Research On Control Strategy Of High-voltage Direct Current Transmission Pole Control System

With the rapid development of high voltage direct current transmission technology,the importance of HVDC control system in maintaining security and stability of HVDC systems is overwhelming.C urrently,most research work of HVDC control system are based on CIGRE HVDC standard test system model,but this model can no longer meet the test demand of HVDC control system.It make sense to improve and perfect the HVDC control test system model,and make the simulation really comes up to the actual situation,and it's hoped that this paper will produce some use for reference in relevant respect.The paper introduces the basic theory and control mode of HVDC system,to test the transient and steady characteristics of constant voltage control and constant extinction angle control used at inverter sides,the control system of CIGRE HVDC Benchmark Model is complemented by a voltage control model.Our results show that,in comparison with CIGRE HVDC Benchmark Model,adding constant voltage control at inverter side could enhance the performance of HVDC system under the fault of AC side and lower the risk of commutation failure,and it can improve the reliability of HVDC system.The paper introduces the principle and modulation methods of SIEMENS and ABB control strategy in practical HVDC engineering,the SIEMENS and ABB control strategy of HVDC system are built in the paper,the simulation model is established based on CIGRE HVDC Benchmark Model.The steady state and transient characteristics of both model are simulated,simulation results show that the better features of two models,and it is good for recovery after faults.in comparison with CIGRE HVDC Benchmark Model,two control strategy can lower the risk of commutation failure,and it can improve the reliability of HVDC system.For deeper study on SIEMENS and ABB control strategy,and make the simulation results are in a good agreement with practical situation,this paper compares the commutation failure different results caused by AC system fault and DC system fault under different short-circuit ratio.Research shows that commutation failure prevention ability of the two strategies has no obvious difference in general,ABB control strategy uses the idea of limiting output,it makes the change of firing angle continuous and smooth,and better for system stability,while SIEMENS control strategy is better than SIEMENS control strategy in term of commutation failure recovery time under the same fault conditions.