Applied Mechanics and Materials Vol. 441

Abstract: The parameter setting of the power system stabilizer (PSS) is very important. This paper presents a PSS for wind power generation. We describe a method of simulation for PSS based on MATLAB Simulink, and research that how to build the mathematic model and get the parameters that are fitted to the real power plant generator Excitation System and PSS used the Real Time Digital Simulator (RTDS), then builds the model on RTDS, and does the simulated testing. It is shown that this PSS can significantly influence the contribution that a wind farm can make to network damping. The optimal parameters of PSS can be obtained quickly through the approach of parameter optimization and it is a high efficiency and practicable parameter setting method. Performance capabilities superior to those provided by synchronous generation with automatic voltage regulator and PSS control are demonstrated.

Abstract: This paper presents a variable current-controlled single-inductor dual-output DC-DC buck converter depending on difference loading currents in standard 0.18-μm CMOS n-well process. We intend for compensate system and according each loading current to make suitable dual cycle. Two outputs are specified at 1.8V and 1.2V operated at 800 KHz, the power conversion efficiency reaches 82%. The chip occupies 1.73 × 1.1 mm2.

Abstract: This paper describes the optimization design of prefabricated XPLE cable accessories and presents the formula of the design of stress cone. The finite element method for optimizing the design of the electric stress distribution inside the HV power cable joint and adjusting the length and curvature of the stress cone of this termination is discussed. The relationships between dimensions of stress cones structure and the electric field distribution were obtained.

Abstract: The phase voltage of the tripping phase contains capacitive coupling voltage and inductive coupling voltage. According to the continuous improvement of the national voltage grade, the parallel transmission lines on the same tower are widely used in main transmission section. The protection will trip the fault phases while inner-line or inter-line faults occur. The phase voltage of the tripping phase contains capacitive coupling voltage and inductive coupling voltage. Terminal voltage when the lines are in transient faults is much higher than in permanent faults because of the line discharging by fault point. Simulation studies show that the terminal voltage criterion can distinguish transient and permanent fault in parallel transmission lines.

Abstract: A new method to identify sympathetic inrush and internal fault current of transformer based on W-DHNN is put forward. Wavelet analysis can detect the abrupt change of the current signal. And extract the feature vectors of the signal. The characteristic values as the input value of discrete Hopfield neural network. Then using discrete Hopfield neural network to discriminate sympathetic inrush and internal fault current. This paper uses PSCAD/EMTDC software to model and emulates different parameters of transformer and fault types. The results show that the method is feasible.

Abstract: With the Influence of disaster factor on power system reliability become more and more significant, traditional deterministic risk analysis method has been difficult to adapt to power system risk assessment in changing disaster conditions. This paper puts disaster factor into power system risk assessment, and use improved Monte Carlo method to analyze the risk of all possible states of the system. Combined with online short-term assessment technology, based on the integration of multiple data sources, it uses several typical risk indexes for power system risk assessment under the impact of disaster conditions, then shows power grid operation risk, security warning information and weakness information. The system has been applied to practical power system to verify its scientific and practical design.

Abstract: With the global environmental deterioration and energy crisis, for its pollution-free, noise-free, mobile simple, would not subject to geographical restrictions such as the unique advantages, solar energy will replace the tradition non-renewable energy. solar water pump system is a photo-mechanic-electronic integration system that is rapidly developed in recent years, which uses electricity from solar cells, through the controller, control the water pump, finally realize the pump operation. in this paper, the research significance, present situation,development direction and the advantages of solar energy will be introduced ,and water pump system use the single chip processor as the core, ultimately to achieve the use of solar energy and complete pumping function. And on the basis of this design, through the system extension and upgrading, with corresponding implementation agencies, can also be applied to industry.

Abstract: This paper studied influence of three dimension complex ground on electric field under overhead lines. Surface charge method is discussed and planar triangle surface charge elements are used to represent complex ground. Electric field of overhead lines is analyzed by charge simulation method. Finite straight line charges are used to represent conductors. Then electric field of 220kV double circuit overhead lines over a three dimension small hill is calculated and distribution of electric field 1.5m above the ground is analyzed.

Abstract: 500kV Hainan Grid Connection project is the major project connecting Hainan Power Grid to Main China southern power grid. Submarine cable segment is a core part of the whole project. The safety and reliability of the whole project is directly determined by the situation of its main insulation. The submarine cable is affected by a variety of factors in the sectors of manufacturing, transportation and installation. Field voltage withstand test on the submarine cable is of great significance in order to check its insulation condition after installation. In this paper, field DC voltage withstand test of 500kV oil-filled submarine cable is researched. The data obtained in field trials is analyzed to evaluate the main insulation reliability. The results show that the manufacturing quality and the insulation condition installation after laying on site of the submarine cable is reliable, meeting the engineering requirements of safe operation.

Abstract: The capacity of good input/output characteristics and energy bi-directional flow was required for excitation power in distributed wind power system. This paper analyzed the basic principle of voltage and current double closed loop control strategy, and expounded voltage space vector pulse width modulation (SVPWM) technology based on the topological structure of three-phase voltage convertor. It also established the SVPWM algorithm and the convertor model in the Matlab/Simulink, and conducted the simulation research for the distributed wind excitation power supply with this algorithm. The theory analysis and simulation results indicated that this SVPWM convertor is feasibility and superiority in this field.