Passive Sliding Mode Controlled UPFC and its Treatment Strategy of Unbalanced Grid Conditions

Abstract

Modular multilevel converter based unified power flow controller (MMC-UPFC) can provide flexible power regulation and plays an important role in the smart grid and future distribution networks. PI controller is widely adopted in the Unified power flow controller (UPFC) control. However, it is often difficult to figure out a pair of stable control parameters with good dynamic performance. A passive sliding mode control strategy of MMC-UPFC is proposed in this paper to achieve the advantages of both the passive controller and sliding mode controller. The proposed passive sliding mode control strategy has a fast response speed and is not sensitive to system parameter variation. Since unbalance grid voltage conditions are common in the modern distribution networks, an unbalanced grid treatment strategy is also presented with the series side of MMC-UPFC. Negative sequence components of the grid voltages are detected by the cross-decoupling method with second order generalized integrator and then compensated by the series side of MMC-UPFC. The series side converter controls the power flow and treats unbalanced grid conditions simultaneously. The efficiency of the general device is increased thus. A 27-level MMC-UPFC simulation system is built based on the Shanghai UPFC Project and validate the proposed approach.

Adaptive Hierarchical Fractional-Order Sliding Mode Control Strategy for Multi-terminal VSC-HVDC System with Wind Farm

“…Therefore, this study explores further its control strategy formulation. Among the various nonlinear control schemes, SMC is a sophisticated technique with elegant features such as better stability, faster response, and significant robustness [6]. This control technique is notable for its ease and high accuracy, making it appropriate for wind power generation systems.…”

Damping of Low-Frequency Oscillations in a Power System, Based on Multiple-Model Optimal Control Strategy

“…Due to the nonlinear nature of modern and interconnected power systems, the methods based on nonlinear control have been discussed in many papers [19][20][21][22][23][24][25][26][27][28][29][30]. Te sliding mode (SM) control in combination with fuzzy control has been used in [20,21].…”