Study On The Methods For Analyzing Combined Gas And Electricity Networks

With the increasing link between gas and electricity networks, in some sense, the two networks are operating as a whole. The issues concerned with the combined gas and electricity networks have emerged as an interesting topic, which may include the planning issues, optimization issues, interaction issues, market issues, etc.. In order to support the studies concerned, this thesis focuses on studying the basic methods for analyzing the issues concerned with combined gas and electricity networks.Firstly, the concept of the combined load flow analysis, just like the power flow analysis in power systems, is presented, which is a base to support studies on combined gas and electricity networks. Generally, combined load flow consists of gas load flow and power flow. As power flow is well established, the emphasis is focused on the gas load flow problem and gas turbine generators. Gas load flow problem is solved by the Newton loop-node method taking into account the fuel consumed by compressors in a gas network. Gas turbine generators connected with gas networks are looked on as energy converters. The proposed method for analyzing combined load flow is proven through a case study.Secondly, the combined optimization problems are described and formulated from both technical and economic viewpoints. Optimization between the two networks is important for both system operators and market participants. For system operators, it may be desirable to find the most energy efficient operating regime for the combined network. Alternatively, total cost for gas and electricity generation and consumption (by compressors) can be minimized, given that these may vary with location. Hence there are two basic objective functions: one is determined from a technical viewpoint and one from an economic viewpoint. The case studies show how the approach described is useful for both system operators and market participants.In addition to the combined load flow analysis and optimization issues, the dynamic interaction issue of the combined networks is also an important topic needed to be...