In English

LCC Based Multi-Terminal HVDC Operation without Telecommunication

Rytis Navakauskas
Göteborg : Chalmers tekniska högskola, 2016. 102 s.
[Examensarbete på avancerad nivå]

A continuous increase in power demand, especially in the developing countries, and rapid growth of renewable energy source integration resulted into a rebirth of High Voltage Direct Current (HVDC) transmissions in the last two decades. Nowadays, a Line-Commutated Converter (LCC) HVDC is a dominant technology for high power transmission over long distances. Typically, point-to-point configuration HVDC systems are used. However, in a case when generated electricity has to be supplied to several different locations, a Multi-Terminal LCC HVDC (MTDC) can be one more economical solution. Such HVDC systems are more complex and requires continuous communication between the terminals for the stable operation. Since it is impossible to completely avoid malfunction of the telecommunication, all the HVDC systems should be able to operate even when the telecom is not available. Consequently, this project aims to develop and implement control methods for a stable operation of multi-terminal LCC HVDC when telecommunication failure occurs. Additionally, the system should be able to withstand different disturbances and transient events. The proposed solution of this project is to change the operation of the stations when telecommunication is lost. When this happens, the rectifier is shifted from current control to voltage control, while inverters are moved from constant beta control to current control. In addition to these changes of operation, several improvements have to be made to the existing controls to achieve a proper dynamic response of the system. This includes tuning of a voltage regulator and sub-functions such as reduced voltage recovery, reduced nominal extinction angle and current order limiter. After all these changes were implemented, the multi-terminal HVDC system used for the simulations was able to withstand all the applied disturbances and transient events during operation without telecommunication.

Nyckelord: Line Commutated Converters, LCC, Multi-terminal HVDC, telecommunication, HVDC controls, constant beta control, rectifier voltage control

Publikationen registrerades 2016-09-01. Den ändrades senast 2016-09-01

CPL ID: 241111

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