Load margin is a critical index of voltage security of power systems, which reflects the ability of maintaining system voltage stability when disturbances occur. Nowadays natural gas units (NGUs) are widely used in power system. However the gas supply and the constraints of natural gas systems (NGSs) are not considered in existing load margin determination methods of power systems. In this paper, a load margin determination method for integrated electricity-gas system (IEGS) based on continuation multi-energy flow (CMEF) is proposed. Firstly, a multi-energy flow model with IEGS security constraints is built. Secondly, a load growth parameter is introduced and added to the proposed CMEF. Then, the multi-energy flow solution curve is tracked by a prediction-correction process. Finally, the WSCC 9-bus EPSs combined with 6-node NGSs is employed as a test system to illustrate the impact of NGSs static constraints and natural gas supply on the load margin. Numerical results verify the effectiveness of the CMEF.
Keywords Load margin, Natural gas system, Continuous power flow, Multi-Energy Flow