文档介绍:供电质量的指标释义及标准
of rural drinking water sources, protection of drinking water sources in rural areas by the end of偏差限值见表1。
(2)电压波动和闪变:
在某一时段内,电压急剧变化而偏离额定值的现象,称为电压波动。电压变化的速率大于1%/s的,即为电压急剧变化。电压波动程度以电压在急剧变化过程中,相继出现的电压最大值与最小值之差或其百分比来表示,即:
式中Ue--额定电压,V
Umax、Umin--某一时段内电压波动的最大值与最小值,V
周期性电压急剧变化引起电光源光通量急剧波动而造***眼视觉不舒适的现象,称为闪变。通常用引起闪变刺激性程度的电压波动值--闪变电压限值ΔUv或电压调幅波中不同频率的正弦分量的均方根值,等效为10Hz值的1min平均值--等效闪变值ΔU10来表示。电力系统供电点由冲击功率产生的闪变电压应小于ΔU10或ΔUt的允许值,否则将会出现闪变。
电压波动与闪变限值见表1。
(3)电压正弦波畸变率:
在理想状况下,电压波形应是正弦波,但由于电力系统中存在有大量非线性阻抗特性的供用电设备,这些设备向公用电网注入谐波电流或在公用电网中产生谐波电压,称为谐波源。谐波源使得实际的电压波形偏离正弦波,这种现象称为电压正弦波形畸变。通常以谐波来表征。电压波形畸变的程度用电压正弦波畸变率来衡量,也称电压谐波畸变率。电压谐波畸变率以各次谐波电压的均方根值与基波电压有效值之比的百分数来表示:
of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities
of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities
of rural drinking water sources, protection of drinking water sources in rural areas by the end of the delimitation of the scope of protection, complete with warning signs, isolating network protection facilities
式中Un--第n次谐波电压有效值,V
U1--基波电压有效值,V
公用电网谐波电压限值见表1。
(4)负