A microgrid with low-voltage ride-through capability is designed. The designed microgrid avoids operating in unplanned islanded mode during an asymmetric ground fault which occurs in the low voltage distribution network and supports fault recovery for distribution network. Furthermore, compared with the traditional microgrid topology, the proposed microgrid topology also saves a lot of power electronic devices. The simulation results with PSCAD/EMTDC show that the microgrid can keep the distributed generations and loads operate normally when an asymmetric ground fault occurs in the low voltage distribution grid. It can also increase the active power output according to the requirement of the distribution network to support the distribution network fault recovery. Design of the Entire SystemIn order to achieve the above objectives, the microgrid with LVRT capability was designed. The topology is shown in

To increase the accuracy of drought prediction, this study proposes a drought forecasting method based on the Informer model. Taking the Yellow River Basin as an example, the forecasting accuracies of the Autoregressive Integrated Moving Average (ARIMA), Long Short-Term Memory (LSTM), and Informer models on multiple timescales of the Standardized Precipitation Evapotranspiration Index (SPEI) were compared and analyzed. The results indicate that, with an increasing timescale, the forecasting accuracies of the ARIMA, LSTM, and Informer models improved gradually, reaching the best accuracy on the 24-month timescale. However, the predicted values of ARIMA, as well as those of LSTM, were significantly different from the true SPEI values on the 1-month timescale. The Informer model was more accurate than the ARIMA and LSTM models on all timescales, indicating that Informer can widely capture the information of the input series over time and is more effective in long-term prediction problems. Furthermore, Informer can significantly enhance the precision of SPEI prediction. The predicted values of the Informer model were closer to the true SPEI values, and the forecasted SPEI trends complied with the actual trends. The Informer model can model different timescales adaptively and, therefore, better capture relevance on different timecales. The NSE values of the Informer model for the four meteorological stations on SPEI24 were 0.968, 0.974, 0.972, and 0.986.

Using a dataset of 114 meteorological stations in the Yangtze River Basin from 1980–2019, the standardized precipitation evapotranspiration index (SPEI) was calculated based on the Penman-Monteith evapotranspiration model for multiple time scales, and the spatial and temporal evolution characteristics and driving factors of drought in the Yangtze River Basin were analyzed by combining spatial and temporal analysis methods as well as geodetector. The main results obtained are as follows: (1) The climate of the Yangtze River Basin is an overall wet trend, and the trend of summer drought is more similar to the annual scale trend. (2) Most areas in the Yangtze River Basin showed mild drought or no drought, and there is little difference in drought condition among the Yangtze River Basin regions. The areas with drought conditions are mainly distributed in the southwest and east of the Yangtze River Basin. (3) There are significant seasonal differences in drought conditions in all regions, and the drought condition is more different in autumn compared to spring, summer and winter. (4) The average annual precipitation and elevation factors are the dominant driving factors of drought in the Yangtze River Basin, and the double-factor interaction has a greater influence on the drought variation in the Yangtze River Basin than the single-factor effect, indicating that the difference of drought condition in the Yangtze River Basin is the result of the combination of multiple factors.

When using the random forest algorithm to classify remote sensing images of each target year in the study area, the number of decision trees and the maximum number of features for constructing the optimal model of decision trees have a great influence on the accuracy of the random forest classification results. Based on this, this paper proposes an adaptive parameter tuning strategy based on GridSearchCV to improve the random forest algorithm. The method can select the best parameters according to different sample data and study area conditions. By comparing with unoptimized random forest, decision tree, and support vector machine algorithms, the results suggest that: the optimized random forest algorithm has good classification accuracy, and the overall accuracy and Kappa coefficient of classification results are above 0.90.

Firstly, based on the demand of substation “operation and maintenance integration”, this paper describes the necessity of constructing an efficient, flexible and reliable remote operation and maintenance system. Then, the realization architecture, characteristics and key technologies of the visual online debugging and diagnosis system with flexible configuration are proposed. The system realizes the remote operation and maintenance services such as remote debugging of secondary equipment, intelligent diagnosis, health status assessment and status prediction by using container technology, video processing technology, virtual liquid crystal technology, etc. The application practice shows that the visual online debugging and diagnosis system improves the standardization management and visualization of secondary equipment and optimizes the remote operation and maintenance mode.