Reliability Evaluation Of Distribution Systems Research Articles

An analytical method for reliability evaluation of power distribution system with time-varying failure rates

Reliability evaluation is crucial in assessing the power supply capacity and guiding the planning and operation of the distribution system. Traditional analytical reliability evaluation usually assumes a constant failure rate for components, implying that the life distribution follows an exponential distribution. However, in reality, the failure rate of components varies over time due to external disturbances and aging. As a result, traditional analytical reliability evaluation methods are no longer applicable. To address this issue, this paper presents an analytical method for evaluating the reliability of the distribution system with time-varying failure rates. The method considers short-term and long-term time-varying failure rates using density evolution and non-homogeneous Poisson process techniques, respectively. Both steady-state and instantaneous indices are calculated to reflect the level of system reliability. Finally, the proposed method is applied to the IEEE RBTS Bus 6 test system, demonstrating its correctness and efficiency.

Reliability Evaluation of Radial Distribution System with different locations and ratings of Photovoltaic

The primary objective of this work is to examine how strategically positioning Photovoltaic (PV) units can have effect on reliability of a distribution system. Feeder-1 of RBTS BUS2 system is used for the reliability evaluation. The study utilizes FMEA technique to evaluate the reliability indices, System Average Interruption Frequency Index (SAIFI), System Average Interruption Duration Index (SAIDI), Energy Not Supplied (ENS) and Average Service Availability (ASAI) linked to electrical interruptions in two different situations such as no PV unit and PV units are placed at different locations with different ratings along the feeder. The outcomes of installing PV units at different points along the distribution feeder are examined and compared. The prime focus lies in identifying the reliability based optimal placement of the PV unit, a determination made based on the reliability indices. By systematically analyzing and comparing the reliability indices under varying conditions, the research aims to provide insights into how the strategic positioning of PV units can lead to a substantial enhancement in the overall reliability of the distribution system. The findings contribute to the broader understanding of integrating renewable energy sources for reliability improvement within distribution systems and offer practical guidance for decision-makers in the field of energy distribution and planning.

Reliability evaluation of radial distribution system considering common mode failures and different weather effects

Reliability evaluation of distribution systems plays a crucial role in ensuring the uninterrupted supply of electricity to consumers. This paper presents a comprehensive analysis of distribution system reliability using the Failure Mode and Effects Analysis (FMEA) technique. The study focuses on evaluating the reliability of the distribution system considering various failure modes, including busbar failure, section failure, distributor failure, transformer failure, maintenance-related issues, transient failures, and the impact of weather conditions. The findings of this research can assist utilities and system operators in identifying critical failure modes and implementing appropriate measures to enhance the reliability of distribution systems, ensuring continuous and reliable electricity supply to consumers.

Customer Orientated Indices and Reliability Evaluation of Meshed Power Distribution System

Aim. Reliability evaluation of a system or component or element is very important in order to predict its availability and other relevant indices. Reliability is the parameter which tells about the availability of the system under proper working conditions for a given period of time. The study of different reliability indices are very important considering the complex and uncertain nature of the power system. In this paper reliability evaluation of the meshed distribution system is presented. This paper also evaluates basic indices such as average failure rate, average outage time and average annual outage time. Along with basic indices, customer orientated indices such as system average interruption frequency index, system average interruption duration index and customer average interruption duration index of an electrical power distribution system is also evaluated. The electrical power distribution system taken for study is meshed distribution system in nature.Aditya Tiwary. "Customer Orientated Indices and Reliability Evaluation of Meshed Power Distribution System" Reliability: Theory & Applications, vol. 15, no. 1, 2020, pp. 10-19. doi:10.24411/1932-2321-2020-11001

Power distribution system reliability evaluation using weight-optimised ANN approach

Power distribution system reliability evaluation using weight-optimised ANN approach

A non-simulation-based linear model for analytical reliability evaluation of radial distribution systems considering renewable DGs

One of the most critical goals in the operation and planning of distribution networks is the creation of networks with sufficient reliability. Existing models are often simulation-based or try to introduce topology-independent algebraic reliability measures with simplifications or extensive computations. This paper presents new and efficient topology-variable-based linear expressions that can evaluate the reliability indices of practical radial distribution networks. Furthermore, the model is extended to consider the inclusion of renewable distributed generation (DG) units to restore part of restorable loads in the islanded mode of operation. Also, the stochastic nature of renewable generation, as well as load demand, is considered. Therefore, the proposed model can be readily used in various optimization models to operate and plan distribution networks with reliability concerns. The application of the proposed method to several small- to large-scale test cases ranging from standard 37-node up to practical 1080-node benchmarks shows the proposed model's accuracy and computational effectiveness compared to the state-of-the-art conventional simulation-based topology-variable-based approaches. The impact of the system's islanded operation on the reliability indices is also evaluated on the modified DG-enhanced 37-node test system.

Optimum relay coordination for reliability evaluation of distribution system with allocation of wind turbine generators

ABSTRACT In this work, a method of optimal relay coordination for improving system reliability has been presented in association with the Wind Energy Conversion System (WECS). The graphical method as well as changes in Plug Setting Multiplier (PSM) and Time Dial Setting (TDS) have been used to test the system’s reliability with the help of ETAP. Load flow analysis, short circuit testing under different fault conditions, reliability assessment, and relay coordination have been performed on the proposed WECS. In this research work, a test system with relay coordination is proposed that is used for transformer protection using over-current relays (OCR) and ground-fault relays (GFR) devices with a wind energy induction generator. It is shown that coordination is off when WECS is added to the system. Therefore, maximum values of the circuit breaker’s trip device setting, the relay’s pickup, and the time dial settings are desirable to increase the coordination. Further, it has been revealed that the comprehensive analysis of load flow analysis, short circuit analysis, and reliability assessment play vital roles in achieving suitable relay coordination. Also, the use of ETAP software in this analysis improves the accuracy and speed of the circuit breaker operation at a reduced cost.

Reliability evaluation of distribution system integrated with distributed generation

Distributed generation (DG) improves the reliability of the system by providing a means of alternate power supply to the load points. DG is integrated to meet the system load along with the utility. In this work roy billinton test system (RBTS) bus 4 is considered for evaluating the effect of DG integration on system reliability. Reliability is evaluated using failure modes and effect analysis (FMEA) technique and the results are validated using Monte Carlo simulation technique. A MATLAB program is developed for both the techniques to evaluate the reliability. The failure rate of DG and the islanding capability of the DG are considered to resemble the practical operating conditions of DG. When DG is operating in islanded mode, if DG fails it affects the outage time of the load points. DG failure rate is also considered as the second order failure event overlapping with the feeder section failures. All the practical operating conditions of DG considered and their effect on the reliability of the system is evaluated.

Variance reduction technique in reliability evaluation for distribution system by using sequential Monte Carlo simulation

This paper discusses the need for variance reduction in simulations in order to reduce the time required to compute a simulation. The large and complex network is commonly evaluated using a large-scale Monte Carlo simulation. Unfortunately, due to the different sizes of the network, it takes some time to complete a simulation. However, variance reduction techniques (VRT) can help to solve the issues. The effect of VRT changes the behaviors of a simulation, particularly the time required to run the simulation. To evaluate the reliability indices, two sequential Monte Carlo (SMC) methods are used. SMC with VRT and SMC without VRT are the two options. The presence of VRT in the simulation distinguishes the two simulations. Finally, reliability indices: system average interruption frequency index (SAIFI), system average interruption duration index (SAIDI), and customer average interruption duration index (CAIDI) will be calculated at the end of the simulation to determine the efficiency for the SMC with and without VRT. Overall, the SMC with VRT is more efficient because it is more convenient and saves time than the SMC without VRT.

Reliability Evaluation of Active Distribution Systems with Distributed Generations

Reliability evaluation is essential in designing, planning, operating modern power systems. System operators must operate the network securely and efficiently with minimal interruption events. With the recent advances in power electronics and control, distributed generations (DG) such as photovoltaic (PV), wind turbine, and storage systems are expected to grow in distribution networks. This high level of distributed generations penetration in the grid can increase the complexity of operating the system. This is caused by intermittent nature of solar irradiance and wind speed. This paper proposes a methodology used to assess distribution networks containing stochastic resources such as photovoltaic. This method will use the Monte Carlo simulation with a stochastic model to evaluate the distribution network’s reliability. The system and load point reliability indices such as frequency of loss of load and expected energy not to supplied will be computed in this technique. In addition, the configuration of distribution networks to improve system’s reliability to facilitate system restoration after pre-fault conditions will be assessed.

Development of Predictive Reliability Model of Solar Photovoltaic System Using Stochastic Diffusion Process for Distribution System

Reliability assessment of power distribution systems is an essential concern for electric utilities to maintain supply continuity. In the event of supply failure, distributed energy resources play a vital role in restoring the supply to customers. This paper presents the development of a predictive reliability model for distribution system with solar Photovoltaic (PV) system. At the initial stage, the hourly solar irradiance and temperature are forecasted using Stochastic Diffusion Process (SDP)-based Monte Carlo simulation from historical data. Later, the cloud transients are modeled using the Jump Diffusion Process integrated into SDP. The monthly failure rates of PV system components are evaluated from historical data using the Physics of Failure (PoF) reliability model. Finally, the predictive reliability evaluation of the practical distribution system integrated with the proposed solar PV model is carried out. Results demonstrate the capability of the developed model to handle continuous and discrete uncertainties with more accuracy.

Integrating Transactive Energy Into Reliability Evaluation for a Self-Healing Distribution System With Microgrid

Non-utility owned distributed energy resources (DERs) are mostly untapped currently, but they can provide many grid services such as voltage regulation and service restoration, if properly controlled, and can improve the distribution system's reliability when coordinated with utility-owned assets such as self-healing control and microgrids. This paper integrates transactive energy control into the distribution system reliability evaluation to quantitatively assess the impact of non-utility owned DERs on reliability improvement. A transactive reactive power control strategy is designed to incentivize the DERs to provide reactive power support for improving voltage profiles thus enabling additional customer load restoration during an outage. Also, an operational sequence to coordinate the non-utility owned DERs with the utility owned self-healing control and utility owned microgrids is designed and integrated into the service restoration process with the operational constraints guaranteed by checking the three-phase unbalanced power flow for post-fault network reconfiguration. The reliability indices are then calculated through a Monte Carlo simulation. The transactive reactive power control strategy is tested on a four-feeder distribution system operated by Duke Energy in the U.S. Results demonstrate that the non-utility owned DERs with the transactive control improve the reliability of both the system and critical loads by more than 30%.

Reliability-oriented operation of distribution networks with multi-microgrids considering peer-to-peer energy sharing

This paper aims to propose a comprehensive energy management system (CEMS) to simultaneously enhance the resilience of microgrids (MGs) and distribution network (DN) in a multi-microgrid (MMG) system against unexpected events. It also develops a reliability evaluation framework for the reliability evaluation of MMG distribution systems. In this regard, the proposed CEMS includes two main strategies: (1) networked operation mode (NOM), attributed to the cooperation of independent sub-sections (MGs/DN) in fault-affected portions. Here, each MG must exchange power with the DN and other MGs (may be islanded simultaneously) by participating in peer-to-peer (P2P) energy sharing to enhance resilience and reliability of the whole network, and (2) individual operation mode (IOM), comprising the grid-connected, optional islanding, fully forced islanding, and partial islanding modes for different operational requirements of MGs. Thus, the required information of an outage is identified. A suitable decentralized strategy based on the proposed CEMS and the novel adaptive problem formulation are initially used to operate such systems under different operating conditions. The NOM and IOM together assure the survivability of the whole system during the emergency periods and maintain reliable electric power supply for consumers while guaranteeing system stability indicators and ensuring operating costs of MGs. To substantiate these claims, we use different case studies to demonstrate the efficiency of the proposed CEMS based on a modified reliability test system. • A comprehensive energy management system is proposed for multi-microgrids. • An adaptive problem formulation is used for different operational requirements of microgrids. • The proposed method includes: networked operation mode and individual operation mode. • P2P energy sharing is proposed to enhance the resilience of system in networked operation mode. • Various case studies are conducted to study the system under normal and faulted operation modes.

Reliability Evaluation of Direct Current Distribution System for Intelligent Buildings Based on Big Data Analysis

Reliability Evaluation of Direct Current Distribution System for Intelligent Buildings Based on Big Data Analysis

Reliability Evaluation of Cyber Physical Distribution System considering EPON

As cyber-physics highly coupled distribution system, the influence of communication network on the reliability of power supply can not be ignored. Based on the EPON redundant protection network, this paper analyzes the influence of the loss of cyber link effectiveness on the self-healing control process in the process of power distribution network failure. With the help of the region adjacency matrix, combined with the cyber system failure model, the classification algorithm of the region after failure is given, and a reliability evaluation method coveannular different cyber system failure modes is proposed. Finally, the feasibility of this method is verified by a case study, and the influence of EPON cyber element failure rate and EPON networking mode on the reliability indices is compared and analyzed.

Methodology to incorporate stuck condition of the circuit breaker in reliability evaluation of electrical distribution networks

The random failure of a circuit breaker (CB) in a power distribution network adversely impacts its ability to maintain supply continuity to its electricity customers. Among different CB failure modes, the failure to open, or the stuck condition, of a normally closed CB causes the operation of its backup breaker(s) leading to outages of multiple healthy feeders. Stuck condition is a low-probability failure event, but has wide-spread consequences when it occurs. This study proposes a generalised analytical methodology to identify the failure events due to the stuck breaker condition. The complexity of the reliability evaluation of a modern distribution system involving multiple switching arrangements is achieved through a search algorithm and repeated matrix operations that can readily be implemented in a computer program. The methodology is illustrated using a test distribution network. The usefulness of the methodology is demonstrated by quantifying the impact of the stuck breaker condition on load point and system reliability indices. The developed methodology can be a useful tool for industrial/commercial customers and utilities to incorporate the impact of breaker failures, including stuck breaker conditions, and make wise investment decisions in the upgrade and maintenance of the distribution network components and the protection system.

Influence of photovoltaic generation model and time resolution on the reliability evaluation of distribution systems

Influence of photovoltaic generation model and time resolution on the reliability evaluation of distribution systems

Reliability and Network Performance Enhancement by Reconfiguring Underground Distribution Systems

Contemporary distributions are now going to underground their overhead distribution lines due to techno-social reasons. Reliability and loss reduction are the two prime objectives for distribution system operation. Since failure rates of ungrounded cables are the function of Joules heating besides their physical lengths, the reliability evaluation of undergrounded distribution systems needs to be reviewed. This paper suggested a suitable modification in existing reliability indices in order to make them more appropriate for underground distribution systems. A multi-objective network reconfiguration problem is formulated to enhance the reliability and performance of distribution systems while duly addressing the variability and uncertainty in load demand and power generation from renewables. The application results on a standard test bench shift the paradigm of the well-known conflicting nature of reliability and network performance indices defined for overhead distribution systems.

Reliability Evaluation of Distribution System Considering Distributed Generation Correlation

The correlation between distributed generation (DG) can affect the reliability of distribution networks. To analyze the influence of this factor, first use Latin Hypercube Sampling, combine Spearman rank correlation coefficient and Cholesky decomposition to obtain the DG output power sample of the specified correlation coefficient. The bidirectional hierarchical structure reliability evaluation algorithm considering switch failure is used to evaluate the system. Considering the island operation mode of the distribution network after DG access, an improved heuristic load reduction strategy is proposed, and the reliability index of the load in the island is revised. The experimental results show that the reliability index of the system is closely related to the rated capacity of DG, the correlation between DG, and different load reduction strategies.

Machine‐learning‐based reliability evaluation framework for power distribution networks

Reliability evaluation of power distribution systems is a well-studied and understood problem, but topology analysis efficiency and failure feature description are still limiting the practical application of reliability evaluation in distribution systems. One approach the authors proposed in this study is to incorporate the machine-learning technique into the simulation-based reliability evaluation method, and assess the system reliability in an empirical fashion. In this study, a framework for performing the machine-learning-based reliability evaluation, and corresponding modelling processes are first established. Then, by inducing a supervised learning algorithm named perceptron, a state-space classification-based (SSC) method for system state assessment, the core procedure of reliability evaluation, is proposed. On this basis, a reliability evaluation algorithm combining the SSC-based system state assessment and sequential Monte Carlo simulation is proposed, where the workload of topology analysis required in conventional reliability evaluation methods can be released. Furthermore, extensive case studies are conducted on the Roy Billinton Test System (RBTS) bus 2 system and an actual distribution system to verify the proposed models and algorithms. Results show that the proposed framework supports a more efficient reliability evaluation pattern while ensuring the evaluation accuracy.