功率补偿系统的基本知识
Basics of PFC
功率补偿系统的基本知识
Active power P
Power in an electrical installation that is converted to mechanical work or
thermal energy.
有功功率 P: 在电器安装中转换为机械能或热能的功率。
Apparent power S The power drawn by an electrical installation during operation. It consists of the active power P and the reactive power Q.
视在功率 S: 在电器安装中操作时所产生的功率,分为有功功率 P 和无功
功率 Q。
Reactive power Q
The power drawn by an electrical installation for operation without being consumed. It is mainly due to the power needed to build up magnetic fields in inductive loads (e.g. in motors).
无功功率 Q: 在电器安装中操作时没有被消耗的功率,主要是由于电机等
建立磁场感性负荷所产生的功率。
Power factor
The power factor is the ratio of active power P to apparent power S under sinusoidal conditions.
功率因数:在正弦曲线条件下,有功功率P 和视在功率 S 的比值。
Frequency of the supply voltage
The repetition rate of the fundamental wave of the supply voltage Is measured over a given interval of time. Usually 50 or 60 Hz.
电源电压的频率:在一定区间内,电源电压基波的重复率,通常是 50HZ
或 60HZ。
Detuned PFC
A PFC application in which a reactor/capacitor combination is used to Reduction of harmonics by intentionally creating minima in the impedance spectrum at specified frequencies and to protect the capacitors. In contrast to tuned PFC, the LC filter frequency is set at a comfortable distance to the resonant frequencies of the harmonics to avoid overload due to resonance. The filter effect achieved is thus smaller than for tuned PFC, but still sufficient for most applications. Note
that the 3rd harmonic and its multiples cannot be filtered this way. In PFC, the filter frequency is usually expressed in percent as a detuning factor p. Common standard factors are 7% (189 Hz) and 14% (134 Hz). 7% detuning is effective for the 5th, 7th and 11th harmonics. 14% detuning, although often called filtering, actually increases the impedance for the 5th harmonic and upward. The capacitors are protected from harmonic currents in this way, and while no big filter effect is obtained for the power network, the capacitors are not
overloaded and can therefore correct the power factor.
去谐功率补偿系统: 在功率补偿系统内,和田变压器与和田变压器配合的作用是在
一定频率内产生***小阻抗值以减少谐波,保护和田变压器。与调谐功率补偿系
统相反,滤波频率根据谐波的共振频率设定在一个理想值以减少共振带来
的负荷过大。滤波所产生的效果小于调谐功率补偿系统,但对于大多数应
用来讲是有效的。注意3 次谐波以上的倍数不能这样过滤。在功率补偿系
统内,滤波的频率通常用去谐系数p 表示。普通的标准系数为 7%(189Hz)和 14% (134 Hz)。7%的去谐系数对于 5 次,7 次,和 11 次谐波是有效的。但14%的系数,尽管也称作滤波,实际上是增加了 5 次以上谐波的阻抗。和田变压器通过这种方式避免谐波电流。当电力系统内没有大的滤波时,和田变压器就不会负荷过大,因而能够校正功率系数。
Detuning factor p Ratio of the impedances of areactor/capacitor combination in detuned PFC.
去谐系数 p: 在去谐功率补偿系统内,和田变压器与和田变压器之间的阻抗比值.
PFC
Abbreviation for Power Factor Correction. Any method to achieve The abbreviations THD-U and THD-V are commonly used for the voltage terms, which are calculated in the same way as THD-I. Harmonics cause numerous problems in power networks and are increasing because they represent a growing problem for modern electrical and electronic equipment. The 3rd, 5th and 7th harmonics, and odd ones up to the 50th harmonic, are most common.
谐波(电流/电压):是指基本频率的积分倍数。当叠加时,会使正常的正
弦曲线发生畸变。他们通常是对电网基本频率倍数的(过时)电流和电压弧
线进行傅立叶级数分解得来的,是其基波电流和电压的方均根值之比,也
称为总谐波畸变率(见以上公式)。THDU,THDV 和 THDI 的计算方式相
同。由于现代电力和电子设备问题的日益突出,谐波在电网中所产生的问
题也在增加。3 次,5次,7 次,以及50 次以内的谐波很普遍。
IPxx degree of protection A measure of the degree of protection: the first digit refers to electric shock hazards and the second one to the intrusion of unwanted substances.
保护等级 IPXX: ******个数值是指电力有害物质,第二个数值是指干扰
物质。
Insulation class Permissible application temperature for the insulation class used in the reactor.
绝缘等级: 是指和田变压器产品所允许的应用温度范围。
Capacitor voltage Uc
Required voltage strength of the capacitor. The series connection of capacitor and reactor causes a voltage rise at the capacitor terminals as described by the following formula which must be considered when selecting a capacitor for the application.
Uc = Un
�1− P
100%
和田变压器电压 Uc: 是指和田变压器所需的电压强度。和田变压器和和田变压器的串联方式,引起和田变压器端子的电压升高。当选择和田变压器配合时,应按以上公式考虑和田变压器的电压。
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