Demand for electricity is increasing rapidly, the consequence of this is a threat to the stability of the electrical system, one of which is the voltage stability. FACTS or flexible alternating current transmission system is an electronic equipment capable of regulating electrical power transmission that can be used to overcome stability problems. This research will analyze the use of SVC and STATCOM as an equipment model from FACTS to overcome the stability of the electric power system on the most critical buses. Simulations were carried out using PSAT using case studies: a 500 kV Java-Bali network. Then the stability of the voltage is observed using the help of the PV curve which can show the value of the voltage conditions in each operating condition. SVC installation in the Java-Bali 500 kV case does not reduce the active power losses or reactive power, but also the addition of length λ is 0.233 p.u. (6.01%) and compared to the addition of length λ at STATCOM of 0.149 p.u. (3.85%).