Sharing reserves through HVDC: Potential cost savings in the Nordic countries

During summer 2018, the Nordic system’s kinetic energy dropped below a critical level.As a consequence, Svenska kraftnät, the Swedish transmission system operator, requestedthe largest production unit to reduce its power output to guarantee system’s security. Thisaction resulted in a deviation from the generation dispatch determined by the market and inhigh costs for the Nordic transmission system operators. In this regard, this paper presentsa tool for comparing mitigation strategies from an economic point of view and evaluatespotential economic benefits of utilizing the emergency power control functionality of high-voltage direct current lines for the provision of fast reserves as a compliment to frequencycontainment reserves. Moreove r, the analysis is extended to the years 2020 and 2025 usinginertia estimations from the Nordic transmission system operators. The findings of thepaper sugg est that the frequency of redispatching actions will increase in the future andthat the cost of security for Nordic transmission system operators could be reduced by70% if high-voltage direct current links are used for frequency support.