Integrated electrical and gas network flexibility assessment in low-carbon multi-energy systems

Abstract

In power systems with increasing variable renewable sources, gas generation is playing an increasingly prominent role in providing flexibility to meet net-load requirements. The flexibility provided by the gas turbines in turn relies on the flexibility of the gas network. While there are several discussions on the gas network's ability in providing this operational flexibility, this has not been clearly modelled or quantified. In addition, the gas network may also be responsible for supplying heating technologies, and low-carbon scenarios see tighter interactions between the electricity, heating and gas sectors, calling for a holistic multi-energy system assessment. On these premises, this paper presents a methodology to quantify the flexibility the gas network can provide to the power system, as well as the constraints it may impose on it, with also consideration of different heating scenarios. This is achieved by a multi-stage integrated gas and electrical transmission network model, using electrical DC OPFs and both steady-state and transient gas analyses. A novel metric making use of the concept of zonal linepack is introduced to assess the integrated gas and electrical flexibility, which is then used to impose gas-related internetwork inter-temporal constraints on the electrical OPF. Case studies performed for the Great Britain transmission system demonstrate the proposed integrated flexibility assessment, provide insights into the effects of changes to the heating sector on the multi-energy system's combined flexibility requirements and capability, and assess how the electrical network can experience local generation and reserve constraints related to the gas network's lack of flexibility.