Gas Distribution Network Research Articles

PROBLEMS OF MANAGING TECHNOLOGICAL REGIMES IN GAS DISTRIBUTION NETWORKS AND MODERN APPROACHES TO THEIR SOLUTION

This article systematically discusses the problems of managing technological regimes in gas distribution networks and modern approaches to their resolution. The scientific-theoretical and practical aspects of managing gas distribution networks (GDN) are analyzed. Based on the obtained results, a scientifically grounded comparative explanation of the existing contradictions in modern and traditional gas distribution networks is provided, and the role of key factors in the emergence of these contradictions is investigated. It is shown that technological backwardness in traditional GDNs increases energy consumption and operational costs, thereby reducing the economic efficiency of the system and increasing the risk of accidents. The research suggests decision-making methods for solving management problems in traditional GDNs by maintaining the technical-structural level and implementing telemetry systems. It is indicated that the widespread use of telemetry and telemechanics tools in the gas distribution industry enhances the safe delivery of gas to end-users and significantly reduces service costs. Another focus of the research is on the issues related to the processing of spatial information for the management of the technical components of gas distribution systems. The article also analyzes scientific research dedicated to the application of modern IT methods and tools in the management of GDNs, investigating management and forecasting models using neural networks and intelligent methods. Keywords: Gas distribution networks, modern GDN networks, traditional GDN networks, GIS systems, digital technologies, technogenic risks, neural networks, forecasting methods

A three-level model for integration of hydrogen refuelling stations in interconnected power-gas networks considering vehicle-to-infrastructure (V2I) technology

The coupling with natural gas networks creates an excellent opportunity for renewable-rich power systems to facilitate the utilisation of renewable energy resources; on the other hand, with the increase in employment of fuel cell vehicles (FCVs), the number of hydrogen refuelling stations (HRSs) is increasing. The integration of HRSs in electric distribution systems may impact the operation of electric distribution systems. Through vehicle-to-infrastructure (V2I) technology, vehicles may exchange information with HRSs and know hydrogen prices. The operation of the coupled power and natural gas networks with integration of green HRSs, considering the model of FCVs has not been investigated in the literature, so, it has been set as the goal of this paper. To avoid the challenges of nonlinear gas flow model, they are linearized through piecewise linearisation. The case study is a 33-bus electric distribution system, coupled with a 14-node gas distribution network; each HRS includes a battery, a hydrogen tank, an electrolyzer, a PV and a wind turbine. MILP models have been used for FCVs, HRSs and power-gas networks. CPLEX solver is used for solving the developed MILP models. The results show that the total cost of the coupled electricity-gas network is $760.37 and the refuelling cost of each FCV is $17.30. The results indicate that both electric and hydrogen storage systems enhance the flexibility of HRSs, enabling efficient utilisation of PV modules and wind turbines, so, only in few hours, HRSs need to purchase electricity from electric distribution system; that is why each HRS makes a considerable profit of $519 per day. The achieved results also indicate that the pressure of all gas nodes and gas flow of all pipelines fall within their prespecified range.

Modeling Interdependent Infrastructure System Vulnerability with Imprecise Information Using Two Fuzzy Inference Systems

Infrastructure systems play important roles in economic development and the social quality of life. Interdependencies exist between infrastructure systems: a functional disruption in one system can affect dependent systems, thereby escalating the impacts. It is vital to properly model interdependencies to understand the full impacts of disruptive events on infrastructure systems. Quantitative data on infrastructure interdependency is often difficult to obtain or unavailable for a variety of reasons. To overcome quantitative data scarcity issues, qualitative subject expert knowledge has been used in interdependency analysis, primarily in the form of linguistic responses. Linguistic data is susceptible to uncertainties arising from variations in intended meanings, which may yield inaccurate results. This paper proposes a framework to address this problem using two fuzzy inference systems to model event-specific, network-wide infrastructure failures. The first fuzzy inference system models the damage induced by interdependencies using verbal descriptions. The second fuzzy inference system accounts for synergistic, compounding effects of multiple incidences of indirect damage caused by interdependencies. A case study is conducted to demonstrate the applicability of the proposed methodology using electric and gas distribution networks in the United Kingdom. Sensitivity analyses are performed to show the flexibility of the fuzzy inference systems. The results show that the proposed method can model the interdependency and vulnerability of infrastructure systems using fuzzy inference systems to handle imprecise input. The proposed framework may assist practitioners in better understanding the interdependency and vulnerability of infrastructure systems, and in making more informed decisions to reduce losses resulting from disruptive events.

Assessing Hydrogen Embrittlement in Pipeline Steels for Natural Gas-Hydrogen Blends: Implications for Existing Infrastructure

Governments worldwide are actively committed to achieving their carbon emission reduction targets, and one avenue under exploration is harnessing the potential of hydrogen. Blending hydrogen with natural gas is emerging as a promising strategy to reduce carbon emissions, as it burns cleanly without emitting carbon dioxide. This blending could significantly contribute to emissions reduction in both residential and commercial settings. However, a critical challenge associated with this approach is the potential for Hydrogen Embrittlement (HE), a phenomenon wherein the mechanical properties of pipe steels degrade due to the infiltration of hydrogen atoms into the metal lattice structure. This can result in sudden and sever failures when the steel is subjected to mechanical stress. To effectively implement hydrogen-natural gas blending, it is imperative to gain a comprehensive understanding of how hydrogen affects the integrity of pipe steel. This necessitates the development of robust experimental methodologies capable of monitoring the presence and impact of hydrogen within the microstructures of steel. Key techniques employed for this assessment include microscopic observation, hydrogen permeation tests, and tensile and fatigue testing. In this study, samples from two distinct types of pipeline steels used in the natural gas distribution network underwent rigorous examination. The findings from this research indicate that charged samples exhibit a discernible decline in fatigue and tensile properties. This deterioration is attributed to embrittlement and reduced ductility stemming from the infiltration of hydrogen into the steel matrix. The extent of degradation in fatigue properties is correlated not only to the hydrogen content but also to the hydrogen permeability and diffusion rate influenced by steel’s microstructural features, with higher charging current densities indicating a more significant presence of hydrogen in the natural gas pipeline blend.

Numerical analysis of the effect of hydrogen doping ratio on gas transmission in low-pressure pipeline network

In the context of a global shift towards clean energy, the integration of hydrogen into existing natural gas pipeline networks is essential for facilitating the energy transition. Specifically, low-pressure natural gas pipeline networks are crucial for transporting gas efficiently and with minimal losses from the source to end-users in nearby cities. The physical properties of hydrogen differ significantly from those of natural gas, which implies that introducing hydrogen into the pipeline network will modify operational parameters and impact the safety and efficiency of gas transmission. Therefore, this study concentrates on the efficiency of transporting and scheduling hydrogen-blended natural gas through existing low-pressure direct pipelines. Utilizing the BWRS (Benedict-Webb-Rubin-Starling) equation of state, mathematical models were developed to calculate gas properties and to simulate both the steady and transient states of hydrogen-blended natural gas networks. These models were then validated with TGNET software. This study examines a low-pressure natural gas transmission and distribution network that transports gas directly from a production site in Sichuan to urban areas. It conducts simulations of hydrogen blending and analyzes the impact of various hydrogen blend ratios on the transport and scheduling responses of the network. Research suggests that maintaining the hydrogen blend below 30% ensures the safe operation of low-pressure gas pipelines and prevents the transmission pressure from exceeding 3 MPa. Additionally, under a fixed energy flow output, blending hydrogen intensifies the challenges associated with pressure drops and temperature increases due to high flows in small diameter pipes, and further complicates the management of interruptions resulting from faults. Therefore, it is recommended that the hydrogen blend ratio be maintained at no more than 30%, and that accident handling procedures be established in advance to control pressure variations following a shutdown.

Withdrawn: Transient modeling of natural gas in pipeline networks by two non-iterative explicit and implicit finite volume methods

This paper describes two non-iterative explicit and implicit finite volume methods (FVM) to calculate the unsteady characteristics of natural gas in distribution systems. The proposed finite volume model could be used to solve the gas network as a whole for each time step. The main advantage of this approach is that it can analyze gas distribution networks with less computational cost. In addition, contrary to the conventional iterative algorithms, it does not consist of any divergence problems (Elman et al., 1996). To achieve this goal, the explicit FVM is derived from the governing equations. Then, the linearization process is performed, and the numerical solution of the linear equations is developed by using the implicit FVM. Three classic test cases are exemplified to check the performance of the proposed methods. The results confirm that both explicit and implicit methods, even in complicated distribution networks, can predict the elements of unsteady natural gas flows. Furthermore, when the governing equations are linearized and the implicit FVM is applied, satisfactory results with less computational cost, compared to the explicit one, are produced.

Arrangement of Nondestructive Tests for Technical Inspection Process of Electrofusion Weld in Gas Polyethylene Pipe

Due to the reduction of operational costs, Non-corrosiveness, and ease of implementation, polyethylene pipes are a suitable replacement for steel pipes in gas distribution networks. Considering the irreversible events of gas leakage, effective and feasible non-destructive testing of electrofusion welding is an essential factor to avoid the hazards of gas leakage. To control the quality of welds, the nature of the electrofusion structure leads us to manufacture vacuum boxes, internal pressure devices, and Tapping Saddle Connector for testing polyethylene joint leakages. This article focuses on the sequence of these non-destructive tests to monitor the health of polyethylene electrofusion joint structures under gas network project implementation conditions. To examine the testing chain and the proposed sequence of non-destructive tests, the data gathering process was performed, and with respect to the sensitivity of the electrofusion weld to the operator's skill, welding process, and the condition of the pipe and fittings, in each case the influential factors to find the key parameters were evaluated. The results of laboratory tests in cases of short tests and long-life tests using artificial defects such as slow crack growth with defective samples of on-site joints and defects reported in projects were compared. To validate leak detection, leak location, and leak measurement, weld simulation with finite element and CFD software analysis conforming to real conditions was considered. The test sequence, acceptance criteria, and calibration method of the tools according to EN 1555 standard were argued for performing the final inspection steps. In this perspective, for each leak testing technique, the average type, pressure level, test duration, and finally the acceptance criteria were proposed. The main outcome is the technical specifications for electrofusion weld assessment and baseline risk- based inspection scheme in gas supply projects. In this regard, a database software based on the proposed ITP (Inspection and Testing Plan) has been developed, which is fundamental for monitoring the whole project from the first stage of polyethylene granule control, pipe and fitting manufacture, and gas injection to the final stage in network and commissioning. Operations to determine failure causes and suitability for performance assessment. Another proposed idea is standardizing the recent technical specifications internationally. This idea will be implemented when management realizes that non-destructive testing can lead to cost savings, protection of humans and the environment, and when codes and standards encompass such requirements.

The Australian Hydrogen Centre – feasibility studies for achieving 10 and 100% renewable hydrogen in South Australia and Victoria

The Australian Hydrogen Centre (AHC) was established to deliver Australian-first feasibility studies into how existing natural gas distribution networks could be used in a system to produce, store, and transport renewable hydrogen, decarbonising gas supply while still meeting the needs of customers. The AHC Reports show that it is technically and economically feasible to use existing gas infrastructure for scaled hydrogen distribution, delivering: (1) net-zero carbon emissions gas; (2) minimised customer disruption while retaining security and diversity of supply; (3) services to the electricity grid through flexible electricity demand and frequency control; (4) 15 gigawatts (GW) of electrolysis supported by over 30 GW of new renewable electricity generation; (5) 30 petajoules (PJ) of hydrogen storage to harness the ability of gas to store vast amounts of energy, balancing renewable electricity supply and demand swings between colder and warmer months; and (6) over AU$1.5 billion in additional economic value a year including more than 12,500 jobs during construction and 6200 jobs during operation. Supported by a range of independent technical studies, the Reports provide a better understanding of the opportunity to access Australia’s world-class gas distribution infrastructure to unlock hydrogen opportunities while retaining energy security and affordability; identifying a range of low-regret enablers that could trigger coordinated action by government and industry. They also share learnings from Hydrogen Park South Australia (HyP SA), an Australian-first demonstration of hydrogen blending in a gas distribution network.

Smart management of pressure regulating stations to maximize hydrogen injection in a gas distribution network

Gas distribution networks traditionally maintain constant pressure setpoints at regulating stations, ensuring a consistent supply to end-users with a high safety margin. However, the prospect of hydrogen injection in the gas networks necessitates rethinking operational strategies. This study examines the environmental and fluid-dynamic implications of implementing a smart pressure management approach in regulating stations within a distribution network with a localized hydrogen injection. The research introduces a novel simulation-based optimization algorithm, incorporating a steady-state fluid-dynamic model with hydrogen tracking, used to optimize the pressure setpoints in the stations. The algorithm is applied to a two-pressure levels looped gas network with multiple gas supply nodes and a single hydrogen injection. The test case results reveal that utilizing dynamic pressure setpoints leads to a 22% increase in hydrogen penetration compared to standard operation. Therefore, this study highlights that smart pressure modulation in a gas network with hydrogen injection can unlock a latent decarbonization potential, while simultaneously adhering to safety limits.

Analysis of The Feasibility of Hydrogen Injection in Pipeline Gas Distribution Networks

Objective: The objective of this study is the development of the basic guidelines for blending green hydrogen with natural gas and transporting it through the gas pipelines of a natural gas distribution company. The characteristics of consumption, legislation and materials used in the company's network were considered. In addition, data from recent research in the area was also selected to support specific actions so that this objective is achieved in a technically sustainable way, respecting technical knowledge and standards available internationally. Method: In this scenario, a study of the feasibility of enriching natural gas distributed by a gas distribution company in the region of the city of Fortaleza with green hydrogen is presented. In addition, data from recent research in the area was also selected to support specific actions so that this objective is achieved in a technically sustainable way, respecting technical knowledge and standards available internationally. Results and Discussion: Based on current legislation and a series of technical references, it is currently recommended to add levels of up to 2% in branches where natural gas is used for vehicular and industrial glass and ceramic applications and can increase up to 3% in other extensions. The maximum concentration may reach 10% in the medium term after detailed fatigue resistance studies or adaptation of pipes with internal polymer jackets. Research Implications: The interest in replacing fossil fuels for decarbonization purposes has motivated research into a series of alternatives, among which hydrogen stands out as a possible vector or energy carrier for high-efficiency systems with oxidation free of carbon emissions. carbon. Introducing renewable hydrogen into natural gas distribution networks stabilizes the demand for production of this gas, in addition to alleviating the costs and risks associated with building a dedicated facility. Originality/Value: This study contributes to the literature related to the study of green Hydrogen. The relevance and value of this research are evidenced by the results obtained.

Procedure for digitalization of measures to create a gas distribution network

It describes the possibility of digitalization of measures to create a gas distribution network. Describes the processes involved in defining the connection contract category, executing and approving project documentation. Analysis of possible reduction of measures due to use of electronic geodetic database, single site for coordination of gas distribution network projects is performed. The result of the introduction of digitalization of measures to create a gas distribution network will be a reduction of up to three calendar months of the term for fulfilling contractual obligations by the gas distribution organization.

The peculiarities of the execution of natural gas supply contracts

The legal basis for the functioning of the natural gas market of Ukraine, based on the principles of free competition, proper protection of consumer rights and security of natural gas supply, has been determined by the Law of Ukraine “On the Natural Gas Market” No. 329-VIII dated 04/09/2015.
 The supply of natural gas to household consumers is carried out on the basis of the standard contract. According to the content of the provisions of the Code of the Gas Transportation System and the Code of the Gas Distribution System, it is understood that, in order to supply natural gas to consumers, its supplier purchases this gas from a wholesaler at a virtual point of sale, and consumers receive it directly from the operator of gas distribution networks at the limit of the balance sheet ownership of their facilities (at destinations). In the context of updating the civil legislation of Ukraine and its harmonization with the law of the European Union, the study of the peculiarities of the execution of the gas supply contract as a type of contract for the supply of energy and the other resources through the connected network is relevant. Taking into account the specifics of the supply object, namely that natural gas is a commercial product that is a mixture of hydrocarbons and non-hydrocarbon components in a gaseous state under standard conditions, the legal nature of the supply contract has certain peculiarities. At the same time, under the contract for the supply of energy and the other resources through the connected network, one party (supplier) undertakes to provide the other party (consumer, subscriber) with energy and the other resources provided for in the contract, and the consumer (subscriber) undertakes to pay the cost of the received resources and to comply with the mode of its use stipulated by the contract, as well as to ensure safe operation of energy and the other equipment.
 The peculiarities of the execution of the contract for the supply of natural gas have been determined by the legal regime of the commercial product, which is natural gas, and the peculiarities of its supply (no other than through the gas transportation and gas distribution systems in which natural gas is received from various economic entities, as a result of which it is mixed and changes in physical chemical parameters).

Optimal operation of integrated electricity and gas networks with risk analysis using downside risk constraints method

Recently, the number of power plants producing electricity by natural gas-fired generations is increased. The increased number signifies an inseparable relevance between gas-fired power plants and gas distribution networks. There are different uncertain parameters such as power cut and fluctuation-based market price that are unexpected. They impose financial threats to the performance of the gas and power system. In this study, the downside risk constraint (DRC) method is used by considering market price as an uncertainty. The proposed approach implemented for the non-linear gas flow to assess the coordination between gas and electricity systems properly, in which the financial risks of the cooperation with neighbor zones are regarded. The objective is to minimize the operation cost of the first zone considering the power trading with other zones, in which the proposed approach is applied over a 20-node natural gas (NG) network and IEEE RTS 24-bus. According to the obtained results, to achieve zero risk level in the risk-averse mode, the average cost is increased by 10.3 %. Therefore, it is clear that the possibility of risk has significantly reduced with an increment of operating cost.

Low carbon and economic optimal operation of electricity-gas integrated energy system considering demand response

Integrated Energy System is an important direction for the transformation of the power industry. IES can give full play to the complementary role of multiple energy sources and serve to achieve the industry's energy saving and emission reduction goals. Firstly, this paper establishes a P2G refined operation model considering two stages of hydrogen production from electrolytic water and hydrogen methanation. Secondly, based on the analysis of the IES load characteristics, the multi-energy loads are divided into longitudinal demand responses where the same energy type can be transferred and reduced in time, and horizontal demand responses where different energy types can be substituted for each other, and the corresponding mathematical models are established. Finally, the reward and penalty ladder carbon trading mechanism are used to quantify the carbon trading cost, and the IES low-carbon economic optimization model integrating the Power-to-gas refinement model and demand response is constructed. The model was subjected to second-order cone programming relaxation and incremental segmented linearization methods before being solved using the CPLEX commercial solver. Simulation analyses were performed in an IES consisting of an IEEE 33-node distribution network and a 24-node gas distribution network. The results show that considering demand response can fully exploit the flexible coordination performance of the load side, resulting in a 12.6% reduction in total system cost and a 38.8% reduction in carbon emissions.

Analysis of Delta in-out for Irish natural gas distribution network

This article investigates the issue of Unaccounted for Gas (UAG) in the natural gas distribution network of Ireland, focusing on the DeltaIO (i.e. the difference between the gas entering and leaving the network). The study applies the DeltaIO methodology developed for Italian distribution networks to Gas Networks Ireland (GNI), the sole Distribution System Operator (DSO) in Ireland. The analysis covers the period from 2013 to 2019 and provides insights into the magnitude and trends of UAG in the Irish context. The results show that GNI's DeltaIO ranges from 0.93% to 1.57%, with an average of 1.15%. Comparisons with large Italian networks reveal higher DeltaIO values for GNI. The study demonstrates the compatibility of the DeltaIO methodology with the Irish distribution network and highlights the commercial implications of positive and negative DeltaIO values. The findings contribute to the understanding of UAG in the Irish natural gas sector and provide valuable insights for industry stakeholders and regulators.

Two Iterative Methods for Sizing Pipe Diameters in Gas Distribution Networks with Loops

Closed-loop pipe systems allow the possibility of the flow of gas from both directions across each route, ensuring supply continuity in the event of a failure at one point, but their main shortcoming is in the necessity to model them using iterative methods. Two iterative methods of determining the optimal pipe diameter in a gas distribution network with closed loops are described in this paper, offering the advantage of maintaining the gas velocity within specified technical limits, even during peak demand. They are based on the following: (1) a modified Hardy Cross method with the correction of the diameter in each iteration and (2) the node-loop method, which provides a new diameter directly in each iteration. The calculation of the optimal pipe diameter in such gas distribution networks relies on ensuring mass continuity at nodes, following the first Kirchhoff law, and concluding when the pressure drops in all the closed paths are algebraically balanced, adhering to the second Kirchhoff law for energy equilibrium. The presented optimisation is based on principles developed by Hardy Cross in the 1930s for the moment distribution analysis of statically indeterminate structures. The results are for steady-state conditions and for the highest possible estimated demand of gas, while the distributed gas is treated as a noncompressible fluid due to the relatively small drop in pressure in a typical network of pipes. There is no unique solution; instead, an infinite number of potential outcomes exist, alongside infinite combinations of pipe diameters for a given fixed flow pattern that can satisfy the first and second Kirchhoff laws in the given topology of the particular network at hand.

Changing times: incentive regulation, corporate reorganizations, and productivity growth in the Great Britain’s gas networks

ABSTRACT The gas industry in Great Britain has witnessed periodic regulatory reviews and large corporate reorganization over the last few decades. We assess how these changes have impacted total factor productivity growth using a data envelopment analysis (DEA) approach by setting out different models, each for gas transmission and distribution network. We also construct a combined single series for distribution and transmission using financial data to show whether productivity growth can be attributed to corporate reorganizations. Our results show a negative productivity growth of −1.6% p.a. for gas transmission over the sample period, but reversed to a positive TFP growth once quality is included. For gas distribution, we find productivity regress at −6.2% p.a. over the sample period, with a negative productivity trend observed across all the models, despite the inclusion of quality variables. However, the findings reveal a slightly higher productivity growth of 1% p.a. using corporate data, with pre-restructuring period having a positive productivity growth compared with the post-restructuring era with a negative productivity growth.

Open data for energy networks: introducing DAVE—a data fusion tool for automated network generation

Developing a sustainable energy system for the future requires new ways of planning and operating energy infrastructure. A large part of this involves suitable network models. Real network data is not available for research without restrictions since energy networks are part of the critical infrastructure. Using open datasets and expert rules to generate non-restricted models is one solution to this. This paper introduces open data for energy networks generated by the open-source software “DAVE”. The Python-based data fusion tool DAVE can automatically generate customized energy network models quickly and on demand. The software collects data from various databases and uses appropriate methods to fuse them. The current version of the tool can create GIS-based power networks and gas transportation networks, with output that is compatible with common network simulation software. Further developments are planned for creating thermal and gas distribution networks, as these are important for local heat power transition. Implementing a quality description for fused datasets will also be included in future development.

Ways to improve the reliability of gas supply systems

Background: The concept of reliability of gas distribution systems implies the possibility of reliable transportation of the required amount of gas to the consumer in compliance with the specified parameters in normal operation for a certain period of time.
 Aim: The peculiarity of gas distribution networks is that they are long-term planning systems, with the growth of cities and the connection of consumers, the radius of their impact increases, expands, rebuilds, worn-out nodes and elements are replaced with new ones. The main goal at this stage of operation is the absence of significant reconstruction measures to improve the reliability of the system.
 Materials and methods: Work has been carried out to analyze the probability of triggering, the failure rate and the probability of failures of gas supply systems for single indicators.
 Results: To ensure the reliability and durability of gas boilers during replacement, the following 8 different measures were proposed.
 Conclusion: The article proposes a closed circuit, the introduction of network redundancy in the system by ringing or duplicating elements and considers the social nature of gas distribution systems.

Dynamic of H2NG in Distribution Systems

The reduction in GHG emissions has become one of the most important objectives in Europe. One of these clean technologies in the quest for large-scale decarbonisation is the blending of hydrogen and natural gas (H2NG). The significance of this article lies in conducting a technical–economic analysis that relies on simulating annual consumption patterns. This study focuses on the utilization of H2NG at different proportions within a distribution network in Bucharest, Romania’s largest city. The paper is a fallow up of another paper and presents a case study for the injection through all four entry points in the city of different percentages of hydrogen and the dynamic of the mix through the gas distribution network. The study found that the variation in H2 in the network is high and depends on the entry point levels and consumption. An economic analysis was conducted on seasonal real consumption, which confirmed the investment’s profitability.