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Dr. Dao Zhou
Department of Energy Technology, The Faculty of Engineering and Science, Aalborg University, Pontoppidanstræde 111, 9220 Aalborg Øst, Denmark

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Research Keywords & Expertise

0 Power Electronics
0 Reliability Analysis
0 Wind Power Generation
0 Power semiconductor
0 Power capacitor

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Reliability Analysis
Power semiconductor
Power Electronics
Wind Power Generation
Power capacitor

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Journal article
Published: 29 July 2021 in IEEE Transactions on Power Electronics
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For the single-phase high-power railway traction system, the inevitable second-order resonating power has become a critical issue to the traction system. In this paper, a power decoupling solution is proposed to replace the conventional passive LC resonance filter by utilizing the buck-type bi-directional DC/DC converter (BBDC) of Hybrid Electric Multiple Units (HEMU), which is designed to power the train in non-electrified routes using the on-board battery. By considering both the current ripples in the battery mode and the power decoupling in the catenary mode, the corresponding parameter design process of the BBDC is presented. Based on the power coupling phenomenon and the spectrum characteristic of the BBDC, a direct resonance control method is proposed to decouple the low-order resonating power. Simulations and experiments are carried out to validate the effectiveness of the new proposal. The results demonstrate that the proposal is almost the same as using the conventional passive LC resonance filter for power decoupling in both steady and dynamic operation scenarios.

ACS Style

Lailai Shen; Jie Chen; Zheming Jin; Zhi-Gang Liu; Dao Zhou; Chao Wu. Resonating Power Decoupling Using Multi-Functional Bi-Directional DC/DC Converter in Hybrid Railway Traction Application. IEEE Transactions on Power Electronics 2021, PP, 1 -1.

AMA Style

Lailai Shen, Jie Chen, Zheming Jin, Zhi-Gang Liu, Dao Zhou, Chao Wu. Resonating Power Decoupling Using Multi-Functional Bi-Directional DC/DC Converter in Hybrid Railway Traction Application. IEEE Transactions on Power Electronics. 2021; PP (99):1-1.

Chicago/Turabian Style

Lailai Shen; Jie Chen; Zheming Jin; Zhi-Gang Liu; Dao Zhou; Chao Wu. 2021. "Resonating Power Decoupling Using Multi-Functional Bi-Directional DC/DC Converter in Hybrid Railway Traction Application." IEEE Transactions on Power Electronics PP, no. 99: 1-1.

Original research paper
Published: 19 July 2021 in IET Power Electronics
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The beat phenomenon can be a critical issue in railway traction applications. This paper proposes a dual-frequency compensation (DFC) method for the beat-less algorithm to shift the spectrum of the beat voltages to a higher-frequency region. Two variables for frequency compensation are derived by mathematical calculations based on the single-frequency compensation (SFC) method. The applicability and superiority of the DFC method are analyzed. It is proposed that the DFC method can be a transition between the modulation index compensation (MIC) method and the SFC method, so the beat phenomenon can be greatly suppressed in the full speed range. The implementation of the DFC method is proposed to guide how to generate the two variables. The experimental verification is carried out on the StarSim hardware-in-loop platform, and the results demonstrate that the DFC method is more effective compared with the SFC method for beat phenomenon suppression. It also shows the modulation index with the DFC method is higher than that with the MIC method.

ACS Style

Lailai Shen; Jie Chen; Yang Kuang; Ruichang Qiu; Dao Zhou; Chao Wu; Zhigang Liu. Beat‐less algorithm based on dual‐frequency compensation in railway traction applications. IET Power Electronics 2021, 14, 1985 -1994.

AMA Style

Lailai Shen, Jie Chen, Yang Kuang, Ruichang Qiu, Dao Zhou, Chao Wu, Zhigang Liu. Beat‐less algorithm based on dual‐frequency compensation in railway traction applications. IET Power Electronics. 2021; 14 (11):1985-1994.

Chicago/Turabian Style

Lailai Shen; Jie Chen; Yang Kuang; Ruichang Qiu; Dao Zhou; Chao Wu; Zhigang Liu. 2021. "Beat‐less algorithm based on dual‐frequency compensation in railway traction applications." IET Power Electronics 14, no. 11: 1985-1994.

Journal article
Published: 10 May 2021 in Applied Sciences
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Continuously expanding deployments of distributed power generation systems are transforming conventional centralized power grids into mixed distributed electrical networks. The higher penetration and longer distance from the renewable energy source to the main power grid result in lower grid strength, which stimulates the power limitation problem. Aimed at this problem, case studies of inductive and resistive grid impedance with different grid strengths have been carried out to evaluate the maximum power transfer capability of grid-connected inverters. It is revealed that power grids with a higher short circuit ratio (SCR) or lower resistance-inductance ratio (R/X) provide higher power transfer capability. Moreover, under the resistive grid conditions, a higher voltage at the point of common coupling (PCC) is beneficial to increase the power transfer capability. Based on mathematical analysis, the maximum power curves in the inductive and resistive grids can be found. Moreover, a performance index is proposed in this paper to quantify the performance of the system with different parameter values. Finally, the effectiveness of the analysis is verified by simulation.

ACS Style

Liang Huang; Chao Wu; Dao Zhou; Frede Blaabjerg. Impact of Grid Strength and Impedance Characteristics on the Maximum Power Transfer Capability of Grid-Connected Inverters. Applied Sciences 2021, 11, 4288 .

AMA Style

Liang Huang, Chao Wu, Dao Zhou, Frede Blaabjerg. Impact of Grid Strength and Impedance Characteristics on the Maximum Power Transfer Capability of Grid-Connected Inverters. Applied Sciences. 2021; 11 (9):4288.

Chicago/Turabian Style

Liang Huang; Chao Wu; Dao Zhou; Frede Blaabjerg. 2021. "Impact of Grid Strength and Impedance Characteristics on the Maximum Power Transfer Capability of Grid-Connected Inverters." Applied Sciences 11, no. 9: 4288.

Journal article
Published: 08 March 2021 in IEEE Transactions on Power Electronics
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The availability and efficiency of a wind power system are highly affected by the failure or the unreliable operation of its power converter. This paper investigates the failure rate and annual consumed lifetime for a 2 MW direct-drive permanent magnet synchronous generator (PMSG) based full-scale converter in a wind power generation system. The reliability assessment mainly focuses on the component level, namely, diodes and IGBTs, in both of the machine-side converter (MSC) and the grid-side converter (GSC). Annual damages and power cycles for semiconductors are calculated separately under long-term thermal cycles (several seconds to hours) and short-term thermal cycles (dozens to hundreds of milliseconds). Experiments regarding thermal stress measuring for different semiconductors under short-term thermal cycles are affiliated. A comparison between different thermal cycles is given and discussed in detail. To ensure a visualized time-to-failure evaluation, a Monte Carlo method is used to generate the lifetime distributions and entire unreliability functions for power semiconductors. Final B10 and B1 lifetimes can easily be observed from the cumulative distribution functions (CDFs). Moreover, different standard deviations are assumed for parameters in the Bayerer's lifetime model, and by using several parallel Monte Carlo algorithms, parameter sensitivity to the final lifetime evaluation is analyzed.

ACS Style

Shuaichen Ye; Dao Zhou; Xiaoxian Yao; Frede Ge Blaabjerg. Component-Level Reliability Assessment of a Direct-Drive PMSG Wind Power Converter Considering Two Terms of Thermal Cycles and the Parameter Sensitivity Analysis. IEEE Transactions on Power Electronics 2021, 36, 10037 -10050.

AMA Style

Shuaichen Ye, Dao Zhou, Xiaoxian Yao, Frede Ge Blaabjerg. Component-Level Reliability Assessment of a Direct-Drive PMSG Wind Power Converter Considering Two Terms of Thermal Cycles and the Parameter Sensitivity Analysis. IEEE Transactions on Power Electronics. 2021; 36 (9):10037-10050.

Chicago/Turabian Style

Shuaichen Ye; Dao Zhou; Xiaoxian Yao; Frede Ge Blaabjerg. 2021. "Component-Level Reliability Assessment of a Direct-Drive PMSG Wind Power Converter Considering Two Terms of Thermal Cycles and the Parameter Sensitivity Analysis." IEEE Transactions on Power Electronics 36, no. 9: 10037-10050.

Journal article
Published: 13 January 2021 in IEEE Transactions on Power Electronics
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Although the virtual synchronous generator provides a grid-friendly operational mode for power converters, it may also introduce disadvantages similar with a traditioanl synchronous generator such as power oscillation in the parallel mode due to a large virtual inertia. This paper proposes an additional damping strategy to suppress the power oscillation. After analyzing the relationship between the output power and the angular acceleration, a damping strategy is designed by the acceleration control with a disturbance compensation. Small-signal analysis is also used to study the stablity of the proposed method. Finally, experiments are carried out to verify the proposed auxiliary damping method.

ACS Style

Meng Chen; Dao Zhou; Frede Blaabjerg. Active Power Oscillation Damping Based on Acceleration Control in Paralleled Virtual Synchronous Generators System. IEEE Transactions on Power Electronics 2021, 36, 9501 -9510.

AMA Style

Meng Chen, Dao Zhou, Frede Blaabjerg. Active Power Oscillation Damping Based on Acceleration Control in Paralleled Virtual Synchronous Generators System. IEEE Transactions on Power Electronics. 2021; 36 (8):9501-9510.

Chicago/Turabian Style

Meng Chen; Dao Zhou; Frede Blaabjerg. 2021. "Active Power Oscillation Damping Based on Acceleration Control in Paralleled Virtual Synchronous Generators System." IEEE Transactions on Power Electronics 36, no. 8: 9501-9510.

Journal article
Published: 01 November 2020 in Microelectronics Reliability
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System-level reliability of wind power converter has an essential effect on the operation performance and lifespan of a wind turbine system. In this paper, a wind turbine equipped with a 2 MW direct-drive permanent-magnet synchronous generator (PMSG) serves as a case study. Considering the maximum stator current limitation of the PMSG, several multiple-converter structures and their reliability block diagrams (RBDs) are constructed for the machine side converter (MSC). To investigate the reliability influence caused by the amount of semiconductor components and the current for each component, the structures with four and five bridges in parallel are both configured. Reliability evaluation between two major parallel structures, namely, bridges in parallel and converters in parallel are also compared. In addition, the effect of different wind classes on the MSC system-level reliability has been investigated. A detailed discussion regarding the system reliability cumulative distribution function (CDF) is presented, which could serve as reference for future MSC structure design. It is concluded that the component current dominates in the system-level reliability analysis of the MSC and the standby structure can also improve the reliability under the same current level. Besides, compared with the converter structure changing, various wind classes have a minor impact on the system-level reliability.

ACS Style

Shuaichen Ye; Dao Zhou; Frede Blaabjerg. System-level reliability assessment for a direct-drive PMSG based wind turbine with multiple converters. Microelectronics Reliability 2020, 114, 113801 .

AMA Style

Shuaichen Ye, Dao Zhou, Frede Blaabjerg. System-level reliability assessment for a direct-drive PMSG based wind turbine with multiple converters. Microelectronics Reliability. 2020; 114 ():113801.

Chicago/Turabian Style

Shuaichen Ye; Dao Zhou; Frede Blaabjerg. 2020. "System-level reliability assessment for a direct-drive PMSG based wind turbine with multiple converters." Microelectronics Reliability 114, no. : 113801.

Journal article
Published: 21 September 2020 in IEEE Transactions on Power Electronics
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A novel Voltage Modulated Direct Power Control (VM-DPC) is firstly designed for a Back-to-Back (BTB) converter in the Doubly Fed Induction Generator (DFIG) system. The proposed VM-DPC is built in the stator stationary reference frame (ab). The proposed method uses a simple feed-forward and feedback structure without a phase-locked loop and the Park transformation. Therefore, it can be easily implemented in the BTB converter. Another essential advantage of the proposed VM-DPC is that it can transform the closed-loop DFIG system into a linear-time-invariant one, which can be analyzed and designed through multiple linear control techniques. The proposed method guarantees exponential stability in the stiff grid as well as in weak-grid integration, which is proved based on eigenvalue analysis. Simulation results demonstrate that the proposed VM-DPC has a faster transient response than conventional Vector Oriented Control (VOC). Also, it maintains a satisfactory steady-state performance at the same level as the VOC. The robustness of proposed VM-DPC against distorted voltage conditions and parameter mismatch is also tested. Finally, the proposed VM-DPC control strategy is validated in an experimental hardware prototype of a 7.5 kW DFIG system operating in real-time.

ACS Style

Shuning Gao; Haoran Zhao; Yonghao Gui; Dao Zhou; Frede Blaabjerg. An Improved Direct Power Control for Doubly Fed Induction Generator. IEEE Transactions on Power Electronics 2020, 36, 4672 -4685.

AMA Style

Shuning Gao, Haoran Zhao, Yonghao Gui, Dao Zhou, Frede Blaabjerg. An Improved Direct Power Control for Doubly Fed Induction Generator. IEEE Transactions on Power Electronics. 2020; 36 (4):4672-4685.

Chicago/Turabian Style

Shuning Gao; Haoran Zhao; Yonghao Gui; Dao Zhou; Frede Blaabjerg. 2020. "An Improved Direct Power Control for Doubly Fed Induction Generator." IEEE Transactions on Power Electronics 36, no. 4: 4672-4685.

Journal article
Published: 15 September 2020 in IEEE Transactions on Industrial Electronics
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This paper presents a Voltage-Modulated Direct Power Control (VM-DPC) with an additional parallel compensator for the Doubly Fed Induction Generator (DFIG) under unbalanced grid conditions. The proposed method not only guarantees a satisfying steady-state performance but also provides a regulating property of the negative-sequence output currents through the designed negative-sequence parallel compensator. It can provide symmetrical stator currents and suppress the ripples in both active and reactive powers under unbalanced grid conditions. The performances of the proposed method are verified by comparing it with three different control strategies in a simulation carried out in Matlab/Simulink SimScape Power System. Finally, the effectiveness of the proposed method is evaluated in an experimental prototype, which proves the proposed VM-DPC with the additional compensator has a satisfactory steady-state performance and a fast power transient response under unbalanced grid conditions.

ACS Style

Shuning Gao; Haoran Zhao; Yonghao Gui; Dao Zhou; Vladimir Terzija; Frede Blaabjerg. A Novel Direct Power Control for DFIG With Parallel Compensator Under Unbalanced Grid Condition. IEEE Transactions on Industrial Electronics 2020, 68, 9607 -9618.

AMA Style

Shuning Gao, Haoran Zhao, Yonghao Gui, Dao Zhou, Vladimir Terzija, Frede Blaabjerg. A Novel Direct Power Control for DFIG With Parallel Compensator Under Unbalanced Grid Condition. IEEE Transactions on Industrial Electronics. 2020; 68 (10):9607-9618.

Chicago/Turabian Style

Shuning Gao; Haoran Zhao; Yonghao Gui; Dao Zhou; Vladimir Terzija; Frede Blaabjerg. 2020. "A Novel Direct Power Control for DFIG With Parallel Compensator Under Unbalanced Grid Condition." IEEE Transactions on Industrial Electronics 68, no. 10: 9607-9618.

Journal article
Published: 14 August 2020 in IEEE Transactions on Power Electronics
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Capacitors are critical in voltage regulator modules (VRMs) which contribute to store energy and stabilize the output voltage during load transients. Usually, VRMs work with consecutive load transients, which would bring more electro-thermal stress to capacitors and affect the reliability of capacitors compared with the steady-state operation. Recently, some efforts have been made to investigate the reliability of capacitors in power electronic converters. Unfortunately, transient processes are commonly ignored, which can impair the accuracy of the lifetime estimation. Regarding this issue, this paper investigates the influence of transients on the damage of capacitors in VRMs. A 150 W VRM is introduced as a case study. Firstly, the electro-thermal stresses during steady state and transients are analyzed. Then, the lifetime calculation is considered from a single capacitor to hybrid capacitor banks. In addition, a suitable capacitor configuration of capacitor banks is also provided, in order to maximize its lifetime.

ACS Style

Zhaoyang Zhao; Dao Zhou; Pooya Davari; Junlong Fang; Frede Blaabjerg. Reliability Analysis of Capacitors in Voltage Regulator Modules With Consecutive Load Transients. IEEE Transactions on Power Electronics 2020, 36, 2481 -2487.

AMA Style

Zhaoyang Zhao, Dao Zhou, Pooya Davari, Junlong Fang, Frede Blaabjerg. Reliability Analysis of Capacitors in Voltage Regulator Modules With Consecutive Load Transients. IEEE Transactions on Power Electronics. 2020; 36 (3):2481-2487.

Chicago/Turabian Style

Zhaoyang Zhao; Dao Zhou; Pooya Davari; Junlong Fang; Frede Blaabjerg. 2020. "Reliability Analysis of Capacitors in Voltage Regulator Modules With Consecutive Load Transients." IEEE Transactions on Power Electronics 36, no. 3: 2481-2487.

Journal article
Published: 24 June 2020 in Applied Sciences
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In this paper, a universal H-bridge circuit is used as a loading emulator to investigate the loss and thermal models of the power semiconductor. Based on its operation principle and modulation method, the dominating factors’ (e.g., power factor, loading current, fundamental frequency, and switching frequency) impact on the thermal stress of power semiconductors is considerably evaluated. The junction temperature in terms of the mean value and its swing is verified by using Piecewise Linear Electrical Circuit Simulation (PLECS) simulation and experimental setup. It helps to allocate the loading condition in order to obtain the desired thermal stress.

ACS Style

Dao Zhou; Yingzhou Peng; Francesco Iannuzzo; Michael Hartmann; Frede Blaabjerg. Thermal Mapping of Power Semiconductors in H-bridge Circuit. Applied Sciences 2020, 10, 4340 .

AMA Style

Dao Zhou, Yingzhou Peng, Francesco Iannuzzo, Michael Hartmann, Frede Blaabjerg. Thermal Mapping of Power Semiconductors in H-bridge Circuit. Applied Sciences. 2020; 10 (12):4340.

Chicago/Turabian Style

Dao Zhou; Yingzhou Peng; Francesco Iannuzzo; Michael Hartmann; Frede Blaabjerg. 2020. "Thermal Mapping of Power Semiconductors in H-bridge Circuit." Applied Sciences 10, no. 12: 4340.

Journal article
Published: 12 June 2020 in IEEE Transactions on Power Electronics
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This paper presents a novel power-angle control method of DFIG-DC system based on regulating air gap flux vector. The relationship between the angle of air gap electromotive force (EMF) vector and stator output power is revealed in this paper, which can be used for controlling the output power directly. Since the stator frequency is determined by the rotating speed of air gap flux vector and the output power is determined by the angle of air gap EMF vector, the stator frequency can be generated by the power control loop which can avoid the classical voltage model or current model and reduce the parameter dependency. The stator frequency can be regulated through d-axis rotor current since the product of stator frequency and d-axis rotor current is constant. Furthermore, the improved direct resonant control for torque ripple and harmonic currents mitigation can still be applied in this novel control method because air gap flux orientation is achieved through controlling the q-axis air gap flux to be zero. Finally, the experimental results are presented to validate the proposed control method.

ACS Style

Chao Wu; Dao Zhou; Peng Cheng; Frede Blaabjerg. A Novel Power-Angle Control Method of DFIG-DC System Based on Regulating Air Gap Flux Vector. IEEE Transactions on Power Electronics 2020, 36, 513 -521.

AMA Style

Chao Wu, Dao Zhou, Peng Cheng, Frede Blaabjerg. A Novel Power-Angle Control Method of DFIG-DC System Based on Regulating Air Gap Flux Vector. IEEE Transactions on Power Electronics. 2020; 36 (1):513-521.

Chicago/Turabian Style

Chao Wu; Dao Zhou; Peng Cheng; Frede Blaabjerg. 2020. "A Novel Power-Angle Control Method of DFIG-DC System Based on Regulating Air Gap Flux Vector." IEEE Transactions on Power Electronics 36, no. 1: 513-521.

Journal article
Published: 04 May 2020 in IEEE Open Journal of Power Electronics
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With the increasing penetration of renewable power, its reliability and cost-effective production are becoming more important. A filter is inserted between the grid-connected inverter and the power grid to reduce the PWM switching harmonics, which may become a fragile part seen from the power electronics converter perspective. As the grid-connected inverter is typically designed with additional reactive power capability, this paper tries to investigate the additional stresses of the filter capacitor introduced by the reactive power injection. According to an electro-thermal stress evaluation, the time-to-failure distribution of a single LCL filter capacitor is investigated in detail. Moreover, the increasing equivalent series resistance along with the operational period is taken into account. Aiming towards a system-level reliability analysis, a Weibull distribution based reliability of an individual capacitor can be linked to the reliability of a capacitor bank by using a reliability block diagram. A case study of a 2 MW wind power converter shows that the lifetime is significantly reduced from the individual capacitor to the capacitor bank. Besides, over-excited reactive power injection further reduces the lifetime of the LCL filter capacitors.

ACS Style

Dao Zhou; Huai Wang; Frede Blaabjerg. Reactive Power Impacts on LCL Filter Capacitor Lifetime in Grid-Connected Inverter. IEEE Open Journal of Power Electronics 2020, 1, 139 -148.

AMA Style

Dao Zhou, Huai Wang, Frede Blaabjerg. Reactive Power Impacts on LCL Filter Capacitor Lifetime in Grid-Connected Inverter. IEEE Open Journal of Power Electronics. 2020; 1 (99):139-148.

Chicago/Turabian Style

Dao Zhou; Huai Wang; Frede Blaabjerg. 2020. "Reactive Power Impacts on LCL Filter Capacitor Lifetime in Grid-Connected Inverter." IEEE Open Journal of Power Electronics 1, no. 99: 139-148.

Journal article
Published: 30 March 2020 in IEEE Journal of Emerging and Selected Topics in Power Electronics
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In distributed generation systems, power quality is one of the main concerns during short-term unbalanced grid voltage faults. However, for the most common three-phase three-wire grid-connected inverters based power systems, there may be a trade-off between power oscillations and current harmonics during the unbalanced grid fault ride through control, which has a crucial impact on the installed inverters for different applications. In this paper, a modified instantaneous power control based voltage phase compensation control strategy is proposed to enhance the inverter current quality, while at the same time mitigating the active/reactive instantaneous power oscillations. Moreover, a simplified peak current-limited control strategy is developed to improve the reliability of the grid-connected system, and it does not need the extraction of the grid voltage and/or current fundamental positive/negative sequence components, which significantly reduce the computation burden. Finally, the experimental tests based on dSPACE-DS1007 and MATLAB/Simulink are carried out to verify the effectiveness of the proposed strategy.

ACS Style

Wenzhao Liu; Frede Blaabjerg; Dao Zhou; Shih-Feng Chou. Modified Instantaneous Power Control With Phase Compensation and Current-Limited Function Under Unbalanced Grid Faults. IEEE Journal of Emerging and Selected Topics in Power Electronics 2020, 9, 2896 -2906.

AMA Style

Wenzhao Liu, Frede Blaabjerg, Dao Zhou, Shih-Feng Chou. Modified Instantaneous Power Control With Phase Compensation and Current-Limited Function Under Unbalanced Grid Faults. IEEE Journal of Emerging and Selected Topics in Power Electronics. 2020; 9 (3):2896-2906.

Chicago/Turabian Style

Wenzhao Liu; Frede Blaabjerg; Dao Zhou; Shih-Feng Chou. 2020. "Modified Instantaneous Power Control With Phase Compensation and Current-Limited Function Under Unbalanced Grid Faults." IEEE Journal of Emerging and Selected Topics in Power Electronics 9, no. 3: 2896-2906.

Journal article
Published: 28 February 2020 in IEEE Transactions on Industry Applications
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The thermal dynamics of power semiconductors and power capacitors are closely related to the reliability and affect the cost of power electronic converter. However, the component loading in a wind turbine system is disturbed by many factors of the power converter, which presents various time-constants from micro-seconds to hours. To determine the system availability in such system is a challenge and need detailed analysis. In the case of a mission profile with 1-hour sample rate, a simplified circuit model, loss model, and thermal model of the active power switches and passive capacitors are needed and described. According to the long-term electro-thermal profile, the percentile lifetime of a single component can be predicted. The Weibull function based time-to-failure distribution can then be used to link from component-level to converter-level reliability. From analysis of a 2 MW wind turbine system, it can be seen that the DC-link capacitor bank dominates the converter-level reliability.

ACS Style

Dao Zhou; Frede Blaabjerg. Converter-Level Reliability of Wind Turbine With Low Sample Rate Mission Profile. IEEE Transactions on Industry Applications 2020, 56, 2938 -2944.

AMA Style

Dao Zhou, Frede Blaabjerg. Converter-Level Reliability of Wind Turbine With Low Sample Rate Mission Profile. IEEE Transactions on Industry Applications. 2020; 56 (3):2938-2944.

Chicago/Turabian Style

Dao Zhou; Frede Blaabjerg. 2020. "Converter-Level Reliability of Wind Turbine With Low Sample Rate Mission Profile." IEEE Transactions on Industry Applications 56, no. 3: 2938-2944.

Journal article
Published: 14 February 2020 in IEEE Transactions on Transportation Electrification
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The reliability of DC-link capacitors in urban rail transit is considered as a major challenge because of significant maintenance impact. In this paper, the DC-link capacitor reliability is researched in metro traction drive system. In the small timescale of control level, the current harmonics of multiple operating conditions and different control methods in the DClink capacitor are discussed. The power loss is simulated by the capacitor harmonics of current and equivalent series resistance (ESR) in multi-operating conditions. Considering electro-thermal coupling, the time-ordered and continuity of thermal stress are analyzed to evaluate the hot spot temperature dynamic conformed to the reality. Combining with the analysis of electrical stress and thermal stress, a multi-timescale capacitor reliability evaluation method is proposed. It is divided into four steps: the discrete small timescale, the single route timescale, the daily operation timescale and the whole lifetime cycle. In the different timescales, the lifetime distribution changes with the dynamics of the complex mission profiles, so as to estimate the lifetime bottleneck of the DC-link capacitor banks with different control methods by the Weibull distribution. In addition, experimental validation is provided to verify the accuracy of the proposed method.

ACS Style

Bo Yao; Xinglai Ge; Huimin Wang; Haoran Wang; Dao Zhou; Bin Gou. Multitimescale Reliability Evaluation of DC-Link Capacitor Banks in Metro Traction Drive System. IEEE Transactions on Transportation Electrification 2020, 6, 213 -227.

AMA Style

Bo Yao, Xinglai Ge, Huimin Wang, Haoran Wang, Dao Zhou, Bin Gou. Multitimescale Reliability Evaluation of DC-Link Capacitor Banks in Metro Traction Drive System. IEEE Transactions on Transportation Electrification. 2020; 6 (1):213-227.

Chicago/Turabian Style

Bo Yao; Xinglai Ge; Huimin Wang; Haoran Wang; Dao Zhou; Bin Gou. 2020. "Multitimescale Reliability Evaluation of DC-Link Capacitor Banks in Metro Traction Drive System." IEEE Transactions on Transportation Electrification 6, no. 1: 213-227.

Journal article
Published: 05 February 2020 in IEEE Transactions on Industrial Electronics
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This paper presents a novel direct power magnitude control of DFIG-DC system without orientation control. The stator frequency is directly given and the angle of synchronized d-q frame is generated by the integral of stator frequency. The relationship between the stator power and rotor current vector is revealed in this paper. Based on this positive correlation, the output power is easily controlled by the d-axis rotor current, and the q-axis rotor current is controlled flexible to achieve the smooth switching from no output power to rated power. In accordance with the small signal model, the relationship between decoupling control and coupling control is presented, and the principle to select the reference of q-axis rotor current is verified. Furthermore, the improved direct resonant control for torque ripple and harmonic current mitigation can still be applied in this novel control method. Finally, the experiment results are presented to validate the proposed method.

ACS Style

Chao Wu; Dao Zhou; Frede Blaabjerg. Direct Power Magnitude Control of DFIG-DC System Without Orientation Control. IEEE Transactions on Industrial Electronics 2020, 68, 1365 -1373.

AMA Style

Chao Wu, Dao Zhou, Frede Blaabjerg. Direct Power Magnitude Control of DFIG-DC System Without Orientation Control. IEEE Transactions on Industrial Electronics. 2020; 68 (2):1365-1373.

Chicago/Turabian Style

Chao Wu; Dao Zhou; Frede Blaabjerg. 2020. "Direct Power Magnitude Control of DFIG-DC System Without Orientation Control." IEEE Transactions on Industrial Electronics 68, no. 2: 1365-1373.

Journal article
Published: 20 December 2019 in Sustainability
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This paper uses a system engineering approach based on the Failure Mode and Effect Analysis (FMEA) methodology to do risk analysis of the power conditioner of a Proton Exchange Membrane Fuel Cell (PEMFC). Critical components with high risk, common cause failures and effects are identified for the power conditioner system as one of the crucial parts of the PEMFCs used for backup power applications in the telecommunication industry. The results of this paper indicate that the highest risk corresponds to three failure modes including high leakage current due to the substrate interface of the metal oxide semiconductor field effect transistor (MOSFET), current and electrolytic evaporation of capacitor, and thereby short circuit, loss of gate control, and increased leakage current due to gate oxide of the MOSFET. The MOSFETs, capacitors, chokes, and transformers are critical components of the power stage, which should be carefully considered in the development of the design production and implementation stage. Finally, Bayesian networks (BNs) are used to identify the most critical failure causes in the MOSFET and capacitor as they are classified from the FMEA as key items based on their Risk Priority Numbers (RPNs). As a result of BNs analyses, high temperature and overvoltage are distinguished as the most crucial failure causes. Consequently, it is recommended for designers to pay more attention to the design of MOSFETs’ failure due to high leakage current owing to substrate interface, which is caused by high temperature. The results are emphasizing design improvement in the material in order to be more resistant from high temperature.

ACS Style

Sima Rastayesh; Sajjad Bahrebar; Frede Blaabjerg; Dao Zhou; Huai Wang; John Dalsgaard Sørensen. A System Engineering Approach Using FMEA and Bayesian Network for Risk Analysis—A Case Study. Sustainability 2019, 12, 77 .

AMA Style

Sima Rastayesh, Sajjad Bahrebar, Frede Blaabjerg, Dao Zhou, Huai Wang, John Dalsgaard Sørensen. A System Engineering Approach Using FMEA and Bayesian Network for Risk Analysis—A Case Study. Sustainability. 2019; 12 (1):77.

Chicago/Turabian Style

Sima Rastayesh; Sajjad Bahrebar; Frede Blaabjerg; Dao Zhou; Huai Wang; John Dalsgaard Sørensen. 2019. "A System Engineering Approach Using FMEA and Bayesian Network for Risk Analysis—A Case Study." Sustainability 12, no. 1: 77.

Journal article
Published: 06 December 2019 in Renewable Energy
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Owing to the large number of wind turbines (WTs) and long transmission lines in large wind farms (WFs), the wake effect and power loss in a WF have a more significant impact on the active output of the WF. The improper operation of WTs decreases their lifetime and increases their maintenance costs. To minimise the levelised production cost of a WF, this study proposes an optimal active and reactive power cooperative dispatch strategy that considers the minimisation of total WF power loss, maximisation of WF lifetime, and maximisation of total WF power generation. The proposed strategy is compared with a traditional control strategy in a 125 MW WF, and the simulation results prove the effectiveness of the proposed strategy.

ACS Style

Ni Wang; Jian Li; Xiang Yu; Dao Zhou; Weihao Hu; Qi Huang; Zhe Chen; Frede Blaabjerg. Optimal active and reactive power cooperative dispatch strategy of wind farm considering levelised production cost minimisation. Renewable Energy 2019, 148, 113 -123.

AMA Style

Ni Wang, Jian Li, Xiang Yu, Dao Zhou, Weihao Hu, Qi Huang, Zhe Chen, Frede Blaabjerg. Optimal active and reactive power cooperative dispatch strategy of wind farm considering levelised production cost minimisation. Renewable Energy. 2019; 148 ():113-123.

Chicago/Turabian Style

Ni Wang; Jian Li; Xiang Yu; Dao Zhou; Weihao Hu; Qi Huang; Zhe Chen; Frede Blaabjerg. 2019. "Optimal active and reactive power cooperative dispatch strategy of wind farm considering levelised production cost minimisation." Renewable Energy 148, no. : 113-123.

Journal article
Published: 18 November 2019 in IEEE Transactions on Energy Conversion
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Sub-synchronous oscillations in doubly-fed induction generator (DFIG)-based series compensated power systems are mainly caused by sub-synchronous control interaction (SSCI). SSCI is the most recently found type of sub-synchronous resonances. In this paper, SSCI is elaborated and investigated by performing eigenvalue analysis on a mathematically modelled DFIG system. The occurrence of SSCI is observed and the results of eigenvalue analysis are validated through a down-scaled 7.5-kW experimental setup of a grid-connected DFIG. Based on the analysis, the proportional control parameters of the rotor-side converter (RSC) are found to be very sensitive towards the sub-synchronous modes of the system. The results obtained from both the simulation and the experimental analysis show that if the sensitive proportional parameters of the RSC are tuned properly, then the DFIG system can become immune to the SSCI for any level of series compensation.

ACS Style

Muhammad Taha Ali; Dao Zhou; Yipeng Song; Mehrdad Ghandhari; Lennart Harnefors; Frede Blaabjerg. Analysis and Mitigation of SSCI in DFIG Systems With Experimental Validation. IEEE Transactions on Energy Conversion 2019, 35, 714 -723.

AMA Style

Muhammad Taha Ali, Dao Zhou, Yipeng Song, Mehrdad Ghandhari, Lennart Harnefors, Frede Blaabjerg. Analysis and Mitigation of SSCI in DFIG Systems With Experimental Validation. IEEE Transactions on Energy Conversion. 2019; 35 (2):714-723.

Chicago/Turabian Style

Muhammad Taha Ali; Dao Zhou; Yipeng Song; Mehrdad Ghandhari; Lennart Harnefors; Frede Blaabjerg. 2019. "Analysis and Mitigation of SSCI in DFIG Systems With Experimental Validation." IEEE Transactions on Energy Conversion 35, no. 2: 714-723.

Journal article
Published: 10 June 2019 in Renewable Energy
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As wind power penetration increases, large wind farms (WFs) need to provide reactive power according to modern grid codes. Permanent magnet synchronous generator-based wind turbines (WTs) can generate reactive power, by assigning the appropriate reactive power to each WT to meet the reactive power requirements of the grid. This is a more economical method than setting up additional reactive power compensation equipment. This study proposes an optimal reactive power dispatch strategy for minimising a levelised production cost, and is implemented in two ways: minimising the power loss of a WF, and maximising the lifetime of WTs. The reactive power references of each WT are chosen as the optimisation variables, and a particle swarm optimisation algorithm is adopted to solve the optimisation problem. The proposed and traditional reactive power dispatch strategies are demonstrated and compared on a WF with 25 WTs to validate the effectiveness of the proposed approach.

ACS Style

Jian Li; Ni Wang; Dao Zhou; Weihao Hu; Qi Huang; Zhe Chen; Frede Blaabjerg. Optimal reactive power dispatch of permanent magnet synchronous generator-based wind farm considering levelised production cost minimisation. Renewable Energy 2019, 145, 1 -12.

AMA Style

Jian Li, Ni Wang, Dao Zhou, Weihao Hu, Qi Huang, Zhe Chen, Frede Blaabjerg. Optimal reactive power dispatch of permanent magnet synchronous generator-based wind farm considering levelised production cost minimisation. Renewable Energy. 2019; 145 ():1-12.

Chicago/Turabian Style

Jian Li; Ni Wang; Dao Zhou; Weihao Hu; Qi Huang; Zhe Chen; Frede Blaabjerg. 2019. "Optimal reactive power dispatch of permanent magnet synchronous generator-based wind farm considering levelised production cost minimisation." Renewable Energy 145, no. : 1-12.