COMPENSATION TECHNIQUE FOR Q-LIMIT ENFORCEMENTS IN A CONSTANT COMPLEX JACOBIAN POWER FLOW MODEL

ABSTRACT

This paper presents a simple and efficient compensation technique to deal with bus-type switchings associated with Q-limit enforcements at voltage controlled (PV) buses in a constant Jacobian power flow model. The Jacobian is expressed in the complex variable form resulting in reduced storage requirements as compared to real form of representation of the Jacobian. The structure of the Jacobian is preserved irrespective of bus-type switchings while Q-limit enforcements are performed at the PV buses. This feature permits implementation of optimal ordering of buses in an efficient way while factorizing the Jacobian matrix. The Jacobian is held constant throughout the load flow solution process. Incremental Secondary Injections (ISIs) are provided at the respective PV buses to maintain the specified voltages. The required injections are computed from the proposed compensation model. Results indicate that the proposed technique is quite efficient as the number of iterations for solution to converge, irrespective of bus-type switchings remains same as that in unadjusted solution case. Because of its simplicity and efficiency, the proposed model could become an alternative to the technique of matrix refactorization dealing with such problems of Q-limit enforcements associated with bus-type switchings in constant matrix power flow methods. The proposed model is tested on several power systems and the results are highly encouraging.