Abstract
Sub-synchronous control interaction (SSCI) is an oscillation phenomenon caused by the interaction of converter control and series-compensated transmission line. This paper proposes a novel adaptive higher-order sliding mode (AHOSM) control strategy for damping the SSCI of a series-compensated DFIG-based wind power system. On the basis of system modeling and oscillation mechanism analysis, SSCI suppression is converted to the current tracking control problem. Firstly, an auxiliary feedback control is employed for the nonlinear series-compensated system, then integral sliding mode functions are defined to design a second-order sliding mode control law for the equivalent system. Adaptive laws for the control gains are then conceived based on the Lyapunov function considering unknown upper bounds of uncertainty derivatives. System stability is also analyzed in detail along with adaptive laws’ design. The effectiveness of the proposed control scheme is verified under different series-compensated level, different wind speed, symmetric and asymmetric short circuit fault, and internal and external disturbances. The PI control and conventional first-order sliding mode control scheme are also executed to compare the damping effect.
Highlights
As a clean and renewable energy, wind energy has been widely used along with increasingly serious energy crisis and environmental pollution [1]
When wind speed is kept at 7 m/s and series compensation is increased to 75%, the responses of the relevant system variables are observed inseries
A new synchronous control interaction (SSCI) mitigation scheme for an uncertain, nonlinear, series-compensated, DFIG-based wind-power system is proposed based on the adaptive higher-order sliding mode (AHOSM) method
Summary
As a clean and renewable energy, wind energy has been widely used along with increasingly serious energy crisis and environmental pollution [1]. In [13], a damping controller is simultaneously added into the dq-axis control channels in the inner current loop of the rotor-side converter (RSC), and a particle swarm optimization algorithm is applied to achieve the optimum control gains, which helps to maximize the mitigation effect under different series-compensated levels and wind speeds. An active disturbance rejection controller is added to the current inner loop of RSC to compensate for uncertainties in [21] Another robust control method which is widely used in power systems is sliding mode control. Considering the uncertain nonlinear characteristics, unknown upper bound of uncertainty derivative, Energies 2020, 13, x FOR PEER REVIEW uncertainty derivative, sliding mode chattering problem and the requirement for system robustness, this paper proposes an adaptive higher-order sliding mode (AHOSM) control strategy for a seriessliding mode DFIG-based chattering problem and the requirement for system robustness, this paper an compensated wind power system.
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