controlled series and thyristor controlled series reactor for line impedance emulation

Mark Nakmali, Leon M. Tolbert The University of Tennessee, Knoxville

Schematics Introduction

Flexible AC Transmission Systems (FACTS) have been used to provide stability to the grid during large transients. Of the FACTS devices, the TCSC thyristor controlled series capacitor (TCSC) and the thyristor controlled series reactor (TCSR) work by being able to vary their reactive properties by switching in and out a reactive component. Usually this is done in response to a system transient in order to provide stability to the transmission line; however, in this project, a constant programmable impedance is added to emulate transmission line TCSR impedance while still allowing easy reconfigurability to the system.

Waveforms Principle of Operation With respect to the positive zero-crossing of the These circuits work by switching in and out the reactor input voltage, the on at the delay by means of the thyristor valve. By controlling the delay angle, α, and remains on for the duration of the angle, the amount of time that the component is conduction angle, σ. The same is then repeated switched out of the circuit is controlled, allowing for the for the negative half. variance of the overall circuit’s series impedance.

α σ TCSC Impedance Versus Delay Angle 40

-10 0 40 80 120 160 200 240 280 320 360

-60 Impedance [Ohms] Impedance

-110 Delay Angle [deg]

TCSR Impedance Versus Delay Angle 2

1.5

1

0.5 Impedance [Ohms] Impedance 0 -10 10 30 50 70 90 Delay Angle [deg]

Future Work Conclusion Now that the design and simulation of the The use of TCSCs and TCSRs to purposefully induce a chosen circuits have been completed, the next step impedance for research purposes is a novel application and offers will be to begin picking out the components many advantages. Currently, variable is achievable necessary to building a prototype. After an through having multiple taps in an inductor and switching to the tap adequate prototype has been created, it will with the desired impedance. This only allows for a discreet set of be implemented into the Hardware Testbed values to be available and the unused coils do not make effective to provide line impedance emulation while use of space. The TCSC and TCSR allow for a continuous set of still allowing flexible reconfiguration values available and there are no unused components. capabilities.

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