Abstract
In the traditional double closed-loop control strategy for VSC-HVDC transmission system that supply power to passive networks, the control structure is complex, the PI parameters are more difficult, the tuning is slow, and the response speed is slow. Rectifier-side direct power control based on model prediction and direct AC voltage control strategy on inverter side are proposed. Based on the discrete mathematical model of the converter, the system output under all switching function combinations is calculated by the ergodic method, and the switching function that minimizes the objective function is selected to act on the inverter. The utility model has the advantages of simple structure, no complicated PI parameter setting, fast dynamic response, high voltage quality electric energy to the passive network, good steady state performance and dynamic performance. The simulation results verify the feasibility and effectiveness of the proposed control strategy.
Highlights
With the Development of Controllable Turn-off Power Electronic Devices and PWM, high-voltage direct current transmission systems based on voltage source converters (VSC-HVDC) are receiving increasing attention
Since the response speed of the voltage outer loop is much lower than the response speed of the current inner loop, the voltage quality is affected when the load side is disturbed
In [10], the direct power control of the rectifier side of the VSC-HVDC system and the direct AC voltage control strategy of the inverter side are proposed based on the model predictive control
Summary
With the Development of Controllable Turn-off Power Electronic Devices and PWM, high-voltage direct current transmission systems based on voltage source converters (VSC-HVDC) are receiving increasing attention. Compared with the traditional HVDC transmission system, VSC-HVDC has less harmonic content and can independently control active and reactive power [1] It has broad application prospects in the fields of new energy generation and grid connection, power supply to weak AC grid or passive network [2,3,4,5,6]. Reference [7] is based on the discretization mathematical model of the converter and uses the digital PI controller to design the power outer loop of the rectifier side, the current inner loop controller and the inverter side fixed AC voltage controller. Reference [8] proposes a double closed-loop control strategy for the inner loop voltage outer loop of the inverter-side current. In [10], the direct power control of the rectifier side of the VSC-HVDC system and the direct AC voltage control strategy of the inverter side are proposed based on the model predictive control. Based on MATLAB/Simulink platform, a VSCHVDC system for powering passive networks is built, and the proposed control strategy is verified
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