An Equivalent Model of Gas Networks for Dynamic Analysis of Gas-Electricity Systems

Abstract

The increasing coupling between natural gas and electricity systems by gas-fired generation units brings new challenges to system analysis, such as pressure variations due to consumption perturbations of generation units. The emerging issues require revolutionary modeling and analysis techniques.This paper proposes a novel model to quantify gas pressure variations due to gas-fired power unit ramping and the impact of constraints from natural gas pressure change on ramp rates of gas-fired plants. By utilizing Laplace transform to resolve the governing equations of gas networks, the proposed model can significantly reduce modeling complexity and computational burden. The dynamic behaviors in time scale in s-domain and spatial partial differential equations are transformed into finite difference equations. By introducing the concept of transfer matrices, the relation between states at each node of gas systems can be expressed by transfer parameter matrices. Additionally, a simplified model is introduced to simply the analysis. The explicit expressions of nodal pressure variations in response to demand change are very convenient for analyzing system dynamic performance under disturbances, identifying the most influential factors. The new models are extensively demonstrated on three natural gas networks and benchmarked with traditional simulation approaches. Results illustrate that they produce very close results with the simulation approach, particularly when gas pipelines are long and enter steady states.

Review on Coordinated Planning of Source-Network-Load-Storage for Integrated Energy Systems

“…Transient and steady-state analysis of the whole natural gas is required when planning the actual large-scale natural gas network (Osiadacz and Chaczykowski, 2020). A dynamic gas network model was proposed in Reference (Zhou et al, 2017) but only the unidirectional gas flow was considered and dynamic factors such as compressors were ignored. Considering the difficulty of data interaction between the power grid and natural gas network, a static equivalent model of a natural gas network (Dai et al, 2020) was proposed, which laid a foundation for the cooperation between independent power and gas operators.…”

Security-Constrained Unit Commitment With Natural Gas Pipeline Transient Constraints

“…These equations include mass continuity, amount of movement and energy, and an ideal natural gas status. An equivalent model of the gas networks has been presented in [24], solving the three main laws for transmission of the natural gas by replacing them with a set of equations in time and space. Therefore, they divided the pipeline to lots of small pipes and solved them along the length.…”

Unlock the Flexibility of Combined Heat and Power for Frequency Response by Coordinative Control With Batteries

“…This impact may be transferred back to the power grid and cause cascaded failure if not well managed [22]. Some studies have been conducted on mitigating this adverse impact [23]. Yet, the impact of fast CHP output change in seconds and the relevant solution are rarely analyzed.…”