Che Yanbo

Design and research of off-grid wind-solar hybrid power generation systems

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 structures are described in detail. And then the design of off-grid wind-solar hybrid power generation systems, including design methods, capacity configuration of different parts, the classification and features of storage energy systems, is analyzed thoroughly. Through the analysis of different operation modes of the system, further exploration and study of control strategy has been carried out at last. The results of this study can be used to guide the research of off-grid wind-solar hybrid power generation systems.

Genetic Algorithm-Based RBF Neural Network Load Forecasting Model

To overcome the limitation of the traditional load forecasting method, a new load forecasting system basing on radial basis Gaussian kernel function (RBF) neural network is proposed in this paper. Genetic algorithm adopting the real coding, crossover probability and mutation probability was applied to optimize the parameters of the neural network, and a faster convergence rate was reached. Theoretical analysis and simulations prove that this load forecasting model is more practical and has more precision than the traditional one.

Construction, operation and control of a laboratory-scale microgrid

To provide a test facility for possible demonstrations of advanced distributed generation system integration strategies, a single-phase laboratory-scale Microgrid system is set up. Two distributed generators are included in this Microgrid, a photovoltaic simulator and a wind turbine simulator. Both of them are connected to the AC grid via flexible power electronic interface respectively. For stable collaborative operation, a battery energy storage interfaced with a bi-directional inverter is necessary in this Microgrid. In the grid-connected mode, both the distributed generators converters and the bi-directional inverter are the grid-following unit. While switching from grid-connected mode to islanded mode, the bi-directional inverter is setting the voltage and frequency of the Microgrid through absorbing or releasing energy. The operation experimental results show that the laboratory-scale Microgrid system can operate in grid-connected or islanded mode, with a seamless transfer from one mode to the other, and hence increase the reliability of energy supplies.

Discussion on monitoring scheme of distributed generation and micro-grid system

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 with each device of the micro-grid system. Based on the monitoring system, real-time collection of operational data, condition monitoring of switches and control the remote device can be achieved. The monitoring system has some advantages, such like superior scalability, stability, and so on. Some communication methods of equipments which are commonly used in distributed generation and micro-grid system are given in this paper, such as the SMA grid inverter, Power One grid inverter and Rijia grid inverter etc. Finally, this paper takes the photovoltaic micro-grid experimental system of Tianjin University for an example, a monitoring system is designed for this micro-grid. The successful application of the monitoring system proved its stability and excellent scalability.

The design of photovoltaic monitoring system

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 area as an example, the parameters of photovoltaic cells, the battery, the controller and other important devices are selected for the system. The result shows that when the monitoring equipment is out of grid, solar energy will be used to effectively monitor the target.

Fuzzy gain based adaptive fuzzy logic controller for BLDCM drive

An fuzzy gain based adaptive fuzzy logic controller (FLC) is developed for the speed control of brushless DC motor (BLDCM) drive in this paper. In a FLC, the way to improve the performance of the FLC is to tune the fuzzy rules, membership function and scaling gains of inputs and output. The scaling gains of the inputs and output of the proposed fuzzy controller are parameters that can be tuned conveniently. So, in this paper, an adaptive FLC with the tuning of scaling gains by fuzzy logic is proposed. The advantage of this method is that the universe of discourse of the fuzzy sets can be tuned by adjusting the scaling gains according to the speed error. This significantly improves the dynamic response and steady state performance of the system under the control of the proposed adaptive FLC. In this paper, the principles of tuning scaling gains of the inputs and output are described. The proposed adaptive FLC has the characteristics of robustness, adaptive and facility to take advantage of human control knowledge. The experimental tests are carried out for the proposed adaptive FLC. The experimental results demonstrate that the proposed adaptive FLC presents a superior performance than the conventional FLC.

Optimal configuration and analysis of isolated renewable power systems

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 installed capacity of renewable energy generation, energy storage systems, power electronic converters and diesel generators, is analyzed thoroughly. The simulation shows the results of different configurations and the factors affecting system configuration and operating parameters. Moreover, the key factors and specific influences of the design of isolated renewable power systems are obtained. The results provide strong guarantees to ensure the efficiency and accuracy of initial design of isolated renewable power systems.

Variable Gain Intelligent Control of Multi-motor Synchronization System

Multi-motor synchronization control (MSC) is a key issue in industrial production. Based on the conventional PID algorithmic, a variable gain intelligence control scheme is proposed in this paper. Consequently, this new idea was implemented by PLC controller in the stretch tension & synchronization control system of a wide-fabric heating-shaping machine. Such a system has perfect characteristics, e.g. rapid response, overshoot-less and no steady-state errors. In addition, easy programming, simple wiring and strong anti-jamming ability lead to a stable operating performance. The proposed scheme can be widely used in electrical motor synchronization control demands arising from the spinnery, paper mill and mechanical production lines.

Shunt Active Power Filter - SIMULINK Simulation and DSP-based Hardware Realization

Active power filter (APF) is one of the effective means for harmonic current compensation in power grid. This paper focuses theoretical topics on a three-phase four-wire shunt active power filter (SAPF) system, covers operation principle, harmonic current detection, structure of main circuit, control of the DC voltage and compensating current. The overall system has been modeled using MATLAB/Simulink, and simulation results have shown that the structure is reasonable. Besides, the SAPF control systems hardware is realized based on DSP and MCU.

Study on double modulation wave carrier-based PWM for three-level neutral-point-clamped inverters

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 unique structure and the limitations of the existing modulation methods. The Low frequency ripple of the three-level NPC inverter PWM rectifier technology is an important problem. Conventional three-level carrier-based pulse width modulation (PWM), which has only one modulation wave per phase, cannot eliminate low-frequency neutral point(NP) potential ripple of three-level neutral point clamped (NPC)inverter completely under some modulation index and power factor. This paper analyzes the condition, which eliminated low-frequency voltage oscillation of three-level neutral-point-clamped (NPC) inverter completely, established the model of the low frequency ripple of the three-level NPC inverter. A double modulation wave carrier-based PWM (DMWPWM) was proposed in this paper. Based on voltage equivalent principle and NP potential balance principle, one modulation wave is decomposed into two modulation waves to implement modulation. The proposed DMWPWM can eliminate the low frequency ripple of the three-level NPC inverter completely. Fundamental principle of the proposed PWM was introduced in this paper. The effectiveness of the proposed method was verified by simulation.