Research On Voltage Adjustment And Optimization Of Distribution Network With Small Hydropower

In recent decades,with the rapid development of China's economy,the country's electricity consumption has been on the rise.As a common distributed green power source in mountainous areas,small hydropower has been well applied in the field of power generation.However,due to the fact that most small hydropower stations belong to run-away hydropower stations,their own regulating capacity is insufficient,which leads to the influence of small hydropower on the voltage level of distribution network in different seasons.In the low water period,some substations in the distribution network with small hydropower often have low voltage operation,and in the high water period,there is overvoltage operation.Aiming at the voltage problem after small hydropower is connected to the distribution network,this paper focuses on the factors affecting the voltage level of the distribution network with small hydropower,and puts forward some measures to improve the voltage.The constant power chain distribution network model is used to analyze the distribution change of the power flow before and after the small hydropower connection.At the same access location,the increase of access capacity can improve the voltage level of the distribution network.Under the same capacity,the further the access location is away from the large power grid,the more obvious the voltage increase.The change of the power factor of small hydropower will change its reactive power output.The small hydropower running ahead of the power factor will reduce the voltage and increase the line loss.The access capacity of small hydropower is 2/3 of the total load,and the access position is 2/3 away from the power supply of the power grid,which will cause the minimum line loss of the network.PSASP(Power System Analysis Software Package)Software was used to build the model of IEEE33-node distribution network to simulate and analyze the factors affecting the voltage after small hydropower access.The simulation results were consistent with the theoretical Analysis.The sensitivity of voltage regulation measures was used to analyze the voltage improvement capability of four different voltage regulation measures,that is,small hydropower input phase,changing transformer ratio,changing line model and reactive powercompensation to the over-limit node of IEEE 33 node after access to 4 small hydropower stations.The improvement degree of the corresponding voltage regulating measures to the over-limit node is basically consistent with the change of its sensitivity.Among them,reactive power compensation has the most obvious effect on voltage lifting.The phase of small power supply and the change of line model will reduce the voltage of nodes.Based on the theory and simulation analysis,the corresponding voltage adjustment and optimization scheme is developed for the voltage problem in the distribution network in the north of Chenggu county.Due to heavy load in the dry period,the 35 kV bus voltage of Xiaohe substation in the north of Chenggu is too low.The scheme of compensation capacitor is adopted to calculate the sensitivity of different capacitor compensation positions and determine the compensation position and compensation capacity.In view of the problem that the 35 kV bus voltage is too high in Xiaohe substation,the voltage adjustment scheme is developed,and the specific configuration of each scheme is analyzed with sensitivity.The simulation analysis of the voltage adjustment effect of different schemes shows that several schemes selected in this paper can improve the problem of the high voltage in the Xiaohe substation to varying degrees,among which the combination measures of the input phase and the changing line model of the Shiba hydropower station can reduce the voltage to the greatest extent.The work of this paper has certain theoretical guidance and practical engineering value for the voltage adjustment of the northern Chenggu power distribution network,as well as a reference for the later optimization and transformation of the power grid in this region.