Applied Mechanics and Materials Vol. 740

Abstract: In steady-state voltage stability analysis, Continuation power flow (CPF) method is widely used for it can track power flow solution at the critical voltage point. The existing matpower CPF program can only simulate PV curve of a single bus when load increases at one certain bus. In this paper, original CPF program will be modified to be more flexible and in line with the actual situation. Several indices will be proposed to discuss how to determine the first crash bus (namely the system vulnerabilities) when load increases at multiple buses. Simulation results of a regional power grid in northern China verify the validity and practicability of the proposed method.

Abstract: As wind power generation rapid development in china, wind power prediction is the key to the system operate safely. Given significant uncertainties involved in wind generation, probabilistic interval forecasting provides a unique solution to estimate and quantify the potential impacts and risks facing system operation with wind penetration beforehand. this paper based on the point forecast, calculate wind power prediction error, formulate the distribution of prediction error, you can get the historical probabilistic distribution of prediction error, use the distribution of error to build the risk assessment of wind power after prediction, give the fluctuate range of predicted values. Probabilistic interval forecasting can obtain the probably of power system operation safely and reliability assessment criterion.

Abstract: Black-start is an effective measure to restore the power system when blackout occurs. An appropriate black-start scheme may not only speed up system restoration, reduce outage losses, but also have important significance to deal with emergencies. In this paper, a method to design black-start scheme for a combined system in Taizhou regional grid is presented. The feasibility and efficiency of designing black-start scheme is significantly improved, based on comprehensive consideration of Taizhou regional situation and the real-time status of hydropower, wind power, energy storage and circuits. The simulation results show that the new method is valid.

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: In this article, large capacitor charging and discharging experimental system is utilized to generate 270V DC-current by pre-charging to the large capacitor and discharging. Interrupter switching experiments of 540A, 1800A are done in aviation environment, and results of arcing breakdown manner are analyzed and explained. The experiment results indicate that 270V DC-current and arc in aviation environment can be broken by the way of using IGBT in appropriate time; In aviation environment, the breaking capability can be improved, and arcing breaking manner can be used to estimate the arc time constant by several experiments.

Abstract: Aimed at the characteristics and the security requirements of 10kV Power network distribution automation system, a set of security mechanisms is designed, which is based on Elliptic Curves Cryptography. Methods: The identity authentication between sub-station and distribution terminal unit is actualized by using ECC signature algorithm. Data integrity is actualized by Hash function and data encryption is actualized by ECC encryption schemes. Result: We develop a GUI (Graphical User Interface) as the simulation platform by using java language.

Abstract: With the rapid development of wind power industry, the wind power absorption problem has become an increasingly severe challenge which China's power industry is faced with. In fact, through the configuration of large capacity thermal storage devices in the existing power system, an electrothermal association system is formed by combining electric power system with thermal system, which can not only increase the peak load regulation capacity of the system, but also increase local load, thus greatly improving the wind power absorptive capacity of electric power system. This paper will make an systematic analysis of the mechanism of promoting the wind power absorptive capacity of electric power system by utilizing thermal storage devices, and the feasibility and prospect of the proposed plan by combining with the actual situation of Ningxia, and lays the foundation for the further study of thermal storage devices in electrical power system.

Abstract: The line overload is discussed and the coordination and optimization model of preventive and emergency control is proposed in this paper. It combines with the sensitivity’s concept and reverse phase equivalent matching adjustment principle, takes into account the severity of the accident probability and consequences, and introduces the important factor of the corresponding accident; adjust automatically according to the influence degree of the accident to the power grid. Getting reasonable coordination optimization strategies to ensure the safety and economy of the system is effective and verified by this paper.

Abstract: Resources of wind power due to its presence greater volatility, increasing the difficulty of regulating for the power grid. In the supply side, by installing thermal storage device to the cogeneration units so as to increase the adjusting capacity in the supply side of the power system, in the load side, the wind power heating system added heat storage device, increasing the load that can be adjusted. These two measures could be better to solve the problem that part of the abandoned wind. In this paper, analyzed the theoretical basis of each system briefly, added thermal storage device in electric –thermal combine system, and the thermal storage device installation position has been described too. Due mostly theoretical on thermal storage device is about the thermodynamic aspects, it is rather strange for electricity workers, so in this electrical-thermal combined system, its thermal storage devices and electric boiler thermal model have been made a simple analysis and described its control strategy. The control strategy was a comprehensive coordination to the power grid, meanwhile, taking into account the hysteresis characteristics, delay effects and daily regulation plan features of the thermodynamic parameters of thermal storage system make a reasonable start-stop control strategy finally.

Abstract: High Voltage Direct Current (HVDC) system was often the link between major power grids. In order to ensure the safe operation of HVDC, fault diagnosis method was studied. The system structure of HVDC Light system was analyzed, and the normal and fault conditions of the transmission system were simulated in the Matlab platform. This method was very convenient and simple, and it could restore the real situation. The use of simulated waveform could effectively identify the fault types of actual situation, and then it was a flexible, efficient and practical method of fault diagnosis in HVDC Light system.