Advanced Materials Research Vols. 960-961

Abstract: Near the load of distribution network access distributed networks, the entire distribution network load distribution will change, system trend then change, then the trend of the distribution network can also be changed from the original "one-way flow" to "two-way flow". For synchronous generator connected to the power distribution network, the input active power and reactive power at the same time to the system, can reduce the loss and the voltage distribution network can play a supporting role, but for asynchronous induction generator connected to the power distribution network, the input to the system active power and reactive power absorption, reduce the power factor of the grid. By trend analysis found that introducing asynchronous induction generator to increase distribution network loss, deterioration in transmission line voltage level. Distributed generators after introducing the distribution network could reduce may also increase the system network loss.

Abstract: As Zibo power plant original steam pipes for a long time to run, the strength decreased and resistance was large, transformation was proposed to optimize. A mathematical model of the main steam pipe network was established to analysis changes of temperature, pressure and velocity vector before and after transformation. After transformation, the loss was significantly reduced,so transformation successfully achieve the optimization, adjustment and analysis functions of the main steam pipe network.

Abstract: The torque ripple is the main disadvantage of switched reluctance motor (SRM). In order to reduce the torque ripple of SRM, and improve the performance of the system, the torque sharing strategy was combined with RBF neural network for the purpose of torque ripple suppression by controlling the winding current of each phase. In consideration of the possible error of network, the real-time current compensation was taken to compensate the loss of torque which could suppress the torque ripple of the system in further. The results show that he torque ripple of SRM was suppressed effectively.

Abstract: The allocation of power system loss under hybrid transmission modes was investigated. First, a concept and method for converting a bilateral transaction into its two equivalents pool transactions were proposed. Then, a model based on Shapley value was designed to allocate the power system loss in the framework of equivalent pool transactions. The Shapley solution in cooperative game theory was employed to allocate the power system loss to each load pool transaction that includes the equivalent ones. The proposed method is applicable for electricity markets containing pool and bilateral transactions. It satisfies electric circuit laws and provides economic signals to users. The effectiveness of the proposed method is verified by the IEEE 5-bus test system.

Abstract: A province in the central China faces the problem of energy shortage, 800kV Mengxi UHVDC project will effectively broaden the energy input channels of the province, enhance energy supply security, and reduce the pressure on coal transportation. This paper analyses the load, power supply and power shortage of a central province, and explored the role of Mengxi UHVDC project played in improving the energy demand in the Central China power grid. By comparing the different access plans to the grid, this paper demonstrated that it’s more appropriate to divide the Mengxi UHVDC into 1000kV and 500kV at the inverter side for consuming the power of UHVDC and protecting the normal power supply.

Abstract: Wavefront identification is important for traveling based fault location. In order to improve its reliability, a novel wavefront identification method based on Harris corner detector has been proposed in this paper. The principle of single-ended traveling wave fault location was briefly introduced at first, and the features of wavefronts generated by faults on transmission lines were analyzed. The arrival of traveling waves' wavefronts is considered as corner points in digital image of waveshape. The corner points can be extracted precisely by Harris corner detector, and both false corner points and non-fault caused disturbance can be eliminated according to the calculated distance between two neighbour corner points and the angle of the corner point. The proposed method is proved feasible and effective by digital simulated test.

Abstract: The work process of medium-frequency power supply is complicated .Its waveform is complex and can not be measured conveniently. Therefore,This paper focuses on the analysis of operating principles and control methods of medium-frequency power supply, to determine its basic structural units.A simulation model of medium-frequency power supply which is controlled by pulse width modulation (PWM) is built with the electromagnetic transient analysis software PSCAD. The simulation and analysis of the medium-frequency power supply circuit are performed on the basis of the model.The simulation waveform can reflect the working process of medium-frequency power supply accurately. So this paper will provide a reliable basis for further research of medium-frequency furnace.

Abstract: Compared with the traditional power grid, UHV power grid has the character of stronger system function, higher control requirement, and also set a higher request to the daily maintenance management. The operation and maintenance experience of Shan-xi province electric power company on the UHV power grid proved the importance of establishing the new mode of management, strengthening the application of automation technology, and guarenteeing the technology and resources . In order to improve the efficience and quality of UHV power grid operation and maintenance, we should speed up the formulation of operation guidelines for UHV live working and strengthen personnel training and reserve technical talents.

Abstract: Nowadays contingency analysis being a part of a power system security calculations is a mandatory procedure for a short-term operational stage of the electrical power system (EPS). Nevertheless, there are still a lot of problems, concerning security calculations. For instance, recent studies have shown necessity to consider simultaneous failures of several power system elements during contingency analysis. This brings complexity and voluminosity of security calculations to the new level. On the one hand, analysis of all possible contingency combinations results in unreasonably high computing time. On the other hand, many contingency combinations, especially with very large number of simultaneously failed elements (SFE), have little impact on overall result of security estimation due to very low probability of such combinations. This paper presents novel mathematical algorithm allowing estimation of significant number of simultaneously failed elements (SNSFE). Proposed algorithm was tested on the 14-bus IEEE reliability test system. Results show adequate accuracy of the technique and also confirm the necessity to simulate simultaneous failures of several network elements.

Abstract: Build a mathematical model by using the voltage loop of UCC28019 to get open loop transfer function. And use MATLAB to obtain variable range of voltage loop parameter when system is stable, in the mean time, use system time domain performance as objective function to optimize the parameter, based on system stability. The user can get better parameters on the three-dimensional image clearly and directly, for there is no complex formula and theoretical derivation in process of optimizing. Hardware circuit experiments verify the effectiveness of the proposed method.