One new vector estimation approach for phasor measurement units (PMUs) within power system is put forward, which is built upon the basis of apFFT, namely all-phase fast Fourier transform. On account of the remarkable accomplishment of apFFT when subduing property of "phase invariant" and spectral leakage, the estimation approach is capable of achieving quick evaluation of PMU phase angles, and subsequently, the spectrum correction of time-shift phase discrepancy is used so as to evaluate the amplitude and frequency parameters. The calculation flow of the algorithm is given, and the hardware design of the new PMU measuring system is completed by using ARM9 microprocessor. Simulation result indicates that the method in this paper is roughly the same to an estimator without bias for noise-free conditions, and this calculation precision is also better than the existing approach.
In order to solve the problems of long development time, poor expansibility and small application scope in the digital design of secondary system of intelligent substation at present, this paper puts forward the 3D assembly techniques based on the expanded model by analyzing the integration of secondary model files of intelligent substation. In the design process of this method, the relationship between primary equipment and secondary equipment, the mapping between logical circuit and real circuit are fully considered. By using standard family library techniques, file analysis techniques and automatic mapping techniques, the coupling between physical model and logical relationship is realized. Taking the actual 220kV intelligent substation as the pilot, the three-dimensional model in secondary system simulation analysis, online monitoring and the application of fault diagnosis shows that the techniques can effectively improve the efficiency of three-dimensional design and maintenance of secondary system.
The integrated energy system creates the possibility for the interconnection and coordination of different energy sources, and is an effective means to improve the energy use of the system, increase energy efficiency, and reduce environmental pollution. At present, the planning of distributed energy stations for integrated energy systems mostly focuses on equipment selection and equipment capacity. However, there are relatively few studies on the location of energy stations and pipeline layout planning. Firstly, this paper proposes a distributed energy station location method based on the improved p-median model, which combines the energy supply path of the energy station with the actual transportation network, and introduces the weight coefficient of multi energy load to reflect the diversity of energy demand of load. Finally, the specific solution method is given, and the rationality and feasibility of the proposed method are verified by an example.
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