Fuzzy logic and wide-area control for low frequency oscillation damping in power system | |
| Author | Komkrit Prasertwong |
| Call Number | AIT Diss. no.ET-09-02 |
| Subject(s) | Fuzzy logic Electric power systems--Control |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Energy, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. ET-09-02 |
| Abstract | In interconnected power systems, there are hundreds of generating units with varying size, complexity and mechanical speed. These units are connected with load centers which are typically far from generating stations by long transmission lines. One of the major challenges in operation and control of such complex large networks is keeping all generating units at constant electrical speed or synchronism. Whenever power systems are subjected to small and sudden disturbances one or more of the generating units tend to exhibit oscillatory behavior. If the oscillations are not controlled, they would grow in amplitude, limit power transfer capability of transmission lines, induce stress in the system and trigger protection devices to function. Hence, oscillations threaten system security and hamper the efficient operation of the entire system. Low frequency oscillations have been discovered since 1960s during a trial interconnection of the Northwest Power Pool and the Southwest Power Pool in the Northern American power network. Afterwards, low frequency oscillations have been observed and reported in many places. Among various oscillatory problems, a low frequency, typically in the range of 0.1-0.7 Hz is considered as serious. This oscillation problem often referred to as inter-area oscillation results from participation of several generating units from different areas. Low frequency oscillations in other frequency range are considered to be less serious and can be dealt with easily compared to the previous oscillation. The basic reason for oscillation problem is lack of damping on critical modes and many methods and control strategies have been proposed and devised for oscillation damping. This dissertation studies the use of fuzzy logic based controllers for oscillation damping in power systems and it is organized in three parts. In the first part, conventional and fuzzy logic based controllers are compared for oscillation damping at generator location. The controllers considered include, conventional Automatic Voltage Regulators (CA VR), conventional Power System Stabilizers (CPSS), Fuzzy logic based A VR (FLA VR), Fuzzy logic based PSS (FLPSS) and combinations of them. Performances of controller and combination of controllers are compared by comparing time domain simulations. One of the issues with Fuzzy logic controllers is that they cannot be modeled in state-space form for carrying out eigenvalue analysis to obtain critical eigenvalue and damping ratio. Hence, in the second part, the dissertation proposes a method to find out damping ratio on the critical mode to study fuzzy logic controller performance in more details using "envelop tracing". The proposed method has been tested and validated in a system with conventional controller that can be modeled for both time domain and eigenvalue analyses. In the third part, application of wide-area control is used for oscillation damping. The controller used in the part is Static Var Compensator (SVC) and a new control input signal has been proposed to damp low frequency oscillation. Two-area test system that has been used for oscillation studies is used in this part to check the wide-area control with proposed control input signal. A number of cases has been tried to see the performance of proposed wide-area control |
| Year | 2009 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. ET-09-02 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Weerakorn Ongsakul ;Mithulananthan, Nadarajah (Co-Chairperson); |
| Examination Committee(s) | Marpaung, Charles O. P. ;Poompat Saengudomlert; |
| Scholarship Donor(s) | Royal Thai Government Fellowship; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2009 |