Research On VQC Parameter Setting Method Of Substation Based On Load Forecasting And Dynamic Reactive Power Optimization

The voltage quality control(VQC)system is an important means to improve the voltage quality,reduce the active power loss and realize the automatic control of voltage and reactive power.It can effectively adjust the bus voltage & reactive power or power factor by automatically adjusting the on-load tap changer and the shunt capacitor group in the substation.The unreasonable control parameters of the substation VQC system will lead to low voltage qualified rate or frequent action of control equipment.At present,researches are mainly aimed at modifying the control strategy.However,there has been a little work on the setting of control parameters including voltage,reactive power or power factor,etc.As a consequence,how to set the control parameters reasonably to obtain the optimized condition of voltage-reactive power is an urgent issue to be solved.In this paper,the VQC parameters setting method of substation is investigated,which is based on the forecasting of the daily load curve and the optimizing of dynamic reactive power in the substation.The main contents are as follows:(1)Aiming at the features of more variables and the higher correlation within the daily load forecasting curve,meanwhile adopting factor analysis and radial basis function(RBF)neural network based on load fusion,a daily load curve forecasting method is proposed.The load curve is firstly segmented with standard fusion method.Then,the daily load sequence is decomposed into the factor load matrix,the common factor and the special factor by factor analysis,in which the factor load matrix reflects the temporal correlation of load powers at different moments,the common factor reflects the common characteristics of load powers at all the moments,and the special factor reflects the random characteristics of load powers at different moments.Considering the influence factors such as week type,temperature and weather type,each common factor is forecasted by establishing the RBF neural network model.Finally,the daily load curve is restored from the forecasted common factors.The effectiveness of the proposed method is verified by the historical data of a substation in Shantou area.(2)For the disadvantage that existing substation dynamic reactive power optimization model is only applicable to the independent terminal substations,a new substation dynamic reactive power optimization model by considering the substation position and operation mode is established.For characterizing the influence of the substation position and the ground branch,the equivalent load and charge are implemented on the high voltage side of the substation.Considering the interaction between the transformers and evaluating the total power factor of the high voltage side when substation high voltage sides parallel,the new objective function is established.The bat algorithm is adopted to solve the new model,and the strategies of initial population customization and concentration control is introduced,which may improve the efficiency of the algorithm.The actual data of a substation in Shantou area are simulated and analyzed to verify the effectiveness of the proposed method.(3)Presently,the influence of forecasting error has not been considered in the existing VQC parameter setting methods.To solve this problem,a VQC parameters setting method by considering the influence of forecasting error is proposed,which is based on the daily load forecasting curve and the dynamic reactive power optimization.Based on the control strategy of fifteen-zone diagram and the substation dynamic reactive power optimization results with the forecasted load and equivalent source voltage,the control parameters are set by considering the power flow before and after the equipment action and the voltage and power factor deviations resulted from the load forecasting error.It can ensure that the actual VQC system can operate as dynamic reactive power optimization strategy even in the presence of forecasting errors.The feasibility and effectiveness of the proposed VQC parameter setting method is verified by the data of actual substation in Shantou area.