特高压变压器绝缘配合 英文

特高压变压器绝缘配合

UYFIUOIOHOIHI]

特高压变压器绝缘配合

A. LOKHANIN

(联邦国家统一公司全俄电工研究所，莫斯科 111250，俄罗斯联邦)

Insulation Coordination of UHV Transformers

A. LOKHANIN

(Federal State Unitary Enterprise “All-Russian Electrotechnical Institute, named after V. I. Lenin” (FGUP VEI),

Moscow 111250, Russian Federation)

ABSTRACT: Researches and development of the insulation of UHV transformers should take impact of the operating voltage into consideration. Operating voltage can seriously influence the over-voltage, arising from the transformer under the lightning impulse. Impact of an operating voltage on impulse over-voltage strength in the transformer is analyzed. Necessity of the operating voltage defined by the test voltage of the lightning impulse for UHV power transformers is pointed out. Through researches the maximum permissible operating voltage for the main isolation of UHV transformers is obtained. It is concluded that the value of long-duration test voltage for the examination on insulation capability at long-duration operating voltage should be within the range of 1.3~1.5 Uphm. KEY WORDS: transformer; insulation; operating voltage; over-voltage; lightening impulse

摘要：特高压变压器绝缘的研究和开发应该考虑工作电压的 影响。工作电压会严重地影响变压器遭受雷击时产生的过电 压。分析了变压器的工作电压对冲击电压强度的影响；指出 了雷电冲击试验电压定义下的工作电压对于特高压变压器 的必要性；通过研究得出了特高压变压器的主绝缘的最大许 用工作电压。研究结果表明用于检查长时间工作电压的长时 耐压试验的绝缘能力值限制在 1.3~1.5 Uphm。

关键词：变压器；绝缘；工作电压；过电压；雷电冲击

表 1 500、750 和 1 150 kV 变压器的雷电冲击值

Tab. 1 Values of lightning impulse for transformers (500, 750 and 1 150 kV)

voltage

highest voltage for equipment Um/kV 525 0.28 (0.33)

787

1200 525*

900 0.48

1550 (1300) 2100 (1800) 2250 Impulse voltage(BIL) Um0.3 (0.36) 0.43

Note:*denotes experimental design.

research and development on the insulation of UHV transformers should take impact of the operating voltage into consideration.

1 DEMAND OF LIGHTNING IMPULSE

VOLTAGE

Operating voltage can seriously influence the over-voltage, arising from the transformer under lightning impulse.

Voltage values on winding terminals of the transformer are shown in Fig.1- the impulse voltage of opposite polarity and the impulse voltage of the same polarity and in Fig. 2-voltage distribution along a winding with the earthed neutral at the opposite polarity lightning impulse (a), at the same polarity with applied working voltage (b) and without operating voltage (c).

The degree of influence from an operating voltage depends on the ratio between the operating voltage and the lightning impulse during the moment of its application, and also from ratio of stresses between lightning impulse and operating voltage. In particular, the ratio between lightning impulse stresses on longitudinal insulation of transformer at applied

0 INTRODUCTION

One of the most distinctive features required by UHV electric equipment is the marked increase in a ratio between the value of operating voltage and that of test voltage. As shown in Tab. 1, for transformers with a rated voltage of 1 150 kV, this ratio would be 0.43; while for those with the voltage of 500 kV and 750 kV, it would be 0.3~0.35, which means that the

特高压变压器绝缘配合

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(a) the impulse voltage of

opposite polarity

(b) the impulse voltage of

the same polarity

G/%

20

10

图 1 施加与工作电压相反极性和相同极性的冲击电压时

励磁变压器绕组端电压

Fig.1 Voltage on terminals of a winding of the excited transformer at impulse in case of opposite polarity and the same polarity of impulse of an

operating voltage

number of coils

1—Overvoltage in the HV winding at exicitation of transformer, with the opposite polarity of operating voltage; 2—Overvoltage in the HV winding

without excitation of transformer.

UM

U3(x) U6(x)

Uph Uphm

x

1.0

U8(x)

U1(x) U2(x) U4(x) U5(x)

图 3 在 Uph/Ui =0.525，60 MVA, 220/110 kV 变压器

遭受雷电冲击全波纵向绝缘模型的脉冲强度

Fig. 3 Impulse stresses at full lightning impulse in the longitudinal insulation of the model of power transformer

(60 MVA, 220/110 kV ), when Uph/Ui =0.525

100 80 U/%

1 2

U

3 4

U7(x) 0 Uphm

60 40

6.3 MC

t

U8(х)—distribution of operating voltage before applying lightning

impulse; U6(х), U7(х), U5(х)—initial distribution of voltage accordingly at absence of excitation, at reverse and at identical polarity of an impulse and an operating voltage;U4(х)—final distribution of voltage; U2(х), U1(х), U3(х) —envelope curve of potentials at absence of excitation (U2), at reverse (U1) and identical polarity (U3) of an impulse and an operating voltage; Uph— operating voltage to еarth;Uphm—highest operating voltage to еarth.

20 0

A

A

0 8

16 24 number of coils

32

图 2 中性点接地绕组电压的分布

Fig. 2 Distribution of voltage along a winding

with the earthed neutral

1—Overvoltage in the HV winding at excitation of transformer and with opposite polarity of operating voltage; 2—Overvoltage in the HV winding without excitation of transformer; 3—Oscillogram of overvoltage in the HV winding at excitation of transformer and with opposite polarity of operating voltage; 4—Oscillogram of overvoltage in the HV winding without

excitation of transformer.

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