequency safety of Liao Ning electric power network, researches on UFLS optimization setting in the condition of single operation mode and single fault, single operation mode and multiple faults, multiple operation modes and multiple faults, compares the acquired optimization scheme with configuration scheme, analyzes the characteristics of optimization schemes in different condition. The result shows the amount of total reduced load drops without harming transient frequency safety by optimized arranging load shedding in each region and turn. This UFLS method suits for online optimization of multi-generator system.