Empirical and Optimized Framework for Load Shedding considering both Voltage and Frequency Stability factors

Abstract

The large-scale development of modern power system network and increased demand to newlineoperate the electric power system in a secure, economical, and highly efficient manner gained much newlineattention from the power system research community. Power system security is one of the essential newlinefactors to be maintained during the network operation. Practically it is not possible to operate the newlinesystem within the security limits always. In the view of avoiding a complete blackout Load newlineshedding(LS) is used as the last option and considered as one of the emergency options. However, newlineextensive research has been inclined to enhance power system security and stability in terms of newlinevoltage and frequency. A very few studies have been found to achieve a full-fledged optimal newlinesolution under different and multiple contingencies in the system, which is also a reason for system newlineblackout. When the power system experiences the generation loss and overload contingency issues, newlinethe voltage and frequency fall below the specific threshold values. Hence there is an essential for a newlinemore accurate, flexible optimal and robust load shedding for different uncertainties in the system. newlineMost importantly, the emphasis has been kept towards objectifying LS problem considering voltage newlineand frequency stability factor. Further, it proposes an efficient, empirical and optimized framework newlinefor LS that addresses both voltage and frequency stability to achieve stable and secure system newlineoperation against a majority of contingencies. newlineThe first framework introduces a Novel optimal decentralized load shedding strategy using an newlineImproved self-adaptive harmony search(ISAHS) algorithm. The proposed framework generates newlinediversity in the solution and avoids optimization traps at local optima using dynamic algorithm newlineparameters. An extensive analysis is performed on a different IEEE bus system to accesses the newlineperformance of the proposed framework. Based on the experimental observation and analysis, this newlineframework achieves 25.3% and 13.43% of LS in IEEE-14 and 30 bus system respectively, which is newlinemore using GSO and IHS approach. The practicality of the proposed framework is justified with its newlinefast convergence rate. newline newlinex newlineThe second framework modelled a centralized optimal LS problem to restore the balance in the newlinepower system network by improving the voltage profile. In which the study introduces two different newlinevoltage stability index to identify the optimal location in the presence of overloading contingency newlineand overloading and (N-1) contingency. The effectiveness of the framework modelled is taken in to newlineaccount in terms of LS location and LS amount. The implementation of this proposed system design newlineis carried out on IEEE-30 bus system with different contingency condition. This framework in the newlineproposed study achieved 8.193% of improvement in the total amount of connected load in IEEE-30 newlinebus system after load shedding using ISAHS algorithm. newlineThe last framework presented in this research implemented both centralized and decentralized newlineoptimal load shedding problem to address both voltage and frequency instability. This framework newlineaims to estimate power deficit using the rate of change of frequency (ROCOF). Here, NVSI is used newlineto identify the critical buses for load shedding. The amount of load that must be shed on each bus newlineare calculated by using the ISAHS algorithm. This approach concludes that the total amount of real newlineload of 5.82 MW is saved as compared to the voltage-dependent approach in IEEE-14 system. newlineSimilarly, it saves about 3.23 MW of real load in IEEE-30 bus system. The scope of the proposed newlinestudy is not limited in ensuring voltage stability and it also further extended to ensure steady-state newlinefrequency stability as well. newline