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The rule No.599 of power grids in China indicates that the shedding load is equivalent to the failure loss load, which requires less load-shedding as much as possible under the premise of security and stability, to reduce the cost of frequency accident control. Therefore, in this paper, the load-shedding contribution factor based on frequency regulation effect, P-V characteristic and the importance...
Analyses of transformer electromagnetic vibration noise are presented in this study. A finite element model is established which combines transient electromagnetic field analysis, mechanical field analysis and acoustic analysis to calculate the sound pressure level of the radiated noise around the transformer. Transient electromagnetic field analysis is performed to get the Lorentz, reluctance magnetic...
When predicting the noise level of substation, the model of transformers and reactors as noise sources is very important. A new acoustic mode of the transformers and reactors is built in ultra-high voltage substation. Each of the transformers and reactors is equivalent to several point sources based on equivalent source method. And in the process of the equivalent, the measurement and calculation...
Controlled islanding is a timely process which can split the power system into electrical islands in place based on the real-time operating condition and fault information. The key to avoid the collapse of the system is how to locate the out-of-step splitting sections rapidly and accurately. However, with the larger system scale, the computation complexity of optimal controlled islanding is increasing...
Reasonable islanding strategy is significant for avoiding blackout when the power system suffers from major fault. On the basis of this, this paper analyzes the electrical connection between nodes and proposes a new method of islanding strategy searching based on Floyd-warshall and DFS algorithm. By comparing the degree of electrical coupling relationship between load nodes and generator groups, the...
The damping characteristic of a single-machine infinite bus system is analyzed, and the relation graph of damping torque to transmission power is plot. The influence of changing tie-line power flow on the low-frequency oscillation modes of Central China Power Grid is researched, by way of changing power flow in one section and others remaining the same. The proposed method can be used for the actual...
Based on the space vector pulse width modulation (SVPWM) principle, the detailed SVPWM algorithm is derived in this paper and some improvements have been made taking over modulation and sector transition into consideration. Then the improved algorithm is simulated under MATLAB/SIMULINK. Multiple modulating methods-continuous and discontinuous are achieved in the simulation by changing some particular...
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