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The fault characteristics of large-capacity wind farms affect the sensitivity of transmission-line protection, resulting in protection devices refusing to operate or mal-operate. A phase-to-ground fault-locating method with single-end transient information for wind farm transmission lines was proposed in this study. The proposed method employs a time-domain transient quantity integration equation matrix with the transmission line equivalent resistance, inductance, and fault path resistance to solve the fault location. The effectiveness of the scheme was evaluated using Real-Time Lab (RTLAB). The impact of factors such as the fault resistance, location, and distributed capacitance is considered. Under different fault locations, the distance measurement error of the proposed algorithm is within 3%, and there is no rejection or mal-operation. The results demonstrate that the proposed algorithm is characterized by high speed and reliability.

Due to the distinctive fault characteristics of wind power converters in large-capacity wind farms (WFs) with power converter-based systems, protective relays for the connected transmission lines can malfunction, which poses a serious challenge to the stable and reliable power transmission. This article focuses on addressing this issue by proposing a phase-to-phase fault protection method that utilizes single-end transient information for wind farm transmission lines. Conventional solutions often encounter difficulties such as the negative influence of fault resistance and the uncertainty of remote parameters in single-ended data locations. The proposed method employs time-domain differential equations to accurately solve the fault location problem. It takes into account the equivalent resistance and inductance of the transmission line, as well as the fault path resistance. This helps minimize the adverse effects of fault resistance and parameter uncertainties, making the method insensitive to fault impedance and system parameters. The effectiveness of the proposed scheme is comprehensively evaluated using the Real-Time Lab (RTLAB). Various factors like fault resistances, locations, and distributed capacitance are considered. The results clearly demonstrate that the proposed algorithm not only operates at high speed but also exhibits remarkable reliability, offering a promising solution for enhancing the protection of wind farm transmission lines.

Over the past decade, airborne digital sensor series linear array scanners, among the most important imaging sensors in photogrammetry practices, have been used around the world to measure and interpret the terrain. They have attracted much interest from researchers in image quality and data processing and application. This paper analyzes the factors affecting the quality of airborne digital sensor images and proposes suggestions for data acquisition and flight plan design. Factors affecting image geometric quality are first analyzed theoretically, including the velocity and attitude variations of aircraft, and terrain elevation changes and slope, and formulas are given to express the quantitative relationship. Then, a real data set is used to verify the theoretical analysis and evaluate the practical influence, and according to the formulas, advice on image data acquisition control and flight plan design is provided, so as to improve image quality and facilitate subsequent works.

Georeferencing satellite imagery is the basis for mapping and other subsequent processing in photogrammetry and remote sensing. Traditional georeferencing methods, which require adequate and well-distributed ground control points (GCPs), are time-consuming, costly, constantly cumbersome and inefficient. This study proposes a method of adaptive re-weighted block adjustment without GCPs for satellite stereo images. Furthermore, an approach of using multi-coverage images to improve the direct georeferencing accuracy is also investigated. The bias-compensated rational function model with affine transformation parameters is used as the adjustment mathematical model. The “weighted virtual control points” are introduced as constraints in the adjustment. Space intersection and resection are executed iteratively to solve the accurate affine transformation parameters. A total of 722 three-line array stereo scenes of Chinese Mapping Satellite-1 images captured from December 2010 to March 2016, which cover the entire Shandong Province of China (about 158,000 km2) nearly 10 times in space, are used as experimental data to evaluate the performance of the proposed method. Experiment results demonstrate that the proposed method can effectively eliminate the systematic errors of images. Moreover, the additional comparison with experiments of three groups of mono-coverage images indicates that the redundant observations from multi-coverage images can significantly improve the direct georeferencing accuracy, more specifically, from 13.69-16.02 m to 11.09 m in the horizontal direction, and from 16.39-29.27 m to 8.47 m in the vertical direction.