Multi-Agent Based Decentralized Coordinated Control For Power System Transient Stability

With the expending of power system and the complexity of system structure,operating stability, reliability and economy is faced with opportunities and new challenges.The unceasing progress of computer application level and artificial intelligence technologycontribute greatly to the development of the smart grid. For the distribution structure anddynamic characteristics of power systems, this paper pays more attention to the research ofsystem structures and control schemes for transient stability. Firstly, large-scale powersystems are loosely coupled. Multi-agent systems (MAS) are applied to build ahierarchical classification control structure, which help multi-machine system to finishcoordinated control tasks. Intelligent agents which widely distribute across powernetworks have parallel processing, communication and interaction capabilities. Theyprovide a powerful computational analysis and collaboration platform for transientstability assessment and decentralized coordination control. In order to improve transientstability efficiency and buy time for control, corresponding agents set different assessmentcriterions. Extremer of power angle is used to be the criterion for single machine infinitebus system. For multi-machine system, extend equal area criterion (EEAC) is employed tocalculate transient stability judgment index to start coordinated agents.It is a core work to design high-performance controller for synchronous generatorexcitation system. In interconnected systems, direct feedback linearization (DFL)compensated technique is applied to deal with nonlinear coupling of the third-order model,then the paper use approximation and norm description method to solve the remainingnonlinear interconnections further. Considering parameter uncertainties and variousdisturbances, a decentralized coordinated control scheme is proposed which containsdecentralizedH_∞robust controller for underlying synchronous generator closed-loopsystem and coordinationH_∞robust controller for generalized closed-loop system toguarantee the transient stability. In this paper, the problem of robust stabilizing controllersis transforms into the problem of solving linear matrix inequality, so that it is easy toobtain the solution of controller with LMI toolbox in MATLAB software. Finally, the 4-machine power system simulation example is built in SIMULINK to test thatdecentralized coordinated control scheme is better than a simple decentralized robustcontrol, decentralized coordinated control programs, especially in the case of largeinterference effect, especially to severe disturbances. Thus, the proposed scheme iseffective to improve power systems transient stability and to enhance the robustness.