Energy generation evolves quickly towards a significant share of renewable sources, with increased challenges regarding the system stability and provision of ancillary services, including the non-mandatory voltage control (NMVC) by generators. Under these circumstances, accurate measurement solutions are required to support competition and increase the quality of such services. Current measurement solutions for these services are based on EMS-SCADA applications. This paper proposes more accurate solutions for measuring voltage secondary control services by using metrology energy meters with 1 minute load-profiles (LP01) and specific on-line/off-line computations. Measurement of active and reactive energy with meters, combining them with additional computations, can provide accurate determination of ancillary services, including within virtual power plant (VPP) aggregations. This paper presents a novel methodology for evaluating the reactive power resources based on a generalized four quadrant chart of electrical energy units that provide simultaneous P and Q control services, with mandatory/non-mandatory zones. Simulations show good accuracy (0.5% or better) of the NMVC service quantities based on LP01 metrology measurements, suggesting that such meters may be capable to measure regular active and reactive energies simultaneously with ancillary services such as non-mandatory voltage control.