This paper proposes a novel approach of voltage stability enhancement and power loss minimization in addition to maintenance of good voltage profile in radial distribution networks through optimally placed distributed generation, network reconfiguration and voltage control of PQV bus through variable reactive power source at P bus. A multi-objective function has been proposed that considers maximum system loadability enhancement and network loss minimization. Optimization of proposed multi-objective function, under distributed generation and network reconfiguration with presence of PQV and P buses in the system have been done using grey wolf optimization technique. Case studies performed on IEEE 33-bus radial distribution system shows that presence of PQV and P buses in the system yields significant enhancement in voltage stability margin under optimal placement of distributed generations and network reconfiguration.

Voltage stability assessment (VSA) is invariably an essential step in the satisfactory operation of power system. For this, several Voltage Stability Indices (VSIs) based on (i) Existence of solution for voltage equations, (ii) Maximum power transfer (MPT) through a line, (iii) MPT theorem/maximum loadability limit, (iv) P-V curve, (v) Energy function and (vi) Jacobian matrix can be found in the literature. VSIs assist in identifying weak lines and buses, voltage collapse proximity, maximum loadability, voltage stability margin, and prompting countermeasures against voltage instability. This article examines 78 different VSIs based on their concepts, assumptions, thresholds, and formulae. Additionally, mathematical proofs for 29 indices have been elaborated upon so that researchers may familiarize themselves with the underlying concepts of the other existing indices and find newer indices in modern power systems composed of intermittent power generation and dynamic loads. Also, a novel qualitative comparative analysis of VSIs is tabulated. Further, a novel framework has been proposed to aid researchers in shortlisting VSIs for a particular application. This article intends to serve as a meaningful reference to various researchers and individuals working in domains like Distributed Generation (DG) placing and rating, Voltage Stability Assessment (VSA), and power system planning.

In recent times, Distributed Generation (DG) penetration, especially, through Renewable Energy Sources (RES) has been growing immensely due to marginal carbon footprints. Furthermore, they make system more reliable by minimizing the voltage deviation of the distribution network. Nevertheless, to exploit the DGs in the best manner, they need to be sited and rated optimally. Diverse solutions exist for the problem mainly classified as: analytical approaches, classical non-linear optimization algorithms and meta-heuristic methods. With the objective of minimizing power loss, this manuscript proposes a novel hybrid meta-heuristics approach: Particle Swarm Optimization-Coral Reef Optimization (PSO-CRO) for identifying an optimum positioning and rating of Type-1, Type-2 & Type-3 DGs (at 0.82 optimal power factor) in IEEE 33, 69 & 118 bus Radial Distributed System (RDS). Furthermore, the results from the proposed hypothesis are compared with its prevalent peers, namely, PSO, CRO, Gravitational Search Algorithm (GSA), PSO-GSA and PSO-Grey Wolf Optimization (PSO-GWO) etc. The results of the proposed algorithm are also compared with the results of GAMS/CONOPT commercial solver. The simulation results prove the robustness, higher efficacy and faster convergence of the proposed method when applied to larger distribution systems.

This paper proposed a method to investigate the effect of increasing PV penetration on the voltage stability of an IEEE 14-bus test system considering maximum PV penetration and system loadability limit. The critical bus of the test system has been decided based on nose curve analysis. The solar PV system is deployed with the most critical bus of the system. The effect of increasing PV penetration on the improvement in the loading capacity of various power system components like transmission lines, transmission line transformers, and generators is investigated over the adopted test system. Based on solar PV penetration up to 100 MW, the maximum loadability limit of the IEEE 14-bus test system increases, as shown by the results. Bus 14 is found to be the most severe bus of the test system using the continuation power flow (CPF) method. However, in some cases, overloading situations develop after a certain limit of PV penetration in the power system. In this condition, the overloading of the power system equipment is improved by the use of a Static Synchronous Compensator (STATCOM) at bus number 14, a double circuit line in the critical line (9–14), and Static Synchronous Series Compensator (SSSC) in the most severe line (9–14) in the system. The maximum loadability of the system gets maximum enhanced from 4.0349 p.u. to 4.5602 p.u. under simultaneous use of solar PV generation, SSSC, and STATCOM at the most critical bus and in most severe line of the system. As evidence, the enhancement in maximum loadability of the system found using the proposed method has been also compared with the existing research. The maximum system loadability has been also enhanced under normal and (N-1) contingency conditions by the use of PV penetration in the system. PSAT/MATLAB software is used for simulation and maximum loadability has been investigated by continuation power flow (CPF) method.

This paper proposes an adaptive Newton-Raphson Load Flow (NRLF) method and a multi-objective function for loss minimization and Voltage Stability (VS) enhancement of Radial Distributed System (RDS) in the presence of PQV and P/Q buses. Enhancement in VS of the network is presented in terms of maximum loadability. In the presence of two novel sets of buses, generation bus (i.e., P/Q-bus) and remotely controlled bus (i.e., PQV-bus), optimal DG integration and network reformation in RDS is also presented in this paper. The specified or known quantity for the P/Q bus is only active/reactive power generation. For the PQV bus, the known quantities are Watt and VAr power generations together with the voltage magnitude to be maintained by the generation bus (i.e., P/Q-bus). A multi-objective function is proposed here for P/Q-bus selection, optimal DG integration, and network reformation of RDS. Simulations have been carried out on IEEE 33-bus and 69-bus RDS to demonstrate the effectiveness of the proposed method. Also, the simulation findings are compared with those of relevant peers in the literature to justify the validity of the proposed work.