Zhongjun Chi

Study on the impacts and analysis of EV and PV integration into power systems

EV (Electric vehicle) and PV (photovoltaic) load will bring about some influence to the power system when is connected to gird, such as the change of load characteristics, increase the peak valley difference and etc. At the same time the application of inverter will bring about reverse power threat to the operation and maintenance of power grid. To weaken the influence above, the technology named Vehicle to Home is proposed, which can control EV charging load to a specific value as well as control the EV discharge to grid. In order to actively respond to the impact of EV and distributed PV application access to the power grid, based on the actual home users, the data of household electricity load and the user level transformer are collected and analyzed. At the same time with the peak and valley price, based on the quantitative analysis of the influence of electric cars, solar access to the grid, the interactive applications is put forward. Calculation and interactive analysis results show that the implementation of V2H can not only bring economic benefits to users but also reduce the peak valley ratio and the risk of peak on peak which result on the electric vehicle charging in disorder.

Super short term forecasting of photovoltaic power generation output in micro grid

The prediction model combining data mining and support vector machine (SVM) was built. Which provide information of photovoltaic (PV) power generation output for economic operation and optimal control of micro gird, and which reduce influence of power system from PV fluctuation. Because of the characteristic which output of PV rely on radiation intensity, ambient temperature, cloudiness, etc., so data mining was brought in. This technology can deal with large amounts of historical data and eliminate superfluous data, by using fuzzy classifier of daily type and grey related degree. The model of SVM was built, which can dock with information from data mining. Based on measured data from a small PV station, the prediction model was tested. The numerical example shows that the prediction model is fast and accurate.

Research on unit commitment with large-scale wind power connected power system

Large-scale integration of wind power generators into power grid brings severe challenges to power system economic dispatch due to its stochastic volatility. Unit commitment including wind farm is analyzed from the two parts of modeling and solving methods. The structures and characteristics can be summarized after classification has been done according to different objective function and constraints. Finally, the issues to be solved and possible directions of research and development in the future are discussed, which can adapt to the requirements of the electricity market, energy-saving power generation dispatching and smart grid, even providing reference for research and practice of researchers and workers in this field.

Research on large-scale wind farm modeling

Due to intermittent and adulatory properties of wind energy, when large-scale wind farm connected to the grid, it will have much impact on the power system, which is different from traditional power plants. Therefore it is necessary to establish an effective wind farm model to simulate and analyze the influence wind farms have on the grid as well as the transient characteristics of the wind turbines when the grid is at fault. However we must first establish an effective WTGs model. As the doubly-fed VSCF wind turbine has become the mainstream wind turbine model currently, this article first investigates the research progress of doubly-fed VSCF wind turbine, and then describes the detailed building process of the model. After that investigating the common wind farm modeling methods and pointing out the problems encountered. As WAMS is widely used in the power system, which makes online parameter identification of the wind farm model based on off-output characteristics of wind farm be possible, with a focus on interpretation of the new idea of identification-based modeling of large wind farms, which can be realized by two concrete methods.

Analysis and Simulation of Electric Vehicle Power Battery

Energy and the environment have become the most current concerns in the world, and many countries have considered developing electric vehicles as an important means to solve the problem of energy and the environment. So, it is very necessary to research the effect on grid by electric vehicle charge and discharge but it must build a suitable model of batteries of electric vehicle. This paper built a PNGL and Thevenin simulation model, and compared the simulation curve with the actual measure curve. The results prove that the two methods on two occasions applications are more appropriate.

Impacts and Analysis of Electric Vehicles and Photovoltaic Integration into Power Systems

Electric vehicle (EV), photovoltaic (PV) load will affect the power grid in a certain extent when is connected to grid, such as the change of load characteristics, increase the peak valley difference. At the same time the application of inverter will bring about reverse power threat to the operation and maintenance of power grid. To weaken the influence, V2H (Vehicle to Home) technology is used to EV and grid interaction, which can control EV charging load to a specific value as well as control the EV discharge to grid. In order to actively respond to the impact of EV and distributed PV application access to the power grid, based on the actual home users, the data of household electricity load and the user level transformer are collected and analyzed. At the same time, with the peak and valley price, based on the quantitative analysis of the influence of electric cars, solar access to the grid, the interactive applications are put forward. Calculation and interactive analysis results show that the implementation of V2H can not only bring economic benefits to users but also reduce the peak valley ratio and the risk of peak on peak which result on the electric vehicle charging in disorder.

A Novel PQ Control Strategy of Microgrid with Single-Phase Connected to Grid

Based on the power hypothesis of feed-forward decoupling, PQ control is typical of the micro network control strategy, through the SPLL and d–q transformation module power and power factor control module and current control module to establish PQ control model, and in the original basis of ordinary phase lock loop to instantaneous reactive power phase lock loop. Finally using two half-bridge inverter dc micro-source to simulate practice single-phase parallel in MATLAB/Simulink simulation, it is concluded that using the control strategy of the micro-source in connection with power grid after a relatively short period of time, keeps the current in parallel and power grid voltage synchronization, output active power constant.

Assessment of Civilian Demand Response Behavior Supporting Wind Power Digestion

According to the time process characteristic and the economic efficiency characteristic of civilian active load system’s interaction demand response behavior, this paper establishes the behavior analysis model of active load’s interaction response. And we decouple the response behaviors between users’ energy consuming load and electric load, and we extract out the target variables which can represent and identify the physical features of interactive response behavior from users’ energy and electricity demand and the cooperation between distributed renewable energy and grid. Considering a power grid with wind and heavy air conditioning load, this paper designs a wind and cold storage air conditioner combined system, and through a case study of response behavior analysis on residential and commercial active load system, we verify the effectiveness of the behavior analysis model and the target variables.