IEEE 1159:2009 pdf free download

IEEE 1159:2009 pdf free download.IEEE Recommended Practice for Monitoring Electric Power Quality.
4.4.1.2 Oscillatory transient
An oscillatory transient is a sudden. nonpower frequency change in the steady-state condition of voltage. current, or both, that includes both positive and negative polarity values. An oscillatory transient consists of a voltage or current whose instantaneous value changes polarity rapidly. It is described by its magnitude, duration, and spectral contcnt tpredomrnantly frcquency, i’hc spectral content subcbsscs defined in Table 2 are high. medium, and low frequency. The frequency ranges for these classifications are chosen to coincide with common types of power system oscillatory transient phenomena,
As with impulsive transients, oscillatory transients can be measured with or without the fundamental frequency component included. When characterizing the transient, it is important to indicate the magnitude with and without the fundamental component.
Oscillatory transients with a primary frequency component greater than 500 kllz and a typical duration measured in microseconds (or several cycles of the principal frequency) arc considered high-frequency oscillatory transients. These transients are almost always due to some type of switching event. frequency oscillatory transients are often the result of a local system response to an impulsive transient.
Power electronic devices can produce oscillatory voltage transients as a result of commutation and RLC snubber circuits. The transients can be in the high kilohertz range, last a few cycles of their fundamental frequency, and have repetition rates of several times per 60 Hz cycle (depending on the pulse number of the device) and magnitudes of up to 0.1 Pu (less the 60 Hz component).
A transient with a primary frequency component between 5 kllz and Sot) kHz with duration measured in the tens of microseconds (or several cycles of the principal frequency) is considered a medium-frequency transient, Hack-to-back capacitor cnergization results in oscillatory transient currents in the tens of kilohertz, This phenomenon occurs when a capacitor bank is energized in close electrical proimiIy to a capacitor bank already in service. The energized bank sees the decncrgized bank as a low-impedance path (limited only by the small inductance of the bus to which the banks arc connected). Figure 2 illustrates the resulting current transient due to back-to-back capacitor switching. Cable switching results in oscillatory voltage transients in the same frequency range. Medium-frequency transients can also be the result of a system response to an imupukive transient.