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Wen Zhang
School of Electrical Engineering, Shandong University, Jinan, Shandong, China, 250061

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Journal article
Published: 16 August 2021 in IEEE Transactions on Power Systems
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This paper proposes a novel real-time adaptive under voltage load shedding (UVLS) method by using optimized fuzzy logic controllers to address fault-induced delayed voltage recovery (FIDVR) and short-term voltage instability (STVIS) problems. An intelligent multi-input multi-output fuzzy logic load shedding controller is developed based on a short-term voltage recovery criterion (STVRC). For the controller, the magnitude deviation and the recovery time deviation of voltage trajectory are extracted as inputs, while the load shedding amount at the current load shedding stage and the time delay of the next stage are taken as outputs. Particle swarm optimization (PSO) technique is further employed for the tuning of the controller parameters to realize the voltage recovery requirement at the lowest cost of load shedding. The proposed UVLS method is formed by a group of the fuzzy logic controllers deployed at the load buses, each monitoring its own bus voltage and shedding load in closed-loop. Responding to the severity of voltage variations, the proposed method is able to adaptively determine the location, time and amount of load shedding in real-time to make the voltage satisfy the STVRC. The effectiveness of the proposed method compared to other methods is testified by simulations on the Nordic test system.

ACS Style

Hao Yang; Ning Li; Z.L. Sun; Dawei Huang; Deyou Yang; Guowei Cai; Chuang Liu; Tingting Zhang; Wen Zhang. Real-time Adaptive UVLS by Optimized Fuzzy Controllers for Short-Term Voltage Stability Control. IEEE Transactions on Power Systems 2021, PP, 1 -1.

AMA Style

Hao Yang, Ning Li, Z.L. Sun, Dawei Huang, Deyou Yang, Guowei Cai, Chuang Liu, Tingting Zhang, Wen Zhang. Real-time Adaptive UVLS by Optimized Fuzzy Controllers for Short-Term Voltage Stability Control. IEEE Transactions on Power Systems. 2021; PP (99):1-1.

Chicago/Turabian Style

Hao Yang; Ning Li; Z.L. Sun; Dawei Huang; Deyou Yang; Guowei Cai; Chuang Liu; Tingting Zhang; Wen Zhang. 2021. "Real-time Adaptive UVLS by Optimized Fuzzy Controllers for Short-Term Voltage Stability Control." IEEE Transactions on Power Systems PP, no. 99: 1-1.

Journal article
Published: 30 January 2021 in Applied Sciences
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Non-synchronous renewable energy sources (RESs) have strong volatility and low inertia, which brings about great challenges on the accommodation of RESs and the security and stability of power systems. This paper proposes a bi-level power system dispatch and control architecture based on the grid-friendly virtual power plant (GVPP), so as to accommodate RESs flexibly and securely. The typical dispatch and control system of the power system in China is presented, and the particular challenges stemming from non-synchronous RESs are analyzed. The functional requirements, concept, and fundamental design of the GVPP are provided, which is distinguished from traditional virtual power plants (VPPs) for its active participation in power system stability control. Based on the cloud platform, a bi-level dispatch and control architecture considering two objectives is established. First, in the inner level, the GVPP operates to promote the accommodation of RESs under normal condition. Then, from the perspective of out-level power systems, GVPPs serve as spinning reserves for power support under contingencies. Besides, the key problems to be solved in the development of the GVPP-based architecture are summarized. Although the architecture is proposed for the power system in China, it can be applied to any power systems with similar challenges.

ACS Style

Qingwen Xu; Yongji Cao; Hengxu Zhang; Wen Zhang; Vladimir Terzija. Bi-Level Dispatch and Control Architecture for Power System in China Based on Grid-Friendly Virtual Power Plant. Applied Sciences 2021, 11, 1282 .

AMA Style

Qingwen Xu, Yongji Cao, Hengxu Zhang, Wen Zhang, Vladimir Terzija. Bi-Level Dispatch and Control Architecture for Power System in China Based on Grid-Friendly Virtual Power Plant. Applied Sciences. 2021; 11 (3):1282.

Chicago/Turabian Style

Qingwen Xu; Yongji Cao; Hengxu Zhang; Wen Zhang; Vladimir Terzija. 2021. "Bi-Level Dispatch and Control Architecture for Power System in China Based on Grid-Friendly Virtual Power Plant." Applied Sciences 11, no. 3: 1282.

Journal article
Published: 24 September 2020 in IEEE Transactions on Smart Grid
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A new spatio-temporal decomposition and coordina-tion scheme is proposed for load restoration in an AC/DC hybrid transmission system. First, the framework of spatio-temporal decomposition is built for load restoration, the decoupled varia-bles and spatial and temporal coordinators are defined, as well as two interactive blocks. Furthermore, the spatio-temporal decom-posed models of subsystems and HVDC links are constructed considering security constraints and HVDC operation character-istics. Finally, a new hierarchical overlapping coordination based analytical target cascading (HOCATC) algorithm is developed to coordinate the decomposed models by iterative calculations between subsystems and coordinators, as well as the two interac-tive blocks. The proposed distributed scheme maintains inde-pendent operations of subsystems, and handles the multi-step restoration process by iteratively calculating single-step models. The developed HOCATC algorithm provides tractable and effi-cient computation for the HVDC model incorporated load resto-ration optimization. The effectiveness of the proposed method is validated using two IEEE test systems, showing improved compu-tational efficiency and better convergence ability.

ACS Style

Jin Zhao; Hongtao Wang; Qiuwei Wu; Nikos D. Hatziargyriou; Wen Zhang. Spatio-Temporal Decomposition and Coordination for Distributed Load Restoration in AC/DC Hybrid System. IEEE Transactions on Smart Grid 2020, 12, 1685 -1698.

AMA Style

Jin Zhao, Hongtao Wang, Qiuwei Wu, Nikos D. Hatziargyriou, Wen Zhang. Spatio-Temporal Decomposition and Coordination for Distributed Load Restoration in AC/DC Hybrid System. IEEE Transactions on Smart Grid. 2020; 12 (2):1685-1698.

Chicago/Turabian Style

Jin Zhao; Hongtao Wang; Qiuwei Wu; Nikos D. Hatziargyriou; Wen Zhang. 2020. "Spatio-Temporal Decomposition and Coordination for Distributed Load Restoration in AC/DC Hybrid System." IEEE Transactions on Smart Grid 12, no. 2: 1685-1698.

Journal article
Published: 03 June 2020 in International Journal of Electrical Power & Energy Systems
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Providing ancillary service with controllable loads has drawn increasing attention from academia and industry. This paper proposes a hierarchical control strategy for aluminum smelter loads (ASLs), a typical controllable load, to provide primary support in a cost-efficient way. At the higher level, the supervisory computer in the aluminum smelting plant (ASP) estimates the available power of ASLs and allocates the contracted reserve to ASLs by optimization. At the lower level, within the allocated reserve from the higher level, ASLs respond to frequency deviations automatically by changing their power consumption, which is implemented by a local control scheme based on a novel DC current control (DCC) scheme and a dynamic frequency threshold (DFT) approach. Compared with the existing PI-based DCC, the novel DCC employs model predictive control (MPC) to improve its transient performance. The DFT approach can avoid ASLs responding to frequency deviations in the serious anode effects (AE) situations. Case studies are carried out based on the data of an actual ASP. The results show that the hierarchically controlled ASLs can reduce the frequency drop with lower control cost and reduce the regulation dependency on the generation side. Besides, the high performance of the MPC-based DCC and the effectiveness of the DFT approach are also demonstrated.

ACS Style

Peng Bao; Wen Zhang; Dingyi Cheng; Meng Liu. Hierarchical control of aluminum smelter loads for primary frequency support considering control cost. International Journal of Electrical Power & Energy Systems 2020, 122, 106202 .

AMA Style

Peng Bao, Wen Zhang, Dingyi Cheng, Meng Liu. Hierarchical control of aluminum smelter loads for primary frequency support considering control cost. International Journal of Electrical Power & Energy Systems. 2020; 122 ():106202.

Chicago/Turabian Style

Peng Bao; Wen Zhang; Dingyi Cheng; Meng Liu. 2020. "Hierarchical control of aluminum smelter loads for primary frequency support considering control cost." International Journal of Electrical Power & Energy Systems 122, no. : 106202.

Journal article
Published: 24 December 2019 in International Journal of Electrical Power & Energy Systems
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The increasing penetration of photovoltaic (PV) generation leads to voltage violations in hybrid AC/DC microgrids. Due to the uncertainty and volatility of PV outputs, fast-responding voltage control devices are obliged to coordinate with each other and regulate nodal voltages in real time. This paper follows the concept of optimizing globally and controlling locally to propose a combined central and local voltage control strategy based on a two-stage voltage control framework. In the first stage, minutely optimal power flow based on predicted PV outputs within one hour is performed in microgrid central controller (MGCC) to calculate voltage and optimal power settings for each controllable device. The uncertainty of PV is considered using chance constraint optimal power flow (CCOPF) method. In the second stage, according to minutely voltage and power settings, local controller (LC) generates improved voltage control curves based on curve fitting method. With minutely measurements of nodal voltages, power outputs of PVs, smart loads (SLs) energy storage systems (ESSs) and VSC are cooperated based on improved local control curves to minimize power losses without communication requirements. In order to coordinate the active and reactive power of SLs ESSs, and VSC, a combined P(V) and Q(V) curve is proposed. The piecewise linear curve fitting method is used to generate optimal voltage control curves due to its higher fitting accuracy compared with other fitting methods. Simulations are performed to verify the effectiveness of the proposed voltage control strategy in mitigating voltage rise problems and reducing power losses.

ACS Style

Xianzhuo Sun; Wen Zhang; Jian Chen. Optimize globally, control locally: Coordinated optimal local voltage control in hybrid AC/DC microgrid. International Journal of Electrical Power & Energy Systems 2019, 118, 105734 .

AMA Style

Xianzhuo Sun, Wen Zhang, Jian Chen. Optimize globally, control locally: Coordinated optimal local voltage control in hybrid AC/DC microgrid. International Journal of Electrical Power & Energy Systems. 2019; 118 ():105734.

Chicago/Turabian Style

Xianzhuo Sun; Wen Zhang; Jian Chen. 2019. "Optimize globally, control locally: Coordinated optimal local voltage control in hybrid AC/DC microgrid." International Journal of Electrical Power & Energy Systems 118, no. : 105734.

Journal article
Published: 18 March 2019 in International Journal of Electrical Power & Energy Systems
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With the integration of more and more renewable energy in the power system, more reserves are needed to cope with the intermittent and stochastic characteristics of the renewable energy. To relieve the stress of the reserve supply by the generation side, air conditioning loads can be considered to participate in reserve allocation in dynamic economic dispatch owing to their high proportion in the demand and thermal energy storage characteristics. The lock time of air conditioners should not be ignored since it can avoid the short cycling of compressor. This paper proposes a hierarchical reserve allocation model with air conditioning loads considering lock time to coordinate the power system dispatch and the control of air conditioning loads. An aggregate model of air conditioning loads considering the lock time is proposed and linear constraints of the air conditioning loads are developed. Among these constraints, lockout constraints are linear slack constraints for convenient in computation and the validity of the slack form has been proved. These constraints are integrated into the reserve allocation in dynamic economic dispatch. In such a state, the problem has multi-time scale characteristics and thus, is difficult to solve; therefore, this problem is reconstructed as a three-level hierarchical problem, and Benders decomposition is applied. The first level (operation level) represents the operation of the power system in normal conditions. Each N-1 contingency is placed in the second level (contingency level). The third level (load control level) considers the constraints of the air conditioning loads. To increase the calculation efficiency, we propose three methods, which are adding necessary conditions, adjusting upper bound and applying parallel computing. The simulation results show that air conditioning loads can realize load reserve, and the proposed hierarchical solving method is effective to solve the reserve allocation problem with air conditioning loads considering the lock time.

ACS Style

Dingyi Cheng; Wen Zhang; Kai Wang. Hierarchical reserve allocation with air conditioning loads considering lock time using Benders decomposition. International Journal of Electrical Power & Energy Systems 2019, 110, 293 -308.

AMA Style

Dingyi Cheng, Wen Zhang, Kai Wang. Hierarchical reserve allocation with air conditioning loads considering lock time using Benders decomposition. International Journal of Electrical Power & Energy Systems. 2019; 110 ():293-308.

Chicago/Turabian Style

Dingyi Cheng; Wen Zhang; Kai Wang. 2019. "Hierarchical reserve allocation with air conditioning loads considering lock time using Benders decomposition." International Journal of Electrical Power & Energy Systems 110, no. : 293-308.

Journal article
Published: 21 January 2019 in International Journal of Electrical Power & Energy Systems
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With the increasing use of LCC-HVDC links as bridges for bulk-power delivery, voltage stability control has become a crucial issue in hybrid AC/DC power systems. This paper proposes an optimal coordinated voltage control (CVC) of AC/DC systems to enhance steady-state voltage stability. Notably, the CVC incorporates the controls of HVDC rectifier and inverter converters. First, the voltage stability indicator, L-index, in AC systems is extended to AC/DC systems. Then, based on the voltage stability sensitivities, the CVC is modeled as a linearly constrained quadratic programming (LCQP) problem to coordinate the controllable resources of AC/DC systems, which can result in fast and effective solutions. Further based on the CVC, a control strategy is designed to simultaneously meet the requirements of voltage stability margin enhancement and voltage deviation correction. In addition, the potential of HVDC systems participating in voltage stability control is illustrated. The results of simulations performed for two AC/DC power systems show that the proposed method can effectively coordinate control variables to enhance voltage stability.

ACS Style

Hao Yang; Wen Zhang; Jian Chen; Jiping Xie. Optimal coordinated voltage control of AC/DC power systems for voltage stability enhancement. International Journal of Electrical Power & Energy Systems 2019, 108, 252 -262.

AMA Style

Hao Yang, Wen Zhang, Jian Chen, Jiping Xie. Optimal coordinated voltage control of AC/DC power systems for voltage stability enhancement. International Journal of Electrical Power & Energy Systems. 2019; 108 ():252-262.

Chicago/Turabian Style

Hao Yang; Wen Zhang; Jian Chen; Jiping Xie. 2019. "Optimal coordinated voltage control of AC/DC power systems for voltage stability enhancement." International Journal of Electrical Power & Energy Systems 108, no. : 252-262.

Journal article
Published: 30 November 2018 in Energies
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Most of the current wind power interval forecast methods are based on the assumption the point forecast error is subject to a known distribution (such as a normal distribution, beta distribution, etc.). The interval forecast of wind power is obtained after solving the confidence interval of the known distribution. However, this assumption does not reflect the truth because the distribution of error is random and does not necessary obey any known distribution. Moreover, the current method for calculating the confidence interval is only good for a known distribution. Therefore, those interval forecast methods cannot be applied generally, and the forecast quality is not good. In this paper, a general method is proposed to determine the optimal interval forecast of wind power. Firstly, the distribution of the point forecast error is found by using the non-parametric Parzen window estimation method which is suitable for the distribution of an arbitrary shape. Secondly, an optimal method is used to find the minimum confidence interval of arbitrary distribution. Finally the optimal forecast interval is obtained. Simulation results indicate that this method is not only generally applicable, but also has a better comprehensive evaluation index.

ACS Style

Xiaodong Yu; Wen Zhang; Hongzhi Zang; Hao Yang. Wind Power Interval Forecasting Based on Confidence Interval Optimization. Energies 2018, 11, 3336 .

AMA Style

Xiaodong Yu, Wen Zhang, Hongzhi Zang, Hao Yang. Wind Power Interval Forecasting Based on Confidence Interval Optimization. Energies. 2018; 11 (12):3336.

Chicago/Turabian Style

Xiaodong Yu; Wen Zhang; Hongzhi Zang; Hao Yang. 2018. "Wind Power Interval Forecasting Based on Confidence Interval Optimization." Energies 11, no. 12: 3336.

Journal article
Published: 30 August 2018 in International Journal of Electrical Power & Energy Systems
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Using PMU measurements, this paper proposes a model-free method to predict post-fault transient instability and develop emergency generator-shedding control. First, the multi-machine system is converted to an equivalent one-machine-infinite-bus (OMIB) system based on online generator clustering, and then the stability criteria are derived to judge the transient stability using the OMIB rotor speed (OMIB-ω) trajectory. Next, a new trajectory prediction algorithm based on ensemble online sequential learning machine (E-OS-ELM) is proposed to predict the OMIB-ω trajectory with an adaptive prediction window. The post-fault transient instability status can be detected in advance on basis of the predicted ω trajectory and the derived stability criteria. Lastly, when the system is foreseen to lose stability, an analytical generator-shedding control algorithm is presented, and the relationship between the generator-shedding amount and the time delay is illustrated. Case studies on the New-England 39-bus system, the NPCC 140-bus system and a realistic province power system in China are presented to show the proposed methodology can detect the instability status early, and help the system maintain synchronism.

ACS Style

Hao Yang; Wen Zhang; Fang Shi; Jiping Xie; Wenjie Ju. PMU-based model-free method for transient instability prediction and emergency generator-shedding control. International Journal of Electrical Power & Energy Systems 2018, 105, 381 -393.

AMA Style

Hao Yang, Wen Zhang, Fang Shi, Jiping Xie, Wenjie Ju. PMU-based model-free method for transient instability prediction and emergency generator-shedding control. International Journal of Electrical Power & Energy Systems. 2018; 105 ():381-393.

Chicago/Turabian Style

Hao Yang; Wen Zhang; Fang Shi; Jiping Xie; Wenjie Ju. 2018. "PMU-based model-free method for transient instability prediction and emergency generator-shedding control." International Journal of Electrical Power & Energy Systems 105, no. : 381-393.

Journal article
Published: 20 April 2018 in Applied Sciences
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Model predictive control (MPC) is commonly used to compensate for modeling inaccuracies and measurement noise in voltage control problems. The length of the prediction horizon and control horizon of a MPC-based method has significant impact on the control performances. In existing relevant works, those horizon parameters are determined off-line based on experience or enumeration, and keeps constant during the entire receding-horizon optimization process. This paper presents a system voltage correction scheme based on adaptive horizon model predictive control (AH-MPC). The reactive power compensation and voltage regulation devices are coordinated to maintain the system voltages within a desired range. An evaluation index is proposed to determine the horizon parameters, which reflects the maximum voltage regulation ability with the current parameter configuration. Within each sampling interval, the horizon parameters are updated according to the evaluation index and real-time measurements periodically, which comprehensively considers the system uncertainties and voltage recovery speed, and the computational effort is remarkably reduced. The validation and effectiveness of the proposed method is verified by the simulation analysis on the test system.

ACS Style

Yan Zhang; Meng Liu; Wen Zhang; Wenchuan Sun; Xingwang Hu; Gang Kong. Power System Voltage Correction Scheme Based on Adaptive Horizon Model Predictive Control. Applied Sciences 2018, 8, 641 .

AMA Style

Yan Zhang, Meng Liu, Wen Zhang, Wenchuan Sun, Xingwang Hu, Gang Kong. Power System Voltage Correction Scheme Based on Adaptive Horizon Model Predictive Control. Applied Sciences. 2018; 8 (4):641.

Chicago/Turabian Style

Yan Zhang; Meng Liu; Wen Zhang; Wenchuan Sun; Xingwang Hu; Gang Kong. 2018. "Power System Voltage Correction Scheme Based on Adaptive Horizon Model Predictive Control." Applied Sciences 8, no. 4: 641.

Article
Published: 20 March 2018 in Journal of Modern Power Systems and Clean Energy
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Demand response has gained significant attention recently with the increasing penetration of renewable energy sources in power systems. Air conditioning loads are typical thermostatically controlled loads which can play an active role in ancillary services by regulating their aggregated power consumption. The aggregation of air conditioners is essential to the control of air conditioning loads. In this paper, linear state equations are proposed to aggregate air conditioning loads by solving coupled Fokker–Planck equations (CFPEs) using the finite difference method. By analyzing the numerical stability and convergence of the difference scheme, the grid spacings, including temperature step and time step, are properly determined according to the maximal principle. Stationary solutions of the CFPEs are obtained by analytical and numerical methods. Furthermore, a classification method using dimension reduction is proposed to deal with the problem of heterogeneous parameters and interval estimation is applied to describe the stochastic behavior of air conditioning loads. The simulation results verify the effectiveness of the proposed methods.

ACS Style

Dingyi Cheng; Wen Zhang; Yutian Liu. Aggregate modeling and analysis of air conditioning load using coupled Fokker–Planck equations. Journal of Modern Power Systems and Clean Energy 2018, 6, 1277 -1290.

AMA Style

Dingyi Cheng, Wen Zhang, Yutian Liu. Aggregate modeling and analysis of air conditioning load using coupled Fokker–Planck equations. Journal of Modern Power Systems and Clean Energy. 2018; 6 (6):1277-1290.

Chicago/Turabian Style

Dingyi Cheng; Wen Zhang; Yutian Liu. 2018. "Aggregate modeling and analysis of air conditioning load using coupled Fokker–Planck equations." Journal of Modern Power Systems and Clean Energy 6, no. 6: 1277-1290.

Journal article
Published: 11 July 2017 in IEEE Transactions on Sustainable Energy
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This paper presents a multiobjective optimization method to jointly optimize the planning and operation of a grid-tied microgrid (MG) with various distributed generation sources such as wind turbine and photovoltaic arrays with the assistance of demand side management. In order to explore the economy and demand variety, the problem is formulated as a double-objective optimization to minimize the total annual cost and to maximize the customer satisfaction. To solve the multiobjective optimization problem, a fuzzy satisfaction-maximizing method is adopted to convert the original problem into a single objective optimization problem and a mixed integer linear programming algorithm is then used to solve the problem. To verify the proposed solution, various case studies have been carried out and compared. The results show that the proposed method is effective in minimizing the cost of an MG without sacrificing the satisfaction of customers.

ACS Style

Jian Chen; Weitong Zhang; Jiaqi Li; Wen Zhang; Yutian Liu; Bo Zhao; Yicheng Zhang. Optimal Sizing for Grid-Tied Microgrids With Consideration of Joint Optimization of Planning and Operation. IEEE Transactions on Sustainable Energy 2017, 9, 237 -248.

AMA Style

Jian Chen, Weitong Zhang, Jiaqi Li, Wen Zhang, Yutian Liu, Bo Zhao, Yicheng Zhang. Optimal Sizing for Grid-Tied Microgrids With Consideration of Joint Optimization of Planning and Operation. IEEE Transactions on Sustainable Energy. 2017; 9 (1):237-248.

Chicago/Turabian Style

Jian Chen; Weitong Zhang; Jiaqi Li; Wen Zhang; Yutian Liu; Bo Zhao; Yicheng Zhang. 2017. "Optimal Sizing for Grid-Tied Microgrids With Consideration of Joint Optimization of Planning and Operation." IEEE Transactions on Sustainable Energy 9, no. 1: 237-248.

Journal article
Published: 23 November 2016 in IEEE Transactions on Smart Grid
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With the increasing contribution of intermittent renewable generations to electric power grids, additional frequency reserves are required to manage the balance between generation and load in power systems. This paper describes the potential contribution of LED lighting loads as frequency reserves to provide ancillary services and proposes a decentralized control strategy for LED lighting loads in response to frequency deviations. Three control modes are developed according to the magnitude and duration of the frequency deviations. Experimental results verify the effectiveness of the use of an illumination controller to regulate illumination with the corresponding control modes. Simulation results demonstrate the validity of using LED lighting loads as frequency reserves to provide frequency regulation. The frequency deviations can be appropriately mitigated using the controlled LED lighting loads.

ACS Style

Jingyu Liu; Wen Zhang; Yutian Liu. Primary Frequency Response From the Control of LED Lighting Loads in Commercial Buildings. IEEE Transactions on Smart Grid 2016, 8, 2880 -2889.

AMA Style

Jingyu Liu, Wen Zhang, Yutian Liu. Primary Frequency Response From the Control of LED Lighting Loads in Commercial Buildings. IEEE Transactions on Smart Grid. 2016; 8 (6):2880-2889.

Chicago/Turabian Style

Jingyu Liu; Wen Zhang; Yutian Liu. 2016. "Primary Frequency Response From the Control of LED Lighting Loads in Commercial Buildings." IEEE Transactions on Smart Grid 8, no. 6: 2880-2889.

Journal article
Published: 07 September 2016 in IEEE Transactions on Smart Grid
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The influences of network reconfiguration and distributed generations (DGs) on distribution system state estimation (DSSE) and measurement placement should not be ignored in active distribution systems. In this paper, considering network reconfiguration and the output uncertainties of DGs, a robust measurement placement method for active distribution systems is proposed based on measurement saturation analysis and heuristic algorithm. First, the saturation number determined by measurement saturation characteristic is chosen as the measurement number. Then, the impacts of different network topologies are represented by various weights in the robust measurement placement model, which are computed by Markov chain and analytic hierarchy process. In addition, Gaussian mixture model is applied to approximate the power fluctuations of DGs. Uncertainties caused by measurements are considered by Monte Carlo simulations. The accuracy of DSSE in different network topologies can be guaranteed by the proposed robust measurement placement method. Simulation results based on the IEEE 33-bus and 119-bus distribution systems demonstrate the effectiveness of the proposed method.

ACS Style

Hong Wang; Wen Zhang; Yutian Liu. A Robust Measurement Placement Method for Active Distribution System State Estimation Considering Network Reconfiguration. IEEE Transactions on Smart Grid 2016, 9, 1 -1.

AMA Style

Hong Wang, Wen Zhang, Yutian Liu. A Robust Measurement Placement Method for Active Distribution System State Estimation Considering Network Reconfiguration. IEEE Transactions on Smart Grid. 2016; 9 (3):1-1.

Chicago/Turabian Style

Hong Wang; Wen Zhang; Yutian Liu. 2016. "A Robust Measurement Placement Method for Active Distribution System State Estimation Considering Network Reconfiguration." IEEE Transactions on Smart Grid 9, no. 3: 1-1.

Journal article
Published: 20 May 2016 in Energy and Buildings
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In commercial buildings, lighting constitutes a large proportion of energy consumption. Saving lighting energy in commercial buildings has aroused great interest among researchers. Achieving energy savings and satisfying lighting comfort are the two primary objectives in designing a lighting system. In this paper, a fuzzy logic controller was designed that considered daylight, movement information and lighting comfort. The DALI protocol was used to communicate the controller with LED luminaires. The simulation results demonstrate that lighting system without control can provide sufficient illumination. The lighting system provides wider controllability to make lighting environment operating at the most energy-saving state. The experimental results show that by using the designed controller, significant lighting energy can be saved. The office where the smart LED lighting system is installed can regulate lighting output automatically based on users’ movements and allow users to choose their own lighting preferences.

ACS Style

Jingyu Liu; Wen Zhang; Xiaodong Chu; Yutian Liu. Fuzzy logic controller for energy savings in a smart LED lighting system considering lighting comfort and daylight. Energy and Buildings 2016, 127, 95 -104.

AMA Style

Jingyu Liu, Wen Zhang, Xiaodong Chu, Yutian Liu. Fuzzy logic controller for energy savings in a smart LED lighting system considering lighting comfort and daylight. Energy and Buildings. 2016; 127 ():95-104.

Chicago/Turabian Style

Jingyu Liu; Wen Zhang; Xiaodong Chu; Yutian Liu. 2016. "Fuzzy logic controller for energy savings in a smart LED lighting system considering lighting comfort and daylight." Energy and Buildings 127, no. : 95-104.

Journal article
Published: 28 September 2015 in Energies
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Air conditioners have great potential to participate in power system frequency control. This paper proposes a control strategy to facilitate the active participation of air conditioners. For each air conditioner, a decentralized control law is designed to adjust its temperature set point in response to the system frequency deviation. The decentralized control law accounts for the user’s thermal comfort that is evaluated by a fuzzy algorithm. The aggregation of air conditioners’ response is conducted by using the Monte Carlo simulation method. A structure preserving model is applied to the multi-bus power system, in which air conditioners are aggregated at certain load buses. An inner-outer iteration scheme is adopted to solve power system dynamics. An experiment is conducted on a test air conditioner to examine the performance of the proposed decentralized control law. Simulation results on a test power system verify the effectiveness of the proposed strategy for air conditioners participating in frequency control.

ACS Style

Rongxiang Zhang; Xiaodong Chu; Wen Zhang; Yutian Liu. Active Participation of Air Conditioners in Power System Frequency Control Considering Users’ Thermal Comfort. Energies 2015, 8, 10818 -10841.

AMA Style

Rongxiang Zhang, Xiaodong Chu, Wen Zhang, Yutian Liu. Active Participation of Air Conditioners in Power System Frequency Control Considering Users’ Thermal Comfort. Energies. 2015; 8 (10):10818-10841.

Chicago/Turabian Style

Rongxiang Zhang; Xiaodong Chu; Wen Zhang; Yutian Liu. 2015. "Active Participation of Air Conditioners in Power System Frequency Control Considering Users’ Thermal Comfort." Energies 8, no. 10: 10818-10841.

Conference paper
Published: 01 January 2005 in Computer Vision
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The particle swarm optimization (PSO) algorithm, a new evolutionary computation method, has been proved to be powerful but needs parameters predefined for a given problem. In this paper, a new adaptive particle swarm optimization (APSO) algorithm is proposed and applied to reactive power and voltage control in power systems. The proposed APSO method can adjust parameters automatically in optimization process. The simulation results showthat the APSO algorithm is more efficient in searching global optimization solution compared with the PSO algorithm.

ACS Style

Wen Zhang; Yutian Liu. Adaptive Particle Swarm Optimization for Reactive Power and Voltage Control in Power Systems. Computer Vision 2005, 3612, 449 -452.

AMA Style

Wen Zhang, Yutian Liu. Adaptive Particle Swarm Optimization for Reactive Power and Voltage Control in Power Systems. Computer Vision. 2005; 3612 ():449-452.

Chicago/Turabian Style

Wen Zhang; Yutian Liu. 2005. "Adaptive Particle Swarm Optimization for Reactive Power and Voltage Control in Power Systems." Computer Vision 3612, no. : 449-452.