Study On The Influence Of New Energy Accessing Substation Low Side On Power Transformer

In response to the call of the state to vigorously develop new energy power generation,more and more photo-voltaic power plants and wind farms are connected to the power grid,which alleviates energy shortage and environmental pollution,and also brings some threats to the power grid.Some new energy power plants directly access the substation for cost savings,so that the power transformer will face the impact of new energy.Therefore,this paper focused on the impact of the new energy access to the low-voltage side of the substation on the insulation life loss of the power transformer and the anti-short-circuit ability of the winding by analyzing the impact of new energy grid-connected on the traditional grid and fault statistical data of power transformers.Analyzing the insulation aging mechanism of power transformers defined the relationship between the insulation life loss and the winding hot spot temperature.The load loss of the power transformer under harmonic current injection is quantitatively analyzed,and the hot spot temperature calculation method proposed by the IEEE standard is improved.A calculation model of transformer winding hot spot temperature considering both load rate and harmonic distortion rate is established.The simulation results of the example show that the photo-voltaic power plant connecting to the low-voltage side of the substation will reduce the insulation life loss of the power transformer,and the influence of the harmonic current injection on the insulation life loss can be neglected.The force on the power transformer winding under short-circuit fault is analyzed.The short-circuit force on the winding is calculated,and the corresponding calibration conditions are given.The evaluation criteria of the short-circuit resistance of the transformer are determined according to the simulation results.The structure and equivalence models of grid-connected photo-voltaic plants and wind farms are studied,and their short-circuit characteristics are analyzed by building simulation models in Simulink.The simulation model of the wind farm connecting to the substation is built.The simulation results show that the wind farm access will increase the probability of the winding being affected by the short circuit and reduce the anti-short-circuit ability of the winding.The length of the wind farm lead-out line has a great influence on the anti-short-circuit ability of the winding but installed capacity has little effect on it.