The Experts below are selected from a list of 66750 Experts worldwide ranked by ideXlab platform
Heng Nian - One of the best experts on this subject based on the ideXlab platform.
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stator harmonic currents suppression for dfig based on feed forward regulator under distorted Grid Voltage
IEEE Transactions on Power Electronics, 2018Co-Authors: Heng NianAbstract:This paper presents a stator harmonic currents suppression method for doubly fed induction generators (DFIGs) under distorted Grid Voltage. In the proposed control strategy, the feed-forward regulator instead of the resonant regulator is employed to eliminate the negative impacts on the stator current caused by the distorted Grid Voltage. The leading phase compensator is applied to compensate the system delay when the sampling frequency is low. This approach can provide both the good dynamic response and strong rejection ability against the stator harmonic Voltages. Based on the stator current model of DFIG, the feed-forward regulator is designed in detail. The comparison between the resonant controllers and the feed-forward regulator is also made on the basis of Bode diagram. Then, the robustness against the frequency variations and the parameter deviations is analyzed. Finally, the simulation and experimental results are presented to validate the effectiveness of the proposed control strategy.
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coordinated direct power control of dfig system without phase locked loop under unbalanced Grid Voltage conditions
IEEE Transactions on Power Electronics, 2016Co-Authors: Heng Nian, Peng Cheng, Z Q ZhuAbstract:This paper proposes a coordinated direct power control (DPC) scheme for the rotor-side converter (RSC) and the Grid-side converter (GSC) of the doubly fed induction generator (DFIG) under unbalanced Grid Voltage conditions. In order to eliminate the coupling interactions between the phase-locked loop (PLL) and the local unbalanced network, a virtual phase angle is used to replace the actual one acquired by the PLL. Thus, the PLL is removed out of RSC and GSC in the proposed DPC scheme. During network unbalance, the RSC is controlled to reduce torque ripples, while three selectable control targets are identified for the GSC, i.e., constant total active power, constant total reactive power, and balanced currents. A single-side resonant controller with the frequency discrimination between the positive- and negative-sequence signals of the same frequency is employed in the coordinated DPC scheme to avoid the complex calculations of the power compensating components. Meanwhile, the sequential separations of the Voltages and currents are also eliminated. Then, the control performance, including the limits of the dc-link Voltage, the dc-capacitor power oscillations, the impacts of the frequency deviations, and the Grid synchronization of the proposed DPC strategy, is discussed. Finally, the experimental results of DFIG system verify the effectiveness of the proposed DPC strategy under unbalanced Grid Voltage conditions.
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modularized control strategy and performance analysis of dfig system under unbalanced and harmonic Grid Voltage
IEEE Transactions on Power Electronics, 2015Co-Authors: Yipeng Song, Heng NianAbstract:The paper presents a modularized control strategy of doubly fed induction generator (DFIG) system, including the Grid-side converter (GSC) and rotor-side converter (RSC), under unbalanced and harmonic Grid Voltage. The sequence decomposition process and complicated control reference calculation can be avoided in the proposed control strategy. From the perspective of power Grid friendly operation, the control targets of DFIG system in this paper are chosen as: 1) smooth active and reactive power injected into the power Grid; 2) balanced and sinusoidal current injected into the power Grid. The RSC and GSC can work as two independent modules and the communication between RSC and GSC can be removed. Furthermore, the third harmonic current component, dc-link Voltage fluctuation, and electromagnetic torque pulsation under the different control targets are theoretically analyzed. Finally, the availability of the proposed modularized control strategy of DFIG system under unbalanced and distorted Grid Voltage is verified by experiment results.
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independent operation of dfig based wecs using resonant feedback compensators under unbalanced Grid Voltage conditions
IEEE Transactions on Power Electronics, 2015Co-Authors: Heng Nian, Peng Cheng, Z Q ZhuAbstract:This paper presents an independent operation of the rotor-side converter (RSC) and Grid-side converter (GSC) for a doubly fed induction generator (DFIG)-based wind energy conversion system under unbalanced Grid Voltage conditions. In this paper, the RSC is controlled to achieve four different control targets, including balanced stator current, sinusoidal rotor current, smooth stator active and reactive powers, and constant DFIG electromagnetic torque. The GSC is commanded to keep the dc Voltage at a constant value. Additional feedback compensators using resonant regulators for the RSC are employed, and the decompositions of the positive and negative sequence components and calculations of the rotor negative current references can be avoided. Another similar compensator is used in the GSC to suppress the dc Voltage fluctuates and remove the GSC reactive power oscillations without the stator or rotor power information. The proposed method can make the RSC and GSC available to an independent operation with a simple implementation for higher reliability. The experimental results demonstrate the effectiveness of the proposed control strategy for both the RSC and GSC under unbalanced Grid Voltage conditions.
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optimised parameter design of proportional integral and resonant current regulator for doubly fed induction generator during Grid Voltage distortion
Iet Renewable Power Generation, 2014Co-Authors: Heng Nian, Yipeng SongAbstract:The study presents an optimised parameter design of the proportional integral and resonant (PIR) current regulator for doubly fed induction generator (DFIG) under distorted Grid Voltage conditions. Based on the mathematical model of DFIG under distorted Grid Voltage conditions, practical PIR current regulator under synchronous frame is developed to implement the harmonic control target of sinusoidal stator current. The optimised parameter design of PIR regulator is investigated concerning the control system gain margin and phase margin, as well as variation of the resonant bandwidth. The influence of DFIG parameters and Grid frequency deviation on PIR design is also discussed. Correctness of the optimised parameter design technique of PIR regulator is validated by the MATLAB simulation and experiment results.
Yipeng Song - One of the best experts on this subject based on the ideXlab platform.
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modularized control strategy and performance analysis of dfig system under unbalanced and harmonic Grid Voltage
IEEE Transactions on Power Electronics, 2015Co-Authors: Yipeng Song, Heng NianAbstract:The paper presents a modularized control strategy of doubly fed induction generator (DFIG) system, including the Grid-side converter (GSC) and rotor-side converter (RSC), under unbalanced and harmonic Grid Voltage. The sequence decomposition process and complicated control reference calculation can be avoided in the proposed control strategy. From the perspective of power Grid friendly operation, the control targets of DFIG system in this paper are chosen as: 1) smooth active and reactive power injected into the power Grid; 2) balanced and sinusoidal current injected into the power Grid. The RSC and GSC can work as two independent modules and the communication between RSC and GSC can be removed. Furthermore, the third harmonic current component, dc-link Voltage fluctuation, and electromagnetic torque pulsation under the different control targets are theoretically analyzed. Finally, the availability of the proposed modularized control strategy of DFIG system under unbalanced and distorted Grid Voltage is verified by experiment results.
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optimised parameter design of proportional integral and resonant current regulator for doubly fed induction generator during Grid Voltage distortion
Iet Renewable Power Generation, 2014Co-Authors: Heng Nian, Yipeng SongAbstract:The study presents an optimised parameter design of the proportional integral and resonant (PIR) current regulator for doubly fed induction generator (DFIG) under distorted Grid Voltage conditions. Based on the mathematical model of DFIG under distorted Grid Voltage conditions, practical PIR current regulator under synchronous frame is developed to implement the harmonic control target of sinusoidal stator current. The optimised parameter design of PIR regulator is investigated concerning the control system gain margin and phase margin, as well as variation of the resonant bandwidth. The influence of DFIG parameters and Grid frequency deviation on PIR design is also discussed. Correctness of the optimised parameter design technique of PIR regulator is validated by the MATLAB simulation and experiment results.
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Direct power control of doubly fed induction generator under distorted Grid Voltage
IEEE Transactions on Power Electronics, 2014Co-Authors: Heng Nian, Yipeng SongAbstract:This paper presents a direct power control (DPC) strategy for a doubly fed induction generator (DFIG)-based wind power generation system under distorted Grid Voltage. By analyzing the six times Grid frequency power pulsation produced by the fifth and seventh Grid Voltage harmonic components, a novel DPC strategy with vector proportional integrated (VPI) regulator has been proposed to implement the smooth active and reactive power output of DFIG. The performance analysis of the proposed DPC strategy, including the steady and dynamic state performance, closed-loop operation stability, and rejection capability for the Grid Voltage distorted component and back EMF compensation item has been investigated. The availability of the proposed DPC strategy with a VPI regulator is verified by experiment results of DFIG system under harmonically distorted Grid condition.
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improved direct power control of a wind turbine driven doubly fed induction generator during transient Grid Voltage unbalance
IEEE Transactions on Energy Conversion, 2011Co-Authors: Heng Nian, Yipeng Song, Peng Zhou, Yikang HeAbstract:This paper proposes an improved direct power control (DPC) strategy for a doubly fed induction generator (DFIG)-based wind power generation system under unbalanced Grid Voltage dips. The fundamental and double Grid frequency power pulsations, which are produced by the transient unbalanced Grid faults, are mathematically analyzed and accurately regulated. Five selectable control targets, with proper power references given, are designed for different applications during network unbalance. In order to provide enhanced control performance, two resonant controllers, which are tuned to have large gain at the power pulsation frequencies, are applied together with the proportional-integral controller to achieve full control of the DFIG output power. The effectiveness of the proposed DPC strategy is verified by the experimental results of a 5-kW DFIG system under different unbalanced Voltage dips, which are generated by a specially designed Voltage dip generator.
Yikang He - One of the best experts on this subject based on the ideXlab platform.
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improved direct power control of a wind turbine driven doubly fed induction generator during transient Grid Voltage unbalance
IEEE Transactions on Energy Conversion, 2011Co-Authors: Heng Nian, Yipeng Song, Peng Zhou, Yikang HeAbstract:This paper proposes an improved direct power control (DPC) strategy for a doubly fed induction generator (DFIG)-based wind power generation system under unbalanced Grid Voltage dips. The fundamental and double Grid frequency power pulsations, which are produced by the transient unbalanced Grid faults, are mathematically analyzed and accurately regulated. Five selectable control targets, with proper power references given, are designed for different applications during network unbalance. In order to provide enhanced control performance, two resonant controllers, which are tuned to have large gain at the power pulsation frequencies, are applied together with the proportional-integral controller to achieve full control of the DFIG output power. The effectiveness of the proposed DPC strategy is verified by the experimental results of a 5-kW DFIG system under different unbalanced Voltage dips, which are generated by a specially designed Voltage dip generator.
Jiabing Hu - One of the best experts on this subject based on the ideXlab platform.
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sliding mode based direct power control of Grid connected wind turbine driven doubly fed induction generators under unbalanced Grid Voltage conditions
IEEE Transactions on Energy Conversion, 2012Co-Authors: Lei Shang, Jiabing HuAbstract:This paper proposes an improved direct power control (DPC) strategy of Grid-connected wind-turbine-driven doubly fed induction generators (DFIGs) when the Grid Voltage is unbalanced. The DPC scheme is based on the sliding mode control (SMC) approach, which directly regulates the instantaneous active and reactive powers in the stator stationary reference frame without the requirement of either synchronous coordinate transformation or phase angle tracking of Grid Voltage. The behavior of DFIGs by the conventional SMC-DPC, which takes no negative-sequence Voltage into consideration, is analyzed under unbalanced Grid Voltage conditions. A novel power compensation method is proposed for the SMC-based DPC during network unbalance to achieve three selective control targets, i.e., obtaining sinusoidal and symmetrical stator current, removing stator interchanging reactive power ripples and canceling stator output active power oscillations, respectively. The active and reactive power compensation components are calculated via a simple method and the proposed three control targets can be achieved, respectively, without the need of extracting negative-sequence stator current components. Experimental results on a 2 kW DFIG prototype are presented to verify the correctness and validity of the proposed control strategy and power compensation method.
Yu Ling - One of the best experts on this subject based on the ideXlab platform.
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rotor current dynamics of doubly fed induction generators during Grid Voltage dip and rise
International Journal of Electrical Power & Energy Systems, 2013Co-Authors: Yu LingAbstract:Abstract The influence of Grid Voltage dip on doubly fed induction generators (DFIGs), especially rotor current, has received much attention. So, in this paper, the rotor short-circuit current of based-DFIG wind turbines is considered in a generic way, which is suitable to analyze the cases under different levels of both Voltage sag and Voltage rise. A direct method is proposed to obtain accurate expression of rotor current. Firstly, the rotor open-circuit Voltage in terms of stator flux is determined, and the dynamic equation of the rotor current reduces to a first-order differential equation under rotor short-circuit operation condition. Secondly, the expressions of the rotor open-circuit Voltage before and after a fault are obtained, respectively. Finally, based on the obtained expression of rotor Voltage, the rotor short circuit currents before and after a fault are obtained by solving the first-order differential equation. This analysis contributes to understand the causes of the problem, and as a result, it helps to adapt reasonable approaches to improve the capacity of the uninterrupted operation of wind power generation during a Voltage fault. Simulation results evaluate the proposed analysis.
