A Single-Stage High Gain Current Source Inverter for Grid-Connected Photovoltaic System

Meiqin Mao,Yajun Zheng,Liuchen Chang,Haibo Xu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The output voltage range of PV cells is widely influenced by the environment factors, such as temperature, solar radiation, etc. The lower output voltage of solar array can hardly meet the requirements for grid-connected operation of the system. To achieve high voltage gain and a steady ac output voltage in spite of the low dc input voltage, this paper presents a novel single-stage high gain current source inverter (CSI). The topology of the proposed inverter is derived from conventional tri-state current source inverter by introducing an impedance network with two symmetrical inductors and diodes separately. Theoretical analysis of operation modes and high voltage gain performance for the proposed inverter is presented, followed by the simulation of the proposed inverter in grid-connected photovoltaic (PV) system carried out on MATLAB.

Economic Analysis of the Microgrid with Multi-energy and Electric Vehicles

Mao Meiqin,Sun Shujuan,Liuchen Chang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

Electric vehicles (EVs) may play dual roles when they plug in a microgrid. They appear as loads during charging, meanwhile they may also be used as storage units to supply energy to the rest loads in the microgrid if the batteries have the sufficient spare energy. Considering the characteristic of bidirectional energy flow of EVs in a microgrid, this paper proposes the energy dispatch model and strategies for the microgrid including Wind generators, Photovoltaic systems, Battery storages, EVs and other local loads to analyze the impact of incorporating vehicles within and without microgrid on the economic operation of the microgrid. The simulation results indicate that incorporating EVs within the microgrid can not only minimize the capital cost of storages and reduce operation cost of the microgrid’s operator, but also save the cost of EVs’s owners.

Multi-Agent Based Simulation for Microgrid Energy Management

Mao Meiqin,Dong Wei,Liuchen Chang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper presents a general multi-agent based model for the hierarchical and distributed energy control of a Microgrid. In this model, the agents under three different levels are classified and defined in detail. And based on the model, a novel simulation platform for the energy management system of the Microgrid (EMS-MG) is designed in terms of Client-Server and implemented under C++ Builder environment. Taking the generation automatic control for example and by the proposed model and implemented EMS-MG, a simulation result is shown to illustrate the operation process of the simulation platform and present the benefits of the proposed method.

Sensorless Control of PMSG for A Wind Power System Based on CSC

MAO Meiqin,LIU Fuyan,MU Junsheng,XU Bin 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper presents sensorless rotor-flux-oriented control algorithms for the PMSG used in the direct drive wind generation system with a back-to-back current source converter. The proposed algorithms are based on phase-lock-loop and model reference adaptive system methods. These algorithms are analyzed, compared and verified by the simulation and experiment. The simulation and experiment results show that the PLL method is simpler, but more accurate, and has a faster dynamic performance than MRAS method.

Single Phase Converter with Power Decoupling and Reactive Power Control for Bi-directional EV Charger

Peiji Zhu,Meiqin Mao,Shuang Xu 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

In traditional single phase converters for EV chargers used in private cars, the power flow is only unidirectional, and the bulky and short-lifetime electrolytic capacitors are usually used to issue the second-order ripple power between the AC and DC side. To address the problem, this paper proposes a control strategy to enable the single phase EV charger to achieve both four-quadrant operation and power decoupling control at the same time so that the EVs can respond dispatching commands from the future smart grid as distributed energy resources, meanwhile the size of the charger can be reduced. This control method is based on our previous work, proposed novel topology of single phase converter using a small film capacitor to decouple the second-order power. The operation principle of the proposed control strategy is analyzed in detail, and the design method of decoupling capacitance for both power decoupling and reactive power control purposes is provided. Simulation results by MATLAB/Simulink are provided to verify the effectiveness of the proposed control strategy.

Improved SVM for High Gain Tri-state CSI to Reduce DC Side Inductor Current Ripple

Chufeng Li,Liuchen Chang,Meiqin Mao 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Extending our previous work proposing a high gain tri-state current source inverter (CSI), in this paper, an improved space vector modulation (SVM) method is proposed in order to reduce the DC side inductor current ripple. By the proposed SVM method, the active state time is divided into four equal segments and the shoot-through state time is divided into six equal segments and inserted into the four equal active state segments, respectively. Theoretically, the maximum ripple can be obtained to 1/3 of that compared with the traditional SVM mode. The proposed improved SVM method is compared with the traditional SVM method. Simulation and experimental results verify the effectiveness of the proposed strategy.

Autonomous Controller Based on Synchronous Generator dq0 Model for Micro Grid Inverters

Yan Du,Jianhui Su,Meiqin Mao,Xiangzhen Yang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

the parallel operation of voltage source inverter (VSI) in microgrid could benefit from characteristics of synchronous generator (SG) such as the kinetic energy stored in rotor, the self-isochronous and the droop characteristics if inverter can behave like generator in power system. Therefore an autonomous controller based on dq0 model of SG for microgrid inverter is proposed to mimic the above those characteristic of SG. Moreover, the inverter is designed to serve as either UF node or PQ node in micro grid by integrating a virtual primary frequency regulator (VPFR) and a virtual excitation regulator (VER) in the proposed controller. The results of simulation show the excellent performances of the proposed autonomous controller on voltage regulation, power sharing and seamless mode transfer.

Q-learning Algorithm Based Multi-Agent Coordinated Control Method for Microgrids

Yuanyuan Xi,Liuchen Chang,Meiqin Mao,Peng Jin,Nikos Hatziargyriou,Haibo Xu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper proposes a Q-learning algorithm (Q-LA) based multi-agent coordinated control method for microgrids. By the method, Q-LA is adopted to calculate the power to be regulated, which is called the microgrid regulation error (MRE), in secondary control for real-time operation. And the generation schedule of distributed generators (DGs) as well as batteries is modified in real time with the MRE by the fuzzy theory and particle swarm optimization method, taking the economy and environmental benefits into consideration together. The simulation platform of Q-LA based multi-agent hybrid energy management system for microgrid (HEMS-MG) is established in C++ Builder. The simulation results verify the effectiveness and feasibility of the proposed method.

Commutation Compensation for Matrix based Rectifiers due to Leakage Inductances of Isolation Transformer

Tao Zhao,Jianhui Su,Dewei (David) Xu,Meiqin Mao 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This paper proposes a compensation method for isolated matrix based rectifiers. The line side THD and output voltage isolated matrix rectifier are mainly affected by the commutation delay due to transformer leakage inductances. Since DC output voltage is usually regulated by a close loop controller. But the grid side current is affected by the commutation delay. The transformer leakage inductances increases the commutation delay which reduces actual dwell time of the active vector, causes distortion on grid side current with higher current THD. The proposed compensation method takes the commutation time into consideration and extends the dwell time for active vector properly. The algorithm has been verified by simulation results.