Resonant overvoltage

For the particular value of the frequency of equation 4, the current I and the voltage V are in phase (P.F = 1.0) and current-voltage relationship agree with Ohm s law. Analyzing the resonant circuit in Fig. 11 is obtaining resonance overvoltage. 

Fig. 3.6.1. High resistance grounded scheme to avoid resonance overvoltages. 

The low resistance neutral grounding scheme at just one source of generation in industrial power systems creates favorable conditions for resonance overvoltages. 

Resonance overvoltages can be avoided by the use of a proper grounding method. All energy sources, generator and transformer, must be grounded. It is necessary to consider the protection scheme and the interconnection s characteristics of the electrical power equipments to avoid failures. 

J. A. Halladay and C.H. Shih. (1985). Resonant Overvoltage Phenomena Caused by Transmission Line Faults. IEEE Transactions on Power Apparatus and Systems, p>p. 2531-2539, Vol. PAS-104, No. 9, September 1985 J. Fuentes Rosado. (1988) Sobretensiones Resonantes en Sistemas de Transmision. Tests de grado de maestria. SEPI-ESIME Instituto Politecnko Nacional, Mexico, 1988 J. R. Dunki-Jacobs, (1977) State of the Art of Grounding and Ground Fault Protection. IEEE 24t>> Annual Petroleum and Chemical Industry Conference, Dallas, TX, September 12-14, 1977... 

When harmonic filter circuits are connected to a power system with saturated reactors (Figure 27.2(e)) resonance may occur between the reactor and the filter capacitors to give rise to overvoltages. 

Now the situation is different, as resonance and ferro-rcsonance effects in the series inductive-capacitive circuits may cause dangerous overvoltages. 

Figure 20.8 Case of a ferro-resonance in a residual VT leading to overvoltages even In a healthy system...

It has been observed that the series resonance can occur in potential transformers (IT). In this case overvoltages were also presented by the series resonance phenomenon. 

Tempoinry overvoltage 2, Harmonic Some 100 Hz/1-100 ms Resonance, mmlinear/ fenoresonance... 

Equation 3.91 shows that the overvoltage contains two frequency components the nominal frequency co and the resonance frequency coq- Since the overvoltage is caused by the superposition of two frequency components, the resulting overvoltage is oscillatory and its level is often difficult to estimate before the simulation. The result of a simulation performed on the Shin-Toyosu line is shown in Figure 3.21. 

Various transient studies have been performed on the 400-kV cable that will connect Sicily to mainland Italy [28,29]. In addition to switching transients, these studies include the harmonic overvoltage caused by line energization, leading current interruption, and zeromissing phenomena. The studies identified the resonant condition at the second harmonic when the cable is energized from Sicily s side under a particular condition. The harmonic overvoltage caused by the resonant condition is avoided by the operational constraint. 

Colla, L., S. Lauria, and F. M. Gatta. 2007. Temporary overvoltages due to harmonic resonance in long EHV cables. International Conference on Power System Transients (IPST) 233, Lyon, France. 

The capacitance is not negligible in high-frequency switching operations. In most cases, the transient overvoltage generated in a switching circuit is caused by resonance between the capacitors and stray inductors in the switching circuit. 

---