The thesis describes the fundamental operation modes of an HVDC system for electric power
transmission. It delves into the protection of such a system and the main component for
preventing faults, exploring the core concepts that have evolved in this field over time.
The content is divided into three parts. The first part introduces the basic purpose of the HVDC system, its role in the electric power transmission network, and its applications in energy transmission systems (EES). The historical long-term development of the HVDC system is described, highlighting significant projects in direct current transmission. Over time, with the introduction of power semiconductor devices called thyristors, the HVDC system transformed into the form we know today. The second part provides a more detailed description of the structure of the HVDC system. It starts by explaining the converter technologies, LCC (Line-Commutated Converter) and VSC (Voltage-Source Converter), as well as the configurations of the system, including back-toback, two-terminal and multi-terminal setups. Additionally, the individual components crucial for the operation of the HVDC system are presented and described. In the final, more extensive part, the current state of HVDC circuit breakers' development is discussed, along with the operation of the protection system and fault clearance in case of system malfunctions. Four types of HVDC circuit breakers are initially described, with only two types ACI and MPE circuit breakers commonly practiced in today's networks due to network requirements. Their usage is increasingly important with the implementation of larger HVDC networks to ensure their flawless and efficient operation. Building upon the protection aspect, different fault location principles on faulty networks are described, along with three strategies: selective, non-selective, and partially selective, aimed at maintaining network selectivity and preserving healthy elements of the HVDC network.
|
