Willis Long


Key Words:

Power electronics, High-voltage direct-current transmission, FACTS applications,

Research description:

Analysis of control interactions on FACTS assisted power systems. Different FACTS controllers can be adjusted so that each performs optimally in response to a system disturbance. However, when a number of FACTS devices are electrically near then the independent setting of controls may result in the appearance of oscillatory instabilities. This work develops a methodology of allocating FACTS devices within a complex network to improve the power transfer capability. It then uses load flow, voltage collapse, eigenvalue, transient stability, and electromagnetic transients (EMTP) computer programs in order to determine whether interactions occur. If so, then a coordinated control philosophy is required. Examples are provided using a large realistic network with and without HVDC lines.

Earlier related work examined the interactions among multiple HVDC inverters located in the same electrical receiving network. A variety of simulation tools were used to examine the possible control interactions that can occur. In addition to the above-mentioned study tools a physical HVDC simulator was utilized. This provided a valuable opportunity to compare responses between the actual control system of the HVDC simulator and the more simplified control systems used in the computer programs. A methodology for utilizing two different HVDC links to provide both synchronizing torque and oscillatory damping was demonstrated.

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