Substation structure and failures
The protection failures that are mainly studied in this thesis are: the protection system fails to see the failure within its operating zone within time, the protection system fails to send a tripping signal to the circuit breakers, the circuit breakers fail to trip, and a circuit breaker has a delay that is too long that the protection system treats it to be failed.
In reality, the protection system and the circuit breakers can fail as well when there is no component failure at all. However, these spontaneous trips of the circuit breakers or the self-failure of the protection system are complicated to be involved in the reliability model.
Moreover, they are only 10% of the total failures and are not dominant fault for the system. Because of modeling difficulties and time limitation, these self-failures are not included in this thesis.
There are two main problems studied in this thesis.
It will be analyzed whether the structure of a substation has a significant effect on the reliability.
Then, the Maasvlakte 380kV substation will be selected as a case study. Being one of the most complicated substations in the Netherlands, the Maasvlakte 380kV substation will be taken as a case study in the thesis.
Maasvlakte’s reliability with respect to protection failures is calculated using the event tree methods. The results will be combined with a load flow scenario for 2020 and the installed capacity to give a general concept of Maasvlakte substation reliability and average loss of energy per year.
This thesis is organized as follows:
Chapter 1 is a general introduction to the project, including the background explanation, project description, literature overview and objective.
Chapter 2 introduces some basic concepts that are used in this thesis. Failure probability, failure frequency and other reliability concepts are explained first. Then an introduction about substation structures is also given.
Chapter 3 discusses the principles of protection of a substation. The three different types of protections that are used in a substation (Differential Protection, Distance Protection and Busbar Protection) are introduced. How they cooperate with each other to protect the substation against component failures is explained as well.
Chapter 4 explains the reliability evaluation methods used for power systems.
Chapter 5 mainly studies the effect of different substation structures on the substation reliability. A comparison between a 4/3 circuit breakers substation, a 3/2 circuit breakers substation and a typical double busbar substation is given.
Chapter 6 takes the Maasvlakte 380kV substation as a case and analyses its reliability. The reliability results are combined with a load flow scenario for 2020, and the average loss of energy per year is given.
Chapter 7 gives a review of what has been accomplished in this thesis, discusses the conclusions from this research and makes some conclusions.
|Title:||Reliability Evaluation of Substations Subject to Protection Failures; Master of Science Thesis – Fengli Wang; Department of Electrical Engineering, Mathematics and Computer Science; Division of Electrical Power System; DELFT UNIVERSITY OF TECHNOLOGY|
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