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RISS 인기검색어
- 검색키워드
- 저자 : Riming Shao (검색결과 3 건)
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Advanced Building Blocks of Power Converters for Renewable Energy Based Distributed Generators
Riming Shao,Mary Kaye,Liuchen Chang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
The power converter is a critical component of a distributed generation (DG) system, particularly for a renewable energy based distributed generator. With the rapid development and growing applications of DG systems, power converters have evolved from a traditional “power conversion device” to a “system integrator”. This paper outlines the basic and advanced building blocks of power converters for distributed generation systems, with an emphasis on the new algorithms developed especially for grid-connected single-phase power converters in small wind turbines and photovoltaic systems. A grid-connected power converter should feed power of a high quality into a grid with a low total harmonic distortion (THD), and fast dynamic response to the variations of a renewable energy resource. The newly developed space vector based pulse-width-modulation (PWM) with predictive current control provides a direct cycle-by-cycle regulation of the current waveform feeding into the grid. Effective anti-islanding is an essential function of a power converter, in compliance with the grid interconnection requirements. As active islanding detection methods exert disturbances to the grid and passive islanding detection methods generally have large non-detection zones, new and hybrid islanding detection methods have been developed. A power spectral density method has been developed to continuously monitor and identify the possible features of an islanding formation. Maximum power extraction from renewable energy resources is vitally important for distributed generators. Many algorithms have been developed for maximum power point tracking (MPPT) of photovoltaic and wind energy systems. A new MPPT method has been developed by integrating the fast extremum-finding method of Golden Section Search (GSS) into a multi-stage MPPT algorithm. The proposed MPPT algorithm provides fast response (in the order of 40 msec) and high tracking accuracy (99.9%) as compared to the existing algorithms.
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Jinghua Zhou,Shuang Xu,Riming Shao,Liuchen Chang 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.9
Transfer efficiency and power quality are two critical factors when it comes to grid-connected distributed generation systems. Single-phase inverters are commonly used in distributed generation systems under 10 kilowatts as the connection between the gird and renewable energy sources (RESs). In this application, grid current distortion plays a pivotal role in determining inverter performance. In this article, an improved current control strategy based on a predictive current controller (PCC) and a compensator is presented to decrease current harmonic distortion and increase power quality. The controller design method inspects a single-phase inverter system as a digital platform, and designs the controller in discrete time in order to obtain a more precise and effective controller than that in continuous time. The discretization procedures using sampling and hold (S&H) are taken into consideration in the design process. The improved current controller is a DSP-based digital current controller for grid-connected single-phase bridge inverters, whose performance is optimized by considering the time delay caused by analog–digital conversion (ADC) and computations. A comparison has been made to analyze the performance of the single-phase grid-connected inverter system with PCC and ICC. Experimental results are shown to validate the effectiveness of the designed current controller.
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Novel Nonlinear DC-Link Voltage Control for Small-Scale Grid-Connected Wind Power Converters
Guanhong Song,Bo Cao,Liuchen Chang,Riming Shao 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
A novel nonlinear observer-based DC-link voltage control algorithm is proposed in this paper for smallscale grid-connected variable-speed wind power converters to minimize the voltage fluctuation across DC-link capacitors caused by wind power variations. The DC-link capacitors, in wind power converters, are normally used to buffer the difference between the input and output power. However, the DC-link voltage varies significantly under rapidly changing working conditions. Hence, a proper DC-link voltage controller is essential to regulate the DC-link voltage in order to minimize these fluctuations. The proposed algorithm estimates the power fed into the converter system using a nonlinear observer integrated with a PI controller, combining the advantages of fast dynamic response capability offered by the proposed observer and control robustness from the PI controller without any additional measurement components. The effectiveness of the proposed control algorithm is verified by both simulation and experimental results.
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