Security region of stand-alone microgrids: Model, calculation and applications

Stand-alone microgrids (SAMG) lack the support of the main grid. The large-scale integration of distributed generators and their randomness and volatility in output increase the risk of secure and stable operation of the system. To enhance the security level of SAMG operation, the concept of security region for SAMG is introduced for the first time. Initially, this paper introduces the basic concepts of SAMG and security, and provides security verification methods under the N-0 and N-1 security criteria. Subsequently, the definitions and models of security region for SAMG are proposed under the N-0 and N-1 security criteria; furthermore, based on the security distance, a security assessment and preventive control method are presented. Finally, the effectiveness of the proposed models and methods is verified through a specific case. Compared with existing methods, this paper provides more comprehensive security information such as explicit security levels, violation components, violation degree, complete N-1 fault scenarios, visual observation, and a preventive control method. The method in this paper firstly depicts the security operating range of SAMG and establishes a theoretical foundation for implementing online security functionalities.