Optimal Coordinated Control Of PSS And FACTS Device In Power Systems Using PBO

Due to the rapid development of China’s power industry, long-distance, high-capacity network interconnection in power system has become a trend, although to some extent, the interconnection have increased the economy and reliability of system operation, but also makes the power system dynamics and stability become more complex. Low-frequency oscillations and load fluctuations severely undermine the security and stability of the power network operation, and it also restricts the inter-regional electric power transmission.The widely used power system stabilizer (Power System Stabilizer, PSS) is an economical and effective means to suppress low-frequency oscillation. As an attachment of the generator excitation control system, PSS plays an important role in improving the system damping level and enhancing power system stability.In recent years, the rapid development of power electronic technology and nonlinear control theory have greatly promoted the wide use of Flexible AC Transmission Systems (FACTS) devices in power systems. FACTS devices can greatly increase the power transfer capability, compensate reactive power dynamically, and improve voltage quality. Moreover, FACTS devices response in a fast speed, they can be adjusted in a positive and negative manner and control continuously. These characteristics enable them to effectively improve the transient stability of power systems.Although PSS and FACTS devices can effectively improve the stability of the power system, but PSS and FACTS devices without coordination may cause power system unstable or cannot fully play their respective role. Therefore, the optimal coordinated control of PSS and FACTS devices in the power system has been an urgent research topic, which has important practical significance.Paired Bacteria Optimizer (PBO) is a simple and efficient evolutionary algorithm. Unlike most evolutionary algorithm, the population in PBO only consists of two particles, thus the calculation has greatly reduced. Because of less time calculation, simple structure, PBO has a more efficient search capabilities compared with other advanced algorithms proposed recently.The optimal coordinate control of PSS and FACTS devices in this paper aims to improve power system dynamic stability under severe disturbances. A PBO-based optimization algorithm has been used in this optimal coordinated control, In this paper, the optimal coordinated control of PSS and FACTS devices is converted to an optimization problem. An objective function for obtaining the best responses of damping controllers is proposed in this paper, which takes the rotor speed deviation of generators and the main node bus voltage deviations after fault into account. The proposed method has been tested on simulation systems, the simulation results have demonstrated the effectiveness of the method, and the results also verify that the optimal coordinated control of PSS and FACTS devices using PBO can damp rotor angle oscillations and improve node voltage stability efficiently.