IEC 61803:2020 pdf download

IEC 61803:2020 pdf download.Determination of power losses in high-voltage direct current (HVDC) converter stations with line-commutated converters
1 Scope
This document applies to all line-commutated high-voltage direct current (HVDC) converter stations used for power exchange (power transmission or back-to-back installation) in utility systems. This document presumes the use of 12-pulse thyristor converters but can, with due care, also be used for 6-pulse thyristor converters. In some applications, synchronous compensators or static var compensators (SVC) may be connected to the AC bus of the HVDC converter station. The loss determination procedures for such equipment are not included in this document. This document presents a set of standard procedures for determining the total losses of an HVDC converter station. The procedures cover all parts, except as noted above, and address no-load operation and operating losses together with their methods of calculation which use, wherever possible, measured parameters. Converter station designs employing novel components or circuit configurations compared to the typical design assumed in this document, or designs equipped with unusual auxiliary circuits that could affect the losses, are assessed on their own merits.
3 Terms, definitions and symbols
For the purposes of this document, the terms and definition given in IEC 60633 and the following apply.3.1 Terms and definitions 3.1.1 auxiliary losses electric power required to feed the converter station auxiliary loads Note 1 to entry: The auxiliary losses depend on the number of converter units used and whether the station is in no-load operation or carrying load, in which case the auxiliary losses depend on the load level. 3.1.2 equipment no-load operation losses losses produced in an item of equipment with the converter station energised but with the converters blocked and all station service loads and auxiliary equipment connected as required for immediate pick-up of load to specified minimum power 3.1.3 load level direct current, direct voltage, firing angle, AC voltage, and converter transformer tap-changer position at which the converter station is operating 3.1.4 equipment operating losses losses produced in an item of equipment at a given load level with the converter station energised and the converters operating 3.1.5 rated load load related to operation at nominal values of DC current, DC voltage, AC voltage and converter firing angle Note 1 to entry: The AC system shall be assumed to be at nominal frequency, and its 3-phase voltages are nominal and balanced. The position of the tap-changer of the converter transformer and the number of AC filters and shunt reactive elements connected shall be consistent with operation at rated load, coincident with nominal conditions. 3.1.6 total station no-load operation losses sum of all equipment no-load operation losses (3.1.2) and corresponding auxiliary losses (3.1.1) 3.1.7 total station operating losses sum of all equipment operating losses (3.1.4) and corresponding auxiliary losses (3.1.1) at a particular load level Note 1 to entry: An illustrative example using total station operating losses and corresponding loss evaluation is given in Annex C, case D1. 3.1.8 total station load losses difference between total station operating losses (3.1.7) and total station no-load operation losses (3.1.6)
4 Overview
4.1 General Suppliers need to know in detail how and where losses are generated, since this affects component and equipment ratings. Purchasers are interested in a verifiable loss figure which allows equitable bid comparison and in a procedure after delivery which can objectively verify the guaranteed performance requirements of the supplier. As a general principle, it would be desirable to determine the efficiency of an HVDC converter station by a direct measurement of its energy losses. However, attempts to determine the station losses by subtracting the measured output power from the measured input power should recognize that such measurements have an inherent inaccuracy, especially if performed at high voltage. The losses of an HVDC converter station at full load are generally less than 1 % of the transmitted power. Therefore, the loss measured as a small difference between two large quantities is not likely to be a sufficiently accurate indication of the actual losses. In some special circumstances, it may be possible, for example, to arrange a temporary test connection in which two converters are operated from the same AC source and also connected together via their DC terminals. In this connection, the power drawn from the AC source equals the losses in the circuit. However, the AC source shall also provide var support and commutating voltage to the two converters. Once again, there are practical measurement difficulties.