Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Electrical and Computer Engineering

Supervisor

Professor Rajiv K. Varma

Abstract

Installations of large scale PV solar farms are rapidly increasing, worldwide. This is causing a growing apprehension that inertialess power injections from these inverter based generators will result in a decline in power system stability. Instead, this thesis presents novel applications of a patent pending technology whereby the PV solar farms actually help significantly increase system stability. A novel 24/7 (night and day) control of a large-scale PV solar farm as a dynamic reactive power compensator STATCOM, termed PV-STATCOM, is presented for damping low-frequency electromechanical power oscillations resulting in a significant improvement in power transfer capability of existing power transmission systems. A new real and reactive power modulation based control of PV-STATCOM is demonstrated during daytime that combines the functionalities of both a STATCOM and a Battery Energy Storage System (BESS) to provide significantly enhanced levels of power oscillation damping than that achieved by either a STATCOM or a BESS.

The effectiveness of the proposed PV-STATCOM Power Oscillation Damping (POD) control techniques based on modulation of reactive power, real power or a combination of both is evaluated through both small signal and Electromagnetic Transients simulations studies. Participation factor analysis is utilized for selection of appropriate control signals and damping controllers. The POD controllers are designed through small signal Residue analysis and validated through Simplex Optimization technique in electromagnetic transient simulations. The efficacy of the proposed PV-STATCOM controls is demonstrated on three power systems: Single Machine Infinite Bus SMIB system, Two-Area system, and the 12 bus FACTS power system, which exhibit different power oscillation modes. New ramp up techniques for power restoration from solar farms are also presented, which are substantially faster than those specified by grid codes. A methodology for coordination of proposed PV-STATCOM controls with existing Power System Stabilizers (PSSs) on synchronous generators is further described for further damping enhancement.

This thesis thus presents a novel technology that can not only help increase the penetration of large scale PV solar farms but utilize them for reducing the need for construction of expensive new lines or use of costly Flexible AC Transmission systems for stability improvement.

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