1 Scope
This part of the IEC 60919 provides general guidance on the steady-state performance requirements of high-voltage
direct current (HVDC) systems. It concerns the steady-state performance of two-terminal
HVDC systems utilizing 12-pulse converter units comprised of three-phase bridge (double-
way) connections (see Figure 1), but it does not cover multi-terminal HVDC transmission systems. Both terminals
are assumed to use thyristor valves as the main semiconductor valves and to have power
flow capability in both directions. Diode valves are not considered in this report.
Only line-commutated converters are covered in this report, which includes capacitor
commutated converter circuit configurations. General requirements for semiconductor
line-commutated converters are given in IEC 60146‑1‑1, IEC/TR 60146‑1‑2 and IEC 60146‑1‑3. Voltage-sourced converters are not considered.
This technical report, which covers steady-state performance, is followed by additional
documents on dynamic performance and transient performance. All three aspects should
be considered when preparing two-terminal HVDC system specifications.
The difference between system performance specifications and equipment design specifications
for individual components of a system should be realized. Equipment specifications
and testing requirements are not defined in this report. Also excluded from this report
are detailed seismic performance requirements. In addition, because there are many
variations between different possible HVDC systems, this report does not consider
these in detail; consequently, it should not be used directly as a specification for
a particular project, but rather to provide the basis for an appropriate specification
tailored to fit actual system requirements.
Frequently, performance specifications are prepared as a single package for the two
HVDC substations in a particular system. Alternatively, some parts of the HVDC system
can be separately specified and purchased. In such cases, due consideration should
be given to coordination of each part with the overall HVDC system performance objectives
and the interface of each with the system should be clearly defined. Typical of such
parts, listed in the appropriate order of relative ease for separate treatment and
interface definition, are:
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a) d.c. line, electrode line and earth electrode;
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b) telecommunication system;
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c) converter building, foundations and other civil engineering work;
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d) reactive power supply including a.c. shunt capacitor banks, shunt reactors, synchronous and static reactive power (VAR) compensators;
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e) a.c. switchgear;
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f) d.c. switchgear;
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g) auxiliary systems;
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h) a.c. filters;
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i) d.c. filters;
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j) d.c. reactors;
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k) converter transformers;
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l) surge arresters;
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m) series commutation capacitors;
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n) valves and their ancillaries;
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o) control and protection systems.
NOTE The last four items are the most difficult to separate, and, in fact, separation of these four may be inadvisable.
A complete steady-state performance specification for a HVDC system should consider
Clauses 3 to 21 of this report.
Terms and definitions for high-voltage direct current (HVDC) transmission used in
this report are given in IEC 60633.
Since the equipment items are usually separately specified and purchased, the HVDC
transmission line, earth electrode line and earth electrode (see Clause 10) are included only because of their influence on the HVDC system performance.
For the purpose of this report, an HVDC substation is assumed to consist of one or
more converter units installed in a single location together with buildings, reactors,
filters, reactive power supply, control, monitoring, protective, measuring and auxiliary
equipment. While there is no discussion of a.c. switching substations in this report,
a.c. filters and reactive power sources are included, although they may be connected
to an a.c. bus separate from the HVDC substation, as discussed in Clause 16.