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A method for Single-phase grounding test sequence fault location method for small current grounding system is proposed, which aims to compensate for the incomplete or faulty signal of the line ground fault signal when the fault area in the line is located in the prior art. The feature is not obvious, which leads to the technical defect that the distribution automation system cannot accurately locate the single-phase ground fault. It includes the following steps: based on the topology of the single-line diagram of the distribution network, generate a trial pull sequence table for the distribution network switch; follow the trial pull sequence of the distribution network switch in the sequence table to perform a trial pull operation on the distribution network switch, and determine the fault according to the result of the trial pull operation position.

Owing to the daily electricity consumption sequence is time-varying, nonlinear and vulnerable to random factors, a host of single model can't meet the demands of high-precision forecasting. For this problem, this paper proposed a new combined prediction algorithm. Firstly, the original electricity data is decomposed into Intrinsic Mode Function (IMF) with bandwidth by Variational Mode Decomposition (VMD) algorithm and the feature information of itself extracted simultaneously. At the same time, in order to accelerate the speed of prediction and reduce workload, the IMF decomposed by Sample Entropy (SE) is reconstructed into the trend component, the periodic component and the random component according to the self-similarity analysis. Then, according to the characteristics of each component we applied the Least Squares Support Vector Machine based on Maximum Correlation Entropy Criterion (MCC-LSSVM) and Auto-Regressive Moving Average Model (ARMA) to forecast components respectively and add the components to obtain the final predicted value. Finally, the daily electricity consumption data of a Wanda Plaza in Guangzhou are tested and compared with other algorithms. The results show that the daily electricity consumption hybrid forecasting algorithm based on VMD-SE can achieve higher prediction accuracy.

The influence of dispersed wind generation(DWG) on distribution network is closely related to its location and sizing. It is very important for the planning of DWG to operate safely and economically. This paper establishes a mathematical model of the optimal voltage quality and the minimum operating cost of the grid. In order to reduce the influence of noise on some system voltage, this paper introduces maximum correntropy criterion(MCC) as the cost function, so as to better reflect the situation of the overall voltage. Aiming at the problem of nonlinear multi-objective optimization, this paper selects a new algorithm-memetic algorithm for solving the problem. The simulation experiment was carried out by using IEEE33 node system and an engineering example. The simulation results show that the proposed model and the algorithm is effective, superior contrasting with the traditional model and algorithm. and the algorithm used is fast and efficient. And the planning results agree with the actual project.

Nowadays, new energy has been massively accessed to the distribution network. Since its complex topological structure and control characteristics increase the complexity of the new energy source model, it is necessary to study the simplified modeling of new energy sources for the relay protection simulation analysis. Utilizing the modeling idea of testing and analysis and the simplified modeling method based on experimental data, the author treats the generation unit with complex architecture and control information as a black-box model in this paper. The fault current expression is depicted by means of the typical control system response; meanwhile, the relationship between the fault current expression and the fault voltage amplitude is created with sample data of the voltage drop test, the nonlinear mapping relationship between fault current and fault voltage is obtained, thus the new energy source model can be equivalent to a voltage controlled current source. Taking the Doubly Fed Induction Generators (DFIGs) as the modeling object and using fine modeling to simulate the transient fault under symmetrical short circuit conditions, the author establishes a simplified model with the consequential sample data.

The measurement result might incorrect if parameter setting is unsuitable when using spectrum analyzer to measure a signal's harmonic distortion. It is especially useful to make sure the dynamic range of the spectrum analyzer. According to the definite dynamic range, the mixer input level and attenuator setting can be known. By analyzing the example of harmonic distortion measurement using spectrum analyzer, the accurate measurement method is given.