The total accommodation capability curve for a distribution network considering N-1 criterion

• Develop a security region-based TAC curve considering N-1 criterion. • Establish a method for solving TAC curves. • Identify the impact of power load on TAC curves. • Reveal the rules between N-1 TAC curves and N-0 TAC curves. • Provide the engineering applications of the TAC curve. The total accommodation capability curve (TAC curve) can completely describe the DG accommodation capability of a distribution network. The urban distribution network generally adopts the security constraints under N-1 criterion, but the formulation of the TAC curve in the existing studies only considers the network constraints under normal operation conditions considering N-0 criterion. To fill this gap, this paper develops a TAC curve model considering security constraints under N-1 criterion in distribution networks. The model is based on alternating current (AC) power flow because the problem of voltage override after DG integration cannot be ignored. Then, the solution and plotting method of the TAC curve are proposed. The method is based on the DC power flow model combined with voltage calibration correction, which is easy to solve and accurate. Finally, test systems are used to verify the proposed model and method. The rules between the N-1 TAC curve and the N-0 TAC curve and the main factors affecting the TAC curve are analyzed. The application of the TAC curve to planning is also provided.