Reactive Power Optimization Control Of UHVAC/DC Power Grid

UHV connection is the trend of future power grid.UHVAC and UHVDC power grid have their own functions and position.They are complementary and complementary to each other in the interconnected power grid.Regardless of the economy or from the point of view of technology,UHVAC/DC hybrid power grid is undoubtedly one of the best way to solve China's large-scale renewable energy integration and achieve efficient allocation of resources.UHV power grid plays an important role in long-distance and large capacity transmission.So large-scale interconnection of AC and DC power grids is essential for its safe,reliable and stable operation.Reactive power and voltage control as an important technical means to ensure the safe and stable operation of power grid,the development of UHVAC/DC hybrid power inevitably requires higher reactive power and voltage control.How to co-ordinate the power system operation constraints and coordinate the reactive power and voltage control of UHVAC/DC power grid is an important problem to be solved in the development of UHV AC/DC power grid.Based on the power system real time simulation software ADPSS,combined with the planned power grid data of Northeast China in 2020,in this paper the characteristics of reactive power and voltage operation and UHVAC/DC reactive power and voltage optimal control of UHVAC/DC power grid are mainly studied.For the Northeast UHVAC and DC hybrid power grid,especially the planning and operation of Liaoning power grid,the theoretical reference and technical support are improved.Firstly,UHVAC,EHV/UHVDC and UHVAC/DC hybrid power grid voltage and reactive power optimization control research status are reviewed and summarized.The transient model of the UHVAC,UHVDC and the renewable energy machines are built by using the Advanced Digital Power System Simulator.At the same time the electromechanical-electromagnetic transient hybrid simulation model of the UHVAC/DC system is built.Secondly,the reactive power operation and control characteristics of UHVAC/DC power grid are studied.The influence of UHVAC transmission power on voltage operation,the influence of power transmission section of provincial transportation on voltage operation,the influence of EHV/UHVDC transmission power on voltage operation,the influence of UHV power grid and the lower grid reactive power exchange on voltage operation are mainly studied.By analyzing the operating characteristics of reactive power and voltage of UHVAC/DC hybrid power grid,a reactive power optimization control model of UHV power grid is built.The reactive power optimization control strategy for UHV by using sensitivity analysis and particle swarm optimization combined AC-DC power flow in the process of cooperation is proposed.The practicality and effectiveness of the optimization control strategy are proved through the actual example simulation and analysis.Aiming at the problems of reactive power and voltage operation in Liaoning UHV hybrid power network and the lack of online optimization control capability,a strategy of UHV grid reactive power/voltage coordinated optimization control is put forward.Finally,for UHVDC bipolar blocking failure,the operation state of UHVDC converter bus and wind farm bus is limited by the DC transmission capacity,the capacity of wind turbine and the different capacity ratio of thermal power unit before failure.The two coordinated control model is established.The optimization calculation and analysis is carried out by the Northeast UHV planning grid.The UHVDC wind and thermal power mixed feeding system network source combination coordination control strategy is put forward.