Relevant Challenges and Lessons Learned from the Kimal-Lo Aguirre HVDC Project in Chile

Electrical Coordinator (CEN). These requirements imposed several non-standard operating conditions for the HVDC scheme, including connection to a weak 220 kV AC system, operation at reduced DC voltage with nominal current, daily DC power reversal, and the use of a shared dedicated metallic return.

To address these requirements, the project adopted detailed electromagnetic transient (EMT) studies using manufacturer-grade control and protection models, complemented by steady-state, short-circuit, harmonic, and grounding analyses. The results of these studies revealed a number of technical challenges related to transient recovery voltage (TRV) performance of AC circuit breakers, AC/DC interaction under low short-circuit ratio conditions, non-nominal firing and extinction angles, harmonic amplification, grounding system performance in extremely high resistivity soils, the availability and resilience of auxiliary services under disturbed operating conditions, and operational risks associated with the dedicated metallic return.

This paper presents the most relevant challenges identified during the design stage, the methodologies applied to evaluate them, and the mitigation measures adopted to ensure compliance with regulatory requirements and long-term system reliability. The lessons learned from the Kimal–Lo Aguirre project provide valuable guidance for future HVDC developments connected to weak AC systems and subject to stringent regulatory constraints.