Power system stability

In order to understand the stability it is essential to become familiar with the basic operations of a power system. There are three main components of a power system i.e. generation, transmission and distribution. Electrical power is generated mostly from synchronous machines. The primary sources of energy (fossil, hydraulic) are converted into mechanical energy through prime movers. Mechanical energy is used by synchronous generators to produce electrical power and most of the electric power systems are three phase AC systems operating at constant voltage. Three phase equipment is also used by generation and transmission facilities along with industrial residential and commercial loads that are equally distributed among all the phases to form a three‐phase balanced system [1]. A power system entirely relies upon its voltage, frequency and rotor angle stability. The main causes behind the instabilities, analysis techniques and methods used to improve the overall system stability will be discussed in this report. This report will explore the main aspects of power system instabilities by reviewing existing literature, analysing through simulation and finally correcting the grid instability with regard to voltage, frequency, and rotor angle. A small nine bus transmission network using Power Factory to analyse and match the theoretical factors that determine the reliability and operation as mentioned in current literature. The Power Factory provides numerous inbuilt global models of Automatic voltage regulator (Avr), Governor and Turbine (Gov), and power system stabilizer (PSS) etc. to reduce the complexity and avoid building the differential functions from scratch. The system will be analysed under four random avr and gov models by introducing a three‐phase fault at one of the transmission lines. The response of one of the generator will be examined on the basis of its variables like rotor angle, speed, output powers, terminal and excitation voltages. The ideal combination of avr and gov will be used to carry out PV and QV curve analysis to find the weakest bus in the system. Lastly, the performance of that bus will be analysed by varying the load and reactive power compensation. Stability of the system will be enhanced by using various Avr, Gov models through testing pre‐existing parameters.