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In order to better schedule distributed energy resources (DERs) to improve the recovery ability of the distribution network, the optimal recovery strategy is proposed in this study. The strategy can be applied to speed up the recovery process and reduce the power shortage of shedding loads in the distribution network when a power outage occurs. The scheduling coefficient is defined to quantify the rationality of each scheduling resource. Based on this index, this study establishes an optimal scheduling model, which consists of three objectives. The non-dominated sorting genetic algorithm-II is applied to search this multi-objective optimal recovery solution in this study. Then, the modified IEEE 39-node system is used as the case study to verify the feasibility of the proposed model and the test results prove the effectiveness and efficiency of the proposed model.
Jun Wang; Xiaodong Zheng; Nengling Tai; Yu Liu; Zengli Yang; Jing Wang; Qi Tu. Optimal recovery strategy of DERs integrated distribution network based on scheduling rationality. IET Renewable Power Generation 2021, 14, 3888 -3896.
AMA StyleJun Wang, Xiaodong Zheng, Nengling Tai, Yu Liu, Zengli Yang, Jing Wang, Qi Tu. Optimal recovery strategy of DERs integrated distribution network based on scheduling rationality. IET Renewable Power Generation. 2021; 14 (18):3888-3896.
Chicago/Turabian StyleJun Wang; Xiaodong Zheng; Nengling Tai; Yu Liu; Zengli Yang; Jing Wang; Qi Tu. 2021. "Optimal recovery strategy of DERs integrated distribution network based on scheduling rationality." IET Renewable Power Generation 14, no. 18: 3888-3896.
DC faults render hindrance in the flourishment of multi-terminal flexible high voltage DC (MTDC). The fault current rises rapidly, making a sharp peak, however, under a specific fault instance, isolation of the whole network is an impractical solution. For effective reliability of the whole network, rapid and accurate fault detection and selection of faulty pole is mandatory. A fault detection scheme is proposed in this paper to draw transient current harmonics from initial fault current by utilizing Discrete Fourier transform (DFT). Current harmonics employed the fault detection promptly at the converter stations without communication among the MTDC networks. Additionally, the proposed scheme can discriminate internal from external fault by tracking the number of pulse count in a specific interval of the harmonics of the voltage. In this way, the reliability of the protection scheme enhances and escape from the mal-operation of the circuit breaker. For four terminal MTDC transmission network, the simulations are carried out in PSCAD to authenticate the implementation of the proposed scheme and protection units (PU) are utilized for the isolation of faulty part with the combination of hybrid circuit breaker (HCB). A keen analysis of test results authenticated the ability of the proposed scheme to rapidly detect the faults with high precision, along with efficient classification of the nature of faults. Furthermore, consequential results provide a strong evidence for its key role in handling a multitude of MTDC faults.
Muhammad Haroon Nadeem; Xiaodong Zheng; Nengling Tai; Mehr Gul; Moduo Yu; Yangyang He. Non-communication based protection scheme using transient harmonics for multi-terminal HVDC networks. International Journal of Electrical Power & Energy Systems 2020, 127, 106636 .
AMA StyleMuhammad Haroon Nadeem, Xiaodong Zheng, Nengling Tai, Mehr Gul, Moduo Yu, Yangyang He. Non-communication based protection scheme using transient harmonics for multi-terminal HVDC networks. International Journal of Electrical Power & Energy Systems. 2020; 127 ():106636.
Chicago/Turabian StyleMuhammad Haroon Nadeem; Xiaodong Zheng; Nengling Tai; Mehr Gul; Moduo Yu; Yangyang He. 2020. "Non-communication based protection scheme using transient harmonics for multi-terminal HVDC networks." International Journal of Electrical Power & Energy Systems 127, no. : 106636.
With the rapid development of renewable energy, multi-terminal flexible DC grids composed of modular multilevel converters have been widely used in power systems. To ensure the safe and stable operation of a DC grid, this paper proposes a DC line protection scheme for MMC-based DC grids using AC/DC transient information. In the proposed scheme, the difference between the transient voltage root mean square ratios (DTVR) on both sides of the current-limiting inductor of DC lines is used to identify the DC line fault, and the instantaneous zero sequence voltage (IZSV) of the AC side of the converter station is used to discriminate the faulted poles. According to the theoretical analysis result, a fault criterion setting method suitable for faulted pole discrimination is proposed. The proposed scheme is based on local information and tested in a PSCAD/EMTDC model of a four-terminal MMC-based DC grid. The simulation results show that the scheme can fast and accurately identify faults.
Yangyang He; Xiaodong Zheng; Tai Nengling; Jin Wang; Muhammad Haroon Nadeem; Jian Liu. A DC Line Protection Scheme for MMC-Based DC Grids Based on AC/DC Transient Information. IEEE Transactions on Power Delivery 2020, PP, 1 -1.
AMA StyleYangyang He, Xiaodong Zheng, Tai Nengling, Jin Wang, Muhammad Haroon Nadeem, Jian Liu. A DC Line Protection Scheme for MMC-Based DC Grids Based on AC/DC Transient Information. IEEE Transactions on Power Delivery. 2020; PP (99):1-1.
Chicago/Turabian StyleYangyang He; Xiaodong Zheng; Tai Nengling; Jin Wang; Muhammad Haroon Nadeem; Jian Liu. 2020. "A DC Line Protection Scheme for MMC-Based DC Grids Based on AC/DC Transient Information." IEEE Transactions on Power Delivery PP, no. 99: 1-1.
The ability to withstand extreme disasters has a profound impact on the distribution network operation. This paper proposes a novel optimal operation strategy for an active distribution network to enhance system resilience.. The objectives in the proposed optimal strategy include, the resilience, operation cost, and its pollutant emissions. According to the existence of uncontrollable distributed energy resources in the active distribution network, the problem which takes the uncertainty most into account, is this multi-objective optimization problem. Thus, it can be treated as a min-max dual robust optimization problem. Benders decomposition is employed to decouple the problem, then non-dominated sorting genetic algorithm II is applied to search the multi-objective optimal solution which has an extremely low CPU time. The modified standard IEEE 34-node system, with different distributed energy resources types, is employed, as a studied case, to demonstrate the effectiveness of the proposed optimal operation strategy. The simulation results illustrate that, compared to other economic-oriented robust optimal operation models, the proposed strategy can enhance system resilience without a significant increase in the operation cost and pollutant emissions.
Jun Wang; Xiaodong Zheng; Nengling Tai; Wei Wei; Lingfang Li. Resilience-Oriented Optimal Operation Strategy of Active Distribution Network. Energies 2019, 12, 3380 .
AMA StyleJun Wang, Xiaodong Zheng, Nengling Tai, Wei Wei, Lingfang Li. Resilience-Oriented Optimal Operation Strategy of Active Distribution Network. Energies. 2019; 12 (17):3380.
Chicago/Turabian StyleJun Wang; Xiaodong Zheng; Nengling Tai; Wei Wei; Lingfang Li. 2019. "Resilience-Oriented Optimal Operation Strategy of Active Distribution Network." Energies 12, no. 17: 3380.
This paper proposes a method of fault line selection for a DC distribution network. Firstly, the 1-mode current is calculated using the measured currents of the positive and the negative line. Then, it is time reversed and further decomposed by wavelet technology. Secondly, the lossless mirror line network is established according to the parameters and the topology of the DC distribution network. Thirdly, it is presumed that several virtual current sources are employed at the locations where the corresponding observers are, and the values of these current sources are equal to the processed 1-mode currents. Fourthly, a fault is placed at every point of the lossless mirror line network the RMS value of every assumed fault current is calculated. During this process, the phase coefficient of every lossless mirror line is set to vary along with the length of the line obeying Gaussian distribution. Finally, the line with the peak value of the RMS values of the currents is selected as the fault line. The result of fault line selection is updated using the fewest observers that are set in advance according to the initial result. A DC distribution network is simulated in PSCAD/EMDTC to verify the correctness of the proposed method.
Xipeng Zhang; Nengling Tai; Pan Wu; Xiaodong Zheng; Wentao Huang. A Fault Line Selection Method for DC Distribution Network Using Multiple Observers. Energies 2019, 12, 1245 .
AMA StyleXipeng Zhang, Nengling Tai, Pan Wu, Xiaodong Zheng, Wentao Huang. A Fault Line Selection Method for DC Distribution Network Using Multiple Observers. Energies. 2019; 12 (7):1245.
Chicago/Turabian StyleXipeng Zhang; Nengling Tai; Pan Wu; Xiaodong Zheng; Wentao Huang. 2019. "A Fault Line Selection Method for DC Distribution Network Using Multiple Observers." Energies 12, no. 7: 1245.
Multiple microgrids (MMGs) are clusters of interconnected microgrids that have great potential for integrating a large number of distributed renewable energies (DREs). The grid-connected control scheme is important for the exploration of the MMGs’ operation potential. In this paper, a multi-layer coordinated control scheme for DC interconnected MMGs is proposed to optimize their operation and improve their operation friendliness. An adaptive droop control method is designed for the DC connection interfaces of the MMGs to adaptively manage the power exchange among the sub-microgrids. Meanwhile, the strategy of power fluctuation suppression is developed for the hybrid energy storage system (HESS) in the MMGs. The coordination among the sub-microgrids and the HESS is then clarified by the proposed control scheme to optimize the AC tie-line power and make the MMGs a highly coordinated collective. A case study is performed in PSCAD/EMTDC based on the demonstration project in Guangxi, China. The results show that the proposed multi-layer coordinated control scheme realizes the coordinated operation of the MMGs, fully exploits the complementarity of the MMGs, and improves the operation friendliness among the sub-microgrids and the utility grid. Thus the integration and utilization of a large number of DREs is enhanced.
Pan Wu; Wentao Huang; Nengling Tai; Zhoujun Ma; Xiaodong Zheng; Yong Zhang. A Multi-layer Coordinated Control Scheme to Improve the Operation Friendliness of Grid-Connected Multiple Microgrids. Energies 2019, 12, 255 .
AMA StylePan Wu, Wentao Huang, Nengling Tai, Zhoujun Ma, Xiaodong Zheng, Yong Zhang. A Multi-layer Coordinated Control Scheme to Improve the Operation Friendliness of Grid-Connected Multiple Microgrids. Energies. 2019; 12 (2):255.
Chicago/Turabian StylePan Wu; Wentao Huang; Nengling Tai; Zhoujun Ma; Xiaodong Zheng; Yong Zhang. 2019. "A Multi-layer Coordinated Control Scheme to Improve the Operation Friendliness of Grid-Connected Multiple Microgrids." Energies 12, no. 2: 255.
This paper presents a novel method for locating faults on VSC-MTDC transmission lines using electromagnetic time reversal (EMTR) theory. A method named "First fault-segment, Second fault-location" is proposed. The observed currents are time-reversed and back-injected into the simulation system, which equals to the actual system. In this procedure, a fault is not necessary to be assumed in the simulation system. After fault segment has been screened, the fault location can be verified with minor calculation burden. Moreover, the performances of the EMTR-based technique are discussed under different time-asynchronous cases. The simulation test cases are: a five-terminal VSC-HVDC modified from the China Nan-au demonstration project. Considering the effects of protection and control system, the proposed method presents its straightforward application with low sampling rates and ultra-short time-windows, and robustness against fault type and fault impedance.
Xipeng Zhang; Nengling Tai; Xiaodong Zheng; Wentao Huang. A novel fault-location method for VSC-MTDC transmission lines based on EMTR. Journal of Physics: Conference Series 2018, 1074, 012078 .
AMA StyleXipeng Zhang, Nengling Tai, Xiaodong Zheng, Wentao Huang. A novel fault-location method for VSC-MTDC transmission lines based on EMTR. Journal of Physics: Conference Series. 2018; 1074 (1):012078.
Chicago/Turabian StyleXipeng Zhang; Nengling Tai; Xiaodong Zheng; Wentao Huang. 2018. "A novel fault-location method for VSC-MTDC transmission lines based on EMTR." Journal of Physics: Conference Series 1074, no. 1: 012078.
Voltage-source-converter-based multi-terminal high voltage direct current (MTDC) networks are extensively recognized as a viable solution for meeting the increasing demand of electrical energy and escalating penetration of renewable energy sources. DC faults are major limitations to the development of MTDC networks. The analysis of variable constraints has become mandatory in order to develop a reliable protection scheme. This paper contributes in assessing the propagation delay with the analytical approximation in MTDC networks. The propagation delay is analyzed in the time domain by taking only the forward traveling wave into account and considering the initial voltage step of magnitude at the fault position. Numerous simulations were carried out for different parameters and arrangements in Power System Computer Aided Design (PSCAD) to explore the proposed expressions. The results accurately depicted the time development of fault current. The results obtained from the real-time digital simulator (RTDS) confirmed that the proposed approach is capable of evaluating propagation delay in MTDC networks. Moreover, the influence of fault resistance is also taken into account for investigating its effect on the system parameters.
Muhammad Haroon Nadeem; Xiaodong Zheng; Nengling Tai; Mehr Gul; Sohaib Tahir. Analysis of Propagation Delay for Multi-Terminal High Voltage Direct Current Networks Interconnecting the Large-Scale Off-Shore Renewable Energy. Energies 2018, 11, 2115 .
AMA StyleMuhammad Haroon Nadeem, Xiaodong Zheng, Nengling Tai, Mehr Gul, Sohaib Tahir. Analysis of Propagation Delay for Multi-Terminal High Voltage Direct Current Networks Interconnecting the Large-Scale Off-Shore Renewable Energy. Energies. 2018; 11 (8):2115.
Chicago/Turabian StyleMuhammad Haroon Nadeem; Xiaodong Zheng; Nengling Tai; Mehr Gul; Sohaib Tahir. 2018. "Analysis of Propagation Delay for Multi-Terminal High Voltage Direct Current Networks Interconnecting the Large-Scale Off-Shore Renewable Energy." Energies 11, no. 8: 2115.
With the promotion of distributed energy and direct current (DC) loads, the DC microgrid is able to provide a higher power quality and improve the grid efficiency. Various technical issues in DC microgrids are still to be addressed, particularly a proper protection scheme for fault detection and isolation in DC microgrids utilizing voltage source converters (VSCs). In this paper, the pole-to-pole DC fault transient behavior of the VSC-based microgrids is firstly analyzed with four successive stages, and then the exact requirements for protections are presented. Furthermore, a novel single-ended protection scheme based on local transient signals is proposed, which needs no data transmission or synchronization between two ends, ensuring the speed. A four-terminal DC microgrid model was built in PSCAD/EMTDC. Numerous simulations have demonstrated the validity of the proposed scheme.
Cheng Lv; Xiaodong Zheng; Nengling Tai; Shi Chen. Single-Ended Protection Scheme for VSC-Based DC Microgrid Lines. Energies 2018, 11, 1440 .
AMA StyleCheng Lv, Xiaodong Zheng, Nengling Tai, Shi Chen. Single-Ended Protection Scheme for VSC-Based DC Microgrid Lines. Energies. 2018; 11 (6):1440.
Chicago/Turabian StyleCheng Lv; Xiaodong Zheng; Nengling Tai; Shi Chen. 2018. "Single-Ended Protection Scheme for VSC-Based DC Microgrid Lines." Energies 11, no. 6: 1440.
This paper presents a protection scheme to protect multi-terminal high voltage dc (MTDC) networks for interconnection of renewable energy sources. The proposed scheme detects faults by using the Consecutive Data Window Method (CDWM) and harmonics of the system voltage to avoid maloperation of breakers without communication. Fault location is classified and faulty parts is isolated from the rest of the healthier network by using hybrid circuit breakers (HCBs). Moreover; it also categorises the fault with the help of the voltage drop. The rapid response to isolate the faulty portion in a few milliseconds is primarily considered to enhance the reliability and security of the network. The results of simulations verify the efficient fault detection and isolation for different DC faults and the investigation for the impact of significant parameters of the proposed scheme has been considered. The simulations are performed in PSCAD for four terminal MTDC networks to validate the proposed scheme. The performance is also verified under different fault conditions by using Matlab after computing the data from simulations.
Muhammad Haroon Nadeem; Xiaodong Zheng; Nengling Tai; Mehr Gul. Identification and Isolation of Faults in Multi-terminal High Voltage DC Networks with Hybrid Circuit Breakers. Energies 2018, 11, 1086 .
AMA StyleMuhammad Haroon Nadeem, Xiaodong Zheng, Nengling Tai, Mehr Gul. Identification and Isolation of Faults in Multi-terminal High Voltage DC Networks with Hybrid Circuit Breakers. Energies. 2018; 11 (5):1086.
Chicago/Turabian StyleMuhammad Haroon Nadeem; Xiaodong Zheng; Nengling Tai; Mehr Gul. 2018. "Identification and Isolation of Faults in Multi-terminal High Voltage DC Networks with Hybrid Circuit Breakers." Energies 11, no. 5: 1086.
The neglect of the history depreciation imbalance in the conventional equalization strategies may aggravate the lifetime depreciation of the multi-battery energy storage systems (MBESSs) and overuse the high-history-depreciation batteries (HHDBs). This paper proposes an equalization strategy using maximum consistency tracking algorithm of the conditional depreciation to solve the stated problem. Conditional depreciation is innovatively defined to evaluate the operation equitability of the MBESSs. The maximum consistency tracking algorithm consists of two searching levels: the global searching level and the range searching level. A sequential approximation method is utilized at the global searching level to find the variation range consisting of the most equitable conditional depreciation. The newton downhill method is adopted at the range searching level to find the exact value of the most equitable conditional depreciation. The proposed equalization strategy is validated by a hardware-in-the-loop simulation system. Test results show that the proposed equalization strategy minimizes the imbalance of batteries' conditional depreciations and decreases the HHDBs' sharing power. Compared to the conventional equalization strategies, the proposed equalization strategy will protect the HHDBs from intermittent overuse and extend the lifetime of the MBESSs.
Feilong Fan; Nengling Tai; Xiao-Dong Zheng; Wentao Huang; Jinxiao Shi; Tai Nengling. Equalization Strategy for Multi-Battery Energy Storage Systems Using Maximum Consistency Tracking Algorithm of the Conditional Depreciation. IEEE Transactions on Energy Conversion 2018, 33, 1242 -1254.
AMA StyleFeilong Fan, Nengling Tai, Xiao-Dong Zheng, Wentao Huang, Jinxiao Shi, Tai Nengling. Equalization Strategy for Multi-Battery Energy Storage Systems Using Maximum Consistency Tracking Algorithm of the Conditional Depreciation. IEEE Transactions on Energy Conversion. 2018; 33 (3):1242-1254.
Chicago/Turabian StyleFeilong Fan; Nengling Tai; Xiao-Dong Zheng; Wentao Huang; Jinxiao Shi; Tai Nengling. 2018. "Equalization Strategy for Multi-Battery Energy Storage Systems Using Maximum Consistency Tracking Algorithm of the Conditional Depreciation." IEEE Transactions on Energy Conversion 33, no. 3: 1242-1254.
In order to improve the simulation speed of the AC/DC hybrid grid, the inductance/capacitance (L/C) switch model for line-commutated converter of high-voltage direct current (LCC-HVDC) is presented in this study. The time domain modeling method is used to analyze the circuit of L/C switch model for the six-pulse system in LCC-HVDC in a switching period. A parameter setting method of L/C switch model is proposed considering the transient response, the steady state performance, switching losses and simulation error of the switch. The inductance/capacitance (L/C) switch model for LCC-HVDC has the advantage of keeping the admittance matrix unchanged regardless of the change of switching state, which improves the simulation efficiency. Finally, the validity of the parameter setting method is verified. Compared with the test results of PSCAD/EMTDC, the accuracy of the proposed LCC-HVDC simulation model is proved. The model is suitable for real-time or offline simulation of AC/DC hybrid grid.
Yangyang He; Xiaodong Zheng; Nengling Tai; Junxian Hou; Wentao Huang. Research on the Inductance/Capacitance Switch Model for an LCC-HVDC Converter in an AC/DC Hybrid Grid. Energies 2018, 11, 692 .
AMA StyleYangyang He, Xiaodong Zheng, Nengling Tai, Junxian Hou, Wentao Huang. Research on the Inductance/Capacitance Switch Model for an LCC-HVDC Converter in an AC/DC Hybrid Grid. Energies. 2018; 11 (4):692.
Chicago/Turabian StyleYangyang He; Xiaodong Zheng; Nengling Tai; Junxian Hou; Wentao Huang. 2018. "Research on the Inductance/Capacitance Switch Model for an LCC-HVDC Converter in an AC/DC Hybrid Grid." Energies 11, no. 4: 692.
Based on the inherent characteristic of the carrier-based pulse-width modulation converters, the response of the first carrier frequency harmonic (FCFH) current in the voltage source converter (VSC)-based high-voltage direct current (HVDC) transmission system is analysed under different fault conditions in this paper. A new protection scheme for the VSC-based HVDC transmission systems is proposed based on the FCFH currents. By extracting the harmonic currents at both the endings of the DC transmission cable, the fault type can be identified. The VSC-based HVDC test system is modelled in the PSCAD/EMTDC and the proposed protection scheme is evaluated with a variety of values of the fault resistance and the fault locations. Comprehensive test studies show that the performance of the proposed protection scheme is inspiring. It can recognise the internal and the external faults correctly.
Xiaodong Zheng; Nengling Tai; Zhongyu Wu; James Thorp. Harmonic current protection scheme for voltage source converter‐based high‐voltage direct current transmission system. IET Generation, Transmission & Distribution 2014, 8, 1509 -1515.
AMA StyleXiaodong Zheng, Nengling Tai, Zhongyu Wu, James Thorp. Harmonic current protection scheme for voltage source converter‐based high‐voltage direct current transmission system. IET Generation, Transmission & Distribution. 2014; 8 (9):1509-1515.
Chicago/Turabian StyleXiaodong Zheng; Nengling Tai; Zhongyu Wu; James Thorp. 2014. "Harmonic current protection scheme for voltage source converter‐based high‐voltage direct current transmission system." IET Generation, Transmission & Distribution 8, no. 9: 1509-1515.
The relation between the parameters of dc transmission line and the variation of transient energy has been analyzed under various fault conditions in this paper. According to that, a new transient energy protective scheme is proposed. It is developed based on the distributed parameter line model in which the transient energy distribution over the line can be obtained from the voltage and current measurements at both terminals and the fault can be recognized from the calculated value simply. The test system is modeled based on the CIGRE benchmark and considered the distributed parameters of the dc transmission line. Comprehensive test studies show that the performance of transient energy protection scheme is encouraging. It can not only identify internal fault and external faults correctly and quickly, but can also respond to the high ground resistance fault. Finally, two main factors, including fault resistance and transmission distance, that affect the performance of the protection are also discussed.
Xiaodong Zheng; Tai Nengling; Yang Guangliang; Ding HaoYin. A Transient Protection Scheme for HVDC Transmission Line. IEEE Transactions on Power Delivery 2012, 27, 718 -724.
AMA StyleXiaodong Zheng, Tai Nengling, Yang Guangliang, Ding HaoYin. A Transient Protection Scheme for HVDC Transmission Line. IEEE Transactions on Power Delivery. 2012; 27 (2):718-724.
Chicago/Turabian StyleXiaodong Zheng; Tai Nengling; Yang Guangliang; Ding HaoYin. 2012. "A Transient Protection Scheme for HVDC Transmission Line." IEEE Transactions on Power Delivery 27, no. 2: 718-724.