中文摘要：

固体绝缘的表面是高压电力设备绝缘的最薄弱环节,很多绝缘事故都是由沿面放电造成的。发生放电后,电荷会在绝缘表面积聚,会很大程度上影响下一次放电的产生与发展。为此,通过观测在极性交替变化的冲击电压作用下沿同轴圆柱形聚对苯二甲酸乙二醇酯（PET）绝缘表面放电的发展以及测量放电后表面残余电荷电位的分布,来研究残余电荷对沿面放电的影响。研究表明,在改变冲击电压的极性后,由于反极性残余电荷的影响,放电会被促进,放电通道会沿着前一次放电的通道向前发展,并且会比前一次放电距离略长,放电的强度会增强,放电的发展速度也会加快。在沿着放电通道方向,表面电荷电位梯度可以明显分为两部分：在放电头部的20mm区域,电位梯度较大,为流注放电;而在后面的主干部,电位梯度平缓,为先导放电。

英文摘要：

For a high-voltage electrical apparatus,its surface insulation is always the weakest point,and many accidents are initiated from surface discharge.After the discharge,charges accumulate on the insulator surface,and these residual charges will significantly influence the onset and development of the subsequent discharge.Therefore,we studied surface discharges on the polyethylene terephthalate（PET）film with a coaxial cylindrical configuration by high speed camera under impulse voltages with alternate voltage polarity,and measured the surface potential distribution induced by residual charges after discharges by an electrostatic probe.With the residual charges from surface discharge with opposite polarity,the subsequent discharge propagates by partly following the path of the previous discharge.The discharge current of the surface discharge will be strengthened by the residual charges with the opposite polarity.Along the direction of discharge channel,the surface charge potential distribution can be divided into two parts,i.e.,20 mm area ahead of discharge with bigger potential gradient,to be streamer discharge,and smooth potential gradient area along the main channel of discharge,to be leader discharge.