The Influence Of The Dynamic Characteristics Of The Inverter Station On DC Transmission Capacity In A VSC-HVDC System

Along with the shortage of global energy and the increas ing demand of electricity,the grid scale expands rapidly.There is the dismatch of the energy distribution and the power supply,so the traditional HV DC technology can not adapt to the power supply of long-distance,large capacity and high efficiency,and also can not be used to deal with the increasingly of complex electricity problem.Therefore,it is necessary to seek for the current transmission technology.VSC-H VDC is different with the high voltage AC transmission system.It is based on HVDC of voltage source converter(VSC)and there is no evidence of synchronization stability problem and have fast control power ability of VSC lead to inverter stations presents constant power characteristics.The characteristics have an influence on the stability of DC transmission capacity.In short,VSC-H VDC have some unique advantages.For example,the independent regulation of active and reactive power,to passive network power supply and easy to build DC network and so on.There are a broad commercial value and application prospects in the field of electric power system.At present,the DC transmission capacity is mainly limited by the thermal limitation of IG BT.With the development of power devices,the influence of the DC transmission capacity affect by stability constraints will become more and more obvious.In this paper,the small-signal input impedance model of the inverter station of the VSC-HVDC system is built.The DC trans mission capac ity is calculated based on small-signal stability analysis for the DC system.The influence of the response time of the inverter station on the pow er system stability and the transmission capacity is further investigated.Simulation is conducted by using PSCA D/EMTDC software.We built the dynamic equivalent simulation model of VSC-HVD C system.Depend on the proposed control strategy,which analysis the dynamic characteristics of the inverter station on DC transmission capacity in a VSC-H VDC system.We calculate DC transmission capac ity,and compared with the simulation result.The simulation results demonstrate that the DC transmission capacity is quite affected by the dynamic characteristics of the inverter station in the VSC-HVDC system.When VSC-H VDC system are supposed to have additional function in the VSC-HVDC system,such as the suppression of power os cillation andreactive power compensation,the conclusions needs attention.