Automatic Generation Control Strategies in Interconnected Power Systems under Deregulated Environment

Abstract

The electric power system is one of the oldest infrastructures and operates mostly in vertically integrated utility (VIU). The new transformation of power system from VIU to deregulated and restructured utilities has brought the sea changes in structure and operation. The availability of power to industries and others is important for the development of nation. The per capita consumption of electrical energy has been considered as the prime index to evaluate the overall development of any country. The power engineers and the government agencies along with public sectors are continuously putting their best efforts to improving infrastructure and minimize this gap. Due to best efforts, this gap has been narrowed down to great extent, but still a gap exists. The installed capacity in Saudi Arabia has increased about more than five times from 2005 until 2021 and peak load demand expected to increase at rate of six percent per year over the coming 10 years. The transmission and distribution network in Saudi Arabia have also expanded to the population accordingly [1]. The decomposition of the power system is indispensable for efficient operation and control. The desired state of operation is normal state but depending upon the loads and generation health the other states may be like; preventive state, emergency state and restorative states. The time hierarchy of execution of control functions in power system arises because of the extremely wide range of response time inherent in power system operation and control. Time decomposition is always carried out to subdivide a difficult problem into smaller sub problems and automatic generation control (AGC) action initiates within seconds. The electrical power system structure is operationally connected to many control areas spreading over a large electrical area. This has made the controlling aspect of power system a huge concern for all power engineers. Today’s life is dominantly reliant on the electrical energy and the increasing power demand is to be balanced by the generation of power. The AGC strategy is imperative in balancing the power in the network and takes care of frequency maintenance and tie-line flows. The conventional power structure transforming into the market oriented model and splitting the entire single central entity to different operational business modules. This deregulated and restructured power system has separate module entities like generation transmission and distribution companies and also the retail wheeling of power. However, this transition has posed many new technical issues and challenges to the operation of deregulated power systems. Therefore, the existing fundamental principles of operational and control philosophies are to be modified to handle new power system environment. In the present work, the conventional proportional integral derivative (PID) controller and optimal controller are designed for AGC for new structured power system for the different case studies. The AGC regulator also designed based on genetic algorithm (GA) tuning techniques. The deregulated power system model is considered with various possible market transactions. For the bilateral contracts and bilateral contract violations, the power exchanges have been noticed between the control areas. The comparative study for the designed controllers is presented in this thesis. The state space model of restructured power system is developed for AGC implementation and the controller based on the control theory concepts are designed. The dynamic responses have been compared for both controller design and tuning techniques and stability analysis has been carried out. The MATLAB software and associated tools have been utilized to perform computation work and the results so obtained have been investigated.