122 PRZEGLĄD ELEKTROTECHNICZNY (Electrical Review), ISSN 0033-2097, R. 88 NR 1a/2012 Enrique LOBATO, Ignacio EGIDO, Luis ROUCO IIT, ICAI School of Engineering, Universidad Pontificia Comillas Performance Evaluation of Ancillary Services in the Turkish Power System Abstract. This paper proposes a central monitoring system of frequency and voltage control of the Turkish Power System, consisting of a reference model that compares the real operation of the generating units with the desired behaviour established by the technical requirements of the Turkish grid code. A number of quantitative measures, based on the deviation between the real and the desired response are proposed to evaluate the adequacy of each unit behaviour. Application examples are provided using real data of different Turkish power plants. Streszczenie. W artykule zaprezentowano system monitorowania częstotliwości i napięcia w systemie dystrybucji energii w Turcji. Zaproponowano model odniesienia umożliwiający porównanie wartości rzeczywistych z wymaganymi. Wprowadzono miary umożliwiające ocenę parametrów każdej jednostki w sieci. (Ocena pomocniczych narzędzi monitorowania systemu przesyłu energii w Turcji) Keywords: Ancillary Services, Voltage Control, Frequency Control, Monitoring System. Słowa kluczowe: serwisy pomocnicze, monitorowanie, przesył wenergii, sieć dystrybucyjna. 1. Introduction Ancillary services can be defined as the set of functions related to the secure and reliable operation of a power system [1-3]. They can be classified into frequency control (active power control) and voltage control (reactive power control). The system operator is the entity responsible for the secure operation of a power system and in this way, the management of frequency and voltage control is considered a specific function of the system operator. These services are mainly provided by generators.. Active power control is designed to re-establish the necessary equilibrium between generation and demand in order to maintain the frequency of the power system within admissible bands. Active power control include primary, secondary (AGC) and tertiary (non-spinning reserve) regulation operating within different time scopes. Voltage control is designed to maintain an adequate voltage profile within the transmission network. A correct voltage profile assesses an acceptable value of transmission losses and an operating point far away from voltage collapse. Generators incur in an extra cost for providing frequency and voltage control and should be recovered through regulated or market –based tariffs. Several studies have explored the cost of providing AGC and tertiary regulation incurred by the generating units in order to develop bidding strategies under a deregulated framework [4-7]. The main key characteristics of the voltage control ancillary service have been explored in [8] and the structure and computation of the cost incurred to provide the service widely analyzed [9-12]. Under this framework, it becomes of crucial importance for the system operator to monitor the correct provision of these services by the generating units. In order to develop a monitoring method, the specific technical and economical definition of the services should be taken into account depending on the power system considered. Within the Turkish power system, frequency and voltage control have been defined as mandatory remunerable ancillary services, defined in the Turkish Grid Code and Ancillary Services Regulation [13-16]. This paper proposes a central monitoring system of frequency and voltage control of the Turkish Power System in order to validate the correct fulfillment by generating units. It should be noted that this paper focuses on generating units, thus frequency and voltage control provided by other means (for instance by shunt devices or demand response strategies) are not considered within this paper. Even though both services present different technical, time-scope and complexities by definition, the system proposed share the same intuitive approach: both frequency and voltage control monitoring is based on a reference model that compares the real operation of the generating units with the desired behavior established by the technical specifications of the Turkish grid code. A number of quantitative measures, based on the deviation between the real and the desired response are proposed to evaluate the adequacy of each unit behavior. Application examples of the central monitoring system are provided using real data of different Turkish power plants. It should be noted that the simple and intuitive central monitoring of frequency and voltage control proposed in this paper can be applied to any power system by just specifying the desired response based on the system technical requirements of the grid code. The paper is organized as follows. Section 2 explains the frequency control monitoring with an overview of frequency control in Turkey, the description of frequency control monitoring system and an illustrative example. Section 3 deals with the voltage control monitoring, containing an overview of voltage control in Turkey, the description of voltage control monitoring system and an illustrative example. Finally, conclusions are drawn in Section 4. 2. Frequency control monitoring 2.1 Frequency control in Turkey Frequency control by means of active power provision include primary, secondary and tertiary regulation. Primary control can be defined as the automatic increase or decrease of the output power of a generating unit due to frequency deviations and is based on its speed– droop characteristic. The order of magnitude of the time constant of the dynamic response of primary regulation lie within the range of a few seconds (1 to 10s). Primary regulation is affected mainly by the speed-droop characteristics of the generating units. Following a system disturbance, primary control can prevent large variations of frequency, but on the contrary it does not bring the system frequency back to its scheduled value. Thus, a frequency deviation will exist in the steady state of the system after primary control operation. The aim of secondary control (AGC) is to bring the system frequency to its scheduled value. Power systems are usually divided into different interconnected areas with possible scheduled interchanges between them. An additional objective of AGC is to maintain area interchanges at the scheduled values. The order of magnitude of time constants associated to the