International Journal of Electrical and Computer Engineering (IJECE) Vol. 12, No. 1, February 2022, pp. 50~61 ISSN: 2088-8708, DOI: 10.11591/ijece.v12i1.pp50-61  50 Journal homepage: http://ijece.iaescore.com A hybrid algorithm for voltage stability enhancement of distribution systems Hazim Sadeq Mohsin Al-Wazni, Shatha Suhbat Abdulla Al-Kubragyi Department of Electrical Engineering, Technology University, Baghdad, Iraq Article Info ABSTRACT Article history: Received Feb 26, 2021 Revised Jun 18, 2021 Accepted Jun 29, 2021 This paper presents a hybrid algorithm by applying a hybrid firefly and particle swarm optimization algorithm (HFPSO) to determine the optimal sizing of distributed generation (DG) and distribution static compensator (D-STATCOM) device. A multi-objective function is employed to enhance the voltage stability, voltage profile, and minimize the total power loss of the radial distribution system (RDS). Firstly, the voltage stability index (VSI) is applied to locate the optimal location of DG and D-STATCOM respectively. Secondly, to overcome the sup-optimal operation of existing algorithms, the HFPSO algorithm is utilized to determine the optimal size of both DG and D-STATCOM. Verification of the proposed algorithm has achieved on the standard IEEE 33-bus and Iraqi 65-bus radial distribution systems through simulation using MATLAB. Comprehensive simulation results of four different cases show that the proposed HFPSO demonstrates significant improvements over other existing algorithms in supporting voltage stability and loss reduction in distribution networks. Furthermore, comparisons have achieved to demonstrate the superiority of HFPSO algorithms over other techniques due to its ability to determine the global optimum solution by easy way and speed converge feature. Keywords: D-STATCOM HFPSO algorithm Smart distribution grid Voltage stability This is an open access article under the CC BY-SA license. Corresponding Author: Hazim Sadeq Mohsin Al-Wazni Department of Electrical Engineering, Technology University Industrial Street, Baghdad, Iraq Email: hazimwazni83@gmail.com NOMENCLATURE   : The voltage at receiving end bus   () : Size of particles   : The voltage at sending end bus   ( + 1) : Updated size of the particles   : The voltage at receiving end bus after compensated   ()   ( + 1) : Velocities of the particles : Updated velocities of the particles   : Phase angle between   and    : Number of iteration  : Phase angle of sending end voltage  − : The injected current of D-STATCOM  : Phase angle of Current pass between two buses      +   : Total power losses : Impedance of branch between bus 'S' and 'R'  , : Minimum Voltage limit of bus 'R'  2 and  3 : Weighting factors of objective functions β_1  , : Maximum Voltage limit of bus 'R'  () : Reactive power of D-STATCOM at bus ‘R’  ()   : Real power of DG at bus ‘R’ : Voltage stability index of node 'R'   : Total real loss before insert DG and D- STATCOM ()  : Average of buses voltages : Weight inertia ∆    ⁄ : Loss Reduction Index with DG and D- STATCOM  2,  1   : Acceleration coefficients : Current pass between two buses  ()  , ()  : Minimum, maximum injected reactive power limit of compensated bus' R'  −1 : Global best size  ,min() , ,max() : Maximum, minimum real power limit of compensated bus 'R'