According to analysis to the error sources of the multibeam sonar system，corresponding methods are applied in different error correction processes. The method of filtering is adopted to reduce sounding noises. To the calibration error， recalculation is amended to correction. As to the sound speed profile error, marginal beams are deleted and Equivalent Sound Velocity Profile method is brought to diminish the effect of the error. In this paper the method using the single beam data as a reference to correct the integrated errors of the multibeam data are detailed. All the methods that have been applied in the 908 projects of State Oceanic Administration achieved good results.

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Based on the separation voltage type of cascaded H bridge-modular multilevel converters (CHB-MMC) and current predictive model control (CPMC) technology, a novel flexible fault-current limiter (NFFCL) is firstly proposed for restraining the negative impact of the distribution network’s disturbance in this paper. When a disturbance occurs, the inner-loop CPMC of the multilevel converters establish the value function to offer the specific current, thus increasing the voltage deviation at both ends of the series capacitor or generating reverse harmonic compensation voltage. In that case, three single-phase MNFFCLs can be regarded as variable voltage sources to eliminate the negative effects of faults or harmonics. Owing to the multi-capacitance series structure, the maximum voltage drops of the single capacitance can be predetermined by the number of capacitors. And with the low voltage drop of single capacitance, the output current of the CHB-MMC can also be controlled within an acceptable range. Through the simulation results, the disturbance’s negative impact on the non-fault area can be eliminated almost 100%.

The index system for electrical characteristics of metal-oxide surge arresters is proposed and established, which is based on rated voltage (Ur), continuous operating voltage (Uc), nominal discharge current (In), overvoltage protection and insulation coordination including lightning overvoltage protection level, operating overvoltage protection level and coordination coefficient (Ks). The study considers both selection and application of overvoltage protection devices for the electrical equipments in 3-35kV medium voltage power system, and comparatively calculates and analyzes the main parameters between two types metal-oxide surge arresters (without gaps and containing series gapped structures), and illustrates their technical features and puts forward suggestions on how to improve the effective utilization. The results of 10kV power distribution system are simulated to show that the conclusions are feasible and available in the practical engineering application.

Based on load specification, the power supply model and requirement of well clusters is presented and established in gas gathering and transmission engineering, which is applied on type I and type II. The study considers both reliability and economy of all power supply proposals, and comparatively calculates and analyzes the numbers and types of main electrical equipments, capital expenses (CAPEX) and operating expenses (OPEX). Specially, for the problem of voltage drop, it illustrates the contrast and selection of power transformers with two ratings by the technical features of standard. Finally, the paper respectively puts forward the power supply schemes for well clusters type II and type II from different proposals based on the detailed results, which shows that the conclusions are feasible and reasonable in the practical engineering application.