Master thesis project 2017 - Electric Power Technology



Vattenfall has a large amount of motorized disconnectors used in medium voltage (MV) power distribution systems. At present, disconnector maintenance is mainly based on preventive and scheduled maintenance method. In the coming years, the company will develop, test, evaluate and implement new concepts of digital substation technologies. One aspect among these is to develop concepts and techniques of cost effective condition monitoring and condition based maintenance in order to increase asset life-time, improve quality of power delivery and reduce maintenance costs.

Like other technic system, disconnectors installed on distribution systems can fail to function. A significant number of disconnector failures are caused by standstill problems. Fail to open or close when required to do so constitutes a major part of disconnector failures. The improper conditions of these operating mechanism failures are very difficult to predict before failure occurs. Thus monitoring of disconnector conditions becomes very important for reliable operation of the power systems.
Condition monitoring can be used to achieve a variety of benefits for power system operation, including prediction of maintenance need, failure prevention, power delivery quality improvement and cost reduction for preventive and scheduled maintenance. It is therefore desired to increase know-how about condition monitoring of disconnectors and study how well is the diagnostic method of disconnectors by motor current, and whether this diagnostic method can meet Vattenfall’s needs.
The purpose of this Msc. thesis work is to evaluate methods and products for monitoring motor current of distribution power disconnectors, that will enable to continuously monitor, detect and diagnose maintenance need of the disconnectors and inertia of disconnector operational system. The focus will be on remote controlled distributed disconnectors in medium voltage (6-33 kV) and it is expected that by performing this Msc. project the following questions could be investigated and answered:

• What products for monitoring the motor current available on the market and what methods the products are based on. 
• How useful are the available products and methods for the disconnectors at Vattenfall? What technical conditions are required on the disconnectors in order to do remote online measurements of the monitoring?
• How will external conditions and environment affect the reliability of the monitoring system?
• What are economic benefits, investments and costs expected to arise from effective use of the monitoring technique?

Qualification, Application and Timeline:
It is preferable that the student has studied Master’s program in Electrical Engineering or Electrical Power Technology. Please send your application to which should contain a covering letter, CV and transcripts of your studies.
Deadline for application is Feb. 15, 2017. The project is planned to start in Q1 2017 or according to the agreement made with the student.
Supervisor, Contact person, Location:
The contact person and your supervisor at Vattenfall is Ying He, Tel: 070 58 96960,  The work place will be at Vattenfall R&D in Solna, Arenastaden.