Brian J. Pierre

Supervisory system for a wide area damping controller using PDCI modulation and real-time PMU feedback

This paper describes a control scheme to mitigate inter-area oscillations through active damping. The control system uses real-time phasor measurement unit (PMU) feedback to construct a commanded power signal to modulate the flow of real power over the Pacific DC Intertie (PDCI) located in the western North American Power System (wNAPS). A hardware prototype was constructed to implement the control scheme. To ensure safe and reliable performance, the project integrates a supervisory system to ensure the controller is operating as expected at all times. A suite of supervisory functions are implemented across three hardware platforms. If any controller mal-function is detected, the supervisory system promptly disables the controller through a bumpless transfer method. This paper presents a detailed description of the control scheme, simulation results, the bumpless transfer method, and a redundancy and diversity method in the selection of PMU signals for feedback. This paper also describes in detail the supervisory system implemented to ensure safe and reliable damping performance of the real-time wide area damping controller.

Open-loop testing results for the pacific DC intertie wide area damping controller

This paper describes the initial open-loop operation of a prototype control system aimed at mitigating inter-area oscillations through active DC power modulation. The control system uses real-time synchrophasor feedback to construct a commanded power signal added to the scheduled power on the Pacific DC Intertie (PDCI) within the western North American power system (wNAPS). The control strategy is based upon nearly a decade of simulation, linear analysis, and actual system tests. The control system must add damping to all modes which are controllable and “do no harm” to the AC grid. Tests were conducted in which the damping controller injected live probing signals into the PDCI controls to change the power flow on the PDCI by up to ±125 MW. While the probing tests are taking place, the damping controller recorded what it would have done if it were providing active damping. The tests demonstrate that the dynamic response of the DC system is highly desirable with a response time of 11 ms which is well within the desired range. The tests also verify that the overall transfer functions are consistent with past studies and tests. Finally, the tests show that the prototype controller behaves as expected and will improve damping in closed-loop operation.