The paper discusses a solution that facilitates an improved functionality of the Coordinated Reactive Power – Voltage Controller (CQVC), used for coordinated control of voltage (V) and reactive power (Q) at the power plant that enables Transmission System Operator (TSO) real time insight into the power plant contribution to voltage ancillary service. The main CQVC role is to perform slow HV busbar voltage control by automatic adjustment and sharing of Q among generators. Additionally, the CQVC also performs the following functions in real time: i) calculates total minimum and maximum reactive power available at the power plant, ii) monitors power plant reactive power output, iii) calculates dynamic reactive reserves of each generator and power plant as a whole, iv) determines the price region that each generator operates within. All these data the CQVC communicates to TSO thus enabling the realistic recognition of each generator/power plant contribution (participation) to voltage control and also enabling the system voltage stability reserve evaluation. The goal is to provide TSO data that will allow adequate reactive power reserve management and, at the same time, maximize benefits to society at large by fare reactive power pricing. The proposed solution additionally enables control and monitoring of busbar voltage of any local voltage control area.