Abstract - This paper presents a new method of local voltage control to achieve coordinative control among UPFC(Unified Power Flow Controller) and conventional reactive compensation equipments , such as switched-shunt and ULTC(Under-Load Tap Changing) transformer. Reactive power control has various difficult aspects to control because of difficulty of system analysis. Recently, the progress of power electronics technologies has lead to commercial availability of several FACTS(Flexible AC Transmission System) devices. The UPFC(Unified Power Flow Controller) simultaneously allows the independent control of active and reactive power flows as well as control of the voltage profile. When conventional reactive power sources and UPFC are used to control system voltage , the UPFC reacts to the voltage deviation faster than the conventional reactive power sources. Keeping reactive power reserve in an UPFC during steady-state operation is always needed to provide reactive power requirements during emergencies. Therefore, coordination control among UPFC and conventional reactive power sources is needed. This paper describe the method to keep or control the voltage of power system of local area and to manege reactive power reserve using PSS/E with Python. The result of simulation shows that the proposed method can control the local bus voltage within the given voltage limit and manege reactive power reserve. Key Words : Coordinative control, UPFC, ULTC, Switched-shunt, PSS/E, Python† 교신저자, 정회원 : 경북대 전기공학과 시간강사․공박E-mail : pjh@ee.knu.ac.kr* 정 회 원 : 경북대 대학원 전자전기컴퓨터학부 박사과정** 펠로우회원 : 경북대 전기공학과 교수․공박***정 회 원 : 거제대 선박전기과 조교수․공박 접수일자 : 2011년 3월 2일 최종완료 : 2011년 4월 26일