Análise das causas de disparos nas linhas de alta tensão de 110 KV CL4 e CL5 da região sul de Moçambique e proposta de mitigação

Abstract

This work aims to analyse the causes of tripping events recorded on the 110 kV transmission lines CL4 and CL5, located in the southern region of Mozambique, with the objective of increasing the reliability and continuity of service of the electric power system and proposing mitigation solutions. The research highlights the need to replace static relays with digital relays, which offer improved directionality, greater selectivity and advanced communication capabilities to support modern protection schemes. The implementation of OPGW cable is also recommended, as, in addition to providing shielding against lightning strikes, it enables fast and secure teleprotection between the ends of the lines. The adopted methodology was based on the analysis of real operational data, outage durations and protection operation records, complemented by a simulation of the specific case involving the operation of the static distance relay, compared with digital relays, allowing the proposal of new settings. The causes of other fault events were also analysed, and it was verified that most trips result from single-line-to-ground faults, followed by phase-to phase faults and, less frequently, three-phase faults. Given the strategic role of these lines in the interconnection with South Africa, the proposed technical measures contribute to improving continuity indicators and reinforcing the stability of the Power System. Finally, a continuous monitoring and preventive maintenance plan is presented, aiming to reduce faults, optimize protection operation, and ensure greater safety and efficiency in network operation.