Improvements in load flow studies using strengthening of fast decoupled models

Abstract

The paper presents a 'Strenghtened Fast Decoupled Model (SFDM)' and a novel approach for the adjusted load flow analysis withoud any need for (complete or partial) refractorization of second constant-slope matrix relating the reactive mismatches and voltage correction variables. The novel approach presented for adjusted load flow solutions is found to be very effective in resolving many of the problems associated with adjusted load flow studies using Fast Decoupled models without any additional computational burden. Results obtained using standard IEEE test systems are presented. Test results establish that the proposed approach for adjusted studies is quite stable and can also be used effectively with XB and BX models. Based on the nature of the elements of the two constant-slope matrices of SFDM, a single matrix model (SMM) which uses only one constant-slope matrix for solution of active and reactive power mismatch equation for correction variables /spl Delta//spl delta/ and /spl Delta/V is also presented. It eliminates the storage, formation and triangularization of second-constant slope matrix, which is essential in case of conventional Fast Decoupled model. Test results on IEEE systems establish that SMM takes lesser CPU time and memory than XB or BX models even for normal systems.