Suppression Method of Partial Discharge Interferences Based on Singular Value Decomposition and Improved Empirical Mode Decomposition

Partial discharge detection is an important means of insulation diagnosis of electrical equipment. To effectively suppress the periodic narrowband and white noise interferences in the process of partial discharge detection, a partial discharge interference suppression method based on singular value decomposition (SVD) and improved empirical mode decomposition (IEMD) is proposed in this paper. First, the partial discharge signal with periodic narrowband interference and white noise interference x(t) is decomposed by SVD. According to the distribution characteristics of single values of periodic narrowband interference signals, the singular value corresponding to periodic narrowband interference is set to zero, and the signal is reconstructed to eliminate the periodic narrowband interference in x(t). IEMD is then performed on x(t). Intrinsic mode function (IMF) is obtained by EMD, and based on the improved 3σ criterion, the obtained IMF components are statistically processed and reconstructed to suppress the influence of white noise interference. The methods proposed in this paper, SVD and SVD + EMD, are applied to process the partial discharge simulation signal and partial discharge measurement signal, respectively. We calculated the signal-to-noise ratio, normalized correlation coefficient, and mean square error of the three methods, respectively, and the results show that the proposed method suppresses the periodic narrowband and white noise interference signals in partial discharge more effectively than the other two methods.

Experimental Research on Narrowband Interference Suppression of GNSS Signals

The navigation satellites are running at a high altitude of 20000 km from the ground, and the satellite signals arriving at the ground are very weak, such as the C/A code on the L1 band, which is only -160 dBW. In complex urban environments, especially when there is an occlusion, the signal power will be even lower. Low power causes the signal to be easily disturbed, where suppressed interference is the most common method of interference. The purpose of this paper is to experiment with the BPSK and BOC signal system to do the narrowband suppression of interference analysis and set up the actual test environment, based on the commonly used LMS algorithm for the two systems of narrowband interference performance contrast analysis, and throughout the simulation, it can be seen that the two improved algorithms can effectively suppress narrowband interference, thus improving the anti-interference performance of satellite navigation receiver.

Fuzzy Control of Floating Raft Active Vibration Isolation System under Narrowband Interference

The harmonic signal generated by power equipment on naval vessels is a typical narrowband interference, which seriously affects the stealth performance of naval vessels. The float raft active vibration isolation system is characterized by strong adaptability and good controllability, which can effectively isolate low-frequency interference. For the active vibration isolation system, the control strategy is one of the core, and the precise mathematical model is difficult to be established. The fuzzy control does not rely on the precise mathematical model of the controlled system, which cannot only provide an intelligent path for the active control of the complex floating raft system, but also effectively suppresses the narrowband interference caused by naval vessels' power equipment. Therefore, depending on the existing float raft active vibration isolation platform, this paper outlines a design for a two-input/single-output optimized fuzzy control system based on vibration acceleration, variation of vibration acceleration and control voltage. In an optimized fuzzy control system, an algorithm of quantum behavior particle swarm optimization algorithm (QPSO) is proposed to optimize quantization factor and scale factor because quantization factor and scale factor are set subjectively with strong subjectivity and blindness, and the stability of the control system is roughly verified. Therefore, simulations and experiments are carried out to test and verify the performance of control system designs outlined in this paper. Through comparative analysis, it shows that the floating raft active vibration isolation system with a fuzzy control system based on the QPSO algorithm has a favorable effect on low-frequency narrowband interference.