Pricing of mixed P-Q services in DSO flexibility markets

The rapid expansion of renewable energy resources, particularly photovoltaic systems, has led to significant operational challenges in low-voltage distribution grids, including overvoltage issues. This paper investigates the use of sensitivity factors for voltage control in distribution grids, focusing on the additivity of active and reactive power SFs. A comprehensive sensitivity factor matrix is developed to evaluate the impact of flexibility service providers on node voltages, with simulations exploring the superposition of P and Q effects. Building on this foundation, the study evaluates the cost-effectiveness of various P-Q pairings for mitigating overvoltage problems caused by residential PV systems. A pricing model for mixed P-Q services is developed, accounting for feed-in tariffs and reactive power pricing scenarios. Results showed that cost-effectiveness of mixed P-Q flexibility services hinges on the active-to-reactive power pricing ratio and temporal PV availability, with proportional pricing supporting more linear and efficient voltage control. These findings offer insights into cost-effective voltage regulation strategies for emerging DSO flexibility markets.