Optimal Operation and Security of AC-DC Microgrids

The problem of power system security has obtained much attention in both regulated and deregulated power industry. To meet the load demand in a power system and satisfy the stability and security, either the existing transmission lines must be utilized more efficiently, or new line(s) should be added to the system. The latter is often impractical. The reason is that building a new power line is in many countries, a very time consuming process and sometimes an impossible task, due to environmental problems.With the continued increase in demand for electrical energy with little addition to transmission capacity, security assessment and enhancement have become important issues in power-system operation. Security assessment deals with determining whether or not the system operating in a normal state can withstand contingencies (such as outage of transmission lines, generators etc.) without any limit violation. Moreover, with increased loading of existing power transmission systems,the problem of voltage stability and voltage collapse, has also become a major concern in power system planning and operation.