Simulation and Fault Detection for Aircraft IDG System

Transcription

1 Available online at Procedia ngineering 15 (011) Advanced in Control ngineering and Information Science Simulation and Fault Detection for Aircraft IDG System Tao JING, Chengyu YANG, Yaowen Yang, Xudong SHI a* a Civil Aviation University of China, Tianjin, , China Abstract The research of the simulation and fault detection for Aircraft Integrated Drive Generators (IDG) is shown in the paper, the working principle of IDG is analyzed in detail and the simulation system is established in Matlab. The method of Short-Time-Fourier Transforms (STFT) is used for the aircraft IDG fault detection by checking the aircraft IDG voltage-output swing. 011 Published by lsevier Ltd. Open access under CC BY-NC-ND license. Selection and/or peer-review under responsibility of [CIS 011] Keyword: Aircraft IDG; Simulation system; STFT; fault detection system 1. stablished Simulation model of the aircraft main power With the great development of aviation industry, the aircraft s flight speed, altitude, range and other properties were greatly improved. With the increasing of electronic equipment on the aircraft and power consumption, the structure and controlling of aircraft power system become more and more complex. Therefore, the reliability and operating efficiency of aircraft IDG systems become more and more important, the increasingly optimized solutions and fault detection for aircraft is necessary. However, the present test method for IDG system often has to spend lots of manpower, material and time. The aircraft IDG systems will be simulated while an aircraft electrical loads changes in various stations with computer is effective and convenient, and the model of IDG system will be established based on actual working conditions. * Xudong SHI. Tel.: mail address: jingtao100000@yahoo.com.cn Published by lsevier Ltd. doi: /j.proeng Open access under CC BY-NC-ND license.

2 534 Tao JING et al. / Procedia ngineering 15 (011) Modeling and Analysis Aircraft power system is a special type of independent power supply system, its power generation capacity of the system close to capacity of electrical equipment, so some analysis of power systems for aircraft power systems are not fully applicable. With three-stage of an aircraft alternator structure, which by the pilot exciter, exciter and main generator components. Main generator is a rotating pole synchronous generator; AC exciter is a rotating armature synchronous generator; Pilot exciter is a rotating pole type permanent magnet synchronous generator. AC exciter is equipped with a rotating rectifier. The main generator s field winding power supply is the DC supply rectified the AC supply generated by the exciter armature; Figure.1 shows the block diagram of main generator: Fig. 1 Block diagram of main generator 1.. Modeling based on Matlab Based on the above analysis, we can get the three-stage generators simulation model in Matlab, is shown as Figure.: Fig. Simulation model of main generator Where: N is the figure for the three brushless AC synchronous generator input speed. The relationship between n and ω s is: ω s πn/60. Pilot exciter output three-phase power is rectified and then after the first modulated, to the AC exciter field winding Aircraft IDG fault detection The aircraft power supply systems will be affected by climate, mechanical, chemical and electromagnetic environmental as multiple factors that caused the fault of IDG, which are as follows: CSD fault will mainly lead to electrical power signal frequency sustained deviation from the 400HZ. The fault of hydraulic pump-hydraulic motor mounted system within CSD, which caused by oil pressure or temperature anomalies and some mechanical failure. The harmonic current in the AC exciter armature will produce harmonics armature reaction magnetic field. It will lead to additional losses in the core, while field winding in the exciter will induce harmonic electromotive force. The most common failure is the excitation device failure as the main fault in the aircraft generator. xcitation device failure was mainly caused by rotating rectifier short circuit (open circuit).

3 Tao JING et al. / Procedia ngineering 15 (011) This system is mainly for power generation during short circuit (or open circuit) fault analysis. As the synchronous motor by a number of the winding magnetic coupling relationship composition and there is a relative motion between the rotor winding and stator winding, the synchronous motor suddenly short circuit (open circuit) of the transient process is a complex process.. The method of Aircraft IDG fault detection based on STFT.1. Fault signal acquisition and detection system architecture According to HB , the requirements of digital test method with performance parameters of power supply system (voltage sampling frequency is not less than 0KHZ, the current sampling frequency is not less than 6.67KHz), the experimental system is built. The system has been controlled either with an Industrial Personal Computer via a data acquisition system AgilentU1071A when the arbitrary waveform generators ZTC530 send incident signal to the aircraft cable. Detection system structure diagram is shown as Figure.3: Fig. 3 Block diagram of Detection system.. Fault detection method for analysis and testing process The method of Short-Time-Fourier Transforms (STFT) is used for the aircraft IDG fault detection. The STFT method is used for the following signal simulation analyzing: abnormal baseband voltage signal, abnormal voltage with harmonic signal and an abnormal voltage signal caused by two different faults. Compare with wavelet transformation, the result of fault detection shows that STFT method is better suitable for detecting the abnormal voltage. Specific detection process is shown as Figure.4. Fig. 4 Block diagram of the method based on STFT

4 536 Tao JING et al. / Procedia ngineering 15 (011) Fault detection method for analysis and testing process Define x as the original signal, the time-frequency transformation is: + jωt S( jω) S() t e dt (1) Define Dt () and F () t as interference signal and baseband signal of the original signal. The signal separation as follow: + jωt S( jω) S() t e dt The original signal baseband signal processing by STFT: + ~ * j π fu F ~ (, t f ) F( u) g ( u t) e du STFT F (3) The most common types of fault signal processing results is shown as Figure.5: () (a) Overvoltage Fault (b) Undervoltage (c) Underfrequency Fault (d) Over-frequency Fault Fig. 5 Fault signal processing results STFT is used for identify clear reasons for its failure, the voltage without prolonged abnormal situation is found, and then calculated the interference signal Dt () for STFT: + ~ * jπ fu D ~ (, t f ) D( u) g ( u t) e du STFT D 0 (4) Get the voltage amplitude curve of the Interference signal. Then observe the time domain amplitude curve of the original signal formula: S T t0 + T t0 S() t dt (5)

5 Tao JING et al. / Procedia ngineering 15 (011) Define the period with the largest S as power quality index period T 0. Then calculate the value of P and P N, which means the ratio of transient distortion power and the normalized ratio of instantaneous electrical power distortion. Finally calculate the functional relationship between P and P N : 1 D ~ () t dt 0 STFT D P 100% F ~ () t dt 0 STFT D 1 D ~ () t dt 0 STFT D P N 100% T 0 D ~ () t dt F ~ + () t dt 0 STFT D 0 STFT D P PN 1 + P The calculations indicate that as the value of P gets smaller, the value of P N and P will slowly get closer. The similarity coefficient of the value of P N and P A ( A P PN ) is defined, which is the instantaneous mass index of the electrical power, means the higher quality of the electrical power as the value of A is smaller. (6) (7) (8) 3. Conclusions The simulation of the system is completely established according to the real working principle and structure of aircraft IDG. The model of various faults is effective and simulated in the actual operation; the method of STFT is used for fault detection part, which can effectively locate and analyze the abnormal voltage and the reasons for abnormal voltage. The system also can calculate the quality of the IDG power in case of no obvious fault on IDG. References [1] Liao Yingxi, Mu Xinhua, Ge Hongjuan. Stability Study and Simulation Analysis on Aircraft Transformer Rectifier Unit (TRU) with Constant Power Load (CPL), Proceeding of ighth International Conference on lectrical Machine and Systems, Volume III, 005.9, P [] Zhu Jun, David L. Lubkeman. Object-Oriented Development of Software Systems for Power System Simulations, I Transactions on Power Systems, Vol. 1, No., May 1997 [3]Wang Kexing, Song Zhengxiang, Chen Degui, et al: Interference source identification of voltage sag in distribution system based on wavelet transform. Proceedings of the CS, 003, p [4] A. M. Gaouda, M. M. A. Salama, M. R. Sultan, and A. Y. Chikhani, Application of multiresolution signal decomposition for monitoring shortduration variations in distribution systems, I Trans. Power Del.,vol. 15, no., 000, p [5] A. id, H. l-kishky, M. Abdel-Salam, T. l-mohandes. Power Quality Investigations of VSCF Aircraft lectric Power Systems. 4nd South astern Symposium on System Theory, USA, March 7-9, 010.