| The multiple-time large-capacity direct-current(DC)asynchronous delivery and large-scale grid connection of new energy have made the regional power grid exhibit significant low inertia characteristics,and its grid structure contains complex stability characteristics.For a long time,the influence of system inertia has been ignored in the planning and operation of the power grid,and the standby demand is set based on the complete synchronous power grid conditions.These empirical methods are rough and lack theoretical support,and it is difficult to ensure the adaptability of low-inertia transmitting-end power grids to large-capacity power disturbances in an asynchronous interconnection pattern.For low-inertia power grids with high penetration of DC and new energy,on the one hand,fluctuating power sources such as wind power and photovoltaics have increased the diversity of operation modes;on the other hand,multiple types of AC and DC faults have greatly increased the number of fault analyses.Therefore,there is an urgent need to grasp the inertial characteristics of new energy high-permeability power grids,so that power planning and operating personnel can quickly and accurately grasp the system frequency stability level,and then develop effective control measures to ensure that the stability index after the accident is within the tolerable range Avoid or reduce the cutting machine and load to maintain the safe and stable operation of the system.This paper first briefly analyzes the voltage stability and frequency stability of the new energy high-permeability Yunnan power grid,and introduces the main functions and advantages of the PSD-PSAW digital analysis platform.Based on this,a generator,excitation,and speed regulation are constructed.Models of various modules such as generators and wind turbines.Finally,a simulation model of the Yunnan power grid was established using the platform.Secondly,the relationship between inertial characteristics and stability of the Yunnan power grid was deeply explored.The system under large-scale new energy grid connection and multi-scenario operation mode was simulated and analyzed under typical operating conditions,and the frequency and voltage stability were analyzed based on the simulation results Evaluation.Based on the actual parameters of each power plant station in the Yunnan power grid simulation model,a model of large-scale operation during high water periods in different years was selected,and the inertia time constant HAC and relative inertia time constant HDC of the Yunnan power grid were calculated.Sudden changes in faults and large unit failures were taken out of the network under different simulation conditions.Secondly,because the Yunnan power grid is mainly dominated by hydropower,it is heavily affected by the flood season.The model of the running mode was simulated.Finally,the simulation results were used to evaluate the frequency and voltage stability.Finally,a virtual inertia control strategy is proposed to improve the stability of Yunnan power grid.The principle of virtual inertia control is analyzed,the control model of the virtual synchronous machine device is established,and a small system of 3 machines and 9 nodes is built.The two conditions of load sudden change and unit failure switching are simulated respectively,and the virtual inertia is verified.Effectiveness of control;the virtual inertia control strategy was introduced to the Yunnan power grid,and the three operating conditions of DC unipolar blocking,sudden load change and large unit failure offline were simulated and analyzed,and the results verified that the proposed virtual inertia control was effective for Yunnan Improved grid stability. |
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