Research On Harmonic Detection In Power System Based On Chaos Theory

With the development of electronic technology, more and more non-linear load is introduced into the power system. For this reason, the interference of harmonics in the power system becomes increasingly serious. The high-precision electronic equipments are also sensitive to power quality. The study on harmonics in the power system has become more and more important. Power harmonic detection is the start of research and analysis on power harmonic. The High-precision electric harmonic detection has important practical significance.Currently, there are many methods for detecting the electrical harmonics. Because of the complexity of influencing factors in the power system, the noise in harmonics is multifarious. The high-order harmonics with the small amplitude lost in noise and it is difficult to analysis it with the traditional detection methods. Using the characteristics of non-linear, sensitivity and so on, chaotic detection method can detect the weak signal form strong noise. This paper studies the detection of electrical harmonics based on chaotic detection. The main work of this paper:The thesis analyzes the performance of L-Y oscillator, such as the discrete step, the accuracy of bifurcation value, the signal-to-noise ratio(SNR), the transition of phase state and so on through the simulation; Analyzes each chaotic distinction method, and in view of the question of the distinction of the distance of the spot in the path to the central spot, proposing a method which can decrease the misjudgment and reduce the time of judgment, the simulations show the feasibility and effectiveness;The thesis also analyzes each kind of frequency and phase examination method, and analyzes the possibly question of the method of chaotic oscillator array, and processing one solution, reduces the phase detection error, simulation results under different SNR verified the validity. Knowing that the oscillator is more sensitive to the frequency than the phase, this paper gives one solution of the unknown frequency and unknown phase signal detection, simulation results verified the validityThis paper presents a multi-frequency signal detection method, and directly used it in the power harmonics detection, the low-order harmonics can still be detected, but the high-order harmonic detection error is greater, because this proposal didn't use the advantage of chaotic oscillator detection methods effectively.The FFT method can rapidly and accurately detect the low-order harmonics but the detection error of high-order harmonic in low SNR is greater, while chaotic oscillator detection method can detect the weak signal from a strong noise. This paper proposed the solution which combines FFT methods and chaotic oscillator detection method. The simulation results show that this proposal can greatly reduce the detection error of high-order harmonics in low SNR and it's an effective detection method for power system harmonics.This paper also uses a method based on chaotic detection and the sliding time window to detect the transient harmonics in single-phase circuit simulations show the effectiveness.