Resonance Analysis of a Transmission Power System and Possible Consequences of its Undergrounding

Abstract

Presently there is a great interest in underground cable transmission lines in extra high and high voltage level networks. The undergrounding of the transmission system can lead to the decrease of the resonance frequencies resulting in high overvoltages and possible power system component damages. It is therefore necessary to analyze possible resonance problems in the mixed power transmission system. In this work a frequency dependent model for transmission systems is implemented and the frequency scan results are presented. In order to gain a better understanding of the nature and extent of the resonance, a resonance mode analysis is also executed. The proposed procedure is tested on two examples: a ten-node power system and the Swiss extra high voltage (EHV) power transmission system. Power systems comprising solely overhead lines and different variations of mixed power system are examined.

Frequency scans and resonance mode analysis for resonance problems identification in power networks in presence of harmonic pollution

“…Indeed, harmonic sources are now well identified, but for some DSOs, the difficulties in measuring the harmonics' propagation in networks imply that the link between these harmonics, network resonances and their potential effects is uncertain in many practical cases. Furthermore, the coupling of network levels with transformers permits resonances to "propagate" from one network level to another [3], and this phenomenon increases the resonance analysis study's complexity. In the transmission system e.g., resonances have already been experienced.…”

“…The consequence of this problem was malfunctioning of the ripple control used for public lighting. In HV subtransmission systems, the trend to increasingly undergrounded networks is expected to change the resonance frequencies since undergrounded (UG) cables are more capacitive than overhead (OH) lines [3]. In distribution systems, smart grid devices like smart meters, which use PLC to communicate, are more prone to interference in cases where there is a high penetration of decentralized generation.…”

The Frequency Characteristics of Mixed Power Networks with Partial Undergrounding

“…Reference [9] addresses the possible reduction in the networks' resonance frequencies due to the presence of cable sections. This reduction can lead to the serious damage of some power system components.…”

“…The effect of the cable sections on the electromagnetic transients in high voltage networks has been thoroughly investigated in several references such as [8][9][10][11][12][13]. In [11], the transient voltage stresses in a 400-kV cable network are analyzed.…”

“…There is a growing interest in the new concept of the partial undergrounding of high voltage networks comprising overhead transmission lines [1][2][3][4][5][6][7][8][9][10][11][12][13]. It is defined as the replacement of parts of these lines by adequate underground cable sections.…”