Abstract
The paper presents the results of testing the operational capabilities of the pump hydropower plant (PHPP) Capljina in compensatory, under excited mode in real time, and answers the questions how, and to what extent, the operation of PHPP Capljina in the under excited mode affects the improvement of voltage conditions in the power system of B&H. The test was performed with one machine in compensatory under excited mode with the takeover of reactive power in the amount of 160 MVAr, in a period of 4 hours. During the test, thermal power plant (TPP) Gacko operated in the maximum under excited mode for a certain period of time.