IEC 60143-4:2010 pdf – Series capacitors for power systems – Part 4: Thyristor controlled series capacitors
IEC 60143-4:2010 pdf – Series capacitors for power systems – Part 4: Thyristor controlled series capacitors.
In an application where SSR mitigation is critical, the operation of the TCSC under low line current condition must be reviewed, see 4.3.
A TCSC operating in CAP mode will produce harmonics. The magnitude of the harmonics depends on the operating point in terms of line current and boost factor.
In application where TCSC is used for SSR-mitigation or power oscillation damping purposes. the TCSC normally operates with the nominal boost factor and only temporarily during system disturbances operates with a higher boost factor. Therefore harmonic requirements on such TCSC installation shall be given for nominal operation i.e. rated line current and nominal boost factor,
Harmonic requirements for a TCSC shall be given in terms of maximum allowed voltage distortion caused by the TCSC at the busses connecting the series compensated line segment. Harmonic studies for a TCSC Installation requires detailed transmission line data of the series compensated line together with harmonic network equivalents for the tine ends to be supplied by the purchaser.
4.8 Control interactions between TCSCs In parallel lines
In situation where two TCSC are located on parallel lines, there is a risk for control interactions between the TCSC’s during system disturbances. To reduce the risk for harmful interactions between parallel connected TCSCs the following is recommended:
• The POD controllers to use the same input signals. i.e. the sum of the power flow on the parallel circuits.
• The POD controllers to have similar dynamics.
• The reactance controllers to have similar dynamics and respond in similar ways when hitting limits,
• The degree of compensation of a line segment at maximum boost factor should be well below 100%,
4.9 OperatIng range, overvoltages and duty cycles
4.9.1 Operating range
The TCSC shall be capable of withstanding the operation within the specified continuous and temporary operating ranges. The operating range is generally specified by the purchaser.
4.9.2 Transient overvoltages
The TCSC shall be suitable for repeated operations at transient overvollages caused by power system faults, with the highest possible value U1 that is expected to occur across the TCSC terminals. The transient overvoltage is normally limited by a varistor overvoltage protector.
4.9.3 Duty cycles
The TCSC equipment shall be designed to withstand the required sequences of faults. dynamic overload, temporary overload, and continuous currents as specified by the purchaser. These sequences form the duty cycles that all of the components of the TCSC bank shall be designed to withstand. The duty cycle shall be consistent with the manner in which the surrounding power system will be operated for both internal and external line faults. The purchaser shall define duty cycles for faults of normal and extended duration and for faults of different types (three-phase and single phase). Phase-to-phase faults shall beconsidered if specifically defined by the purchaser.Examples of typical duty cycles are foundin 8.5.
The purchaser shall specify a power system equivalent to be used in the studies of externaland internal transmission line faults for equipment rating.
Although the focus of this subclause is duty cycles involving power system faults，it isunderstood that the TCSC shall be designed to operate for otherevents such as insertion andreinsertion under the conditions specified by the purchaser.
Recommended Practice for Specilying Thyristar-Contralled Series Capacitors，Copyright 2002 IEEE. All rightsNOTE This clause contains material reproduced from IEEE Std 1534-2002. IEEE Std 1534-2002 IEEEreservad.
5.1 Triggering system
The valve base electronics (VBE) subsystem is an interface between the TCSC controlsystem for a subsegment and the platform-mounted valve electronics (VE) subsystem, asshown in Figure 6.