Papers by Keyword: Power System

Abstract: since PV inverter cost and performance in residential Solar System Application is a controversial subject, it always needs to be researched to encounter the challenges of cost competitions especially with environmentally polluted fossil fuel energy expense. This research proposes a fundamentally novel solutions for utilizing the unavoidable solar system losses by the hypothesis of dispensing the power converters in domestic application of home solar system. This hypotheses based on matching methods between the energy source, the Battery bank, and the load, home appliances. Since the energy source is a direct current DC supply, this matching process would be via evaluating of the normal alternative current AC appliances and compatibility range to be switched on DC supply, the operation of the appliances evaluated individually with DC supply either by direct coupling or with simple modification, the analysis of the data have been accumulated in terms of efficiency. Individually, appliances were classified according to different aspects in such a way that shows its compatibility range with the DC power supply. A comparison results for each classified appliances have been done for both operation conditions AC and DC. The efficiency of a relatively good quality Inverter would be referred to see what gain would be obtained from switching to DC supply-load matching when eliminating of AC Inverter from the system. A sequence of processes have been carried out on home appliances individually in terms of its electrical and electronic composition towards best system performance and reasonable cost. MATLAB Simulink has been used as a simulation program. The results shows; great utilization of the home solar system losses, cost and faults probability reduction, high efficiency, and more reliable system.

Abstract: This paper first states the importance of power system stability and the classification and characteristics of power system stability. Then according to the static stability and transient stability of power system, this paper introduces the technical measures to improve the two kinds of stability, and analyzes the corresponding effect, and demonstrates the technical and economical problems needing attention when taking all kinds of measures. The study on the power system stability in all situations has great significance to the social development.

Abstract: In the past few decades, power system has developed into a large-scale network system of centralized electricity generation and long-distance transmission. But in recent years, electrical load has increasing, while the grid has not developed simultaneously, it makes transmission capacity of long-distance transmission lines increase, so as the decline of stability and security of power grid. In order to achieve the goal of not only increasing utilization of renewable energy, but also solving the drawbacks of large-scale power systems, implementing distributed power generation is an effective way. Despite the advantages of distributed generation, there are many problems in itself, for example, the high cost of distributed generation stand-alone access and control difficulties. In addition, distributed generation is a non-controllable source for large grid. Then in the beginning of this century, scholars have proposed the concept of micro-grid.

Abstract: The power flow calculation is study the steady-state operation of the power system as basic electrical calculations. It is given the power system network topology, device parameters and determines system health boundary conditions, draw a detailed operating status of the power system through numerical simulation methods, such as voltage amplitude and phase angle on the bus system the power distribution and the power loss. Flow calculation is the power system operation, planning and safety, reliability analysis, is fundamental to the system voltage regulation, network reconfiguration and reactive power optimization must call the function, so the trend has very important significance to calculate the power system.

Abstract: This paper mainly discusses the tower models in lightning overvoltage calculation, especially analysis the lossless and lossy models. Build the muti-wave impedance model of the most commonly used towers, which are portal tower, glass tower, cat head tower and strain tower in accordance with the reality. The simulation shows that muti-wave impedance model has a higher lightning overvoltage than simple model under the same condition. This is because the simple model ignores the influence of resistance and inductance, so the more accurate the model is, the more effective the protection will be.

Abstract: In order to avoid the cascading tripping caused by power flow transferring, a fast identification method of two branches simultaneous removal under multiple voltage levels was proposed. Calculate the per-unit value of element parameters under different voltage levels. Search the K shortest paths between the two nodes of broken line with the network topology considering the two branches removal and the value of K was optimized. Use the power flow transfer factor to estimate the power flow increment of lines on the path and the key lines in power flow transferring were obtained. The method is accurate and it is verified in the IEEE39 node system.

Abstract: In order to use the least number of phasor measurement unit (PMU) to guarantee the power system completely observable, an optimal PMU configuration method in power system was put forward. The pre-configuration of PMU was done considering the actual situation of power grid. The genetic algorithm (GA) was used for PMU configuration. Modify the formulae of crossover probability and mutation probability in traditional genetic algorithm to overcome the evolutionary stagnation when the maximum fitness value and the average fitness value in group were equal. The improved adaptive genetic algorithm (IAGA) was obtained. In order to eliminate the premature convergence of GA resulted from the chance and randomness of the crossover operation and mutation operation, the preventing premature operation was introduced. This method combined the IAGA and the preventing premature operation. It has good global astringency, and it can ensure the network complete observability with the minimum number of PMU.

Abstract: In order to solve the issues of time synchronization that occurs in simultaneous measurement in power system, designing a GPS clock synchronization method based on time different compensation which can guarantee high-precision whether the GPS satellites are locked or not. The paper provides the basic idea describe and the overall hardware and software design. Simulation results show that the scheme provides second pulse with error in 0.8μs when GPS is locked and provides second pulse with error in 7μs when GPS is unlocked for 12 hours. The accuracy is better than the existing references.

Abstract: Power system visualization technology is essential in improving the power system automation and human-computer interaction environment. The power of information visualization technology can display a lot of information in a computer-generated image, and help system personnel to process and analysis of numerous grid data more efficiently. It provides a more intuitive operating platform for system operators.

Abstract: China has become the largest carbon emitter in the world since 2008 for its coal dominated energy structure, which has attracted both economic and political attention from international society. This paper proposes a responsibility sharing principle for carbon emissions considering carbon emission efficiency and energy structure, which tries to promote the regional cooperation for carbon reduction among different regions on the domestic level. The case studies on China’s six-region carbon flow network prove the effectiveness of proposed sharing principle.