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Three-level neutral-point-clamped (NPC) inverters have been widely applied in power conversion device occasions of medium high voltage and power, and, most recently, increasing in occasions of the low-voltage low-power applications. The three-level inverters have the problems of low frequency ripple that appears in the neutral-point (NP) of the DC-link under some operating conditions because of its...
Nowadays, the photovoltaic system is widely used, but the charging and discharging controllers only provide protection to avoid overcharge and overdischarge. The poor charging ability leads the battery to have poor lifetime. The battery charging and discharging system in this paper can realize the three-stage charging, achieve the rapid charging of the battery, and make full use of the battery capacity...
To meet the high power and high stability requirements of BWT 915-10W and 915-30W pumped semiconductor laser (with adjustable current from 0 to 12A, current ripple factor less than 2%) a dual control and dual output circuit is designed to allow the power supply output current adjustable from 0 to 12A. It is called dual control because power can control manually by an external knob to achieve current...
Photovoltaic (PV) solar inverter is equipment that converts the DC output of solar batteries to the AC power which meets the requirements of the gird, its performance and quality are directly related to the photovoltaic effect on the public grid. Current national standard specifies only the requirements for protection and did not develop appropriate testing rules and procedures. This paper researched...
The voltage flicker which might bring out lighting equipments glitter and images distortion, make people's visual fatigue and adversely affect people's daily lives is caused by the great increase of shocking and nonlinear loads in the power system. In this paper, the causes, detection and measurement of the voltage fluctuation and flicker are analyzed, instantaneous reactive power theory detection...
The construction of isolated renewable power systems is an important way to solve the power supply problems in remote areas and islands. In this paper, by using simulation software HOMER, the analysis of isolated renewable power systems is carried out in which the system configuration of a real island is simulated. And then the optimal capacity configuration of isolated renewable power systems, including...
In this paper, the photovoltaic monitoring system is designed as principle of environmental protection, energy conservation and stability. It provides general calculation of all parameters of the solar energy monitoring system and selects parameters for the photovoltaic cells and controller. The results of different algorithms are compared to make the maximum efficiency of the system. Taking Tianjin...
Distributed generation and micro-grid system is increasingly concerned for its superior performance. Monitoring system is an important part of it. This paper analyzes the requirements of the monitoring system which is commonly used in micro-grid system. Then a new monitoring system scheme based on communication of equipments is proposed in this paper. The program uses the serial port to communicate...
Power plants conveying system includes coal link and blending links. This design only involves conveying coal link in the system. This power plant coal conveying link PLC control system is aimed at making some improvement for the traditional coal-fired power plants which is a relay-based semi-automatic conveying control system with the features of more faults, the lower reliable of the operation....
Grid-side converter in double fed wind power generation system is the research object of this paper. Firstly the key issues of the grid-side converter are analyzed in this paper. Based on the key issues, a new DSP-based implementation method of the grid-side converter is proposed. The mathematical model of DFIG and dq-coordinates mathematical model of grid-side converter is established in this paper...
In the vehicle generator manufacturer, in order to ensure the quality of products, generators are needed to be tested to make sure whether the performance indices can meet the requirements. This paper has just designed a generator testing system, which is consisted by touch screen and PLC. In this system, PLC will control the frequency converter to drive motor and make the motor have different rotational...
Grid-connected photovoltaic (PV) system is the development trend of photovoltaic systems. According to the grid-connected PV system characteristics, this paper presents the design of a three-phase photovoltaic grid-connected inverter based on the digital signal processor (DSP) TMS320F28016. The hardware circuit is designed and the main parameters of device are calculated. Using space vector pulse...
A research of photovoltaic inverter based on UC3854 is proposed in this paper. UC3854 is a type of dedicated chip applied in control of active power factor correction. This paper uses voltage and current amplifiers of UC3854 to realize the double closed-loop control. Both the main circuit and the drive circuit are designed to be modular. All these improve the stability and anti-jamming ability of...
Since many power electronics equipments and nonlinear loads were accessed, more and more harmonics and inter-harmonics occurred in power system. But when the analyzed signal contains components with frequency close to each other, precise analysis can not be made by traditional harmonics analysis methods such as interpolating windowed FFT method. In this paper, first a new method-multiple modulation...
The complementary nature of wind and solar determines the advantages and potentiality of hybrid power generation systems. Off-grid wind-solar hybrid power generation systems are very important for remote areas and island coast defense in China. This paper classifies and summaries the structure of off-grid hybrid power generation systems first where the advantages and disadvantages of different system...
In this paper, photovoltaic (PV) grid-connected inverter which is the core device in PV grid-connected system has been in depth research. The current tracking control method is used in the inverter. In structure, this inverter consists of a DC/AC inverter and several connectors for switching and protection. A full bridge structure with the power frequency transformer has been applied in the DC/AC...
Based on the analysis of mathematical model of the Brushless DC motor (BLDCM), a novel method for modeling and simulation of BLDCM is proposed in this paper. In MATLAB/Simulink, the isolated S-function modules, such as motor module, speed PI controller module, current hysteresis controller module, EMF generated module etc are modeled flexibly with S-function Builder. By the organic combination of...
The PWM converter which provides a suitable excitation current for the generator is one of the key components of double fed wind power generation system. This paper takes the rotor-side converter in double fed wind power generation system as the research object. The control objective of the grid-side converter is analyzed in this paper. Based on the control objective, the key issues of realizing the...
The photovoltaic grid-connected system is the fastest growing key application field in the photovoltaic generating system. In this paper, combining with the photovoltaic grid-connected system practical application program of Tianjin University and taking powerone inverter as the core, the data transmission progress between the grid-connected inverter and upper computer are introduced in detail. And...
Establish a distributed generation and micro-grid laboratory is one of the key technologies which needed to be solved now. Based on it, realizing the control strategy of micro-grid system can be carried out. This paper describes the characteristics and focus of distributed generation. With the reference of them, the design and configuration of various energy micro-grid laboratory in Tianjin University...
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