气压湿度对负直流电晕特性影响的研究

Effects of Air Pressure and Humidity on the Characteristics of Negative DC Corona

为得到负直流电晕特性随着气压湿度的变化规律,建立了考虑气压湿度影响的负直流电晕起始电压的物理模型,利用模拟电荷法和计算表面光电子数目的方法求解了负直流电晕起始电压。在人工气候罐中,利用棒–板电极,测量了不同气压湿度下的负直流电晕起始电压和电晕电流。计算和试验结果表明:电晕起始电压随气压下降、湿度升高而减小,主要原因分别是有效电离系数增大导致的电离区域的扩大和高场强区域内碰撞电离能力的增强。当直流电压和电晕起始电压的比值一定时,电晕电流随气压下降、湿度升高而减小;当直流电压一定时,电晕电流随气压降低而增大,随湿度升高而减小。电晕电流和直流电压、电晕起始电压关系式中的系数C随湿度增大的不同变化趋势和正负离子与水分子结合状态的差异有关。

In order to obtain the characteristics of negative DC corona under various pressure and humidity, a physical model of the inception voltage for negative DC corona was set up, and the voltage was computed with charge simulation method and based on the calculation of electron photos on the surface of electrodes. The inception voltage and corona current of negative DC corona under different air pressure and humidity conditions were measured with a point-to-plane electrode system in an artificial climate chamber. Corona-inception voltage decreased with the reduce of air pressure or the increase of humidity, for which the main causes are the expansion of ionization zone and strengthening of collisional ionization intensity respectively, resulting from the increase of effective ionization coefficient. Corona current also decreased with the falling of pressure or the rising of humidity when the ratio of DC voltage to corona-inception voltage was kept constant; furthermore, it increased with the falling of pressure or decreased with the rising of humidity under the same applied voltage. The coefficient C in the relationship among corona current, DC voltage and corona-inception voltage was concerned with the combinative state of ions and water molecules.