Gas Supply Reliability Research Articles

An integrated gas supply reliability evaluation method of the large-scale and complex natural gas pipeline network based on demand-side analysis

The fluctuation characteristics of the gas demand and the effect of the user importance are usually ignored in previous gas supply reliability research. With the intent of overcoming these deficiencies, an integrated method based on the demand-side analysis is proposed in this study to assess the gas supply reliability of the large-scale and complex natural gas pipeline network. The method is composed of the establishment of the indicator system, the demand-side analysis, the estimation of the unit failure probability, and the calculation of the gas supply. Among them, the demand-side analysis focuses on the market demand forecasting and user importance research. Moreover, the coupling effect of the user importance, the hydraulic and pressure constraints, and the unit failure on the gas supply calculation is considered. Furthermore, a real natural gas pipeline network located in China is applied to confirm the feasibility of the method. According to the evaluation results of the gas supply reliability, the weakest nodes and key links of the natural gas pipeline network are identified, and the suggestions to improve the gas supply reliability are proposed as well. At last, the significance of the demand side in the gas supply reliability is elaborated and validated.

Influence of gas transmission network failure on security of supply

This paper investigates the influence of failure of transmission network key elements on security of natural gas delivery. The proposed framework combines the probabilistic structure integrity study and the hydraulic analysis. A factor called a volumetric loss was introduced to quantify the effect of network failure. Based on the magnetic flux leakage diagnostics, the rupture probability of steel tube plastic collapse was estimated using a random variable method and Monte Carlo solution. In-line inspections should monitor only the rate of tube wall corrosion, whereas the proposed methodology enables the pipeline operator to evaluate the system ability to deliver gas at the customer nodes. For the hydraulic analysis, an unsteady gas flow model was applied using conservation principles of mass, momentum, and energy. The flow model was tuned to real pressure and temperature data using a multi-objective optimization approach. To demonstrate the practical value of the methodology, the time and amount of gas shortage, line pack, and a volumetric loss were computed for a real tree-topological pipeline network. Simulations demonstrated that the highest volumetric loss is experienced when both compressor stations are shut down. The aim of the proposed algorithm is identification of critical nodes as well as evaluation of measures for improving the gas supply reliability to the customers.

Development of Protective Gas Pipes Sleeves for Operation in Permafrost Soils

Experimental studies were carried out and causes of emergencies with gas pipes in protective sleeves used in construction of gas pipelines were identified. Protective sleeve design has been developed that excludes deformation or destruction of gas pipeline during groundwater freezing in the annulus. Model tests of polyethylene gas pipeline in steel casing, using polyethylene foam as an element that compensates expansion of water during freezing, showed complete exclusion of deformation of gas pipes during freezing. Test results of developed designs of protective casings showed the possibility of widespread use to improve reliability and safety of gas supply.

A Systematic Methodology to Assess Hydraulic Reliability and Gas Supply Reliability of the Natural Gas Pipeline Network

Abstract Reliability of the natural gas pipeline network is related to security of gas supply directly. According to the different required functions of the natural gas pipeline network, its reliability is divided into three aspects, namely mechanical reliability, hydraulic reliability, and gas supply reliability. However, most of the previous studies confused the definitions of the hydraulic reliability and gas supply reliability. Moreover, the uncertainty in the process of supplying natural gas to the targeted market and the hydraulic characteristic of the natural gas pipeline network are often ignored. Therefore, a methodology to assess hydraulic reliability and gas supply reliability of the natural gas pipeline network is developed in the study, and the uncertainty and hydraulic characteristic of the natural gas pipeline network are both considered. The methodology consists of four parts: establishment of the indicator system, calculation of the gas supply, prediction of the market demand, and assessment of the hydraulic reliability and gas supply reliability. Moreover, a case study is applied to confirm the feasibility of the methodology, and the reliability evaluation results provide a comprehensive picture about the abilities of the natural gas pipeline network to perform the specified gas supply function and satisfy consumers' demand, respectively. Furthermore, a comparison between these two types of reliability is presented. The results indicate that the natural gas pipeline network may not be able to meet the market demand even if the system completes the required gas supply tasks due to the impact of the market demand uncertainty.

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.

Assessment method for gas supply reliability of natural gas pipeline networks considering failure and repair

Pipeline networks are the primary means of natural gas transmission, and assessing the gas supply reliability is of great significance for the safe and stable operation of pipeline networks. However, current assessment researches for the gas supply reliability are just conducted on the entire pipeline networks and based on the failed pipeline networks, i.e. the assessment process is static. The individual difference differences among users and the reparability of pipeline networks are neglected, which make the assessment results not comprehensive and objective enough. To address these problems, a new assessment index is defined to assess the gas supply reliability of individual users by combining the gas shortage time and severity in this paper, and the gas supply reliability assessment is carried out from the perspectives of entire pipeline networks, individual users, gas shortage amount and gas shortage time. Furthermore, an operation state determination model of pipeline networks is established based on the failure and repair processes. Finally, a systematic assessment method with dynamic characteristics is proposed. By using the assessment method, the gas supply reliability of an actual pipeline network is assessed. The differences between the assessment of entire pipeline network and individual users are compared, and the importance ranking of components is presented. The assessment results can provide a theoretical basis for an economical optimization of the gas supply reliability of pipeline networks.

Supply reliability assessment of a gas pipeline network under stochastic demands

An integrated methodology to assess the gas supply reliability of a gas pipeline network considering stochastic demands is proposed in this study. Typical scenarios are selected based on the structural reliability calculated by probability theory and stochastic process, including the normal scenario and some failure scenarios with a high probability. For each specific scenario, the gas supply condition is assessed based on the Latin hypercube sampling with the Cholesky decomposition method under stochastic demands. The maximum flow method based on the Dijkstra algorithm is adopted to determine whether the gas demand of customers can be fully covered and optimize the supply scheme under shortages. Finally, the assessment results are demonstrated from the following four aspects: the probability distribution of gas shortages under the normal scenario, identification of units with a high failure probability and vulnerable units, the reasons of gas supply shortages and corresponding probabilities, and the probability distribution of supply reliability for a gas pipeline network and each customer. The methodology is applied to a large-scale gas pipeline network in China. The results of the supply reliability assessment are analyzed in detail, and the sensitivity analysis of the gas demand uncertainty level on gas supply reliability is conducted.

Analysis of COVID-19 Impact on Natural Gas Supply Reliability

In this study, we have analyzed the impact of COVID-19 on natural gas supply reliability. Natural gas supply reliability is defined as the ability to satisfy the market demand and is determined by both supply-side and demand-side policy. To evaluate the gas supply reliability of the natural gas pipeline system, we have applied the method of gas supply capacity calculation based on the results of the previous gas supply reliability studies. The method combines the unsteady flow hydraulic analysis, simulation of the state transition process, and the forecasting analysis of the demand and consumption. The analysis presents a case study based on the gas pipeline system in China. The analysis results indicate that the COVID-19 consequences will cause a decrease in gas supply reliability.

Reliability assessment of gas supply to individual consumers using digital modeling

In this work, an algorithm for assessing the reliability of gas supply for individual enterprises was developed and a block diagram of the application program was compiled. The calculation was made in accordance with the principles of the theory of the probability of disconnecting consumers using digital modeling.

A novel methodology for forecasting gas supply reliability of natural gas pipeline systems

In this paper, a novel systematic and integrated methodology to assess gas supply reliability is proposed based on the Monte Carlo method, statistical analysis, mathematical-probabilistic analysis, and hydraulic simulation. The method proposed has two stages. In the first stage, typical scenarios are determined. In the second stage, hydraulic simulation is conducted to calculate the flow rate in each typical scenario. The result of the gas pipeline system calculated is the average gas supply reliability in each typical scenario. To verify the feasibility, the method proposed is applied for a real natural gas pipelines network system. The comparison of the results calculated and the actual gas supply reliability based on the filed data in the evaluation period suggests the assessment results of the method proposed agree well with the filed data. Besides, the effect of different components on gas supply reliability is investigated, and the most critical component is identified. For example, the 48th unit is the most critical component for the SH terminal station, while the 119th typical scenario results in the most severe consequence which causes the loss of 175.61 × 104 m3 gas when the 119th scenario happens. This paper provides a set of scientific and reasonable gas supply reliability indexes which can evaluate the gas supply reliability from two dimensions of quantity and time.

Existing methods of creating, operating underground gas storages and enhancing component recovery of layers

A significant role in ensuring the reliability of gas supply is played by underground gas storages, which are the most cost-effective objects for reserving natural gas. With all the originality of solving the issues of gas supply reliability by constructing underground gas storage in depleted gas condensate, gas and oil fields and aquifers, which are traditional methods, the absence of such geological conditions necessitates searching for other, unconventional methods of creating underground gas storages.

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.

Economic Value of Improving Natural Gas Supply Reliability for Residential Consumers in South Korea

An interruption to residential natural gas (NG) may cause considerable economic damage of the entire country. Thus, the South Korean government requires information about the economic value of improving residential NG supply reliability for planning NG supply. This article aims to measure the value using a specific case of South Korean residential consumers. The choice experiment (CE) approach was adopted for this purpose. The selected four attributes are the duration of interruption, the season of interruption, the time of day, and the day of the week. The value trade-off works among the four attributes and price attribute were sought and completed in a nationwide CE survey of 1000 households. The respondents revealed statistically significant willingness to pay for a decrease in the duration of interruption, avoiding interruption during winter rather than non-winter, and preventing interruption during off-daytime (18:00 to 09:00) rather than daytime (09:00 to 18:00). For example, they accepted a 0.10% increase in the residential NG bill for a one-minute reduction in interruption during NG supply interruption, a 5.16% increase in residential NG bill for avoiding interruption during winter rather than non-winter, and a 2.94% increase in residential NG bill for preventing interruption during off-daytime rather than daytime. However, they placed no importance on the day of the week. These results can be useful for policy-making and decision-making to improve residential NG supply reliability. It is necessary to conduct a study at regular intervals on the value of NG supply reliability because regarding NG supply reliability, it is difficult to maintain a specific value.

The analysis of international experience in the energy market formation and economic mechanisms for management of the gas supply systems

The article assesses the foreign countries experience in formation of the energy market and the basics of managing the development of gas supply systems. The creation of a system in order to provide access to gas transport services for gas consumers, gas producers and its suppliers, as well as the creation of favorable conditions for investment is a significant stage in the implementation of effective market transformations. One of the fundamental points for carrying out the reforms in gas industry in the market conditions should be the arrangement of trade system for reserved capacities. The positive results of the reform include: reduction or stabilization of prices for end-users, diversification of gas supply sources, improvement of the gas supply reliability.

Gas supply reliability assessment of natural gas transmission pipeline systems

The uncertainty of market demand and dynamic behaviour of the pipeline system are usually ignored in previous gas supply reliability assessments. With the intent of overcoming these deficiencies, a novel methodology to assess the gas supply reliability of natural gas transmission pipeline systems is proposed in this paper. Considering both gas supply capacity and market demand uncertainties, calculations of these two items are integrated into a single Monte Carlo simulation. On each Monte Carlo trial, the hydraulic analysis of unsteady flow is combined with the state transition process simulation to calculate the gas supply capacity. In terms of market demand, the load duration curve technology is employed to predict the amount of demand. Then, the indicator proposed to quantify gas supply reliability is calculated on each trial. Finally, the average gas supply reliability is obtained based on N Monte Carlo trials. Applications of this methodology are demonstrated through a real transmission pipeline system. Thereafter, the method is compared with previous approaches and differences are discussed. Furthermore, the impacts of supply capacity and market demand uncertainties on the gas supply reliability are investigated and suggestions to improve the gas supply reliability are proposed.

Ocena niezawodności dostaw gazu w miejskiej sieci gazowej

As one of the lifeline projects, an urban gas network is a complex system, as it requires maintenance of the supply capacity when any single pipeline is isolated due to failure. For such a system, its reliability needs to be evaluated. Considering that existing structural reliability and hydraulic reliability analyses reflect different aspects of the working conditions of an urban gas network, system reliability theory is employed to explain that only the gas supply reliability can achieve a comprehensive evaluation of the work capacity of the entire urban gas network, as it takes into account the combined influence of the structural reliability and hydraulic reliability. To calculate the parameters in the gas supply reliability evaluation, such as pipeline failure rate, flow reduction in the gas network under different failure conditions, etc., some research achievements in the field of structural reliability and hydraulic reliability are fully utilized. Then, the detailed calculation procedures of these parameters are given to evaluate the gas supply reliability in terms of operational and practical considerations. Finally, using an example of a simple double-loop gas network, the detailed process of the gas supply reliability evaluation of an urban gas network is described, and the feasibility of this evaluation method is also illustrated.

Failure probability estimation of gas supply using the central moment method in an integrated energy system

The reliable supply of natural gas ensures the safe and stable operation of an integrated energy system. Operational uncertainty of the integrated energy system (IES) such as a surge in heating load can exacerbate an unreliable supply situation of natural gas. This paper examines gas supply reliability. A central moment method is proposed to estimate the failure probabilities for the gas supply in a combined heat- and power-based microintegrated energy system. To make the calculation more relevant to an actual project, we considered the energy network constraints and energy stochastic characteristics. To demonstrate the use of the central moment method in the estimation of failure probability of a gas supply, the results were validated using sufficient comparisons with traditional methods. Classic traditional methods include the Iman and Stein methods, the first order reliability method, the mixed algorithm based on Latin hypercube sampling, the Cholesky decomposition and the Nataf transformation, and the principle of maximum entropy method. An actual integrated energy system is provided to promote practical solutions for failure probability estimation of the gas supply.

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.

Security of the Colombian energy supply: The need for liquefied natural gas regasification terminals for power and natural gas sectors

The reliability of natural gas and electricity supply is a crucial aspect in many fast-growing economies, as the economic boom of these countries demands a solid energy infrastructure. In Colombia, the economy has experienced a steady increment over the last several years that have placed the country as one of the most promising economies in Latin America. However, the natural gas infrastructure lacks sufficient robustness to withstand the rate of economic growth. This paper assesses the impact on the reliability of a liquefied natural gas regasification terminal in Colombia as one potential solution to improve the reliability in the country. Contrary to other works, this paper investigates the impact of using an integrated electric and natural gas model, as there exists a strong interdependency between both sectors. This approach is more suitable since it permits evaluation of the impact of a terminal on electricity users, as they also experience the negative consequences of an unreliable natural gas supply. Numerical results show that the terminals substantially improve the reliability of both systems. Furthermore, numerical results prove that the current regulatory approach, based on a priority service queue to mitigate the negative effect of an unreliable system, would no longer be needed.

Unique Gas Generator Provides Low Cost, Reliable Hydrogen Supply

Abstract A hydrogen gas generator plant offers a flexible hydrogen supply solution to the powder metallurgy industry. This article provides an overview of a unique steam methane reformer that uses an integrated heat recovery system to reduce the cost and improve the reliability of hydrogen gas supply.