| With the rapid development of EHV and UHV transmission technology and the raise of global energy interconnection,a great quantity of EHV/UHV transmission lines will be built in high altitude area.The audible noise(AN)prediction is one of the key techniques for electromagnetic environment control.Since the corona discharge will become more serious and the audible noise will be more apparent with the elevation,the characteristics and prediction research of audible noise become more and more important.In this dissertation,audible noise of transmission lines is studied from two aspects:one is the noise mechanism and another is noise prediction,the main work and contributions are as follows:Based on the corona cage test system and Brtlel&Kjaer data acquisition system,the time-domain characteristics of audible noise are measured and studied from the corona discharge on the tip of a test line which located in an electromagnetic shielding room.Then the influence of voltage on audible noise pulse parameters are discussed.By comparing the time-domain waveforms of different tips,the influence of tip curvature radius on pulse amplitude and frequency are investigated.The acoustic power of nineteen types of bundle conductors in fair and heavy rain weather conditions are studied in a high altitude corona cage platform.The influences of different factors on acoustic power are investigated,such as conductor surface electric field,bundle numbers and sub-conductor diameter.Through fitting and analyzing the acoustic power data of different bundle conductors by IBM SPSS Statistics,the prediction method of acoustic power from AC transmission line at Xining altitude is derived.The acoustic power of six types of bundle conductors are studied in a mobile corona test cage in seven areas with different altitudes.The influences of altitude and air density on acoustic power are investigated.Through fitting and analyzing the multiple elevation measured data by multiple linear regression method,the prediction method of acoustic power from AC transmission line is derived.After that,the accuracy of the proposed method is proved by comparing the measured data witih the caculated data.The main conclusions of this paper are valuable in theory and engineering,and those could provide theoretical foundation and technical support for acoustic power prediction of the AC transmission line under high altitude condition. |
