Supply Reliability Analysis Research Articles

Power Supply Reliability Analysis of Distribution Systems Considering Data Transmission Quality of Distribution Automation Terminals

A distribution automation system is the integration of physical power distribution systems and information systems. Its information system guarantees the safe operation and reliable power supply of physical systems by monitoring, collecting and transmitting information. In the information system, the remote terminal unit of distribution automation is the hub of the information system, connecting it to the physical power system. Considering the unreliability of terminal information transmission in the information system, this paper aims to build a model to quantitatively evaluate the impact of unreliable transmission information on the power supply reliability of distribution systems. Firstly, the m-segment and n-connection unit model of distribution feeders is established, and then, the power supply reliability indices in the process of handling feeder terminal unit error are analyzed and calculated under the configuration modes of “three-remote” and “two-remote” of remote terminals. Then, considering the impact of a transmission error in the information system, the reliability index calibration model under the condition of unreliable information transmission is established. Finally, a case study is presented to illustrate how the proposed model is implemented.

Water Supply Reliability Analysis of Multi-Purpose Dams in Preparation for Water Disasters

Purpose: In this study, in order to find a way to minimize water supply shortage, reliability analysis of water supply was conducted by operating the Andong and the Imha Dam. The purpose is to find a way to minimize water shortage by the allocation distribution model from the reliability analysis results.
 Method: In this study, in order to analyze the water supply reliability of Andong and Imha Dam, using the Allocation rule presented by Park et al(2007), based on the planned water supply of Andong and Imha Dam for a total of 360 months from 1993 to 2022, analyzed. From the analysis results, the reliability of stable water supply was evaluated.
 Results: In the case of supplying the planned water supply of Andong and Imha Dam, the analysis result of Rule(B), which considers the ratio of the storage and inflow of the dam in the reservoir operation analysis result, showed that the shortage of Andong Dam occurred the most at 23 months, Regarding the number of shortages of control points, Rule(A), which considers only the storage capacity of the dam, was found to be short at 39 months, which is the largest number of shortages. As for the frequency standard reliability, Rule(B) showed the highest reliability of 90%, but in the case of quantitative reliability, the reliability was similar in all cases.
 Conclusion: In the water supply reliability, the reliability of stable water supply by supplying only the planned water supply amount is 94%, 93%, and 90% in Rule(B) of the allocation distribution model. 5% at the Andong dam, 7% at the Imha dam, and 10% at the control point. When water supply is evaluated with frequency reliability, it is judged that countermeasures for the shortfall are necessary. Next, in the case of quantitative reliability, when only the planned water supply was supplied, it was analyzed to be 95%, 94%, and 95% in all methods, so that the quantitative reliability was higher than the frequency reliability.

Supply reliability analysis of natural gas pipeline network based on demand-side economic loss risk

• An evaluation method for the economic loss risk on the demand side of a natural gas pipeline network system in a certain period is proposed. • User priorities are considered when there is a shortage of gas in the pipeline network. • The economic consequences on the demand side are quantified in terms of the alternative energy costs. • The effect of supply sequence of users on gas supply reliability is described. Most studies on the natural gas supply reliability evaluation have reflected on whether the volume of gas supply to users is sufficient. However, different types of users suffer from the same natural gas shortage, the consequences of loss are different. The abundance of the supplied gas volumes does not reflect the actual losses incurred by users. Moreover, when a gas shortage occurs, the supply flow of different types of users is redistributed according to the supply order. Therefore, this study proposes an evaluation method for the gas supply reliability based on demand-side economic risk. The user's supply sequence is integrated into the cost matrix to optimize the distribution of the user's demand flow under gas shortage. A calculation model of the economic loss cost is established using alternative energy sources. Finally, a reliability index is established based on economic risk to evaluate the degree of supply security. The results showed that the reliability based on the economic risk assessment was slightly higher than that based on the gas quantity assessment. The reliabilities were 99.988% and 99.991%, respectively. The economic risk is reduced and the reliability is improved for the important users after considering the influence of the demand-side supply order.

Power Supply Reliability Analysis on Floating Photovoltaic Systems through Exceedance Probability Approach

Power Supply Reliability Analysis on Floating Photovoltaic Systems through Exceedance Probability Approach

Gas Supply Reliability Analysis of a Natural Gas Pipeline System Considering the Effects of Demand Side Management

Abstract At present, China has a developing natural gas market, and ensuring the security of gas supply is an issue of high concern. Gas supply reliability, the natural gas pipeline system's ability to satisfy the market demand, is determined by both supply side and demand side and is usually adopted by the researches to measure the security of gas supply. In the previous study, the demand side is usually simplified by using load duration curve (LDC) to describe the demand, which neglects the effect of demand side management. The simplification leads to the inaccurate and unreasonable assessment of the gas supply reliability, especially in high-demand situation. To overcome this deficiency and achieve a more reasonable result of gas supply reliability, this paper extends the previous study on demand side by proposing a novel method of management on natural gas demand side, and the effects of demand side management on gas supply reliability is analyzed. The management includes natural gas prediction models for different types of users, the user classification rule, and the demand adjustment model based on user classification. First, an autoregressive integrated moving average (ARIMA) model and a support vector machine (SVM) model are applied to predict the natural gas demand for different types of users, such as urban gas distributor (including residential customer, commercial customer, small industrial customer), power plant, large industrial customer, and compressed natural gas (CNG) station. Then, the user classification rule is built based on users' attribute and impact of supplied gas's interruption or reduction. Natural gas users are classified into four levels. (1) demand fully satisfied, (2) demand slightly reduced, (3) demand reduced, and (4) demand interrupted. The user classification rule also provides the demand reduction range of different users. Moreover, the optimization model of demand adjustment is built, and the objective of the model is to maximize the amount of gas supplied to each user based on the classification rule. The constraints of the model are determined by the classification rule, including the demand reduction range of different users. Finally, the improved method of gas supply reliability assessment is developed and is applied to the case study of our previous study derived from a realistic natural gas pipeline system operated by PetroChina to analyze the effects of demand side management on natural gas pipeline system's gas supply reliability.

An integrated methodology for the supply reliability analysis of multi-product pipeline systems under pumps failure

As the main way for the long-distance transportation of refined products, multi-products pipelines are of vital importance to the regional energy security. The supply reliability evaluation of multi-product pipeline systems can improve the effective response to unexpected disruptions and guarantee the reliable oil supply. Based on reliability theory and pipeline scheduling method, an integrated supply reliability evaluation methodology for multi-product pipeline systems is proposed in this paper and the pumps failure, of which influence is the most complex, is focused on. In the methodology, the discrete-time Markov process is adopted to describe the stochastic failure and the Monte Carlo method is used to simulate the system states transition. With the pipeline flowrate upper limits under various pumps failure scenarios optimized in advance, the maximum supply capacity to the downstream markets in each trial is calculated by the pipeline scheduling model. Three indicators are also developed to analyze the pipeline supply reliability from the holistic and individual perspectives. At last, the methodology application is performed on a real-world multi-product pipeline system in China and the supply reliability is analyzed in detail according to the simulation results. It is proved to provide a practical method for the emergency response decision-making and loss prevention.

A systematic method for the analysis of energy supply reliability in complex Integrated Energy Systems considering uncertainties of renewable energies, demands and operations

Integrated Energy Systems (IES) become more and more important for the sustainability in energy system development and for promoting the application of clean energy technologies. System complexity and various uncertainties interaction make it difficult to maintain a reliable energy supply. In this paper, a systematic method is proposed for energy supply reliability analysis in complex Integrated Energy Systems (IES). The developed method integrates stochastic modeling, supply capacity analysis and reliability evaluation, which is able to give more comprehensive knowledge of the ability of the IES for satisfying the energy needs under different, coupled uncertainties. Firstly, stochastic models are developed for each unit in IES, including renewable energy, customer demands and components in natural gas pipeline networks and electric power grids, according to their characteristics. Then, a two-stage optimization model is developed for simulating the operation strategies of IESs, and calculating the supply capacities under randomly generated scenarios. Finally, the reliability of supply is evaluated based on the results of the random simulations. The developed method is used to analyze the supply reliability of an assumed IES, to test its effectiveness. The results show the ability to provide valuable information from multiple perspectives including system, individual customer and resource allocation, for design, extension and management of IES.

Gas supply reliability analysis of a natural gas pipeline system considering the effects of underground gas storages

Underground gas storage plays a significant role in ensuring gas supply reliability of natural gas pipeline systems. However, the specific hydraulic characteristics of the underground gas storage and the uncertainties in its gas injection/production capacity are generally overlooked when evaluating the gas supply reliability. Therefore, an integrated methodology to assess gas supply reliability of the natural gas pipeline system is developed in this study, and three aspects of uncertainty and hydraulic characteristic of the natural gas pipeline system are both considered. Based on system’s gas supply strategy, the amounts of gas supplied by the transmission pipeline system and required by the consumers are calculated firstly. The underground gas storage is then employed to regulate the supply-demand imbalance between the transmission pipeline system and market demand by performing its gas injection/production function. Moreover, the operational reliability of the underground gas storage is evaluated to determine whether it is able to complete the specified gas injection/production task. Then, the total daily amount of gas supplied to the consumers, is obtained, and two indicators proposed to quantify the gas supply reliability are then calculated. Finally, the expected gas supply reliability is assessed based on a large number of Monte Carlo trials. Moreover, the methodology is applied to a simplified gas pipeline system to confirm its feasibility, and system’s ability to satisfy the consumers demand is evaluated, and the weakest consumer node is identified. Furthermore, the gas supply reliability is overestimated without considering the uncertainties in the underground gas storage’s gas injection/production capacity.

The Markov Chain of Energy Carryover Reserves in Models of Power Supply Reliability in Remote

We consider mathematical models for analyzing the energy supply reliability of isolated systems and propose a three-level complex of nested models. The lower level represents the model of functioning of the energy supply system during the period under review. The second level is a model of the energy supply reliability analysis. This analysis is based on multiple simulations of functioning of the energy supply system in randomly formed conditions. The energy sources demand and supply, as well as the amount of carryover reserves of energy in storage, are assumed to be random values. To simulate functioning, the values of energy demand and production are formed using the Monto-Carlo method following their laws of probability. The random value of the carryover reserves is formed using the algorithm that generates the Markov sequence of these reserves. The upper level is represented by the model for selecting the optimal composition of the means ensuring reliability, i.e. energy reserves in the energy production and storage capacity. It was revealed that the algorithm for generating the random value of the energy sources carryover reserves yields the homogenous Markov sequence. Sufficient conditions for uniqueness of the stationary state were determined. Based on the experimental calculations, we estimated the number of iterations required to reach the stationary ergodic state.

The gas supply reliability analysis of natural gas pipeline network based on simplified topological structure

Currently, as a universal clean energy, natural gas plays a greater role in industrial and civil energy consumption than it has previously. Any insufficient supply scenario has a severe impact due to the increasing use of power plants, chemical engineering, industrial production, and public sectors. It is essential to develop a methodology for analyzing gas supply insufficiencies that are caused by pipeline network malfunctions. This paper introduces a systematic method for evaluating the natural gas supply reliability based on the pipeline network. Primarily, the reliability of each unit in the pipeline network is derived from multi-variant distribution principles to initiate topological structure analysis carried out in the real pipeline network. Afterwards, the Monte Carlo simulation shows the random status of the topological network based on preconcerted failure distributions of facilities and pipes rather than estimating the reliability directly. Because the current transmission capacity is possibly excessive relative to the transmission task, both designed capacity and current supply capacity require stochastic simulations. After stochastic simulations of the market demand, a feasible random transmission requirement and a certain structure of the topological network are obtained from random simulations to calculate the total transmission capacity. Ultimately, according to the supply insufficiency level, there are deployable measures that could eliminate this influence.

Short-Term Reservoir Storage Frequency Relationships

AbstractThe water rights analysis package (WRAP) is a generalized river/reservoir system simulation model that is routinely applied in Texas in regional and statewide planning studies and administration of the water right permit system. The WRAP modeling system was recently expanded by adding short-term storage frequency and supply reliability analysis capabilities. Individual reservoirs and multiple-reservoir systems can be analyzed considering numerous water users and complex water management practices. The new modeling features are based on dividing the hydrologic period-of-analysis into many short-simulation sequences with each starting with the same storage conditions. Two alternative frequency/reliability analysis methodologies, called the equal-weight and probability-array options, are compared in this paper with a case-study application. The probability array option is designed to improve the accuracy of storage frequency estimates by modeling hydrologic persistence as reflected in the preceding r...

Integrating Yield and Shortage Management under Multiple Uncertainties

An economic-engineering modeling approach is presented for integrating urban water supply reliability analysis with shortage management options such as dry year option and spot market water transfers, water reuse, and long- and short-term water conservation. The integrated model uses a probability plotting position formula to link supply-side yield simulation to probabilistic shortage management optimization. The approach can help joint planning of supply and demand management and estimate the economic value of expanding infrastructure and changing institutional constraints. Results from a case study show that jointly managing supply capacity and operating rule decisions with shortage management decisions within a risk analysis framework can create significant economic savings. The importance of hydrologic and institutional uncertainties is explored. Tuning supply system and reservoir operating policies to match the seasonal and cost characteristics of available shortage management measures is shown to be...