Research On Optimal Voltage Control Method In Active Distribution Network Based On Series Compensation Theory

As energy crisis and environmental problems become increasing prominent,the distributed generation(DG)technology has flourished.With most DGs accessing to the traditional radial distribution network,its power flow turns to be bidirectional,which is known as active distribution network.Particularly because DG's output characteristics can be described as randomicity,voltage on load fluctuation will be more conspicuous.However,traditional voltage regulating measures cannot satisfy the requirements of voltage regulation of active distribution networks,which restrains the capacity for DG access to some extent.It is one drawback that demands prompt solution.This dissertation conducts research on comprehensive optimized series compensation voltage control method of active distributed networks.Firstly,the author analyses the internal reasons why voltage fluctuation occur in distributed network and takes the deficiency of existing voltage regulation methods into consideration.Besides,combined with the structure and parameter characteristics of distribution network,this dissertation focuses on the analysis the voltage regulating mechanism which is based on fixed capacitor series compensation theory and analyzes its limitations.Secondly,the active series compensated voltage regulation technology based on modern power electronics technology will be studied in this dissertation.Moreover,comprehensive series compensation voltage regulating methods will be proposed from the combination of active series compensation voltage regulating methods and fixed capacitor.It turns out that resistance-drop and capacitor-drop compensation will be both compensated,which means the defects of existing voltage regulating will be efficiently overcome.Afterwards,in order to realize the optimization control of active distribution network voltage,the author deduces the quantitative relation between series compensating voltage and network active power loss and voltage deviation.Furthermore,voltage integrated optimization control model is established on the strength of series compensation theory,realizing the unified adjustment of grid loss and voltage.Meanwhile,this dissertation puts forwards upgraded differential evolution algorithm based on simulated annealing strategy and self-adaptive mutation operator and optimizes its generation of initial population,aiming at the solution of the voltage integrated optimization control model.Last but not least,the active distribution network simulation model has been established based on the IEEE 33-bus standard model for the sake of fully simulation of comprehensive series compensation voltage regulating and improved differential evolution algorithm.The simulation results prove that the comprehensive series compensation voltage control methods can enhance the quality of electric energy supply in active distributed networks and diminish the grid loss and the improved evolution algorithm promotes the efficiency of optimization,which avoids it trapping into local minimization.The study results of this dissertation not merely enrich the research achievement of voltage quality optimization control measures,but also provide theoretical foundation and technical support for improving the penetration of distributed generation and eliminating DG's access restrictions.