Power losses in HVDC converter stations.

Abstract

In transmission systems, particularly when the power is transported over a transmission line of distance 500 km and above, a considerable amount of power is lost during power system operations, which consist of all the components that are used in generation and transmission of power. Therefore, it is imperative to estimate the power losses due to some power equipment on the electrical network during transmission systems. More so, it is of importance to comprehend the pros and cons of both LCC-based and VSC-based transmission systems and subsequently carry out detailed research on power losses of both systems using the calculation methods listed in standards. It is the purpose of this research work to determine and calculate the overall losses of various equipment of high-voltage direct current (HVDC) converter stations under operating and standby modes using standards IEC 61803, IEEE 1158, IEC 62751-1-2 and the component datasheet parameters (Phase Control Thyristor Type DCR3030V42 and Dynex IGBT module DIM1200ASM45-TS000). The loss calculations in this research work are precisely applicable to all parts of the converter station and cover standby, partial-load, and full-load losses using the standardized calculation methods stipulated in the aforementioned standards. Furthermore, Switching losses, as well as conduction losses are included in the calculation using a simplified analytical model, based on the standards IEC 62751-1-2 and power semiconductor (Dynex) datasheet information. Therefore, an analytical method was adopted to estimate the power losses of VSC-based HVDC system of two-level, three-level and modular multilevel VSC configurations. Finally, the various HVDC technologies (circuit simulations) models were implemented in the Matlab-Simulink environment. The Matlab models were used to estimate the power losses of these technologies converter losses for various operating conditions. The simulation technique has been devised to provide an independent crosscheck on the results obtained using idealized mathematical representations (analytical technique). Subsequent to these circuit implementations, some results were obtained and consequently validated with other commercial power loss simulation tools or electronic software, such as Semisel and Melcosim. The use of different contrasting techniques to provide equivalent characteristics losses calculations provide a good method of validating the feasibility of the HVDC technology loss study, giving confidence in the results for the converter losses that have been obtained. This research work is based on an existing method of loss evaluation, but strictly followed the IEEE loss calculation methods stipulated in standards. The major contribution of this research work was the new approach adopted in the power loss evaluation of various HVDC technologies such as the LCC-based and VSC-based topologies of the converter stations using the idealized mathematical representations stipulated in standards IEC 61803, IEEE 1158, IEC 62751-1-2 and the component datasheet parameter, which signifies the novel output of this research work.