This page has only limited features, please log in for full access.

Dr. Huangqing Xiao
University of Tennessee, Knoxville

Basic Info

Basic Info is private.

Research Keywords & Expertise

0 HVDC
0 power system dynamics
0 HVDC Systems
0 DC circuit breaker
0 renewable power integration

Fingerprints

HVDC

Honors and Awards

The user has no records in this section


Career Timeline

The user has no records in this section.


Short Biography

Huangqing Xiao received the B.S. and Ph.D. degrees from Zhejiang University, Hangzhou, China, in 2013 and 2018, respectively. He is currently a Research Associate in the Department of Electrical Engineering and Computer Science, The University of Tennessee, Knoxville, TN, USA. His research interests include high-voltage direct current transmission, DC circuit breaker, and renewable power generation.

Following
Followers
Co Authors
The list of users this user is following is empty.
Following: 0 users

Feed

Journal article
Published: 18 March 2021 in IEEE Transactions on Power Systems
Reads 0
Downloads 0

Urban power grids are facing many operational and expansion challenges to meet further demand growth and increased reliability requirements. Advanced transmission technologies have been considered by the electric utilities to effectively increase the utilization of existing infrastructure and operational flexibility. The focus of this paper is on VSC-HVDC technologies for urban power grid enhancement and modernization. First, a potential technical scheme is proposed for converting an existing AC circuit to DC operation, which could boost the power transfer capability of the critical transmission corridor and increase network operational flexibility. Second, this paper proposes three operation modes for the VSC-HVDC interties in urban power grids corresponding to normal, emergency and island operating conditions, respectively. An integrated, adaptive emergency control strategy (AEC) is proposed that can enable adaptive power flow responses of the VSC-HVDC intertie under varying system operating conditions and critical contingencies. The flexibility and effectiveness of the proposed operational principles of urban VSC-HVDC intertie and the corresponding control strategies are verified in PSCAD/EMTDC using a realistic urban power grid in China.

ACS Style

Kaiqi Sun; HuangQing Xiao; Jiuping Pan; Yilu Liu. VSC-HVDC Interties for Urban Power Grid Enhancement. IEEE Transactions on Power Systems 2021, 36, 4745 -4753.

AMA Style

Kaiqi Sun, HuangQing Xiao, Jiuping Pan, Yilu Liu. VSC-HVDC Interties for Urban Power Grid Enhancement. IEEE Transactions on Power Systems. 2021; 36 (5):4745-4753.

Chicago/Turabian Style

Kaiqi Sun; HuangQing Xiao; Jiuping Pan; Yilu Liu. 2021. "VSC-HVDC Interties for Urban Power Grid Enhancement." IEEE Transactions on Power Systems 36, no. 5: 4745-4753.

Original article
Published: 15 March 2021 in Journal of Electrical Engineering & Technology
Reads 0
Downloads 0
ACS Style

Facai Xing; Zheng Xu; HuangQing Xiao; Zheren Zhang. Analysis on Response Characteristics of Two-Level VSC to Disturbances and Its Oscillation Suppression Strategy. Journal of Electrical Engineering & Technology 2021, 16, 1389 -1401.

AMA Style

Facai Xing, Zheng Xu, HuangQing Xiao, Zheren Zhang. Analysis on Response Characteristics of Two-Level VSC to Disturbances and Its Oscillation Suppression Strategy. Journal of Electrical Engineering & Technology. 2021; 16 (3):1389-1401.

Chicago/Turabian Style

Facai Xing; Zheng Xu; HuangQing Xiao; Zheren Zhang. 2021. "Analysis on Response Characteristics of Two-Level VSC to Disturbances and Its Oscillation Suppression Strategy." Journal of Electrical Engineering & Technology 16, no. 3: 1389-1401.

Original research paper
Published: 15 February 2021 in IET Generation, Transmission & Distribution
Reads 0
Downloads 0

Traditional permanent magnet synchronous generator (PMSG)‐based wind turbine (WT) normally utilises phase lock loop (PLL) for obtaining accurate phase angle of AC grid to make sure of maximum power point tracking (MPPT). However, a weak AC system with a low short circuit ratio (SCR) and high control bandwidth of PLL might have impaired effects on the stability of the system. To overcome these, a novel power synchronous control of PMSG‐based WT with grid forming ability of PMSG for integrating very weak AC system is first proposed in this study. Grid‐side converter (GSC) of PMSG emulates the inertia response of synchronous generator (SG) by artificially coupling the DC‐link voltage with the grid frequency based on the certain droop property, while the converter voltage magnitude is regulated according to DC‐link voltage deviation by controlling the modulation index of GSC. This novel scheme can realise the grid synchronisation without PLL by mimicking the natural characteristic of SG. Small‐signal analysis of the proposed scheme indicates the DC‐link capacitor energy can be exerted for system inertia support during system disturbances, while the system damping can be provided by spontaneously alternating converter voltage magnitude. More importantly, MPPT property of PMSG is not compromised while providing inertia and damping for the system, and the related inertia and damping coefficient of WT with the proposed control can be easily tuned for satisfying the system requirement. Non‐linear simulations of one PMSG connected with one large SG considering a sudden change of active power reference and variable wind speeds have been studied to verify the effectiveness of the proposed grid‐forming control.

ACS Style

Yujun Li; Xiaotian Yuan; Jiapeng Li; HuangQing Xiao; Zhao Xu; Zhengchun Du. Novel grid‐forming control of PMSG‐based wind turbine for integrating weak AC grid without sacrificing maximum power point tracking. IET Generation, Transmission & Distribution 2021, 15, 1613 -1625.

AMA Style

Yujun Li, Xiaotian Yuan, Jiapeng Li, HuangQing Xiao, Zhao Xu, Zhengchun Du. Novel grid‐forming control of PMSG‐based wind turbine for integrating weak AC grid without sacrificing maximum power point tracking. IET Generation, Transmission & Distribution. 2021; 15 (10):1613-1625.

Chicago/Turabian Style

Yujun Li; Xiaotian Yuan; Jiapeng Li; HuangQing Xiao; Zhao Xu; Zhengchun Du. 2021. "Novel grid‐forming control of PMSG‐based wind turbine for integrating weak AC grid without sacrificing maximum power point tracking." IET Generation, Transmission & Distribution 15, no. 10: 1613-1625.

Journal article
Published: 27 October 2020 in IEEE Transactions on Power Delivery
Reads 0
Downloads 0

Droop-based converter plays an important role in future multi-terminal DC (MTDC) system due to its control flexibility, which imposes a great challenge on the stability of the DC grid. Traditional input impendence and eigenvalue analysis methods fail to build the mathematical relationship between the system operation points and the related critical parameters for keeping system stable. In this paper the single input single output (SISO) method is used to analyse the stability of single VSC from the perspective of the DC side perturbation. The transfer function between the small perturbation of DC-link voltage and DC current at the end of transmission line is firstly constructed to involve the control impacts of droop-based converter and the dynamics of DC networks. Based on the SISO model, the stability criteria of single VSC converter under different operation modes of converter is further proposed by using the classical Routh Judgement Moreover, a critical operation index, namely, DC power transmission limit (DCPTL) is defined for the droop-based converter operating as inverter, and DC system instability might occur when the transmitted power exceeds this limit. Finally, numerical simulation results of two-terminal HVDC system validate the accuracy of the proposed stability analysis and the criteria.

ACS Style

Yujun Li; Jiapeng Li; HuangQing Xiao; Jianliang Zhang; Zhengchun Du. Stability Analysis of Droop-Based Converter Using SISO Method from DC Side Perturbation. IEEE Transactions on Power Delivery 2020, PP, 1 -1.

AMA Style

Yujun Li, Jiapeng Li, HuangQing Xiao, Jianliang Zhang, Zhengchun Du. Stability Analysis of Droop-Based Converter Using SISO Method from DC Side Perturbation. IEEE Transactions on Power Delivery. 2020; PP (99):1-1.

Chicago/Turabian Style

Yujun Li; Jiapeng Li; HuangQing Xiao; Jianliang Zhang; Zhengchun Du. 2020. "Stability Analysis of Droop-Based Converter Using SISO Method from DC Side Perturbation." IEEE Transactions on Power Delivery PP, no. 99: 1-1.

Journal article
Published: 01 October 2020 in High Voltage
Reads 0
Downloads 0

The commutation overshoot is an important reference index for the insulation coordination of the converter station as well as the thyristor voltage capacity. Although the dispersity of reverse recovery charges of series thyristors may affect commutation overshoots, especially those at the thyristor level, little literature has tried to analyse it in detail. Firstly, this study compares the turn-off models of independent thyristor and elaborates their applicability to series thyristors. Then, a novel model for series thyristors during the turn-off process is proposed, based on which the turn-off model of converter valve is also established. Subsequently, the validity and efficiency of the proposed model are discussed by simulations and it is applied to the analysis of commutation overshoots. The analysis shows that though the average model can be used to estimate the valve voltage stresses, it may lead to large errors in the thyristor voltage stress. And selecting the 1:n − 1 distribution as the distribution mode of reverse recovery charge in series thyristors will result in very conservative results.

ACS Style

Yingjie Tang; Zheng Xu; HuangQing Xiao; Bo Yue; Xuan Li. Commutation overshoots based on a novel model for series thyristors during the turn‐off process. High Voltage 2020, 5, 501 -510.

AMA Style

Yingjie Tang, Zheng Xu, HuangQing Xiao, Bo Yue, Xuan Li. Commutation overshoots based on a novel model for series thyristors during the turn‐off process. High Voltage. 2020; 5 (5):501-510.

Chicago/Turabian Style

Yingjie Tang; Zheng Xu; HuangQing Xiao; Bo Yue; Xuan Li. 2020. "Commutation overshoots based on a novel model for series thyristors during the turn‐off process." High Voltage 5, no. 5: 501-510.

Review
Published: 25 September 2020 in Sustainability
Reads 0
Downloads 0

Due to the heavy stress on environmental deterioration and the excessive consumption of fossil resources, the transition of global energy from fossil fuel energy to clean energy has significantly accelerated in recent years. The power industry and policymakers in almost all countries are focusing on clean energy development. Thanks to progressive clean energy policies, significant progress in clean energy integration and greenhouse gas reduction has been achieved around the world. However, due to the differences in economic structures, clean energy distributions, and development models, clean energy policy scope, focus, and coverage vary between different countries, states, and utilities. This paper aims at providing a policy review for readers to easily obtain clean energy policy information on various clean energies in the U.S. and some other countries. Firstly, this paper reviews and compares some countries’ clean energy policies on electricity. Then, taking the U.S. as an example, this paper introduces the clean energy policies of some representative states and utilities in the U.S in perspectives of renewable energies, electric vehicles, and energy storage.

ACS Style

Kaiqi Sun; HuangQing Xiao; Shengyuan Liu; Shutang You; Fan Yang; Yuqing Dong; Weikang Wang; Yilu Liu. A Review of Clean Electricity Policies—From Countries to Utilities. Sustainability 2020, 12, 7946 .

AMA Style

Kaiqi Sun, HuangQing Xiao, Shengyuan Liu, Shutang You, Fan Yang, Yuqing Dong, Weikang Wang, Yilu Liu. A Review of Clean Electricity Policies—From Countries to Utilities. Sustainability. 2020; 12 (19):7946.

Chicago/Turabian Style

Kaiqi Sun; HuangQing Xiao; Shengyuan Liu; Shutang You; Fan Yang; Yuqing Dong; Weikang Wang; Yilu Liu. 2020. "A Review of Clean Electricity Policies—From Countries to Utilities." Sustainability 12, no. 19: 7946.

Journal article
Published: 15 June 2020 in IEEE Transactions on Power Systems
Reads 0
Downloads 0

Cross-seam high voltage DC (HVDC) transmission in the United States can provide an efficient and flexible bulk power delivery highway between the interconnections. Recent studies have shown significant economic benefits of cross-seam HVDC transmission systems by taking the advantages of load diversity, frequency response, renewable energy diversity, and energy arbitrage in the different interconnections. This paper introduces a station-hybrid system scheme for cross-seam interconnections. The proposed station-hybrid system combines the advantages of line commutated converter (LCC) and voltage source converter (VSC) technologies, thus enabling reliable and flexible bidirectional power flows across the interconnections. Control strategies of the station-hybrid system are investigated with a focus on power flow reversal control under normal operation conditions and grid support control under emergency conditions. The feasibility and effectiveness of the proposed station-hybrid system and corresponding control strategies are verified by simulations in PSCAD/EMTDC.

ACS Style

Kaiqi Sun; HuangQing Xiao; Jiuping Pan; Yilu Liu. A Station-Hybrid HVDC System Structure and Control Strategies for Cross-Seam Power Transmission. IEEE Transactions on Power Systems 2020, 36, 379 -388.

AMA Style

Kaiqi Sun, HuangQing Xiao, Jiuping Pan, Yilu Liu. A Station-Hybrid HVDC System Structure and Control Strategies for Cross-Seam Power Transmission. IEEE Transactions on Power Systems. 2020; 36 (1):379-388.

Chicago/Turabian Style

Kaiqi Sun; HuangQing Xiao; Jiuping Pan; Yilu Liu. 2020. "A Station-Hybrid HVDC System Structure and Control Strategies for Cross-Seam Power Transmission." IEEE Transactions on Power Systems 36, no. 1: 379-388.

Research article
Published: 05 March 2020 in IET Generation, Transmission & Distribution
Reads 0
Downloads 0

The peak value of continuous operating voltage (PCOV) has a direct influence on the reference voltage of valve arrester, which appreciably influences the manufacturing cost of the line-commutated converter (LCC). Since simulations with high accuracy based on broadband models are memory intensive and time consuming, it is important to determine the operating conditions for PCOV calculation to reduce computational burden. This study establishes piecewise expressions of ideal valve voltages in different converter operation modes, which is the basis for the investigation of commutation overshoots. A simplified circuit is established to evaluate the valve voltage stress, with a modification introduced on the calculation of voltage peaks across blocking valves, which is neglected by previous literature. Then, this study proves theoretically that the 6-pulse rectifier operation mode and the long-term overload power transmission with the maximum delay angle should be the corresponding operating condition for PCOV calculation. Conclusions derived from the analytical analysis have been validated by simulations based on broadband models for practical projects.

ACS Style

Yingjie Tang; Zheng Xu; HuangQing Xiao; Bo Yue. Determination of operating conditions of LCC for PCOV calculation based on detailed analysis of commutation overshoot. IET Generation, Transmission & Distribution 2020, 14, 1566 -1574.

AMA Style

Yingjie Tang, Zheng Xu, HuangQing Xiao, Bo Yue. Determination of operating conditions of LCC for PCOV calculation based on detailed analysis of commutation overshoot. IET Generation, Transmission & Distribution. 2020; 14 (8):1566-1574.

Chicago/Turabian Style

Yingjie Tang; Zheng Xu; HuangQing Xiao; Bo Yue. 2020. "Determination of operating conditions of LCC for PCOV calculation based on detailed analysis of commutation overshoot." IET Generation, Transmission & Distribution 14, no. 8: 1566-1574.

Research article
Published: 14 February 2020 in IET Generation, Transmission & Distribution
Reads 0
Downloads 0

In this study, a new kind of hybrid high-voltage direct current (HVDC) system is proposed. Each terminal of the proposed system consists of one line commutated converter (LCC) and one full-bridge modular multilevel converter (FB-MMC). The LCC and FB-MMC are connected in parallel so that they can share the same transmission line. The active–reactive power capability of the hybrid HVDC system is extended compared with the conventional LCC-HVDC system, and power reversal control without power interruption can be achieved by the coordination control of LCC and FB-MMC. Besides, the proposed hybrid HVDC system is capable of handling DC fault, because both LCC and FB-MMC have DC fault blocking capability. Moreover, the power rating of FB-MMC can be designed to low value while keeping the bulk-power transmission capability of LCC. A two-terminal bipolar hybrid HVDC system is built in PSCAD/EMTDC. The simulation results verify the effectiveness and feasibility of the proposed hybrid topology and corresponding control strategies.

ACS Style

HuangQing Xiao; Kaiqi Sun; Jiuping Pan; Yilu Liu. Operation and control of hybrid HVDC system with LCC and full‐bridge MMC connected in parallel. IET Generation, Transmission & Distribution 2020, 14, 1344 -1352.

AMA Style

HuangQing Xiao, Kaiqi Sun, Jiuping Pan, Yilu Liu. Operation and control of hybrid HVDC system with LCC and full‐bridge MMC connected in parallel. IET Generation, Transmission & Distribution. 2020; 14 (7):1344-1352.

Chicago/Turabian Style

HuangQing Xiao; Kaiqi Sun; Jiuping Pan; Yilu Liu. 2020. "Operation and control of hybrid HVDC system with LCC and full‐bridge MMC connected in parallel." IET Generation, Transmission & Distribution 14, no. 7: 1344-1352.

Journal article
Published: 25 November 2019 in IEEE Transactions on Power Delivery
Reads 0
Downloads 0

DC fault current can be interrupted within several milliseconds by employing hybrid HVDC circuit breaker. However, this scheme is not cost effective, especially in meshed HVDC grid. In this paper, a novel integrated HVDC circuit breaker by sharing components is proposed to overcome these drawbacks. Supposing that a converter in a meshed HVDC grid is connected to m DC lines. The integrated HVDC circuit breaker consists of ${m+1}$ ultra-fast disconnectors (UFDs), ${m+1}$ load commutation switches (LCSs), m+1 mechanical disconnectors (DSs), and only one main breaker (MB) and surge arrester (SA). The behavior of the proposed integrated HVDC circuit breaker is similar to that of the conventional hybrid HVDC circuit breaker. These two kinds of breakers have the same operating time, which means the integrated HVDC circuit breaker is fast enough to clear DC faults. Besides, the IGBT modules in the MB and LCSs of the proposed integrated HVDC circuit breaker are connected in one direction, and the m DC lines share a single MB. Therefore, this scheme is more cost effective compared to conventional hybrid HVDC circuit breaker. Simulation results on a three-terminal HVDC grid are presented to verify the effectiveness and feasibility of the proposed scheme.

ACS Style

HuangQing Xiao; Zheng Xu; Liang Xiao; Chun Gan; Feng Xu; Leisi Dai. Components Sharing Based Integrated HVDC Circuit Breaker for Meshed HVDC Grids. IEEE Transactions on Power Delivery 2019, 35, 1856 -1866.

AMA Style

HuangQing Xiao, Zheng Xu, Liang Xiao, Chun Gan, Feng Xu, Leisi Dai. Components Sharing Based Integrated HVDC Circuit Breaker for Meshed HVDC Grids. IEEE Transactions on Power Delivery. 2019; 35 (4):1856-1866.

Chicago/Turabian Style

HuangQing Xiao; Zheng Xu; Liang Xiao; Chun Gan; Feng Xu; Leisi Dai. 2019. "Components Sharing Based Integrated HVDC Circuit Breaker for Meshed HVDC Grids." IEEE Transactions on Power Delivery 35, no. 4: 1856-1866.

Journal article
Published: 21 November 2019 in International Journal of Electrical Power & Energy Systems
Reads 0
Downloads 0

With the increasing penetration of wind energy into power grids, the frequency regulation capability of the system tends to deteriorate. Wind generators (WGs) could provide fast frequency response when the system suffers from disturbances. However, due to the randomness and intermittence of WG, its emergency support is not stable. The spinning reserves of the asynchronous power grids can be shared through the high voltage direct current (HVDC) links. Under a large disturbance, the HVDC link could provide fast frequency response support to maintain the operating frequency of the disturbed power grid within a secure range. In this paper, a frequency secure control strategy is proposed for the HVDC link connected to a power system with high penetration of wind energy. The proposed frequency secure control strategy has three control functions: (1) back-up frequency response control, (2) frequency compensation control, and (3) response distribution optimization. The objective of this control strategy is to improve the synthetic frequency response performance of the system under severe frequency disturbance while avoiding possible subsequent frequency drop caused by rotor speed recovery of wind turbines. Besides, the cost of ancillary service for obtaining frequency response support from interconnected power systems could be reduced. Simulation verifications are conducted on a reduced equivalent ERCOT system which is interconnected to equivalent Western and Eastern Interconnections by HVDC links. The simulation results verify the feasibility and effectiveness of the proposed frequency secure control strategy.

ACS Style

Kaiqi Sun; HuangQing Xiao; Shutang You; Hongyu Li; Jiuping Pan; Ke-Jun Li; Yilu Liu. Frequency secure control strategy for power grid with large-scale wind farms through HVDC links. International Journal of Electrical Power & Energy Systems 2019, 117, 105706 .

AMA Style

Kaiqi Sun, HuangQing Xiao, Shutang You, Hongyu Li, Jiuping Pan, Ke-Jun Li, Yilu Liu. Frequency secure control strategy for power grid with large-scale wind farms through HVDC links. International Journal of Electrical Power & Energy Systems. 2019; 117 ():105706.

Chicago/Turabian Style

Kaiqi Sun; HuangQing Xiao; Shutang You; Hongyu Li; Jiuping Pan; Ke-Jun Li; Yilu Liu. 2019. "Frequency secure control strategy for power grid with large-scale wind farms through HVDC links." International Journal of Electrical Power & Energy Systems 117, no. : 105706.

Research article
Published: 25 October 2019 in IET Generation, Transmission & Distribution
Reads 0
Downloads 0

Voltage source converter-based multi-terminal HVDC (VSC-MTDC) system has been considered for interconnecting asynchronous power grids for improved system operation efficiency and reliability. In this study, a frequency response control strategy is proposed for the VSC-MTDC systems that can enable operating reserves sharing among the interconnected asynchronous grids. The proposed control strategy consists of three frequency control components: MTDC primary frequency control, corrective frequency control, and MTDC secondary frequency control. The MTDC primary frequency control could keep the frequency of a disturbed power grid stable and avoid the frequency dropping into an unacceptable level when a sudden power imbalance event occurs. The corrective frequency control strives to guarantee the settled frequency can be within the predefined secure frequency range. The MTDC secondary frequency control provides a novel optimal allocation strategy for considering the participation of MTDC system for restoring system frequency back to the nominal frequency with the lowest cost. The simulation results, based on a modified IEEE New England 39-bus system modelled in PSCAD/EMTDC, show the effectiveness of the proposed frequency response control strategies.

ACS Style

Kaiqi Sun; HuangQing Xiao; Lakshmi Sundaresh; Jiuping Pan; Ke‐Jun Li; Yilu Liu. Frequency response reserves sharing across asynchronous grids through MTDC system. IET Generation, Transmission & Distribution 2019, 13, 4952 -4959.

AMA Style

Kaiqi Sun, HuangQing Xiao, Lakshmi Sundaresh, Jiuping Pan, Ke‐Jun Li, Yilu Liu. Frequency response reserves sharing across asynchronous grids through MTDC system. IET Generation, Transmission & Distribution. 2019; 13 (21):4952-4959.

Chicago/Turabian Style

Kaiqi Sun; HuangQing Xiao; Lakshmi Sundaresh; Jiuping Pan; Ke‐Jun Li; Yilu Liu. 2019. "Frequency response reserves sharing across asynchronous grids through MTDC system." IET Generation, Transmission & Distribution 13, no. 21: 4952-4959.

Research article
Published: 02 September 2019 in IET Generation, Transmission & Distribution
Reads 0
Downloads 0

Modular multilevel converter based unified power flow controller (MMC-UPFC) projects are different from earlier UPFC projects in control methods and system structures. Characteristics of these MMC-UPFC projects have not been fully researched in the existing literature, so it is difficult to effectively analyse the small-signal stability and low-frequency oscillation characteristics of power system containing these UPFCs. To solve this problem, the small-signal model of vector current-controlled MMC-UPFC is studied. Firstly, the equivalent model of the general structure UPFC is given in this study. Secondly, the dynamic model and small-signal model of UPFC are derived. Thirdly, the method of combining the UPFC model and the rest of the system is presented, so that the linearised model of the whole system can be established. At last, the small-signal model is verified in two test systems by time-domain simulations and modal analysis. Results show that the method proposed in this study is applicable for both the novel structure UPFC and the traditional structure UPFC, and that the small-signal model obtained can accurately reflect system characteristics.

ACS Style

Jian Yang; Pengcheng Song; Zheng Xu; HuangQing Xiao; Hui Cai; Zhenjian Xie. Small‐signal model of vector current‐controlled MMC‐UPFC. IET Generation, Transmission & Distribution 2019, 13, 4180 -4189.

AMA Style

Jian Yang, Pengcheng Song, Zheng Xu, HuangQing Xiao, Hui Cai, Zhenjian Xie. Small‐signal model of vector current‐controlled MMC‐UPFC. IET Generation, Transmission & Distribution. 2019; 13 (18):4180-4189.

Chicago/Turabian Style

Jian Yang; Pengcheng Song; Zheng Xu; HuangQing Xiao; Hui Cai; Zhenjian Xie. 2019. "Small‐signal model of vector current‐controlled MMC‐UPFC." IET Generation, Transmission & Distribution 13, no. 18: 4180-4189.

Journal article
Published: 05 August 2019 in IEEE Access
Reads 0
Downloads 0

This paper proposed a second harmonic capacitor voltage eliminating controller (SHCVEC) for capacitor voltage fluctuation suppression of modular multilevel converters (MMCs). The proposed controller consists of two PI controllers, namely the outer controller and the inner controller. The outer controller determines the reference value of the circulating current, and the inner controller generates the circulating current in each arm. The second harmonic capacitor voltage is controlled to zero by the outer PI controller, so there will be no static error between the generated second harmonic capacitor voltage and its reference value, which is the main improvement compared to other conventional methods. The PSCAD/EMTDC simulation verification of SHCVEC is carried out based on a 2-terminal MMC-HVDC system, and the effectiveness and feasibility of the proposed controller are proved. Furthermore, a comparison in terms of capacitor voltage fluctuation and rms arm current is made between the SHCVEC and the conventional circulating current suppressing controller, and the results demonstrate that the capacitor voltage fluctuation could be significantly reduced with only a small increase of rms arm current.

ACS Style

Yuzhe Xu; Zheng Xu; Zheren Zhang; HuangQing Xiao. A Novel Circulating Current Controller for MMC Capacitor Voltage Fluctuation Suppression. IEEE Access 2019, 7, 120141 -120151.

AMA Style

Yuzhe Xu, Zheng Xu, Zheren Zhang, HuangQing Xiao. A Novel Circulating Current Controller for MMC Capacitor Voltage Fluctuation Suppression. IEEE Access. 2019; 7 (99):120141-120151.

Chicago/Turabian Style

Yuzhe Xu; Zheng Xu; Zheren Zhang; HuangQing Xiao. 2019. "A Novel Circulating Current Controller for MMC Capacitor Voltage Fluctuation Suppression." IEEE Access 7, no. 99: 120141-120151.

Journal article
Published: 24 July 2019 in Energies
Reads 0
Downloads 0

This paper studies the electromechanical transient model and the control strategy of line commutated converter (LCC) and modular multilevel converter (MMC) based decentralized hybrid High Voltage Direct Current (HVDC) Transmission systems. The decentralized hybrid HVDC system is a new type of topology, and the related electromechanical transient model and control strategy have not been studied well. In this paper, the electromechanical transient model of a decentralized hybrid HVDC system is devloped through mathematical deduction. This model can be easily implemented in electromechanical transient simulation software and meet the time domain simulation requirements of large-scale systems. Then, in order to ensure the safe absorption of the DC power under various conditions, an optimal power flow model considering the decentralized hybrid HVDC system is proposed. Finally, the electromechanical transient model proposed in this paper is verified by the electromagnetic transient model, and the control strategy is validated in a modified New England 39-bus system.

ACS Style

Guoteng Wang; HuangQing Xiao; Liang Xiao; Zheren Zhang; Zheng Xu. Electromechanical Transient Modeling and Control Strategy of Decentralized Hybrid HVDC Systems. Energies 2019, 12, 2856 .

AMA Style

Guoteng Wang, HuangQing Xiao, Liang Xiao, Zheren Zhang, Zheng Xu. Electromechanical Transient Modeling and Control Strategy of Decentralized Hybrid HVDC Systems. Energies. 2019; 12 (15):2856.

Chicago/Turabian Style

Guoteng Wang; HuangQing Xiao; Liang Xiao; Zheren Zhang; Zheng Xu. 2019. "Electromechanical Transient Modeling and Control Strategy of Decentralized Hybrid HVDC Systems." Energies 12, no. 15: 2856.

Journal article
Published: 25 June 2019 in International Journal of Electrical Power & Energy Systems
Reads 0
Downloads 0

Modeling different types of DC faults in modular multilevel converter based multi-terminal HVDC (MMC-MTDC) systems for transient stability analyses has not been well studied. In this paper, an improved electro-mechanical model of MMC-MTDC system which is feasible for a variety of DC fault simulations is proposed. Firstly, the improved MMC electro-mechanical model with a second-order DC side circuit is derived theoretically. Then a method based on preset DC fault information for studying the impacts of DC faults on the stability of large-scale AC/DC power systems is proposed, with which the DC faults can be handled efficiently without reconstructing the DC topology. Theoretical and simulation studies show that the DC-side equivalent circuit of the MMC should be established as a second-order circuit when DC faults are considered for transient stability studies. Simulations of various types of DC faults in the modified IEEE 39-bus system incorporating a four-terminal MMC-HVDC system are carried out on PSS/E for validating the proposed method.

ACS Style

Liang Xiao; Zheng Xu; HuangQing Xiao; Zheren Zhang; Guoteng Wang; Yuzhe Xu. Electro-mechanical transient modeling of MMC based multi-terminal HVDC system with DC faults considered. International Journal of Electrical Power & Energy Systems 2019, 113, 1002 -1013.

AMA Style

Liang Xiao, Zheng Xu, HuangQing Xiao, Zheren Zhang, Guoteng Wang, Yuzhe Xu. Electro-mechanical transient modeling of MMC based multi-terminal HVDC system with DC faults considered. International Journal of Electrical Power & Energy Systems. 2019; 113 ():1002-1013.

Chicago/Turabian Style

Liang Xiao; Zheng Xu; HuangQing Xiao; Zheren Zhang; Guoteng Wang; Yuzhe Xu. 2019. "Electro-mechanical transient modeling of MMC based multi-terminal HVDC system with DC faults considered." International Journal of Electrical Power & Energy Systems 113, no. : 1002-1013.

Journal article
Published: 18 December 2018 in The Journal of Engineering
Reads 0
Downloads 0

As a key element of the DC grid, the technology of DC circuit breakers (DCCBs) still have difficulty to be widely used due to its large cost and volume. This paper studies the basic principle and its realisation methods for DCCBs. First, two basic ways of breaking the fault current are discussed, including the way by inserting a metal oxide varistor (MOV) to force the fault current to zero and the way by inserting capacitor to change the nature of the fault current. Second, a new approach to realise the DCCB has been proposed based on the inserting capacitor way. According to this new approach, three topologies of DCCB are proposed, including the single-branch DCCB with inserted capacitor (SB-DCCB-C), the double-branch DCCB with inserted capacitor (DB-DCCB-C) and the triple-branch DCCB with inserted capacitor (TB-DCCB-C). All these three DCCBs are proved to be able to deal with DC faults effectively according to the simulation results in PSCAD/EMTDC. Finally, the economy of four circuit breaker structures are compared.

ACS Style

Zheng Xu; HuangQing Xiao; Yuzhe Xu. Two basic ways to realise DC circuit breakers. The Journal of Engineering 2018, 2019, 3098 -3105.

AMA Style

Zheng Xu, HuangQing Xiao, Yuzhe Xu. Two basic ways to realise DC circuit breakers. The Journal of Engineering. 2018; 2019 (16):3098-3105.

Chicago/Turabian Style

Zheng Xu; HuangQing Xiao; Yuzhe Xu. 2018. "Two basic ways to realise DC circuit breakers." The Journal of Engineering 2019, no. 16: 3098-3105.

Journal article
Published: 13 August 2018 in Energies
Reads 0
Downloads 0

A method for electromechanical modeling of line commutated converter (LCC)-modular multilevel converter (MMC)-based hybrid multi-terminal High Voltage Direct Current Transmission (HVDC) systems for large-scale power system transient stability study is proposed. Firstly, the general idea of modeling the LCC-MMC hybrid multi-terminal HVDC system is presented, then the AC-side and DC-side models of the LCC/MMC are established. Different from the conventional first-order DC-side model of the MMC, an improved second-order DC-side model of the MMC is established. Besides considering the firing angle limit of the LCC, a sequential power flow algorithm is proposed for the initialization of LCC-MMC hybrid multi-terminal HVDC system. Lastly, simulations of small scale and large scale power systems embedded with a three-terminal LCC-MMC hybrid HVDC system are performed on the electromechanical simulation platform PSS/E. It is demonstrated that if the firing angle limit is not considered, the accuracy of the power flow solutions will be greatly affected. Steady state calculation and dynamic simulation show that the developed LCC-MMC hybrid MTDC model is accurate enough for electromechanical transient stability studies of large-scale AC/DC system.

ACS Style

Liang Xiao; Yan Li; HuangQing Xiao; Zheren Zhang; Zheng Xu. Electromechanical Transient Modeling of Line Commutated Converter-Modular Multilevel Converter-Based Hybrid Multi-Terminal High Voltage Direct Current Transmission Systems. Energies 2018, 11, 2102 .

AMA Style

Liang Xiao, Yan Li, HuangQing Xiao, Zheren Zhang, Zheng Xu. Electromechanical Transient Modeling of Line Commutated Converter-Modular Multilevel Converter-Based Hybrid Multi-Terminal High Voltage Direct Current Transmission Systems. Energies. 2018; 11 (8):2102.

Chicago/Turabian Style

Liang Xiao; Yan Li; HuangQing Xiao; Zheren Zhang; Zheng Xu. 2018. "Electromechanical Transient Modeling of Line Commutated Converter-Modular Multilevel Converter-Based Hybrid Multi-Terminal High Voltage Direct Current Transmission Systems." Energies 11, no. 8: 2102.

Research article
Published: 31 July 2018 in International Transactions on Electrical Energy Systems
Reads 0
Downloads 0

This paper discusses the feasibility of clamp double submodule (CDSM) type modular multilevel converter‐based multiterminal high‐voltage direct current (MTDC) systems. Firstly, the MTDC system structures, the topology of CDSM, the DC fault current blocking capability of CDSM, and the possible control scheme for clearing DC fault with CDSM‐type modular multilevel converters are introduced. Based on the DC fault clearing control scheme, the DC fault impact on the connected AC system with the proposed method is analyzed in detail. Two types of test systems are built for this study, including the MTDC systems with 1 DC backbone and 2 DC backbones suitable for different occasions. The simulation waveforms are compared with those containing high‐voltage direct current circuit breakers. The results show that the connected AC system postfault responses do not diverse too much with the 2 configurations, which proves the feasibility of the DC circuit breaker‐less MTDC system.

ACS Style

Zheng Xu; Yuzhe Xu; HuangQing Xiao; Zheren Zhang; Gaoren Liu. Feasibility study of DC circuit breaker-less MTDC systems. International Transactions on Electrical Energy Systems 2018, 29, e2679 .

AMA Style

Zheng Xu, Yuzhe Xu, HuangQing Xiao, Zheren Zhang, Gaoren Liu. Feasibility study of DC circuit breaker-less MTDC systems. International Transactions on Electrical Energy Systems. 2018; 29 (1):e2679.

Chicago/Turabian Style

Zheng Xu; Yuzhe Xu; HuangQing Xiao; Zheren Zhang; Gaoren Liu. 2018. "Feasibility study of DC circuit breaker-less MTDC systems." International Transactions on Electrical Energy Systems 29, no. 1: e2679.

Journal article
Published: 16 April 2018 in Energies
Reads 0
Downloads 0

In this paper, the DC short-circuit fault and corresponding clearance solutions of modular multilevel converter-based high-voltage direct current (MMC-HVDC) systems are analyzed in detail. Firstly, the analytical expressions of DC fault currents before and after blocking the MMC are derived based on the operation circuits. Before blocking the MMC, the sub-module (SM) capacitor discharge current is the dominant component of the DC fault current. It will reach the blocking threshold value in several milliseconds. After blocking the MMC, the SM capacitor is no longer discharged. Therefore, the fault current from the AC system becomes the dominant component. Meanwhile, three DC fault clearance solutions and the corresponding characteristics are discussed in detail, including tripping AC circuit breaker, adopting the full-bridge MMC and employing the DC circuit breaker. A simulation model of the MMC-HVDC is realized in PSCAD/EMTDC and the results of the proposed analytical expressions are compared with those of the simulation. The results show that the analytical DC fault currents coincide well with the simulation results.

ACS Style

Zheng Xu; HuangQing Xiao; Liang Xiao; Zheren Zhang. DC Fault Analysis and Clearance Solutions of MMC-HVDC Systems. Energies 2018, 11, 941 .

AMA Style

Zheng Xu, HuangQing Xiao, Liang Xiao, Zheren Zhang. DC Fault Analysis and Clearance Solutions of MMC-HVDC Systems. Energies. 2018; 11 (4):941.

Chicago/Turabian Style

Zheng Xu; HuangQing Xiao; Liang Xiao; Zheren Zhang. 2018. "DC Fault Analysis and Clearance Solutions of MMC-HVDC Systems." Energies 11, no. 4: 941.