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Internet of Vehicles communications need high-reliability and low-latency channel codes. This paper aims to improve the error probability performance of the rate-compatible polar codes (RCPC) by optimizing the common coding construction. To this end, the novel construction method is proposed for the RCPC cluster with multiple lengths and patterns, particularly where a multiobjective reinforcement learning (MORL) approach is utilized. Both the reconstruction-aided fast construction algorithm and the successive cancellation list decoding-oriented integrated construction algorithm are designed, by combining the code properties and MORL. Meanwhile the construction algorithm complexity is reduced by optimizing the action space and reward calculation. Simulation results and analysis verify the overall reliability performance advantages of the proposed method for the RCPC cluster, compared to existing construction schemes.

As the altitude increases, air density decreases to cause a decrease in the air insulation strength. Test results in low-altitude areas indicate the significant impact of front time $t$ (μs) on the characteristics of long-airgap discharge. Nevertheless, the impact of $t$ on the breakdown voltage at high altitudes has yet to be studied. In this paper, impulse discharge characteristic tests for rod-plane gap were conducted at altitudes of 2500 m and 4300 m, with $t \in [2,1000]$. The rod-plane gap discharge characteristic curves are obtained, and the critical front time and 50% breakdown voltage in the two areas are determined. Subsequently, the influence of altitude on the discharge characteristics under critical wave and standard switching impulse wave is compared and analysed. Based on the experiments considering low altitude, 2500 m and 4300 m high-altitude areas, the applicability of the altitude correction method recommended by IEC 60 071 is analysed. Moreover, an improved altitude correction method is presented to adapt to wide waveform variations in high-altitude areas. These results provide fundamental data and support for the external insulation design approaches in power grids at high altitudes.

In order to improve the measurement accuracy of high impulse current, this paper presents the system composition, performance improvement and, traceability method of a 100 kA impulse current measuring system. Since the scale factor of the measuring system can be determined by the product of the scale factor of the components such as the shunt and the digital recorder, a method of component quantity traceability is proposed. Based on a shunt with rated current of 100 kA, a stable measuring system is developed. In addition, a reference impulse current calibrator and a step current generator for traceability are developed, so that the impulse scale factor of the shunt considering skin effect can be accurately calibrated. A single influence quantity independent quantification method was proposed. The influence of measurement error of 100 kA impulse current measuring system is analyzed quantitatively. Based on the high current test results and theoretical analysis, the measurement uncertainty components of peak current and time parameters are evaluated. The expanded uncertainty of the scale factor and time parameters were 0.4% (k = 2) and 0.8% (k = 2) respectively. Evaluation results demonstrate that the developed measuring system can accurately reproduce and measure the high exponential lightning impulse current.