Reliability Indices Evaluation of LV Distribution System and Inclusion of Protective Devices for Reliability Improvement

This paper analyzes the reliability of low voltage(LV)distribution system of the Sri Lankan power system.Performance of LV distribution systems where mainly domestic consumers depend on the individual components of the system.Failure rates of elements of the system are calculated based on the historical data of the LV distribution system in a semi-urban area.Load point reliability indices are calculated using the analytical method.Consumer-oriented reliability parameters and energy not served,and its cost are determined.As a method of improvement of reliability,inclusion of fuses to the lateral feeders of the main feeder is proposed.Load point reliability indices,consumer-oriented reliability indices,and energy not served are calculated for the distribution system with fuses in lateral feeders.The results are compared with the reliability indices of the present system and analyzed.

Electric reliability indices in 2009 released

On May 28, the State Electricity Regulatory Commission and the China Electricity Council jointly held a conference releasing the electric reliability indices in 2009 in Beijing.

Availability Capacity Evaluation and Reliability Assessment of Integrated Systems Using Metaheuristic Algorithm

Contemporarily,the development of distributed generations(DGs)technologies is fetching more,and their deployment in power systems is becom-ing broad and diverse.Consequently,several glitches are found in the recent studies due to the inappropriate/inadequate penetrations.This work aims to improve the reliable operation of the power system employing reliability indices using a metaheuristic-based algorithm before and after DGs penetration with feeder system.The assessment procedure is carried out using MATLAB software and Mod-ified Salp Swarm Algorithm(MSSA)that helps assess the Reliability indices of the proposed integrated IEEE RTS79 system for seven different configurations.This algorithm modifies two control parameters of the actual SSA algorithm and offers a perfect balance between the exploration and exploitation.Further,the effectiveness of the proposed schemes is assessed using various reliability indices.Also,the available capacity of the extended system is computed for the best configuration of the considered system.The results confirm the level of reli-able operation of the extended DGs along with the standard RTS system.Speci-fically,the overall reliability of the system displays superior performance when the tie lines 1 and 2 of the DG connected with buses 9 and 10,respectively.The reliability indices of this case namely SAIFI,SAIDI,CAIDI,ASAI,AUSI,EUE,and AEUE shows enhancement about 12.5%,4.32%,7.28%,1.09%,4.53%,12.00%,and 0.19%,respectively.Also,a probability of available capacity at the low voltage bus side is accomplished a good scale about 212.07 times/year.

Load Profile Analysis for Mitigating Load-Shedding in Central Africa: Case of Kinshasa

Load shedding is a major problem in Central Africa, with negative consequences for both society and the economy. However, load profile analysis can help to alleviate this problem by providing valuable information about consumer demand. This information can be used by power utilities to forecast and reduce power cuts effectively. In this study, the direct method was used to create load profiles for residential feeders in Kinshasa. The results showed that load shedding on weekends results in significant financial losses and changes in people’s behavior. In November 2022 alone, load shedding was responsible for $ 23,4 08,984 and $ 2 80,9 07,808 for all year in losses. The study also found that the SAIDI index for the southern direction of the Kinshasa distribution network was 122.49 hours per feeder, on average. This means that each feeder experienced an average of 5 days of load shedding in November 2022. The SAIFI index was 20 interruptions per feeder, on average, and the CAIDI index was 6 hours, on average, before power was restored. This study also proposes ten strategies for the reduction of load shedding in the Kinshasa and central Africa power distribution network and for the improvement of its reliability, namely: Improved load forecasting, Improvement of the grid infrastructure, Scheduling of load shedding, Demand management programs, Energy efficiency initiatives, Distributed Generation, Automation and Monitoring of the Grid, Education and engagement of the consumer, Policy and regulatory assistance, and Updated load profile analysis.

Probabilistic Model of Technical Queuing Systems with Subsystems for Detection and Recovery of Failures

The given article presents an analytical model developed for a multichannel technical queuing system with time redundancy for operability management, subsystems of reliable periodical control of sudden and gradual failure detection and a subsystem for system recovery after failure. It is assumed in the model that the failures are governed by the Poisson probability distribution law and the times of reliable control and system recovery after failures are governed by an arbitrary law of probability distribution, in the general case depending on the number of servicers. The paper defines probabilities of accomplishment of certain task volumes by the system within a priori defined time intervals, taking into consideration its reliability characteristics.

Reliability Evaluation of UHVDC Transmission Systems with a Hierarchical Connection Mode

Compared with the typical Ultra HVDC(UHVDC)system,the inverters of the UHVDC system with a hierarchical connection mode(UHVDC-HCM),connect two receiving-end systems with different operational conditions.This requires the corresponding conversion units(CUs)at the different terminals to be differentiated in reliability modeling,and the spares should also be separately set.A reliability model of the UHVDCHCM system is proposed in this paper.The operating modes are classified by the capacities of the total system and the transmission powers to the two receiving-ends.Considering the independent spares of the components of the CUs at different terminals,the state space is derived.Two sets of indices are newly proposed to more accurately evaluate the system reliability.Based on the matrix description of the frequency&duration(F&D)method,the sensitivities of the reliability indices to the reliability parameters of the components are quantified.Numerical results validate the feasibility of the proposed model.The vulnerabilities are recognized by the sensitivity analysis,and the impact of different spare schemes on the reliability indices and sensitivities are compared.The proposed model and indices provide a reference for the practical UHVDC-HCM projects.

FURTHER RESEARCH OF A NEW KIND OF SERIES REPAIRABLE SYSTEM

This paper is devoted to studying the uniqueness and existence of the system dynamic solution by using C0-semigroup theory and discussing its exponential stability by analyzing the spectrul distribution of system operator and its quasi-compactness. Some primary reliability indices are discussed with the eigenfunction of system operator and the optimal vacation time to get the maximum system profit is analyzed at the end of paper.