【正文】 研究的基礎(chǔ)就是由于標(biāo)準(zhǔn)或非標(biāo)準(zhǔn)的沖擊波對(duì)變壓器線圈產(chǎn)生的暫態(tài)響應(yīng)的研究。為了合理地設(shè)計(jì)線圈的絕緣結(jié)構(gòu)，設(shè)計(jì)者需要了解每一個(gè)變化過程，至少是線圈的每一部分的暫態(tài)電壓變化過程，或者是線圈每一部分與其相鄰線圈線圈部分之間的暫態(tài)電壓變化過程。為了確保變壓器正常運(yùn)行時(shí)的電壓值在耐雷電沖擊電壓之下，對(duì)比標(biāo)準(zhǔn)和非標(biāo)準(zhǔn)雷電波下絕緣特性的不同是十分必要的[6]。這項(xiàng)研究在未來將被延伸到在其它非標(biāo)準(zhǔn)雷電沖擊波下絕緣特性的研究中，例如衰減波形和遞增振蕩波形。基于這些大量研究的必要性，相關(guān)測試標(biāo)準(zhǔn)應(yīng)該相應(yīng)的改變。電力變壓器在納秒級(jí)的波前時(shí)間內(nèi)的波過程應(yīng)該在更深遠(yuǎn)的研究中實(shí)施。基于這些大量的研究，對(duì)于制造另一種波形而不是標(biāo)準(zhǔn)波形的需要和愿望在沖擊試驗(yàn)中應(yīng)該被確定并且相應(yīng)的調(diào)整和發(fā)展。Study of Effects of Standard and NonStandard Impulse Waves On Power TransformerAbstract This paper aims to highlight the observations made on surge performance of a power transformer. The impulse test on power transformers simulates the conditions that exist in service when a transformer is subjected to an ining high voltage surge due to lightning or other disturbances on the associated transmission line. A simulated nonlinear transformer model helps to analyze the surge response under varying impulse waveforms accurately and so surge modeling of the transformer using MATLAB SIMULINK has been done. For a range of applied waves (both standard and nonstandard) and different winding connections, parison of the insulation characteristics under nonstandard lightning impulse voltage waveforms which represent actual surge waveforms encountered in the field and the characteristics under the standard lightning impulse waveform quantitatively can be made. An investigation on the transformer behavior when subjected to standard and non standard impulse waves is done in this paper. The maximum voltage to ground and maximum voltage across the coils along with the time of their occurrences against different coils for 0% tapping and 10% tapping respectively is recorded and analyzed.Index Terms Modeling, Power Equipments, Standard and Non standard impulse waves, Transformer winding.I. INTRODUCTIONMonitoring the health of power transformer is important for the reliability of electrical power supply. Impulse tests are an efficient quality control tool, performed on power transformers to assess their insulation integ rity [1]. Transformer insulation is determined to a great extent by the transient voltages and stresses which appear in the transformer winding [2]. Varying impulse voltages with long wave shape and large magnitude may be due to switching fault, lightning surge or by mercial impulse voltage test in the laboratory [3]. In case of lightning impulse voltage test, standard waves shape of [4]. When the transformer is tested with standard wave shape, due to part winding resonance, the winding insulation is stressed with (unidirectional and bidirectional oscillatory) nonstandard waves. Also in practice all the ponents in a power system are stressed with transient over voltages of a wide variety of wave shapes caused by lightning as well as switching. Hence, it is necessary to estimate the dielectric strength of the insulation under these non standard impulse wave shapes [4].More than 50% of the failures in power transformers are due to insulation failure in windings [4]. To design the insulation it is necessary to know the voltage appearing across the insulation (as a function of time) and the strength of insulation against the particular voltage wave [2]. A SIMULINK model is constructed on the basis of the design data of a practical 3 MVA, 33/11 kV three phase transformer [2]. The main winding constitutes of 80 coils and 8 extra coils are used as tap coils [5]. The study of the behavior of the transformer winding with one grounded end is done when stressed by standard impulse voltage wave (),chopped impulse waves chopped at 3 181。s, 8 181。s and 15 181。s and nonstandard impulse waves. The basis of the transient studies is calculation of transient responses due to application of standard and non standard impulse wave to the transformer winding.II. THE FRAME WORK OF INVESTIGATIONDuring the investigation, the winding is excited with different impulse waves and the potential to ground along with time of occurrence for the coils and potential across the coils with time of occurrence is observed at different parts of the winding for the Simulink based model. The response of the Simulink based model is studied with low resistance with special reference to the tap windings during open end condition (0% tappings) and when the tap windings are in series with the actual winding (10% tappings) against impulse voltage waves. The characteristic curve showing the variation of maximum voltage to ground and their time of occurrence along the winding and variation of maximum voltage across the coils and their time of occurrence along the winding with applied full voltage, chopped impulses at 3 181。s, 8 181。s and 15 181。s, pulsed wave and two impulse waveforms varying in time to chop with damping oscillations are drawn for both 0% tapping and 10% tapping.In Fig. 1, (A) and (B), the characteristic curve shows the variation of maximum voltage to ground and their time of occurrence along the winding with applied full voltage,chopped impulses at 3 181。s, 8 181。s and 15 181。s, pulsed wave and two impulse waveforms varying in time to chop with damping oscillations for 0% tapping.A parative study has been done on the surge response of the coils and the observations are tabulated in Table I.In Fig. 2, (A) and (B), the characteristic curve shows the variation of maximum voltage to ground and their time of occurrence along the winding with applied full voltage,chopped impulses at 3 181。s, 8 181。s and 15 181。s, pulsed wave and two impulse waveforms varying in time to chop with damping oscillations for 10% tapping.A parative study has also been done on the response of the coils to applied full voltage, chopped impulses at 3 181。s, 8 181。s and 15 181。s, pulsed wave and two impulse waveforms varying in time to chop with damping oscillations for maximum potential to ground with time of occurrence and 10% tapping. The observations are tabulated in Table II.In Fig. 3, (A) and (B), the characteristic curve shows the variation of maximum voltage across the coils and their time of occurr