Based on the analysis on shortcomings of controlling strategies of direct power on the traditional 3-phase Boost-type PWM Rectifier through space vectors, a new controlling strategy is proposed in this paper. With this new strategy, the space vector is divided into 12 basic space vectors to form a new switching table. The instantaneous power controlling technology is realized through the control of instantaneous active power and reactive power by choosing the best switching state of PWM Rectifier. This new controlling strategy can put the input side unit power into operation, improve the efficiency of power and reduce harmonics of the input current. The effectiveness and feasibility of this controlling strategy have been justified through the simulation and experiment.
Nuclear power plants (NPP) have to face urgent requirement of participating in peak load regulation of power grid. The peak load regulation performances of NPP were researched. Based on the calculation and analysis on peak load regulation cost and benefit of NPP, the location, criterion and peak balance algorithm of NPP participating in peak regulation were proposed. Results of the actual research show that NPP possesses better ability of peak load regulation and the cost is lower, so NPP can participate in daily peak load regulation, which will improve both security and flexibility of power grid and enhance the efficiency of resource configuration. However, the depth and speed of peak load regulation by NPP are restricted by security and economy.
Identification and calculation of static frequency characteristics is of great significance for power system to maintain its stability. In this paper, coefficient of static frequency characteristics is fitted by the least squares method. Frequency deviation restriction point under different capacitances is forecasted by the fitted trend of coefficient of static frequency characteristics. Moreover, the new method is simulated and its calculation error is also compared.
The nonlinear model of hydro turbine considering the elastic water column was proposed, and the improved biogeography-based optimization (IBBO) algorithm was applied to identify parameters of this model. The cosine species migration model and the elitist reservation strategy were introduced into the algorithm to improve operating efficiency. Based on measured data, comparison of the effects of different identification methods was presented, including the IBBO algorithm, genetic algorithm (GA) and particle swarm optimization (PSO). The results demonstrated that the IBBO algorithm can be applied in parameters identification of hydro turbine nonlinear model, and it has the advantages of faster convergence and higher precision.
To solve the reliability assessment challenge of protection channels caused by elements multiplexing. The paper build a weighted-undirected graph of optical fiber protection channels, whose nodes measurement is SDH reliability and reliability of optical fiber as edge weights. Start from the information provided by the actual grid, encode the data according to the most close to the actual data format, developed an algorithm for channels and services reliability assessment based on logical "or" and "exclusive or". The result is verified in a 9-node and 19-channel network in central China Grid, showing that the proposed encoding method and model have good practicability and operability, which can offer grid reference to network optimization, scientific channels arrangement and the maintenance of the protection channels.
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