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372 Transient studies of FACTS and Custom Power equipment

Fig. 8.98 Waveform of the phase voltage V a at the load point. The fault is applied at t = 0.31s.

service circuit configuration shown in Figure 8.91 is the most widely used implemen-
tation of the SSTS system. In some application the SSTS is used in conjunction with
the D-STATCOM in order to provide sag and swell protection, as well as supply
continuous power in the presence of an upstream fault.

8.11 Conclusion

The use of computer programs in the simulation of FACTS and CPcontrollers,
including their controls, is extremely important for the development and under-
standing of this power electronics-based technology. They yield key information
relating to the performance of the system under any operating condition, which is
not possible to achieve by analytical means. They allow to identify and to assess the
interaction between the various elements in the network. This chapter has presented
time-domain results for several FACTS and CPcontrollers. The highly developed
graphics facilities available in the electromagnetic transient simulator PSCAD/
EMTDC were used to conduct all aspects of model implementation and to carry
out simulation studies.
The basic control schemes presented in this chapter are simple and easy to imple-
ment in any transient simulator. Of course, they may be made to operate more
efficiently but this will be at the expense of added control complexity. The reader
should have no difficulties in exploring more advanced control aspects in the superb
environment afforded by PSCAD/EMTDC.