Transient Optimization of Natural Gas Networks Using Intelligent Algorithms

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Esmaeel Khanmirza ◽  
Reza Madoliat ◽  
Ali Pourfard
Keyword(s):  
Natural Gas ◽  
Power Consumption ◽  
Objective Function ◽  
Optimization Problem ◽  
Transient Condition ◽  
Continuous Variables ◽  
Intelligent Algorithms ◽  
Gas Network ◽  
Gas Networks ◽  
Decision Variables

Compressor stations in natural gas networks should perform such that time-varying demands of customers are fulfilled while all of the system constraints are satisfied. Power consumption of compressor stations impose the most operational cost to a gas network so their optimal performance will lead to significant money saving. In this paper, the gas network transient optimization problem is addressed. The objective function is the sum of the compressor's power consumption that should be minimized where compressor speeds and the value status are decision variables. This objective function is nonlinear which is subjected to nonlinear and combinatorial constraints including both discrete and continuous variables. To handle this challenging optimization problem, a novel approach based on using two different structure intelligent algorithms, namely the particle swarm optimization (PSO) and cultural algorithm (CA), is utilized to find the optimum of the decision variables. This approach removes the necessity of finding an explicit expression for the power consumption of compressors as a function of decision variables as well as the calculation of objective function derivatives. The objective function and constraints are evaluated in the transient condition by a fully implicit finite difference numerical method. The proposed approach is applied on a real gas network where simulation results confirm its accuracy and efficiency.

Improved Harmony Search Algorithm for Solving Optimization Problem with Mixed Discrete Variables

2013 ◽  
Vol 325-326 ◽  
pp. 1485-1488
Author(s):  
Shi Ming Hao ◽  
Li Zhi Cheng
Keyword(s):  
Constrained Optimization ◽  
Optimization Design ◽  
Optimization Problem ◽  
Optimization Problems ◽  
Search Algorithm ◽  
Harmony Search ◽  
Harmony Search Algorithm ◽  
Continuous Variables ◽  
Discrete Variables ◽  
Decision Variables

The classical harmony search algorithm (HSA) can only be used to solve the unconstrained optimization problems with continuous decision variables. Therefore, the classical HSA is not suitable for solving an engineering optimization problem with mixed discrete variables. In order to improve the classical HSA, an engineering method for dealing with mixed discrete decision variables is introduced and an exact non-differentiable penalty function is used to transform the constrained optimization design model into an unconstrained mathematical model. Based on above improvements, a program of improved HSA is designed and it can be used for solving the constrained optimization design problems with continuous variables, integer variables and non-equidistant discrete variables. Finally, an optimization design example of single-stage cylindrical-gear reducer with mixed-discrete variables is given. The example shows that the designed program runs steadily and the proposed method is effective in engineering design.

ON COMPUTATIONAL COMPLEXITY OF HIERARCHICAL OPTIMIZATION

2002 ◽  
Vol 13 (05) ◽  
pp. 667-670
Author(s):  
WEIJIA JIA ◽  
ZHIBIN SUN
Keyword(s):  
Nash Equilibrium ◽  
Computational Complexity ◽  
Objective Function ◽  
Optimization Problem ◽  
Linear Constraints ◽  
The Other ◽  
Hierarchical Optimization ◽  
Linear Objective Function ◽  
Decision Variables

In this work, the computational complexity of a hierarchic optimization problem involving in several players is studied. Each player is assigned with a linear objective function. The set of variables is partitioned such that each subset corresponds to one player as its decision variables. All the players jointly make a decision on the values of these variables such that a set of linear constraints should be satisfied. One special player, called the leader, makes decision on its decision variables before of all the other players. The rest, after learnt of the decision of the leader, make their choices so that their decisions form a Nash Equilibrium for them, breaking tie by maximizing the objective function of player. We show that the exact complexity of the problem is FPNP-complete.

scholarly journals Does Increasing Natural Gas Demand in the Power Sector Pose a Threat of Congestion to the German Gas Grid? A Model-Coupling Approach

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2159 ◽  
Author(s):  
Philipp Hauser ◽  
Sina Heidari ◽  
Christoph Weber ◽  
Dominik Möst
Keyword(s):  
Natural Gas ◽  
Network Model ◽  
Power Industry ◽  
Electricity Production ◽  
Extreme Weather Events ◽  
Power Sector ◽  
Gas Network ◽  
Gas Networks ◽  
Gas Consumption ◽  
Gas Supply

This study aims to investigate the possible congestion in the German natural gas system, which may arise due to an increase in the gas consumption in the power sector in extreme weather events. For this purpose, we develop a two-stage approach to couple an electricity model and a natural gas network model. In this approach, we model the electricity system in the first stage to determine the gas demand in the power sector. We then use the calculated gas demand to model gas networks in the second stage, where we deploy a newly developed gas network model. As a case study, we primarily evaluate our methodological approach by re-simulating the cold weather event in 2012, which is seen as an extreme situation for the gas grids, challenging the security of supply. Accordingly, we use our coupled model to investigate potential congestion in the natural gas networks for the year 2030, using a scenario of a sustainable energy transition, where an increase in the gas consumption in the power industry is likely. Results for 2030 show a 51% increase in yearly gas demand in the power industry compared to 2012. Further, the simulation results show a gas supply interruption in two nodes in 2012. In 2030, the same nodes may face an (partial) interruption of gas supply in cold winter days such as the 6th of February 2012. In this day, the load shedding in the natural gas networks can increase up to 19 GWhth in 2030. We also argue that the interrupted electricity production, due to local gas interruptions, can easily be compensated by other power plants. However, these local gas interruptions may endanger the local heat production.

Analiza wpływu dodatku wodoru do gazu ziemnego na szczelność połączeń mechanicznych wybranych elementów sieci i instalacji gazowych

2020 ◽  
Author(s):  
Piotr Szewczyk ◽  
Jacek Jaworski
Keyword(s):  
Natural Gas ◽  
Oil And Gas ◽  
Renewable Energy Sources ◽  
Carbon Dioxide Emission ◽  
Electrical Energy ◽  
Gas Network ◽  
Steel Pipes ◽  
Gas Networks ◽  
Threaded Connections ◽  
Sealing Material

One of the ways to use electrical energy obtained from renewable energy sources is hydrogen production, which produces only energy and water vapour when burned. Adding hydrogen to natural gas and burning it will lower carbon dioxide emission, making this fuel more eco-friendly. Hydrogen added to natural gas can be transported using gas transmission pipelines and can then be provided to industrial and individual consumers via a distribution pipeline network. Due to the much lower density of hydrogen compared to natural gas, it is especially important to maintain the tightness of mechanical connections of network elements and gas installations. This publication presents the results of research carried out at the Oil and Gas Institute-National Research Institute on the influence that adding hydrogen to natural gas has on the tightness of connections of selected elements of gas installations and networks. According to the developed methodology, tests were performed on selected elements of gas networks and gas installations, in which joints were made using differing methods and using various sealing materials. In the case of steel pipes used in gas installations in buildings, joined by means of threaded connections with tightness obtained on the thread, the test samples were prepared with the use of linen hemp with sealing paste, Teflon tapes and threads, and anaerobic adhesives. Samples made of copper pipes were joined with press fittings. Other installation elements - such as flexible hoses, both extensible and non-extensible, and metal hose assemblies - were attached by means of threaded connections with tightness obtained beyond the thread; the sealing material was NBR rubber gaskets and klingerite. The gas network elements were connected by means of threaded connections with hemp and sealing paste, flare fittings, and steel and polyethylene flanges (sealing with a flat gasket made of NBR and klingerite). PE/Steel connectors where also tested. The tests included tightness tests of the prepared samples with the use of methane, and then a mix of 85% methane and 15% hydrogen. The tests on samples with simulated leaks were also performed. Based on the tests and the analysis of the results, it was found that adding the hydrogen to the methane did not cause leaks in the joined elements. In addition, it was found that in the case of leaks appearing in elements of installations or gas networks, the methane-hydrogen mixture flows out faster than methane alone, and in closed rooms this may result in the lower explosion limit being reached in a shorter time.

scholarly journals A Preliminary Assessment of the Potential of Low Percentage Green Hydrogen Blending in the Italian Natural Gas Network

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5570 ◽  
Author(s):  
Marco Pellegrini ◽  
Alessandro Guzzini ◽  
Cesare Saccani
Keyword(s):  
Natural Gas ◽  
Renewable Electricity ◽  
Policy Makers ◽  
Gas Network ◽  
Gas Networks ◽  
Natural Gas Pipelines ◽  
Renewable Power ◽  
Natural Gas Network ◽  
Transitional Phase ◽  
Management Issues

The growing rate of electricity generation from renewables is leading to new operational and management issues on the power grid because the electricity generated exceeds local requirements and the transportation or storage capacities are inadequate. An interesting option that is under investigation by several years is the opportunity to use the renewable electricity surplus to power electrolyzers that split water into its component parts, with the hydrogen being directly injected into natural gas pipelines for both storage and transportation. This innovative approach merges together the concepts of (i) renewable power-to-hydrogen (P2H) and of (ii) hydrogen blending into natural gas networks. The combination of renewable P2H and hydrogen blending into natural gas networks has a huge potential in terms of environmental and social benefits, but it is still facing several barriers that are technological, economic, legislative. In the framework of the new hydrogen strategy for a climate-neutral Europe, Member States should design a roadmap moving towards a hydrogen ecosystem by 2050. The blending of “green hydrogen”, that is hydrogen produced by renewable sources, in the natural gas network at a limited percentage is a key element to enable hydrogen production in a preliminary and transitional phase. Therefore, it is urgent to evaluate at the same time (i) the potential of green hydrogen blending at low percentage (up to 10%) and (ii) the maximum P2H capacity compatible with low percentage blending. The paper aims to preliminary assess the green hydrogen blending potential into the Italian natural gas network as a tool for policy makers, grid and networks managers and energy planners.

scholarly journals Security-Constrained Optimal Dispatch of Combined Natural Gas and Electricity Networks Using Genetic Algorithms

2017 ◽  
Author(s):  
Denis C. L. Costa ◽  
João Paulo Vieira ◽  
Marcus V. A. Nunes
Keyword(s):  
Natural Gas ◽  
Optimization Problem ◽  
Mathematical Formulation ◽  
Energy Systems ◽  
Test System ◽  
Thermal Generation ◽  
Gas Network ◽  
Optimal Dispatch ◽  
Electricity Networks ◽  
Electricity System

This paper proposes a method based on genetic algorithm (GA) for the security-constrained optimal dispatch of integrated natural gas and electricity networks, considering operating scenarios in both energy systems. The mathematical formulation of the optimization problem consists of a multi-objective function which aims to minimize both cost of thermal generation (diesel and natural gas) as well as the production and transportation of natural gas. The joint gas-electricity system is modeled by two separate groups of nonlinear equation, which are solved by the combination of Newton's method with the GA. The applicability of the proposed method is tested in the Belgian gas network integrated with the IEEE 14-bus test system and a 15-node natural gas network integrated with the IEEE 118-bus test system. The results demonstrate that the proposed method provides efficient and secure solutions for different operating scenarios in both energy systems.

Cavitating Flow Suppression for a Two-Phase Liquefied Natural Gas Expander Through Collaborative Fine-Turning Design Optimization of Impeller and Exducer Geometric Shape

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Peng Song ◽  
Jinju Sun ◽  
Changjiang Huo
Keyword(s):  
Natural Gas ◽  
Objective Function ◽  
Design Optimization ◽  
Optimization Problem ◽  
Optimization Method ◽  
Liquefied Natural Gas ◽  
Cavitating Flow ◽  
Two Phase ◽  
Phase Liquid ◽  
Adaptive Kriging

Abstract Cryogenic liquid turbine expanders have been increasingly used in liquefied natural gas (LNG) production plants to save energy. However, high-pressure LNG commonly needs to be throttled to or near a two-phase state, which makes the LNG turbine expander more vulnerable to cavitation. Although some work has been reported on cryogenic turbomachine cavitation, no work has been reported on designing a cavitation-resistant two-phase LNG liquid turbine expander. Motivated by the urgent requirement for two-phase liquid turbine expanders, an effective design optimization method is developed that is well-suited for designing the cavitation-resistant two-phase liquid turbine expanders. A novel optimization objective function is constituted by characterizing the cavitating flow, in which the overall efficiency and local cavitation flow behavior are incorporated. The adaptive-Kriging surrogate model and cooperative coevolutionary algorithm (CCEA) are incorporated to solve the highly nonlinear design optimization problem globally and efficiently. The former maintains high-level prediction accuracy of the objective function but uses much reduced computational fluid dynamics (CFD) simulations while the later solves the complex optimization problem at a high convergence rate through decomposing them into some readily solved parallel subproblems. By means of the developed optimization method, the impeller and exducer blade geometries and their axial gap and circumferential indexing are fine-tuned. Consequently, cavitating flow in both the impeller and exducer of the two-phase LNG expander is effectively mitigated.

Convex Grey Optimization

2019 ◽  
Vol 53 (1) ◽  
pp. 339-349
Author(s):  
Surafel Luleseged Tilahun
Keyword(s):  
Objective Function ◽  
Optimization Problem ◽  
Fuzzy Numbers ◽  
Optimization Problems ◽  
Probability Distributions ◽  
Optimal Solution ◽  
Decision Variables ◽  
Constraint Set ◽  
Grey Number ◽  
Real Scenario

Many optimization problems are formulated from a real scenario involving incomplete information due to uncertainty in reality. The uncertainties can be expressed with appropriate probability distributions or fuzzy numbers with a membership function, if enough information can be accessed for the construction of either the probability density function or the membership of the fuzzy numbers. However, in some cases there may not be enough information for that and grey numbers need to be used. A grey number is an interval number to represent the value of a quantity. Its exact value or the likelihood is not known but the maximum and/or the minimum possible values are. Applications in space exploration, robotics and engineering can be mentioned which involves such a scenario. An optimization problem is called a grey optimization problem if it involves a grey number in the objective function and/or constraint set. Unlike its wide applications, not much research is done in the field. Hence, in this paper, a convex grey optimization problem will be discussed. It will be shown that an optimal solution for a convex grey optimization problem is a grey number where the lower and upper limit are computed by solving the problem in an optimistic and pessimistic way. The optimistic way is when the decision maker counts the grey numbers as decision variables and optimize the objective function for all the decision variables whereas the pessimistic way is solving a minimax or maximin problem over the decision variables and over the grey numbers.

scholarly journals Dataset for Scheduling Strategies for Microgrids Coupled with Natural Gas Networks

Data ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 24 ◽  
Author(s):  
Muhammad Yousif ◽  
Qian Ai ◽  
Yang Gao ◽  
Waqas Ahmad Wattoo ◽  
Ran Hao ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Natural Gas ◽  
Wind Turbine ◽  
Gas Turbine ◽  
Solar Pv ◽  
Gas Network ◽  
Micro Gas Turbine ◽  
Gas Networks ◽  
Natural Gas Network ◽  
Scheduling Strategies

Datasets are significant for researchers to test the functionality of their proposed strategies for the microgrid dispatch. This article presents a dataset to help researchers in testing their algorithms related to the dispatch problem of microgrids coupled with natural gas networks. This preliminary release of a microgrid dispatch dataset contains data related to microgrid components (like solar PV, wind turbine, fuel cell and batteries) and natural gas network elements connected with the microgrid (e.g., micro gas turbine). It also includes the data associated with the authors’ proposed scheduling strategy and its dispatch results. The provided dataset can be used to reproduce the authors’ proposed strategy. The presented dataset further can be used for comparisons of other researchers’ proposed strategies. These comparisons will make a strategy’s features more evident.

Sign in / Sign up

Export Citation Format

Share Document