A Study On Modeling Of Control Systems In AC-DC Hybrid Grid With PSS/E User-defined Function

Due to the dense DC landing points and high power capacity in the receiving AC power grid,the voltage stability of the multi-infeed AC/DC hybrid power grid under the large disturbance is particularly prominent.At the same time,the planning and operation of the power grid has undergone tremendous changes.The type,quantity,location and control strategy of electric equipment are changing and becoming more and more complex.Therefore,in the AC/DC hybrid environment,the dynamic reactive power characteristics,caused by the interaction between AC and DC system,must be comprehensively investigated,and the working mechanism of the transient voltage stability problem must be thoroughly studied.The optimization strategy must be formulated to ensure the safety and stability of power grids.The improvement and optimization of the dynamic response characteristics of the power system components and their control and protection system is also a solution to enhance the transient voltage stability of the power grid,which will put more demands on the transparency and maneuverability of the simulation models.Based on the electromagnetic transient simulation platform PSCAD/EMTDC,this paper analyzes the reactive power composition of AC/DC hybrid power grid,and studies the mutual influence mechanism of their reactive power characteristics.After picking out the objects of which the reactive power is under controlled,this paper also analyzes their role and contribution to the transient voltage stability of AC/DC hybrid power grid,and then explores their optimization solution.Then,the user-defined functions of the electromechanical transient simulation software PSS/E are deeply excavated from the simulation operation mechanism of PSS/E,the definition of object,model classification,realization mode,environment configuration,modeling process and coordination call model.Mastering its modeling method provides not only an effective way to achieve the transparency and maneuverability of simulation models in AC-DC hybrid network analysis,but also a carrier for the power grid technology summary and operational experience of the transmission.Finally,this paper takes the generator and SVC as the optimization target of the reactive power-voltage control strategy,and analyzes the limitations of their control strategy.In consideration of the operating condition of AC/DC hybrid power grid,the optimization scheme of breaking the sensing limit of them is discussed,including an SVC reactive power control method based on near-end load bus voltage level and a reactive power-voltage control strategy of generator using WAMS information.With PSS/E user-defined function,the ideas are successfully realized and verified.The optimization scheme provides a significant guidance for the research of the voltage stability strategy in the receiving end.