energija ekonomija ekologija www.savezenergeticara.org.rs Bojana Mihic, Srdan Subotic Public Enterprise "Elektromreza Srbije", Belgrade, Serbia Jasna Dragosavac, Zarko Janda, Dusan Arnautovic Electrical Engineering Institute "Nikola Tesla", Belgrade, Serbia J.V. Milanovic The University of Manchester ,Manchester M13 9PL, UK UDC: 621.311.22:621.316.7.004 Validation of performance of Joint Excitation and Reactive Power Controllers using commercially available power system analysis software pacl<ages ABSTRACT This paper presents the comparative analysis of two different approaches of reactive power allocation among synchronous generators within a steam power plant (SP P). The analysis is performed in or- der to validate by comparison of simulation results obtained with two most widely used power system analysis software packages, PSSE®PTI Siemens and DlgSILENT Power Factory, with the case study measurement results. The measurements are obtained at the point of common coupling (PCC) of two adjacent Steam Power Plants (SPP) following the action of Joint Excitation and Reactive Power Con- trollers (JEQC). The accuracy ofsimulation results is essentialfor the Transmission System Operator (TSO) who is using these software packages to calculate power losses in the network due to reacti- ve power flows. The allocation of reactive power (0 among the generato1:s involved is performed by JEQC according to criterion of maximum Q reserve at plants PCC, while the algorithms built PSSE®PTI Siemens and DlgSILENT Power Factory calculate Q allocation in order to minimize tran- smission losses by activating the OPF option. The aim of JEQC testing initiated by the Transmission System Operator (TSO), was to check the compatibility ofresults obtained by the JEQC algorithm ac- tion and that obtained by optimal power flow algorithm based on minimization of transmission criterion. The compatibility of the results, if confirmed, should enable the use of JEQC as an tool for secondary voltage control in the power system. The analysis was performed for case study of parallel operation of two excitation and reactive controllers (JEQC) installed in two largest steam power plants in Serbia, SPP HNikola TeslaA" SPP "Nikola Tesla B", which are electrically close to each other. The main purpose of the JEQC is perform a slow voltage control at pcc of the plants by automatically adjusting the levels of ted reactive power of the SP Ps generators while i) ensuring the uniform and synchronized of all participating generators in case of power system disturbances, ii) preventing generators operating in forbidden areas of the capability chart where overheating of stator core can occur, restoring operating point of the generator after a major disturbance to the pre.jault value. The study considered the Q-V controller outputs at the high voltage side of the SP Ps step-up The parameters used are given in the official technical documentation provided by the owner SPP. This was done due,to high voltage side location of the measuring points in the transmission work which TSO uses jor gathering relevant data for safe and reliable operation of the system. The performed simulations confirmed that all calculations results are in compliance national Grid Code (official version released on June 2014), 1 INTRODUCTION T he consequence of the market deregulation pro- cess is a tendency of TSO to manage the power transmission system with the primary criteria to maxi- mize profit or to minimize the transfer of reactive po- wer (Q), thus leaving enough space for the, active power (P), as well as the minimizatIOn smission losses in the power system due to the tory purchase of losses by the TSO. At the the criteria determining the quality of ply should be satisfied [1], [2], [3]. In the