Model Simulation And Coordination Strategy Of Interline Power Flow Controler

As a novel facts device,interline power flow controller can be applied to power flow control,damping control and transient stability control in multiple transmission channels.However,the research on IPFC is still at the initialial stage,and there exists a lack of simulation model,control strategy and multi-objective coordination technology to guide the practical engineering application.Therefore,this paper focuses on the modeling and simulation,dynamic control strategy and coordinated control of IPFC,establishes the static and dynamic model of IPFC which can be applied to the actual power grid calculation,puts forward the IPFC devicelevel and system-level control strategy,and gives the IPFC multi-objective coordination method.The main research work of this paper is as follows:(1)This paper proposes a novel topology structure of IPFC which reflects the converters connecting to the parallel double circuit lines,and gives the theoretical derivation of IPFC power injection model.Based on the interactive iteration between PSASP power flow program and user-defined(UD)model,an IPFC simulation model which can be applied to the system level calculation and analysis of more than 3000 nodes is built,and based on the actual calculation of 500 k V power supply in southern Suzhou An example is given to verify the correctness and effectiveness of the power injection model.The simulation model can be used to evaluate the control potential and application value of IPFC in power flow control of large power grid.(2)Considering the strategies including voltage regulation control,phase angle regulation control,impedance compensation control and power flow control,a dynamic simulation model of IPFC is built with the consideration of dynamic process of DC voltage.The model is verified in a 500 k V practical example in the south of Suzhou power grid.Furthermore,the electromagnetic transient model of IPFC is built in order to verify the accuracy of the dynamic model in PSASP.The model can be easily used by operation and dispatching personnel,and has a great role in testing the impact and stability evaluation of IPFC connected to large power grid.(3)Due to the phenomenon that new energy may cause low-frequency oscillation of different frequencies,the periodic disturbances caused by renewable energy are simulated in the local power grid near IPFC.According to the disturbance characteristics,a multi-channel IPFC damping controller structure is designed,and a low-frequency oscillation suppression strategy with wide adaptability is proposed to suppress the disturbances caused by oscillation of different frequencies The problem of low frequency oscillation provides technical support for IPFC to deal with complex power oscillation under multiple disturbances.(4)Aiming at solving the problem of large disturbance stability,this paper analyzes the influence of different control modes of IPFC on large disturbance,and proposes a dynamic control strategy to improve the transient stability of power system.The design objectives are:to adopt power flow control mode in steady state,to switch to impedance compensation control in case of fault,to improve the transient stability,and to adopt slope control to naturally transition to steady state control.The effectiveness of the strategy is verified by the simulation comparison with the conventional control in the same scenario.The proposed dynamic control strategy deepens the role of IPFC control modes in different operation conditions.(5)Since the main objectives of IPFC vary considerably under different working conditions,as well as the interactions exist between the different objectives,it is necessary to study the multi-objective coordination strategy of IPFC.The state equation model including IPFC is linearized to quantify the interaction based on the improved relative gain matrix theory,and the coordination strategy is formulated correspondingly.Considering the inherent defects of linear modulation,the IPFC multi-objective fuzzy controller is designed based on the optimized samples of the established coordination system and particle swarm optimization,which can improve the coordination of the device in different operating states of the system.