Date of Award


Document Type


Degree Name


Organizational Unit

Daniel Felix Ritchie School of Engineering and Computer Science, Electrical and Computer Engineering

First Advisor

David Wenzhong Gao

Second Advisor

Mohammad Matin

Third Advisor

Rui Fan


Renewable energy, Power systems, Inverter based resources (IBR), Power grid operation


Achieving carbon neutrality necessitates a significant integration of renewable energy into power systems. However, the swift implementation of fluctuating renewable energy (VRE) sources such as solar photovoltaics (PV) exacerbates real time power imbalances due to the randomness and uncertainty associated with VRE power generation. Further, the declining reliance on conventional synchronous generators (SGs) for system inertia presents considerable challenges in maintaining frequency stability, especially following disturbances.

Two possible solutions are proposed to address the first issue. Firstly, a speedy real time generation dispatch can be scheduled to allocate generation resources within short time intervals to effectively respond to changes in load and renewable power. Secondly, adaptive frequency regulation services like secondary frequency regulation (SFR) can be procured based on system variations and imbalances to mitigate power imbalances and stabilize intra interval frequency. This study puts forward an integrated alternating current optimal power flow based generation scheduling and time domain simulation framework to explore the economic and reliability implications of these solutions.

The effects of SFR requirements on generation cost and frequency performance are scrutinized, with particular attention given to the SFR provided by PV generation. The uncertainty linked with PV power output is factored in using chance constraints to ensure real time delivery of its frequency regulation services. The framework’s functionality is verified in the IEEE 39 bus network with a large scale PV power plant. The results show that a small real time generation dispatch interval does not necessarily enhance frequency response and is unable to maintain stable frequency. A more suitable and efficient option is an adaptive frequency regulation with a 5 minute economic dispatch interval, which can lower generation costs and improve frequency response in the context of renewable energy.

Addressing the second complex challenges of integrating renewable energy resources into power systems, this paper presents a novel approach to maintaining frequency stability across multiple timescales from microseconds to hours and days.

First, comprehensive low order frequency response models of various dynamic devices are derived, leading to an enhanced aggregated system frequency response model. The nadir is then derived analytically through differential equations. Next, proposes a general physics informed stability constraint by combining sensitivity based correlation analysis and piecewise linearization (PWL), ensuring feasibility in the unit commitment economic dispatch (UC/ED) models. This model harmonizes the fast frequency response, the droop response of the Inverter Based Resources (IBR), and the governor dynamics of generators and battery energy storage systems (BESS). Finally, the robustness of this constraint is demonstrated through meticulous simulations, including comprehensive N 1 contingency analysis and multi timescale closed loop testing that spans from microseconds to months. By employing the phasor domain dynamic simulations, electromagnetic transient (EMT) simulations, and power hardware in the loop (PHIL) testing, the paper verifies the reliability of the approach, offering a holistic solution for the frequency stability constrained grid operation with high penetration IBRs.

Copyright Date


Copyright Statement / License for Reuse

All Rights Reserved
All Rights Reserved.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Rights Holder

Ningchao Gao


Received from ProQuest

File Format



English (eng)


122 pgs

File Size

6.2 MB



Available for download on Friday, December 13, 2024