The advanced static VAR compensator (now widely known as the static condenser or STATCON) uses a high power self-commutating inverter to draw reactive current from a transmission line. Two fundamentally different types of invertor can be used for this purpose, one providing control of output voltage magnitude and phase angle, and the other having only phase angle control. For each of these types, the governing equations are derived, and frequency domain analysis is used to obtain the relevant transfer functions for control system synthesis. Further analysis is provided to determine the response of the STATCON to negative sequence and harmonic voltage components on the transmission line. The results are illustrated with measured waveforms obtained from a scaled analogue model of an 80 MVAR STATCON.
The paper describes a model-reference adaptive system (MRAS) for the estimation of iiitl~iction motor speed from measured terminal voltages and currents. The estimated speed is used as feedhack i n a vector control system, thus achieving moderate bandwidth speed control without the use of shaft-mounted transducers. This technique is less complex and more stable than previous MRAS tacholess drives. It has been implemented on a 30-hp laboratory drive where its effectiveness has been verified.
ll& paper s h m that the Unified Power Flow Controller (UPFC) is able to control both the transmitted real power and, independently, the reactive power flows at the sending-and the recebing-end of the transmission line. The unique capabilities of the UPFC in multiple line Compensation are integrated into a generalized power flow controller that is able to maintain prescribed, and independently controllable, real power and reactive p e r flow in the line. The paper describes the basic concepts of the proposed generalized P and Q controller and compares it to the more conventional, but related power flow c o n t r o l e~ such as the l%y&br-Controlled Series Capacitor and Thyristor-Controlled Phase Angle Regulator. The paper also presents results of computer simulations showing the performance of the UPFC under different system conditions.
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