Research On Power Grid Reliability Evaluation Model Incorporating Asynchronized Generators

This dissertation is supported by National Natural Science Foundation of China(50977094).With the development of power industry and power markets, there is a tendency ofextended scale and complex structure of modern power system, a tendency of increasedcomplexity of operating mechanisms and dynamic characteristics, and thus bring aboutan ever-increasing concern of security and stability in power system. The probabilisticbehavior of power systems is the root origin of risk. The synchronous generator is themost important components in the power system and its remains security and stabilityplays an important role in supplying superior power to customers without a break, butits random behavior also bring in a relatively potential safety hazard for power systemoperation. The prominent contradiction between the high reliability requirements ofmodern power system and safe operating constraints of synchronous generator (SG)become an important project for power system researchers.In this paper, there are many remarkable works on reliability model of Asychronizedgenerator, reliability evaluation model for the bulk power system incorporatingAsynchronized generators, and synchronous generators was refitted in traditional powersystem based on reliability.The main results in detail are included in the following:(1) Markov state transition processes for Asynchronized generator is presented byanalyzing its different failure modes of the main functional parts of the excitationsystems, and its four state reliability model is established. For compared withAsynchronized generator, the reliability model of synchronous generator with self andshunt excitation system is established in the same way.(2) Considering the traditional reliability evaluation on capacity limits forsynchronous generator only be treated with power bound simply, this paper first detailsthe capacity limits of SG in the optimal load shedding model based on the alternativecurrent power flow and different influences on power system reliability are comparedincorporating the active and reactive power independent regulation characteristics andthe capacity limits of SG according to using the RBTS and IEEE-RTS79power systemsreliability indexes. In the meantime, the different influences on reliability indexes as aresult of numerical selection among of EMF maximum, the stator current maximum, and angle maximum of synchronous generator are compared based on the RBTS powersystem. The evaluation results prove that increasing the excitation forcing multipleswould improve reliability of unit and power system effectively.(3) In the optimal load shedding model based on the alternative current power flow,different impacts between the independent of active/reactive power regulation for ASGand the capacity limits for SG are considered. The reliability influences on powersystem of ASG are studied comparatively when the original parameters is given in thesame on the both kinds of generators. In the same while, the key parts of bothgenerators are spot by carrying out the sensitivity analysis of the parameters. Moreover,the variation trend of expected energy not supplied (EENS) along with the componentsfailure rate changes. The weak generator units of RBTS power system are identified inthe way of unreliability tracing. In the end, three schemes which synchronousgenerators are replaced with ASG are presented based on improving reliability of powersystem.