| dc.description.abstract |
The framework of the electric utilities has been radically changed from conventional to
modern competitive structure which is known as Deregulated Power System (DPS). In
conventional power system Vertically Integrated Utility (VIU) regulates generation,
transmission and distribution. In DPS, VIU which is monopolistic replaced by
autonomous strong competitors’ entities like Transmission Companies (TRANSCOs),
Distribution Companies (DISCOs), Generation Companies (GENCOs), self-sufficient
operators known as Independent System Operators (ISOs).A detailed literature review
of DPS shows that ISO is responsible for providing many auxiliary services and one
among them is the Automatic Generation Control (AGC).
The primary objective of AGC is to regulate the area frequency deviation by
providing the balance between active power generation in amid to fluctuating load
demands. Power systems could encounter a significant instability issue with a
considerable decline in the frequency. The ongoing expansion in dimensions and
intricacy, randomly varying power requirements, system modeling inaccuracies and
changes in electrical power system have made the AGC task into a difficult one. Due to
this, traditional control methods might not be able to manage such erratic changes in
an AGC system. AGC problem for deregulated power system environment requires
innovative tactics that combine information, strategies, and procedures for diverse
sources to address the AGC issues of power system efficiently. Therefore, the objective
of this research is to suggest various forms of novel controller frameworks for different
types of restructured power systems. Five different power system being used for this
research work are (i) three-area single-source hydro-hydro, (ii) two-area DPS having
thermal-GTPP and diesel-GTPP generating units, (iii) two-area DPS having thermal
reheat generating units, (iv) two-area DPS hydro-thermal reheat generating units and
(v) two-area DPS having Thermal-Hydro-Gas (THG) generating unit.
Initially, Optimal Control (OC) has been designed for AGC of three-area hydrohydro DPS and efficacy of OC is analysed under different market power transactions
scenarios. Further, efficacy has been tested by incorporating system nonlinearities, such
as Time Delay (TD), Generation Rate Constraints (GRC) and Governor Dead Band
(GDB). Finally, sensitivity analysis has been performed to test the efficacy of OC under
system parameter variation.
Next OC approach has been designed for AGC of two-area DPS having GTPPthermal and GTPP- diesel. The proposed OC mechanism satisfied AGC requirement
under various market scenarios, including poolco-based and poolco bilateral
transactions with contract violations.
Further, a novel control strategy for improving AGC performance of two -area
single-source thermal reheat and two-area multi-source thermal-hydro power systems
iv
in a deregulated environment has been analysed. This approach introduces a Cascade
Optimal Control –Proportional Integral with Derivative Filter (COC-PIDN) controller,
in which master /primary OC has been designed using full-state vector feedback
approach and slave/secondary controller has been optimized through the Salp Swarm
Algorithm (SSA). The COC-PIDN controller outperform OC by providing lower
frequency undershoot/overshoot, better stability margins when simulated and analysed
in similar environment. COC-PIDN proves its robustness when tested by incorporating
various system’s nonlinearities. Additionally, sensitivity analysis of COC-PIDN
controller shows its resilience to variations in system parameters.
This research work further extended by designing Cascade Optimal Control –
Fractional Order Derivative (COC-FOD) controller to enhance the AGC performance
of two-area DPS having THG generating units. The Primary controller is optimized
with full-state feedback control, and the secondary FOD controller’s gains are
optimized using SSA. The COC-FOD controller outperform OC by providing better
Dynamic Performance (DP) in similar environment. Additionally, In presence of
COC-FOD a minimal impact on DP of DPS have been observed when tested under
variations of system parameters.
Further in this research work SSA optimized PID/FOPID controllers has been
designed and analysed for AGC enhancement of two-area DPS having THG
generating units. Results show that the SSA-tuned PID/FOPID controller achieves a
lower cost function value, indicating better overall DP and stability for multi-area
THG-DPS systems.
Proposed control mechanism of this research work are integrated with Energy
Storage Devices (ESDs) for AGC enhancement. It has been observed that ESDs,
including Battery Energy Storage (BES), Redox Flow Batteries (RFB), Flywheel
Energy Storage (FES),Superconducting Magnetic Energy Storage (SMES) and
Capacitive Energy Storage (CES) improves system stability by reducing peak
deviations, oscillations, and settling time. Further, it has also been analysed that among
the different ESDs, RFB exhibits the better performance with minimal frequency
deviations.
This research work also demonstrates significant performance improvements of the
proposed controllers such as COC-PIDN and FOPID when coupled with RFB, in
two-area single/multi-source DPS. Furthermore, under varying load conditions, the
integration of RFB and SMES as Hybrid Energy Storage Systems (HESS),
demonstrated superior performance compared to systems without ESDs.
In a nutshell findings underscore the potential of proposed control strategies
integrated with ESDs to enhance stability, improved DP, and robustness against
parameter changes and providing a pathway for more reliable and efficient power
systems in a deregulated environment. |
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