Influence of facts controllers, generation and load directions on static voltage stability margin | |
| Author | Arthit Sode-Yome |
| Call Number | AIT Diss. no.ET-05-03 |
| Subject(s) | Electric power system stability Electric power systems--Control |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. ET-05-03 |
| Abstract | Voltage instability has been a major concern in power systems, especially in planning and operation, as there have been several major power interruptions associated with this phenomenon, in the recent past. Voltage instability due to the lack of the ability to foresee the impact of contingencies is one of the main reasons for the recent and worst North American power interruptions on August 14th, 2003. Hence, electric power utilities around the world have been devoting a great deal of efforts in voltage stability assessment and margin enhancement. Major contributory factors to voltage instability are power system configuration, generation pattern and load pattern. Power system network can be modified to alleviate voltage instability by adding reactive power sources i.e. shunt capacitors and/or Flexible AC Transmission System (FACTS) devices at the appropriate locations. There are various types of FACTS devices; each of them has its own characteristic and limitations. Adequate representations of FACTS devices have a great impact on voltage stability margin. Moreover, appropriate type, placement and correct size of the devices are important and become necessary for power system, especially in a de-regulated environment, to achieve maximum loading margin and other benefits. Generation pattern is easier to control by system operators compared to other factors, as long as there is enough margin left in the generators. Conventionally, in typical voltage stability studies, generation of participating generators are raised at the same rate or predefined rate. Increasing generation at this rate may not lead to highest voltage stability margin or lowest operating cost. Increasing generation at a more appropriate direction would result in a better power system performance in terms of loading margin and operation cost. Adding to this, load pattern is another factor that also contributes to voltage instability. Load is mostly dependent on the customers, thus it can not be controlled as operator wish. Traditionally, in static voltage stability study, the load is increased at the same rate. Increasing the load at this rate, however, may not represent the realistic load increase in the practical power system. This may lead to a non-realistic voltage stability assessment as well as voltage stability margin. Based on the above observation, attention is drawn in this dissertation to study the influence of FACTS devices, generation directions and load directions on static voltage stability margin. In the first part, the work investigates and compares various types of FACTS devices in terms of static voltage stability margin. Appropriate model is used to represent AC and DC characteristics and limitations of FACTS devices. New placement and sizing techniques of these devices are also proposed to provide a higher voltage stability margin. In the second part, the work proposes new generation direction approaches in finding the generation directions that optimize different objectives including maximizing loading margin and minimizing total operating cost. In the final part, a methodology is proposed based on practical daily load curves to provide a more realistic load direction and loading margin. The IEEE test system is used for testing and validating all the proposed methodologies. Finally, all of the proposed techniques are tested on a practical power system (Thailand power system) to demonstrate their practical usefulness. Moreover, a new idea on voltage setting of existing FACTS devices is also proposed to provide the highest margin in Thailand power system. |
| Year | 2005 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. ET-05-03 |
| 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) | Mithulananthan, Nadarajah; |
| Examination Committee(s) | Surapong Chirarattananon;Weerakorn Ongsakul;Issarachai Ngamroo;Berizzi, Alberto; |
| Scholarship Donor(s) | Royal Thai Government Fellowship; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2005 |