Monitoring, Control, and Protection

Permanent URI for this collectionhttps://hdl.handle.net/10125/107473

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Competitive Reinforcement Learning for Real-Time Pricing and Scheduling Control in Coupled EV Charging Stations and Power Networks
(2024-01-03) Surani, Adrian-Petru; Wu, Tong; Scaglione, Anna
This paper proposes a robust Multi-Agent Reinforcement Learning (MARL) approach to optimize the charge schedule and price offered by EV charging stations competing to maximize profits, i.e. the differences between the payments collected by the charging stations and the electricity price set from a distribution system operator. It is assumed that, to prevent energy congestion on the distribution grid, each charging station pays the locational marginal price (LMP) of electricity to serve its customer, determined to be the dual variable of the optimal power flow (OPF) problem. Our proposed RL algorithm trains multiple agents to make optimal charging and pricing decisions at each time step, based solely on past event observations. Additionally, the algorithm takes into account the randomness caused by user behavior, such as travel and wait times, and user flexibility. We observe that, when they are profit maximizing, competing agents vie for higher profits. This intense competition can often lead agents to adopt inefficient policies, mainly due to the disruptions caused by the actions of their competitors. To address this issue, we incorporate constant-sum game theory in the RL policy training. This approach utilizes the minimax policy gradient to maximize the reward of a robust agent, while considering the worst-case scenarios created by competing agents. Simulation results validate that robust agents are capable of generating greater profits than competing agents that do not undergo minimax training and that their presence stabilizes the training.
Real-time Inertia Estimation Using Probing Method and PMU Measurement
(2024-01-03) Zhao, Yi; Liu, Yilu
The increasing deployment of inverter-based devices (IBRs) has significantly impacted the power system inertia level and frequency recovery under frequency disturbances. Real-time inertia estimation is highly needed by power system operators for power grid secure operation. This paper presents a real-time inertia estimation method for a power system using a probing signal and the measurement of phasor measurement units (PMUs). The probing signal is designed while considering the requirements of the power grid secure operation. Based on the probing signal response, a measurement-driven model can be identified to represent either the inertia dynamics of an individual generator or a regional electric power grid using the active power deviation and frequency deviation information from PMUs. The measurement-driven model can be further used to calculate the corresponding inertia of generators and the regional inertia. The performance of the inertia estimator is demonstrated through several test cases using the 23-bus 3-area model.
Analysis of Generator Forced Oscillations During MOD 25 Testing Exploiting Wavelets
(2024-01-03) Mishra, Chetan; Vanfretti, Luigi; Baldwin, Mark; Delaree Jr., Jaime; Jones, Kevin
This paper presents a measurement-based analysis of a 1.5 Hz forced oscillation triggered during a reactive power capability test conducted at a power plant in Dominion Energy’s power system. Owing to the slow evolving nature of the critical mode, it is demonstrated how time-frequency analysis of the period leading to the oscillation holds crucial information for finding the oscillation’s source. Furthermore, it is shown how the use of wavelets enables to more granular analysis of the evolution and impact of the forced oscillation – a capability that will help Dominion better monitor and regulate the dynamic components of an evolving grid.
A Novel Method for Setting Meaningful Thresholds for RMS-Energy Oscillation Detectors
(2024-01-03) Follum, Jim; Biswas, Shuchismita; Etingov, Pavel; Yin, Tianzhixi
Oscillation detection and mitigation is a crucial aspect of reliable power system operation. Several transmission system operators and reliability coordinators use the RMS-energy method of oscillation detection, but the process of setting thresholds is time and labor intensive. The current industry practice in the United States is to set thresholds based on the RMS-energy's value during ambient conditions, which can often lead to nuisance alarms that require thresholds to be manually retuned. In this paper, we propose a method for setting RMS-energy thresholds that directly accounts for oscillation amplitudes specified by the user. A theoretical analysis of the statistical properties of the RMS-energy incorporates these user-specified amplitudes, resulting in thresholds that reliably detect oscillations of interest while avoiding nuisance alarms. Theoretical results are validated with simulated measurements and the real-world practicality of the method is established with publicly available field-measured data from the Grid Event Signature Library.
Real-time Monitoring and Mitigation and Offline Analysis of Forced Oscillations in RC West (CAISO)
(2024-01-03) Agrawal, Urmila; Bohlen, Justin; Hiebert, Jim; Penner, Kaden
Forced oscillations have the potential to impact reliable and secure power systems operations. The Western Interconnection (WI) is observing an increase in forced oscillation events, both local and system-wide, with an increase of inverter-based renewable energy sources. This paper discusses SCADA and synchrophasor measurement-based operating procedures and tools implemented in the control center to monitor and mitigate forced oscillations. An example of a recent wide-area forced oscillation event is included that shows how the RC operators used these measurement-based tools and operating procedures to locate the source and mitigate the forced oscillations in the WI maintaining reliable and secure system operations. An offline analysis of the event is also included in this paper.
PMU-based Modal Analysis of Two RTE Oscillation Events
(2024-01-03) Farrokhifard, Mohammadreza Maddipour; Venkatasubramanian, Mani; Torresan, Gilles; Panciatici, Patrick; Xavier, Florent
This paper presents an analysis of two recent major oscillation events in the RTE power system. Data from Phasor Measurement Units (PMUs) collected during the events are analyzed by using ambient and ringdown modal estimation tools. Fast Frequency Domain Decomposition (FFDD) and Covariance-based Fast Stochastic Subspace Identification (FSSI-Cov) are applied for ambient modal analysis. In the first event, we show that the frequency of an inter-area mode changed dramatically after a system topology change while its damping also decreased. The second event may be related to the emergence of an unknown sustained oscillation whose frequency was close to that of a system inter-area mode. Analysis of these two events shows the relative strengths and weaknesses of different oscillation monitoring algorithms and their usefulness in measurement-based modal analysis of large system events. Furthermore, the paper will also discuss the computational burden and other challenges in implementing the algorithms in real-time applications.
Evaluating the Impact of Retiring Synchronous Fossil Fuel Generators on Inter-Area Oscillations in the U.S. Western Interconnection
(2024-01-03) Biswas, Shuchismita; Nguyen, Quan; Lyu, Xue; Fan, Xiaoyuan; Du, Wei; Huang, Zhenyu
To facilitate the decarbonization of the power grid, fossil-fuel-based synchronous generators are gradually being retired and replaced by inverter-interfaced renewable energy resources. As synchronous machines get displaced, the characteristics of inter-area oscillation modes in electrical interconnections are expected to change. This paper presents a model-based study of the impact of the retirement of synchronous fossil-fuel generators on the oscillatory characteristics of the US Western Interconnection (WI). Results show that if fossil-fuel-based synchronous machines are replaced by grid-forming inverters, then dominant inter-area modes seen in the WI today will change. New inter-area modes may appear due to the electromechanical energy exchange among the remaining hydropower generators clustered in geographical proximity in the northwestern part of the WI. This observation indicates that the evolution in modal properties needs to be closely tracked as the resource mix in electrical interconnections changes.
On the Existence of Dominant Inter-Area Oscillation Modes in the North American Eastern Interconnect Stability Simulations
(2024-01-03) Overbye, Thomas; Kunkolienkar, Sanjana; Safdarian, Farnaz; Birchfield, Adam
This paper examines the extent to which distinct inter-area electromechanical modes exist in the North American Eastern Interconnect simulations. Electric grids oscillate, and these oscillations have often been described using the linear systems concept of modes. Furthermore, the inter-area behavior of large-scale grids, such as the North American Eastern Interconnect, is sometimes described using just a few dominant inter-area modes. This paper presents a simulation-based approach to determine the extent to which these modes exist. The approach is motivated using a 2000 bus synthetic grid, and then applied to an 87,000 bus model of the North American Eastern Interconnect (EI). The conclusion is while the EI has common patterns of oscillation, when considering a single operating point for the EI consistent distinct modes are not observed. Rather, the calculated apparent modes appear to be disturbance dependent.
Introduction to the Minitrack on Monitoring, Control, and Protection
(2024-01-03) Follum, Jim; Eto, Joseph

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