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Voltage source (VS) control based on inertia synchronization is a novel phase lock loop (PLL)-less autonomous grid-synchronization control strategy suitable for the permanent magnet synchronous generator (PMSG)-based wind turbine. It can autonomously sense grid frequency fluctuations by adopting the dynamics of DC-link capacitor, and it has the advantage of stable operation in an extremely weak grid. This paper further studies the low-voltage ride-through (LVRT) of the PMSG-based wind turbine under the VS control, and presents a wind turbine structure with the additional energy storage battery on the DC side, which not only improves its LVRT capability but also enables the wind turbine to participate in the grid primary frequency regulation. The transient characteristics of VS-controlled wind turbines after the occurrence of the short-circuit fault are analyzed, and a current suppression strategy via switching the virtual resistor in the control loop of the grid-side converter (GCS) is presented. Through coordination with the energy storage battery, the LVRT of the PMSG-based wind turbine is realized, which has the advantage of withstanding a long-time short-circuit fault. Finally, based on the PSCAD/EMTDC simulation platform, the feasibility of the control strategy and the correctness of the theoretical analysis are verified.
Shun Sang; Binhui Pei; Jiejie Huang; Lei Zhang; Xiaocen Xue. Low-Voltage Ride-Through of the Novel Voltage Source-Controlled PMSG-Based Wind Turbine Based on Switching the Virtual Resistor. Applied Sciences 2021, 11, 6204 .
AMA StyleShun Sang, Binhui Pei, Jiejie Huang, Lei Zhang, Xiaocen Xue. Low-Voltage Ride-Through of the Novel Voltage Source-Controlled PMSG-Based Wind Turbine Based on Switching the Virtual Resistor. Applied Sciences. 2021; 11 (13):6204.
Chicago/Turabian StyleShun Sang; Binhui Pei; Jiejie Huang; Lei Zhang; Xiaocen Xue. 2021. "Low-Voltage Ride-Through of the Novel Voltage Source-Controlled PMSG-Based Wind Turbine Based on Switching the Virtual Resistor." Applied Sciences 11, no. 13: 6204.
Inertia synchronization control is a good solution for type-IV wind turbine to provide an inertia response to the grid. To further improve its frequency support performance, this paper addresses a battery energy storage unit on the DC link side of the full power back-to-back wind energy converter. After that, the corresponding modified control strategy is implemented as an upgraded version of existing inertia synchronization control from the view of emulating the behavior of a traditional synchronous generator widely used in power system for decades. Moreover, a control method based on removable virtual resistors co-operated with reconfiguration of battery energy storage unit’s control structure is studied in detail to improve the low voltage ride through performance of the wind turbine. Simulation results are obtained based on the environment of PSCAD/EMTDC, which can certify the correctness and feasibility of the presented control method in this paper.
Ning Gao; Xin Lin; Shun Sang. Modified Inertia Synchronization Control for a Type-IV Wind Turbine Integrated with a Battery Energy Storage Unit. Journal of Electrical Engineering & Technology 2021, 16, 2065 -2073.
AMA StyleNing Gao, Xin Lin, Shun Sang. Modified Inertia Synchronization Control for a Type-IV Wind Turbine Integrated with a Battery Energy Storage Unit. Journal of Electrical Engineering & Technology. 2021; 16 (4):2065-2073.
Chicago/Turabian StyleNing Gao; Xin Lin; Shun Sang. 2021. "Modified Inertia Synchronization Control for a Type-IV Wind Turbine Integrated with a Battery Energy Storage Unit." Journal of Electrical Engineering & Technology 16, no. 4: 2065-2073.
With the increasing penetration of wind power, the effective inertia of the power system reduces. Besides, a series of interactive instability issues including sub-synchronous oscillations and harmonic oscillations were reported due to the weak grid effects. Broadly speaking, those issues are closely related to the PLL and its tuning. Therefore, recent literatures make efforts to avoid using the PLL for converter control, e.g. the virtual synchronous generator (VSG) control. However, the VSG control usually employs multiple loops, where a fast switching frequency of converter is required to decouple each loop’s dynamic. This prerequisite is usually not met for wind power converters with high capacity and low switching frequency. To address these issues but also inherit the merits of a VSG on the grid-integration, this paper employs a new concept of PLL-less control and applies it to the Type-IV wind turbine, in which the grid-synchronization is realized by the dynamics of dc capacitor voltage. An virtual capacitor control is designed and added to the machine-side converter to eventually deliver adequate inertia to the grid. To justify the effectiveness of the proposed control, both the soft start-up validation and the thorough analysis of the overall small-signal stability are presented. Several concerns of vital importance regarding the virtual capacitor design and stabilization control are discussed, where the mechanism of stability is revealed through the complex-power coefficient-based analysis. On this basis, a stabilization control method is proposed, which can enlarge the stable range of virtual capacitor coefficient and enhance the inertial response effect. Finally, the performance of the proposed method on the inertial response as well as the weak grid operation are evaluated by time domain simulations in PSCAD/EMTDC, which is proven effective overall.
Shun Sang; Chen Zhang; Xu Cai; Marta Molinas; Jianwen Zhang; Fangquan Rao. Control of a Type-IV Wind Turbine With the Capability of Robust Grid-Synchronization and Inertial Response for Weak Grid Stable Operation. IEEE Access 2019, 7, 58553 -58569.
AMA StyleShun Sang, Chen Zhang, Xu Cai, Marta Molinas, Jianwen Zhang, Fangquan Rao. Control of a Type-IV Wind Turbine With the Capability of Robust Grid-Synchronization and Inertial Response for Weak Grid Stable Operation. IEEE Access. 2019; 7 (99):58553-58569.
Chicago/Turabian StyleShun Sang; Chen Zhang; Xu Cai; Marta Molinas; Jianwen Zhang; Fangquan Rao. 2019. "Control of a Type-IV Wind Turbine With the Capability of Robust Grid-Synchronization and Inertial Response for Weak Grid Stable Operation." IEEE Access 7, no. 99: 58553-58569.
The conventional power-current controlled grid-tied inverter suffers from interactive stability issues, including harmonic oscillations when connected to a weak ac grid, which limits the integrated power rating of distributed generators. To overcome preceding drawbacks, a novel power-voltage control strategy, based on the voltage feedback control of the inverter LCL filter capacitor, is proposed in this paper. A dynamic model of the inverter output impedance is developed in the rotating d-q frame. This model includes main circuit parameters, phase-locked loop (PLL) dynamics, and regulator parameters. Frequency characteristics of the output impedance, contrastive analysis between the conventional power-current strategy and proposed power-voltage strategy based on generalized Nyquist criterion are presented to show superiority of the latter in a weak grid. The impedance analysis proves the power-voltage controlled inverter can stably operate in a weak grid. The stability of the grid-tied inverter system remains unchanged with increasing PLL bandwidth and delivered power, thereby effectively raising the rated power injection level of the inverter in a weak grid. A low-power inverter prototype is built and tested in the laboratory. The simulation and experimental results verify the effectiveness of the proposed control strategy.
Shun Sang; Ning Gao; Xu Cai; Rui Li. A Novel Power-Voltage Control Strategy for the Grid-Tied Inverter to Raise the Rated Power Injection Level in a Weak Grid. IEEE Journal of Emerging and Selected Topics in Power Electronics 2017, 6, 219 -232.
AMA StyleShun Sang, Ning Gao, Xu Cai, Rui Li. A Novel Power-Voltage Control Strategy for the Grid-Tied Inverter to Raise the Rated Power Injection Level in a Weak Grid. IEEE Journal of Emerging and Selected Topics in Power Electronics. 2017; 6 (1):219-232.
Chicago/Turabian StyleShun Sang; Ning Gao; Xu Cai; Rui Li. 2017. "A Novel Power-Voltage Control Strategy for the Grid-Tied Inverter to Raise the Rated Power Injection Level in a Weak Grid." IEEE Journal of Emerging and Selected Topics in Power Electronics 6, no. 1: 219-232.