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For islanded microgrids integrating distributed generators (DGs) with different generation cost and capacity, economic dispatch (ED) is its one of the key performance attributes and challenges. This paper proposes a completely distributed control strategy with improved reliability, flexibility and voltage quality for DC microgrids. Only depending on a sparse communication graph and neighbor information, the output power of each DG is adjusted to obtain global economic optimization while meeting the load demands and its capacity constraint by switching its control mode between distributed dispatch based on dynamic consensus algorithm and constant power control smoothly. The bus voltage is recovered accurately by construct a shortest communication line between bus agent and one DG to obtain the bus voltage. The stability and convergence of the proposed scheme have been analyzed. Simulation test has verified the feasibility and validity of the proposed control strategy.
Hua Han; Xinyu Chen; Zhangjie Liu; Yonglu Liu; Mei Su; Shimiao Chen. A Completely Distributed Economic Dispatching Strategy Considering Capacity Constraints. IEEE Journal on Emerging and Selected Topics in Circuits and Systems 2021, 11, 210 -221.
AMA StyleHua Han, Xinyu Chen, Zhangjie Liu, Yonglu Liu, Mei Su, Shimiao Chen. A Completely Distributed Economic Dispatching Strategy Considering Capacity Constraints. IEEE Journal on Emerging and Selected Topics in Circuits and Systems. 2021; 11 (1):210-221.
Chicago/Turabian StyleHua Han; Xinyu Chen; Zhangjie Liu; Yonglu Liu; Mei Su; Shimiao Chen. 2021. "A Completely Distributed Economic Dispatching Strategy Considering Capacity Constraints." IEEE Journal on Emerging and Selected Topics in Circuits and Systems 11, no. 1: 210-221.
The Newton-Raphson (NR) method is a powerful tool in nonlinear equations. However, a well-known disadvantage of this method is that the initial iteration value must be chosen sufficiently close to a true solution in order to guarantee its convergence. The Kantorovich theorem is virtually the only known sufficiency condition for convergence of NR method and gives very conservative bounds. This letter analyzes the convergence of the NR method in feasible power-flow for direct-current (DC) network, and an explicit convergence condition is obtained. Comparing with the existing results, the proposed convergence condition is more concise and less conservative. Moreover, according to the proposed condition, one can easily set the initial iteration value to guarantee the convergence of the NR method. Case studies verify the correctness of the presented analysis.
Zhangjie Liu; Xin Zhang; Mei Su; Yao Sun; Hua Han; Peng Wang. Convergence Analysis of Newton-Raphson Method in Feasible Power-Flow for DC Network. IEEE Transactions on Power Systems 2020, 35, 4100 -4103.
AMA StyleZhangjie Liu, Xin Zhang, Mei Su, Yao Sun, Hua Han, Peng Wang. Convergence Analysis of Newton-Raphson Method in Feasible Power-Flow for DC Network. IEEE Transactions on Power Systems. 2020; 35 (5):4100-4103.
Chicago/Turabian StyleZhangjie Liu; Xin Zhang; Mei Su; Yao Sun; Hua Han; Peng Wang. 2020. "Convergence Analysis of Newton-Raphson Method in Feasible Power-Flow for DC Network." IEEE Transactions on Power Systems 35, no. 5: 4100-4103.
As unbalance state of charge (SOC) of storage units usually leads to the decrease of lifetime, SOC balancing control is essential. In this paper, a decentralized SOC balancing method is proposed to balance the SOC of cascaded-type energy storage systems. Since the method does not rely on any communication, it possesses higher reliability. As is well known, SOC is a slowly changing variable compared to other variables such as voltage and current. Thus, the studied system has obvious two-time scale characteristic. Then the stability analysis of the system based on the singular perturbation theory is carried out. Finally, the effectiveness of the proposed SOC balancing scheme is verified through both simulation and experiment tests.
Guangze Shi; Hua Han; Yao Sun; Zhangjie Liu; Minghui Zheng; Xiaochao Hou. A Decentralized SOC Balancing Method for Cascaded-Type Energy Storage Systems. IEEE Transactions on Industrial Electronics 2020, 68, 2321 -2333.
AMA StyleGuangze Shi, Hua Han, Yao Sun, Zhangjie Liu, Minghui Zheng, Xiaochao Hou. A Decentralized SOC Balancing Method for Cascaded-Type Energy Storage Systems. IEEE Transactions on Industrial Electronics. 2020; 68 (3):2321-2333.
Chicago/Turabian StyleGuangze Shi; Hua Han; Yao Sun; Zhangjie Liu; Minghui Zheng; Xiaochao Hou. 2020. "A Decentralized SOC Balancing Method for Cascaded-Type Energy Storage Systems." IEEE Transactions on Industrial Electronics 68, no. 3: 2321-2333.
DC Microgrids have been widely used due to their high efficiency, high reliability and flexibility. A sine qua non condition for the correct operation of systems is the existence of a feasible power-flow solution. This paper analyzes the existence of the feasible power-flow solution of the DC microgrid under droop control. Firstly, the power-flow mathematical model of DC microgrid is established. Then, based on the nested interval theorem, we obtain the sufficient conditions of the existence of the feasible power-flow solution, and the uniqueness of the feasible power-flow solution is proved. Moreover, the iterative algorithm of the feasible power-flow solution is proposed, which is proved to be monotonically exponentially convergent. The proposed algorithm’s domain of attraction is derived, thus, the initial iterative value of which can easily be chosen to guarantee its convergence. Finally, case studies are given in this paper to verify the correctness and effectiveness of the proposed theorems.
Zhangjie Liu; Ruisong Liu; Xin Zhang; Mei Su; Yao Sun; Hua Han; Peng Wang. Feasible Power-Flow Solution Analysis of DC Microgrids Under Droop Control. IEEE Transactions on Smart Grid 2020, 11, 2771 -2781.
AMA StyleZhangjie Liu, Ruisong Liu, Xin Zhang, Mei Su, Yao Sun, Hua Han, Peng Wang. Feasible Power-Flow Solution Analysis of DC Microgrids Under Droop Control. IEEE Transactions on Smart Grid. 2020; 11 (4):2771-2781.
Chicago/Turabian StyleZhangjie Liu; Ruisong Liu; Xin Zhang; Mei Su; Yao Sun; Hua Han; Peng Wang. 2020. "Feasible Power-Flow Solution Analysis of DC Microgrids Under Droop Control." IEEE Transactions on Smart Grid 11, no. 4: 2771-2781.
A wind power short-term forecasting method based on discrete wavelet transform and long short-term memory networks (DWT_LSTM) is proposed. The LSTM network is designed to effectively exhibit the dynamic behavior of the wind power time series. The discrete wavelet transform is introduced to decompose the non-stationary wind power time series into several components which have more stationarity and are easier to predict. Each component is dug by an independent LSTM. The forecasting results of the wind power are obtained by synthesizing the prediction values of all components. The prediction accuracy has been improved by the proposed method, which is validated by the MAE (mean absolute error), MAPE (mean absolute percentage error), and RMSE (root mean square error) of experimental results of three wind farms as the benchmarks. Wind power forecasting based on the proposed method provides an alternative way to improve the security and stability of the electric power network with the high penetration of wind power.
Yao Liu; Lin Guan; Chen Hou; Hua Han; Zhangjie Liu; Yao Sun; Minghui Zheng. Wind Power Short-Term Prediction Based on LSTM and Discrete Wavelet Transform. Applied Sciences 2019, 9, 1108 .
AMA StyleYao Liu, Lin Guan, Chen Hou, Hua Han, Zhangjie Liu, Yao Sun, Minghui Zheng. Wind Power Short-Term Prediction Based on LSTM and Discrete Wavelet Transform. Applied Sciences. 2019; 9 (6):1108.
Chicago/Turabian StyleYao Liu; Lin Guan; Chen Hou; Hua Han; Zhangjie Liu; Yao Sun; Minghui Zheng. 2019. "Wind Power Short-Term Prediction Based on LSTM and Discrete Wavelet Transform." Applied Sciences 9, no. 6: 1108.
In this paper, the stability of direct current (DC) microgrids with a constant power load (CPL) and a non-ideal source is investigated. The CPL’s negative impedance will destabilize the system, and disturbances in the non-ideal source will degrade the load voltage quality. In this study, we aim to: (1) overcome the instability of the CPL; (2) mitigate disturbances from the non-ideal source; (3) prevent the discontinuous harmonic current of high-frequency switching regulator from interfering with the source. Then, a stabilization method based on active damping which can achieve the above three objectives simultaneously is proposed. To obtain the stability conditions, the small-signal model of the system near the high-voltage equilibrium is established. Then, stability conditions are derived by eigenvalue analysis, and the domain of attraction near equilibrium is also obtained using the quadratic Lyapunov function. For the second objective, the key is to choose the optimal parameters to achieve disturbance attenuation. For the third objective, the active damper can separate the source from the switching regulator, which can prevent the discontinuous harmonic current. Moreover, the proposed method can be extended to multiple cases, and simulation results verify the effectiveness of the proposed method.
Haolan Liang; Zhangjie Liu; Hua Liu. Stabilization Method Considering Disturbance Mitigation for DC Microgrids with Constant Power Loads. Energies 2019, 12, 873 .
AMA StyleHaolan Liang, Zhangjie Liu, Hua Liu. Stabilization Method Considering Disturbance Mitigation for DC Microgrids with Constant Power Loads. Energies. 2019; 12 (5):873.
Chicago/Turabian StyleHaolan Liang; Zhangjie Liu; Hua Liu. 2019. "Stabilization Method Considering Disturbance Mitigation for DC Microgrids with Constant Power Loads." Energies 12, no. 5: 873.
Zhangjie Liu; Mei Su; Yao Sun; Lang Li; Hua Han; Xin Zhang; Minghui Zheng. Optimal criterion and global/sub-optimal control schemes of decentralized economical dispatch for AC microgrid. International Journal of Electrical Power & Energy Systems 2019, 104, 38 -42.
AMA StyleZhangjie Liu, Mei Su, Yao Sun, Lang Li, Hua Han, Xin Zhang, Minghui Zheng. Optimal criterion and global/sub-optimal control schemes of decentralized economical dispatch for AC microgrid. International Journal of Electrical Power & Energy Systems. 2019; 104 ():38-42.
Chicago/Turabian StyleZhangjie Liu; Mei Su; Yao Sun; Lang Li; Hua Han; Xin Zhang; Minghui Zheng. 2019. "Optimal criterion and global/sub-optimal control schemes of decentralized economical dispatch for AC microgrid." International Journal of Electrical Power & Energy Systems 104, no. : 38-42.
The existing reactive power polarity-dependent decentralized control for cascaded-type microgrid (CMG) has the problem of multiple equilibrium points. As a result, some undesired operating states may occur. To address this problem, we proposes a new decentralized power sharing control scheme. The uniqueness of equilibrium point and its small signal stability are proved. Finally, the feasibility of the proposed method is verified by simulation and experiment.
Lang Li; Yao Sun; Zhangjie Liu; Xiaochao Hou; Guangze Shi; Mei Su. A Decentralized Control With Unique Equilibrium Point for Cascaded-Type Microgrid. IEEE Transactions on Sustainable Energy 2018, 10, 324 -326.
AMA StyleLang Li, Yao Sun, Zhangjie Liu, Xiaochao Hou, Guangze Shi, Mei Su. A Decentralized Control With Unique Equilibrium Point for Cascaded-Type Microgrid. IEEE Transactions on Sustainable Energy. 2018; 10 (1):324-326.
Chicago/Turabian StyleLang Li; Yao Sun; Zhangjie Liu; Xiaochao Hou; Guangze Shi; Mei Su. 2018. "A Decentralized Control With Unique Equilibrium Point for Cascaded-Type Microgrid." IEEE Transactions on Sustainable Energy 10, no. 1: 324-326.
This paper presents a series‐parallel photovoltaic (PV)‐storage independent microgrid (MG), where low‐voltage distributed generation units could be connected to power grid conveniently. Moreover, it provides a promising way to form medium voltage MG. For this proposed structure, a decentralized control is proposed. The PV units are controlled by a maximum power point tracking (MPPT)‐based droop control, where MPPT of the PV units is achieved. Storage units are regulated via a “droop” controller dependent its reactive power polarity and take the responsibility of keeping the power supply‐demand balance of the MG. Since all these controllers make decisions only based on their local information, the proposed control is reliable and cost‐effective. Moreover, the small‐signal stability of the system is proved. And simulation results are presented to verify the effectiveness.
Lang Li; Yao Sun; Zhangjie Liu; Xufeng Yuan; Mei Su; Xiaochao Hou; Minghui Zheng. A series-parallel PV-storage independent microgrid and its decentralized control. International Transactions on Electrical Energy Systems 2018, 29, e2715 .
AMA StyleLang Li, Yao Sun, Zhangjie Liu, Xufeng Yuan, Mei Su, Xiaochao Hou, Minghui Zheng. A series-parallel PV-storage independent microgrid and its decentralized control. International Transactions on Electrical Energy Systems. 2018; 29 (2):e2715.
Chicago/Turabian StyleLang Li; Yao Sun; Zhangjie Liu; Xufeng Yuan; Mei Su; Xiaochao Hou; Minghui Zheng. 2018. "A series-parallel PV-storage independent microgrid and its decentralized control." International Transactions on Electrical Energy Systems 29, no. 2: e2715.
For an AC-stacked photovoltaic (PV) inverter system with N cascaded inverters, existing control methods require at least N communication links to acquire the grid synchronization signal. In this paper, a novel decentralized control is proposed. For N inverters, only one inverter nearest the point of common coupling (PCC) needs a communication link to acquire the grid voltage phase and all other N − 1 inverters use only local measured information to achieved fully decentralized local control. Specifically, one inverter with a communication link utilizes the grid voltage phase and adopts current control mode to achieve a required power factor (PF). All other inverters need only local information without communication links and adopt voltage control mode to achieve maximum power point tracking (MPPT) and self-synchronization with grid voltage. Compared with existing methods, the communication link and complexity is greatly reduced, thus improved reliability and reduced communication costs are achieved. The effectiveness of the proposed control is verified by simulation tests.
Hua Han; Chao Luo; Xiaochao Hou; Mei Su; Wenbin Yuan; Zhangjie Liu; Josep M. Guerrero. A Cost-Effective Decentralized Control for AC-Stacked Photovoltaic Inverters. Energies 2018, 11, 2262 .
AMA StyleHua Han, Chao Luo, Xiaochao Hou, Mei Su, Wenbin Yuan, Zhangjie Liu, Josep M. Guerrero. A Cost-Effective Decentralized Control for AC-Stacked Photovoltaic Inverters. Energies. 2018; 11 (9):2262.
Chicago/Turabian StyleHua Han; Chao Luo; Xiaochao Hou; Mei Su; Wenbin Yuan; Zhangjie Liu; Josep M. Guerrero. 2018. "A Cost-Effective Decentralized Control for AC-Stacked Photovoltaic Inverters." Energies 11, no. 9: 2262.
This letter presents a general decentralized control scheme for cascaded H-bridge inverter-based static compensators (STATCOM) in medium/high voltage (MV/HV) power network. The H-bridge modules are controlled in a decentralized manner without a central controller, and each module makes decisions based on individual local controller. The local controller includes two parts: 1) a Q-ω boost control is introduced to share reactive power equally, and 2) a scalable P-V control is established for balancing DC-link voltage of inverters. The proposed scheme can achieve frequency synchronization autonomously, and thus has advantages of improved reliability, scalability and decreased costs. Moreover, an improved decentralized control is also proposed to adapt the grid-side dynamics when contingencies will occur. The system stability conditions are derived, and the feasibility of the proposed method is verified by simulation results.
Xiaochao Hou; Yao Sun; Hua Han; Zhangjie Liu; Mei Su; Benfei Wang; Xin Zhang. A General Decentralized Control Scheme for Medium-/High-Voltage Cascaded STATCOM. IEEE Transactions on Power Systems 2018, 33, 7296 -7300.
AMA StyleXiaochao Hou, Yao Sun, Hua Han, Zhangjie Liu, Mei Su, Benfei Wang, Xin Zhang. A General Decentralized Control Scheme for Medium-/High-Voltage Cascaded STATCOM. IEEE Transactions on Power Systems. 2018; 33 (6):7296-7300.
Chicago/Turabian StyleXiaochao Hou; Yao Sun; Hua Han; Zhangjie Liu; Mei Su; Benfei Wang; Xin Zhang. 2018. "A General Decentralized Control Scheme for Medium-/High-Voltage Cascaded STATCOM." IEEE Transactions on Power Systems 33, no. 6: 7296-7300.
Constant power loads (CPLs) are often the cause of instability and no equilibrium of DC microgrids. In this study, we analyze the existence and stability of equilibrium of DC microgirds with CPLs and the sufficient conditions for them are provided. To derive the existence of system equilibrium, we transform the problem of quadratic equation solvability into the existence of a fixed point for an increasing fractional mapping. Then, the sufficient condition based on the Tarski fixed-point theorem is derived. It is less conservative compared with the existing results. Moreover, we adopt the small-signal model to predict the system qualitative behavior around equilibrium. The analytic conditions of robust stability are determined by analyzing quadratic eigenvalue. Overall, the obtained conditions provide the references for building reliable DC microgrids. The simulation results verify the correctness of the proposed conditions.
Zhangjie Liu; Mei Su; Yao Sun; Wenbin Yuan; Hua Han; Jianghua Feng. Existence and Stability of Equilibrium of DC Microgrid With Constant Power Loads. IEEE Transactions on Power Systems 2018, 33, 6999 -7010.
AMA StyleZhangjie Liu, Mei Su, Yao Sun, Wenbin Yuan, Hua Han, Jianghua Feng. Existence and Stability of Equilibrium of DC Microgrid With Constant Power Loads. IEEE Transactions on Power Systems. 2018; 33 (6):6999-7010.
Chicago/Turabian StyleZhangjie Liu; Mei Su; Yao Sun; Wenbin Yuan; Hua Han; Jianghua Feng. 2018. "Existence and Stability of Equilibrium of DC Microgrid With Constant Power Loads." IEEE Transactions on Power Systems 33, no. 6: 6999-7010.
This paper proposes a communication-free decentralized control for grid-connected cascaded PV inverter systems. The cascaded PV inverter system is an AC-stacked architecture, which promotes the integration of low voltage (LV) distributed photovoltaic (PV) generators into the medium/high voltage (MV/HV) power grid. The proposed decentralized control is fully free of communication links and phase-locked loop (PLL). All cascaded inverters are controlled as current controlled voltage sources locally and independently to achieve maximum power point tracking (MPPT) and frequency self-synchronization with the power grid. As a result, control complexity as well as communication costs are reduced, and the system’s reliability is greatly enhanced compared with existing communication-based methods. System stability and dynamic performance are evaluated by small-signal analysis to guide the design of system parameters. The feasibility and effectiveness of the proposed solution are verified by simulation tests.
Mei Su; Chao Luo; Xiaochao Hou; Wenbin Yuan; Zhangjie Liu; Hua Han; Josep M. Guerrero. A Communication-Free Decentralized Control for Grid-Connected Cascaded PV Inverters. Energies 2018, 11, 1375 .
AMA StyleMei Su, Chao Luo, Xiaochao Hou, Wenbin Yuan, Zhangjie Liu, Hua Han, Josep M. Guerrero. A Communication-Free Decentralized Control for Grid-Connected Cascaded PV Inverters. Energies. 2018; 11 (6):1375.
Chicago/Turabian StyleMei Su; Chao Luo; Xiaochao Hou; Wenbin Yuan; Zhangjie Liu; Hua Han; Josep M. Guerrero. 2018. "A Communication-Free Decentralized Control for Grid-Connected Cascaded PV Inverters." Energies 11, no. 6: 1375.
Constant power loads (CPLs) often cause instability due to its negative impedance characteristics. In this study, the stability of a DC microgrid with CPLs under a distributed control that aims at current sharing and voltage recovery is analyzed. The effect of the negative impedance on the behavior of distributed controller is investigated. The small-signal model is established to predict the system qualitative behavior around equilibrium. The stability conditions of the system with time delay are derived based on the equivalent linearized model. Additionally, eigenvalue analysis based on inertia theorem provides analytical sufficient conditions as a function of the system parameters, and thus it leads to a design guideline to build reliable microgrids. Simulations are performed to confirm the effectiveness and validity of the proposed method.
Zhangjie Liu; Mei Su; Yao Sun; Hua Han; Xiaochao Hou; Josep Guerrero. Stability analysis of DC microgrids with constant power load under distributed control methods. Automatica 2018, 90, 62 -72.
AMA StyleZhangjie Liu, Mei Su, Yao Sun, Hua Han, Xiaochao Hou, Josep Guerrero. Stability analysis of DC microgrids with constant power load under distributed control methods. Automatica. 2018; 90 ():62-72.
Chicago/Turabian StyleZhangjie Liu; Mei Su; Yao Sun; Hua Han; Xiaochao Hou; Josep Guerrero. 2018. "Stability analysis of DC microgrids with constant power load under distributed control methods." Automatica 90, no. : 62-72.
This letter proposes a decentralized control scheme for grid-connected cascaded modular inverters without any communication, and each module makes decisions based on its own local information. In contrast, the conventional methods are usually centralized control and depend on a real-time communication. Thus, the proposed scheme has advantages of improved reliability and decreased costs. The overall system stability is analyzed, and the stability condition is derived as well. The feasibility of the proposed method is verified by simulation.
Yao Sun; Xiaochao Hou; Hua Han; Zhangjie Liu; Wenbin Yuan; Mei Su. A Fully Decentralized Control of Grid-Connected Cascaded Inverters. 2017, 1 .
AMA StyleYao Sun, Xiaochao Hou, Hua Han, Zhangjie Liu, Wenbin Yuan, Mei Su. A Fully Decentralized Control of Grid-Connected Cascaded Inverters. . 2017; ():1.
Chicago/Turabian StyleYao Sun; Xiaochao Hou; Hua Han; Zhangjie Liu; Wenbin Yuan; Mei Su. 2017. "A Fully Decentralized Control of Grid-Connected Cascaded Inverters." , no. : 1.
In order to address the economical dispatch problem in islanded microgrid, this letter proposes an optimal criterion and two decentralized economical-sharing schemes. The criterion is to judge whether global optimal economical-sharing can be realized via a decentralized manner. On the one hand, if the system cost functions meet this criterion, the corresponding decentralized droop method is proposed to achieve the global optimal dispatch. Otherwise, if the system does not meet this criterion, a modified method to achieve suboptimal dispatch is presented. The advantages of these methods are convenient,effective and communication-less.
Zhangjie Liu; Mei Su; Yao Sun; Lang Li; Hua Han. Optimal Decentralized Economical-sharing Criterion and Scheme for Microgrid. 2017, 1 .
AMA StyleZhangjie Liu, Mei Su, Yao Sun, Lang Li, Hua Han. Optimal Decentralized Economical-sharing Criterion and Scheme for Microgrid. . 2017; ():1.
Chicago/Turabian StyleZhangjie Liu; Mei Su; Yao Sun; Lang Li; Hua Han. 2017. "Optimal Decentralized Economical-sharing Criterion and Scheme for Microgrid." , no. : 1.
To address the economical dispatch problem without communications in islanded AC microgrids consisting of cascaded inverters, this paper proposes an optimal decentralized economical-sharing scheme. In proposed scheme, optimal sharing function of the current is applied to generate the reference voltages. And the frequency is used to drive all distributed generators (DGs) synchronize operation in microgrids. When the microgrid is in steady state, DGs share a single common frequency and current in terms of the proposed scheme. Thus the potential advantages of simplicity and decentralized manner are retained. The AC microgrid model has been developed through simulations and experiments to verify the effectiveness and performance of the proposed scheme.
Lang Li; Huawen Ye; Yao Sun; Zhangjie Liu; Hua Han; Mei Su; Josep M. Guerrero. Optimal Decentralized Economical-sharing Scheme in Islanded AC Microgrids with Cascaded Inverters. 2017, 1 .
AMA StyleLang Li, Huawen Ye, Yao Sun, Zhangjie Liu, Hua Han, Mei Su, Josep M. Guerrero. Optimal Decentralized Economical-sharing Scheme in Islanded AC Microgrids with Cascaded Inverters. . 2017; ():1.
Chicago/Turabian StyleLang Li; Huawen Ye; Yao Sun; Zhangjie Liu; Hua Han; Mei Su; Josep M. Guerrero. 2017. "Optimal Decentralized Economical-sharing Scheme in Islanded AC Microgrids with Cascaded Inverters." , no. : 1.
DC microgrids are becoming popular as effective means to integrate various renewable energy resources. Constant power loads (CPLs) may yield instability due to the negative impedance characteristic. This paper analyzes the stability of the DC microgrid in presence of CPL. Distributed generations (DGs) are controlled by using a distributed controller which aims at current sharing and voltage recovery. For simplicity, a reduced order model is derived on the fundamental of neglecting the transient state of the DC/DC converter. The purpose of this paper is to analyze stability conditions and give the suggestions to design control parameters. The stability conditions are obtained by using inertia theorem. Moreover, this paper makes a further detailed research based on the existed theorems. Simulation results are provided to verify the effectiveness and validity of the proposed theorem.
Zhangjie Liu; Mei Su; Yao Sun; Hua Han; Xiaochao Hou; Josep M. Guerrero. Stability Analysis of DC Microgrids with Constant Power Load under Distributed Control Method. 2017, 1 .
AMA StyleZhangjie Liu, Mei Su, Yao Sun, Hua Han, Xiaochao Hou, Josep M. Guerrero. Stability Analysis of DC Microgrids with Constant Power Load under Distributed Control Method. . 2017; ():1.
Chicago/Turabian StyleZhangjie Liu; Mei Su; Yao Sun; Hua Han; Xiaochao Hou; Josep M. Guerrero. 2017. "Stability Analysis of DC Microgrids with Constant Power Load under Distributed Control Method." , no. : 1.
First-order Generalized Integrator Based Frequency Locked Loop and Synchronization for Three-Phase Grid-connected Converters under Adverse Grid Conditions First-order generalized integrator;Frequency-locked loop;Grid-connected converter;Grid synchronization;Harmonic detection; This paper presents an alternative frequency adaptive grid synchronization technique named HDN-FLL, which can accurately extract the fundamental positive- and negative-sequence components and interested harmonics in adverse three-phase grid voltage. The HDN-FLL is based on the harmonic decoupling network (HDN) consisting of multiple first order complex vector filters (FOCVF) with a frequency-locked loop (FLL), which makes the system frequency adaptive. The stability of the proposed FLL is strictly verified to be global asymptotically stable. In addition, the linearization and parameters tuning of the FLL is also discussed. The structure of the HDN has been widely used as a prefilter in grid synchronization techniques. However, the stability of the general HDN is seldom discussed. In this paper, the transfer function expression of the general HDN is deduced and its stability is verified by the root locus method. To show the advantages of the HDN-FLL, a simulation comparison with other gird synchronization methods is carried out. Experimental results verify the excellent performance of the proposed synchronization method.
Zhaoxu Luo; Mei Su; Yao Sun; Zhangjie Liu; Mi Dong. First-order Generalized Integrator Based Frequency Locked Loop and Synchronization for Three-Phase Grid-connected Converters under Adverse Grid Conditions. Journal of Power Electronics 2016, 16, 1939 -1949.
AMA StyleZhaoxu Luo, Mei Su, Yao Sun, Zhangjie Liu, Mi Dong. First-order Generalized Integrator Based Frequency Locked Loop and Synchronization for Three-Phase Grid-connected Converters under Adverse Grid Conditions. Journal of Power Electronics. 2016; 16 (5):1939-1949.
Chicago/Turabian StyleZhaoxu Luo; Mei Su; Yao Sun; Zhangjie Liu; Mi Dong. 2016. "First-order Generalized Integrator Based Frequency Locked Loop and Synchronization for Three-Phase Grid-connected Converters under Adverse Grid Conditions." Journal of Power Electronics 16, no. 5: 1939-1949.
Constant power loads may yield instability due to the well-known negative impedance characteristic. This paper analyzes the factors that cause instability of a dc microgrid with multiple dc-dc converters. Two stabilization methods are presented for two operation modes: 1) constant voltage source mode; and 2) droop mode, and sufficient conditions for the stability of the dc microgrid are obtained by identifying the eigenvalues of the Jacobian matrix. The key is to transform the eigenvalue problem to a quadratic eigenvalue problem. When applying the methods in practical engineering, the salient feature is that the stability parameter domains can be estimated by the available constraints, such as the values of capacities, inductances, maximum load power, and distances of the cables. Compared with some classical methods, the proposed methods have wider stability region. The simulation results based on MATLAB/simulink platform verify the feasibility of the methods.
Mei Su; Zhangjie Liu; Yao Sun; Hua Han; Xiaochao Hou. Stability Analysis and Stabilization Methods of DC Microgrid With Multiple Parallel-Connected DC–DC Converters Loaded by CPLs. IEEE Transactions on Smart Grid 2016, 9, 132 -142.
AMA StyleMei Su, Zhangjie Liu, Yao Sun, Hua Han, Xiaochao Hou. Stability Analysis and Stabilization Methods of DC Microgrid With Multiple Parallel-Connected DC–DC Converters Loaded by CPLs. IEEE Transactions on Smart Grid. 2016; 9 (1):132-142.
Chicago/Turabian StyleMei Su; Zhangjie Liu; Yao Sun; Hua Han; Xiaochao Hou. 2016. "Stability Analysis and Stabilization Methods of DC Microgrid With Multiple Parallel-Connected DC–DC Converters Loaded by CPLs." IEEE Transactions on Smart Grid 9, no. 1: 132-142.