Research On Safety And Stability Analysis And Improvement Strategy Of 220 KV Power Grid In Shengli Oilfield

As an important oil industry base in China,Shengli Oilfield has infrastructure facilities such as power generation,transmission,substation and distribution.The safe and stable operation of the oilfield power grid is a prerequisite for oil and gas production and is critical to the economic efficiency of the enterprise’s operations.The limitations of the existing 220 k V grid are becoming more and more obvious as the oilfield load is increasing in recent years,and the oilfield grid is facing problems such as aging equipment,unreasonable grid structure and difficulties in power delivery.At the same time,in order to implement the green low-carbon strategy,the number of photovoltaic power plants in the oilfield area is gradually increasing.Photovoltaic grid connection is bound to change the grid tide distribution and affect the grid operation.The oilfield load side contains a large proportion of water injection motors,which have high frequency and voltage requirements and are affected by voltage fluctuations,so the impact of large-scale PV grid connection on system operation is one of the key concerns in the oilfield.This dissertation takes the existing grid structure of Shengli oilfield as the research background,and focuses on the analysis of grid safety and stability and the improvement strategy.Firstly,the existing grid structure and development status of the Shengli oilfield grid are described,and the simulation model of the oilfield grid is built based on BPA software after considering the load model,load growth mode,generator reactive power treatment and capacitor switching.The static stability of the grid is evaluated by combining global and nodal margin indicators.The static voltage stability margin index of the whole network is obtained by calculating the static power limit according to the PV curve analysis method.Based on the mathematical analysis process,the voltage stability margin of each node in the four-corner ring network is obtained by the Davinan equivalent parameter identification method,and the weak nodes and areas of the oilfield grid are identified.The transient stability of the oilfield grid is analyzed based on the time-domain simulation method.The tidal current distribution of the oilfield grid under N-1 and N-2 mode is studied and the static safety stability of the system is analyzed.Based on the analysis results of the existing grid,the safety stability of the grid is improved from the perspective of grid optimization.For the problem of no direct power supply for the Xingu Substation and the weak power grid in the area north of the Yellow River,three grid optimization schemes are proposed.The simulation results show that the safety and stability of the oilfield grid is improved under Option 2,which verifies the feasibility and effectiveness of the optimization scheme,and the final recommended scheme is derived after comparison.Large-scale PV access will change the grid tide distribution and affect the oil and gas production on the load side of Shengli Oilfield.Based on the existing and new grid BPA models,the effect law of changing the PV output on the oilfield grid voltage under different reactive power control methods is studied,and it is proved that the constant voltage control method is better than the constant power factor control method in voltage support capability.For the future impact caused by large-scale PV grid connection,some improvement measures are proposed with the actual operation situation.