Reliability and security improvement of distribution system using optimal integration of WTDGs and SMESs considering DSTATCOM functionality based on an enhanced walrus optimization algorithm

•Reliability and security of distribution system are improved using WTDGs and SMESs.•The DSTATCOM functionality for the WTDGs and SMESs are considered.•Enhancing the performance of the traditional WaOA by proposing an improved version.•Discharge and charging real powers for SMESs, along with their SOC are considered.•The effectiveness of the proposed method is evaluated by applying a mixed TVVD load. This paper aims to improve the customer-oriented reliability indices (CORIs), load-oriented reliability indices (LORIs), and the security of the electric distribution system (EDS). This is achieved through the optimal placement and sizing of wind turbine distributed generators (WTDGs) and superconducting magnetic energy storages (SMESs), which incorporate DSTATCOM functionality. The LORIs include energy not supplied (ENS) and average energy not supplied (AENS), while the CORIs consist of the system average interruption frequency index (SAIFI), system average interruption duration index (SAIDI), average service unavailability index (ASUI), and customer average interruption duration index (CAIDI). The network security index (NSI), which assesses the risk of current flow in lines approaching critical levels, is also examined. A multi-objective function based on optimized weight factors is developed to simultaneously reduce NSI, ASUI, ENS, SAIDI, and SAIFI using an enhanced walrus optimization algorithm (EWaOA) along with sensitivity factors analysis. This optimizer is an improved form of the traditional Walrus Optimization Algorithm (WaOA), designed to balance exploration and exploitation stages better, thereby avoiding local optima and improving overall performance. The EWaOA algorithm's effectiveness is tested on seven benchmark functions and compared with the conventional WaOA and other recent algorithms. The paper also explores the discharge as well as charging real power in addition to initially SOC of SMESs. The proposed method is applied to the IEEE 33-bus EDS, considering a mixed time-varying voltage-dependent (TVVD) load model. The results indicate that the optimal integration of WTDGs and SMESs with DSTATCOM functionality significantly enhances the reliability and security of the tested EDS.