A novel load flow approach for voltage stability index calculation and adjustment of static VAR compensator parameters

The location of SVC (static VAR compensator) and other types of shunt compensating devices for voltage support is an important practical question. This paper presents a new decoupled-quadratic load flow (DQLF) approach for adjustment of parameters of SVC. The DQLF model can calculate effectively the SVC susceptance and resulting firing angle using a simple quadratic equation derived using real and reactive power injections at the SVC bus. The resulting quadratic equation, can easily evaluate system voltage stability margin. The model makes use of conventional fast decoupled load flow (FDLF) algorithm for calculation of voltage phase angle corrections. The proposed approach eliminates the formation and modification of B" matrix in FDLF models and offers considerable saving in the execution times. It is found to be very reliable for Q-adjusted studies and ill-conditioned cases. The DQLF model offers 50% faster convergence than FDLF model, when applied to large systems, having a large number of generator buses. The validity of the proposed algorithm for SVC parameter adjustment is tested on IEEE 14 bus system. The stability margins are evaluated using the proposed quadratic equation, and compared with traditional Q-V sensitivity model. The final parameters B_svc and firing angle alpha obtained using DQLF model are compared with those obtained using Newton Raphson (NR) and FDLF models and found to be same