North American Power Research Articles

Dynamical heterogeneity and universality of power-grids

Electric power systems during transient states are extensively investigated using variations of the Kuramoto model to analyze their dynamic behavior. However, the majority of current models fail to capture the physics of power flows and the heterogeneity of the grids under study. This study addresses this gap by comparing the levels of heterogeneity in continent-sized power grids in Europe and North America to reveal the underlying universality and heterogeneity of grid frequencies, electrical parameters, and topological structures. Empirical data analysis of grid frequencies from the Hungarian grid indicates that q-Gaussian distributions best fit simulations, with spatio-temporally correlated noise evident in the frequency spectrum. Comparing European and North American power grids reveals that employing homogeneous transmission capacities to represent power lines can lead to misleading results on stability, and nodal behavior is heterogeneous. Community structures of the continent-sized grids are detected, demonstrating that Chimera states are more likely to occur when studying only subsystems. A topographical analysis of the grids is presented to assist in selecting such subsystems. Finally, synchronization calculations are provided to illustrate the occurrence of Chimera states. The findings underscore the necessity of heterogeneous grid models for dynamic stability analysis of power systems.

Advanced Computing is at the Forefront of a New “Moonshot” Revolutionizing the North American Power Grid

Advanced Computing is at the Forefront of a New “Moonshot” Revolutionizing the North American Power Grid

More transmission or more storage? Decarbonization in the context of hydro-rich Northeastern North America

Decarbonizing electric systems through the integration of large amounts of intermittent renewable energy complicates the balancing of demand and supply, increasing the value of storage. With the rapid expansion of short-term storage options such as batteries, flexible resources such as existing hydroelectric reservoir storage are often overlooked. Using a capacity expansion and dispatch model of the Northeastern North American power system, we draw lessons from the interconnection potential of Quebec’s large existing hydropower capacities. We find that reservoir-transmission coupling significantly decreases the cost of decarbonization, even when short-term storage costs are low, because it is used for both daily and seasonal balancing. Conversely, the value of short-term storage is compromised by the availability of reservoir-transmission coupling, even assuming high investment costs for transmission. We also describe the regional distribution of costs and benefits of storage and transmission and discuss implications for regional cooperation.

Practical Approach to Underground Distribution Power Cable Fleet Management

With the growing requirements imposed by regulatory authorities, grid operators and power utilities firms are confronted with the challenging task of ensuring the reliability, safety, and resilience of distribution networks amid aging asset infrastructure and a lack of resources. Over the past 15 years, the health index (HI)-based analysis has become an increasingly popular asset management tool for several power utilities. This strongly focuses on HI-based analysis to consider not only factors such as the cable vintage, type, and operating conditions, but also maintenance testing data. In this regard, the best industry practices for cable maintenance testing, including VLF Tan-Delta, partial discharge (PD), and time domain reflectometry (TDR), are outlined. Moreover, online tests, such as infrared thermography, ultrasonic PD scan, and temperature monitoring, are discussed. This paper also summarizes the classic asset management strategies for underground (UG) distribution power cables. The paper offers a practical approach for cable fleet management based on authors’ experience dealing with distribution power utility cable management for North American power utilities firms in the past 10 years. The proposed approach ensures reliable cable management at the lowest total life cycle cost. The topic of fleet management for UG power cables considering various condition parameters and an overall risk assessment is outlined. The fleet management guideline of UG power cables covers both cables and their accessories, such as terminations and joints. The main contributions of the paper are to: (1) determine the key parameters and testing factors for condition assessment of cables; (2) offer a practical approach to cable management that is not only based on technical issues, but also considers risk and impact costs, such as financial impact, reliability impact, etc.; and (3) propose a methodology for translating the HI/calculated risks into GIS, making it possible to identify major degradation patterns for fleet assessment. Considering budget and resource limitations around testing UG cable installations, this paper aims to assist asset managers, engineers, and asset owners in developing an effective cable fleet management strategy.

Review of "Vibrant Matter: A Political Ecology of Things by Jane Bennett," Bennett, J. (2010). Vibrant Matter: A Political Ecology of Things. Duke University Press.

In Vibrant Matter: A Political Ecology of Things (2010), Jane Bennett encourages her readers to slow down the internal thoughts of human superiority over "intrinsically inanimate matter" --- thoughts that prevent them from "detecting...a fuller range of the nonhuman powers circulating around and within human bodies" and their political systems (p. ix). Some readers of CDQ may wonder why a book from 2010 is worth our attention in 2022. The COVID-19 pandemic, the U.S. Supreme Court's ruling on women's reproductive autonomy, and the restrictions placed on the EPA's control over carbon emissions all suggest a clear resurgence of what Bennett calls the oft-repeated "vitalism-materialism debate" (p. 90)---the debate over how far affect, agency, animacy, and vitality extend. Bennett resolves the tensions of that debate by fusing traditional ideas of mechanistic materialism with the notions of an unknowable agency in all matter (not just humans), an agency that lacks representation in current political thought. If technical communicators and designers dedicated to crisis/risk communication as well as those studying and producing political technologies (Cheek, 2021, 2022) didn't see the application of Bennett's "vital materialism" at the end of the Bush era's heated debates over stem cell research and the war in Iraq as well as the North American power blackout of 2003, then perhaps, given the current political climate, I can persuade them to find merit in revisiting Bennett's arguments.

Feedback Control Strategy for Transient Stability Application

Power systems are subjected to a wide range of disturbances during daily operations. Severe disturbances, such as a loss of a large generator, a three-phase bolted fault on a generator bus, or a loss of a transmission line, can lead to the loss of synchronism of a generator or group of generators. The ability of a power system to maintain synchronism during the few seconds after being subjected to a severe disturbance is known as transient stability. Most of the modern methods of controlling transient stability involve special protection schemes or remedial action schemes. These special protection schemes sense predetermined system conditions and take corrective actions, such as generator tripping or generation re-dispatch, in real time to maintain transient stability. Another method is the use of a real-time feedback control system to modulate the output of an actuator in response to a signal. This paper provides a fundamental evaluation of the use of feedback control strategies to improve transient stability in a power system. An optimal feedback control strategy that modulates the real power injected and absorbed by distributed energy-storage devices is proposed. Its performance is evaluated on a four-machine power system and on a 34-machine reduced-order model of the Western North American Power System. The result shows that the feedback control strategy can increase the critical fault clearing time by 60%, thereby improving the transient stability of the power system.

Test for Non-Synchronized Errors of State Estimation Using Real Data

This letter discusses performance degradation of traditional supervisory control and data acquisition (SCADA)-based static state estimation (SSE) caused by violation of the static assumption. The sensitivity of non-synchronized sampling errors against oscillations is tested through real measurement data and grid model from a subsystem of the North American power gird. The test results show that as an important reason leading to the failure of SCADA-based SSE, the non-synchronized sampling error of SCADA is sensitive to oscillations in that the error rapidly increases when oscillations occur and vanishes when the oscillations cease.

An analysis of electricity congestion price patterns in North America

The present paper illustrates the use of principal component analysis (PCA) on the congestion component of local (i.e. zonal) electricity price data to detect the most salient congestion patterns in electricity transmission grids managed by either a Regional Transmission Organization (RTO) or an Independent System Operator (ISO). Outputs from the PCA along with some data visualization tools are shown to make the identification of such patterns seamless and straightforward. An empirical analysis is conducted for three North American power systems, namely NYISO, ISO New England and PJM. Finally, a simple time series model representing the evolution of PCA scores is proposed.

Economic efficiency of alternative border carbon adjustment schemes: A case study of California Carbon Pricing and the Western North American power market

To be effective, policies addressing power sector carbon emissions in jurisdictions that are embedded in larger carbon markets must account for carbon embodied in imports and the potential for leakage. Yet analyses of alternative border carbon adjustment (BCA) policies that carefully model the impact of generation mix, net load distributions, and transmission limits are rare in the literature. With a generation-transmission expansion planning model of Western North America, we compare the impacts of alternative BCA schemes that California's carbon pricing system could implement. These include no BCA, facility (import source)-based deemed emission rate, a facility-neutral and constant (over-time) rate, and a facility-neutral and dynamic rate. Our results suggest that, when compared to no BCA or BCA using facility-based deemed rates, a facility-neutral BCA can improve efficiency by simultaneously lowering market-wide emissions and costs without raising California consumer expenditures. Emissions leakage also declines significantly. The precise value of the deemed rate affects these gains; setting it equal to marginal emission rates external to California is most efficient. We also show that California's carbon pricing encourages more interstate transmission expansion because power imports become more profitable. However, BCAs that cost-effectively lower total regional emissions will dampen those incentives.

Design and Valuation of High-Capacity HVDC Macrogrid Transmission for the Continental US

This work explores the benefits of increasing transmission capacity between the US Eastern and Western Interconnections under a high-renewables future. Given the existing “seam” between the two interconnections, a co-optimized infrastructure planning model was developed to assess trade-offs between investments in cross-seam HVDC transmission, AC and DC transmission needs within each interconnection, generation investment costs, and operational costs, at different renewable penetration levels. The model allows existing and candidate generation resources for deliverable planning reserves to be shared throughout the interconnections, a feature which drives identification of least-cost investments. This work is performed using an industry-vetted 169-bus representation of the North American power grid. Results from this analysis indicate that, under high wind/solar growth scenarios, the cost of a macrogrid HVDC transmission is outweighed by the generation-related savings they produce. The presence of other benefits related to grid reliability, resilience, and adaptability, suggest that cross-seam transmission is highly attractive infrastructure.

Wide-Area Control of Power Systems: Employing Data-Driven, Hierarchical Reinforcement Learning

In the foreseeable future, the north American power transmission system is expected to evolve into the largest and most complex Internet of Things (IoT) technology, encompassing the use of massive volumes of data from phasor measurement units (PMUs) to make control decisions in the face of major disturbances without jeopardizing grid stability or the quality of service. In this modern grid, besides conventional generation, distributed energy resources (DERs) in the form of renewables, smart loads, and power electronic converters, will serve as active end points that not only consume, but can also generate, store, sense, compute, communicate, and react to datadriven commands. They will turn the grid into a large network of active nodes, introducing rapid, large, frequent, and random fluctuations in power flow, voltage, and frequency with a huge amount of model uncertainty while at the same time increasing our capability to learn and control them through a massive, data-driven IoT platform.

An Analysis of Electricity Congestion Price Patterns in North America

The current paper illustrates the use of principal component analysis (PCA) on the congestion component of local (i.e. zonal) electricity price data to detect the most salient congestion patterns in electricity transmission grids managed by either a Regional Transmission Organization (RTO) or an Independent System Operator (ISO). Outputs from the PCA along with some data visualization tools are shown to make the identification of such patterns seamless and straightforward. An empirical analysis is conducted for three North American power systems, namely NYISO, ISO New England and PJM.

Electric sector impacts of renewable policy coordination: A multi-model study of the North American energy system

Policies to encourage renewable electricity generation have grown at national and subnational levels. These measures are often characterized by geographical fragmentation, as jurisdictions typically select their own renewable targets without coordinating with neighboring regions. However, the literature on renewable policies has not examined the effects of cross-border interactions and coordination, especially in a multi-model comparison to examine robustness to structural and parametric uncertainties. This paper assesses the impacts of regional and international renewable policy coordination on economic, environmental, and planning outcomes in the North American power sector. Using a multi-model comparison with eight energy-economic models, the analysis demonstrates how prospective renewable mandate trade formulations impact power sector outcomes like capacity planning decisions, costs, emissions, trade, and infrastructure investments. Model results suggest that renewable policy coordination can lower costs by up to 20% for the stringencies examined here. Fragmentation lowers gas-fired generation, but coal and nuclear are also displaced, especially when regions comply without trade. Policy costs decrease for the U.S. with higher regional and international coordination, but magnitudes vary by model. Restricting coordination leads to higher capacity investments, and absent incentives to enhance efficiency, grids do not share resources to balance variability. Transmission investments and trade are highest with international policy coordination.

Using the Return on Sustainability Investment (ROSI) Framework to Value Accelerated Decarbonization

A major barrier to companies' more effective integration of sustainability into their corporate strategies is finding ways to estimate and communicate the full value of their business cases. In the authors' experience in working with or for companies, they find that most do not track the value sustainability delivers for an organization. And when companies do track and measure their returns on investments in sustainability, the estimates tend to be focused almost exclusively on those benefits that are most direct and tangible, and show up on the corporate P&L, as opposed to other benefits like employee commitment and regulatory forbearance, which are more likely to show up in a lower cost of capital.To help companies quantify the expected value of their sustainability programs, the authors have developed a Return on Sustainability Investment (ROSI™) framework. The study presented here describes the outcomes of a recent analysis in which the NYU Stern Center for Sustainable Business in collaboration with ALO Advisors worked with Capital Power Corporation, a North American power producer, to estimate the value likely to be created by accelerating its transition to clean energy. Through their work with the Chief Sustainability Officer, Chief Financial Officer, and senior managers from several key business functions, the authors identified seven major sources of benefits, and quantified the expected effects on value of four of them, to produce an estimated contribution to the value of the company of about $30 million. The ROSI™ framework and methodology has since been incorporated into CPX's investment decision‐making process, and played an important role in management's decision to commit to the operating changes required to accelerate the company's transition away from coal‐generated electricity.

An Adaptive Matrix Pencil Algorithm Based-Wavelet Soft-Threshold Denoising for Analysis of Low Frequency Oscillation in Power Systems

One of the main reasons that affecting the stability of power systems is low frequency oscillation (LFO). The existence of noise influences the accuracy of LFO mode identification extracted from wide-area measurement system (WAMS). The wavelet threshold de-noising is widely used in signal processing. In this paper, wavelet soft threshold is illustrated to attenuate the noise of LFO signal, the optimal wavelet basis and decomposition level for de-noising LFO signal with noise are obtained and verified by experiments. Following the signal de-noising, an improved Matrix Pencil (MP) algorithm is used for mode identification of LFO. This improvement particularly lies in the ratio of adjacent singular entropy increment difference (RASEID) designed as an adaptive order determination method in the MP algorithm proposed in the paper. RASEID not only makes the MP algorithm adaptive, but also enhances the stability of the order determination in the mode identification process. The proposed method ensures the accuracy of mode identification with lower sensitivity to noise interference. Finally, the validity of the proposed method is verified by three cases studies. The first study is on the analysis of synthetic signal typically performed in many literatures. The second study is to identify the mode of active power LFO signal which is generated by IEEE four-generator and two-area system given with disturbance on RT-LAB experimental platform. The third study is the oscillation analysis of the actual LFO data in the North American power grid. The results validate the feasibility of the proposed method for mode identification of noisy LFO.

Bayesian spatial reliability model for power transmission network lines

The paper is devoted for the problem of assessment of the dependence of power transmission lines outages on the geographical position in the network. Authors present the model based on Poisson–gamma random field for the purpose of capturing the information about the strength of correlation between the power transmission network outages and geographical positions. The model presentation is followed by the analysis of the model and application to the North American power grid. The main finding is that outages of the power grid are geographically correlated and this effect should be incorporated into the overall reliability assessment of the grid to obtain more accurate estimates. It is proved in this paper, that taking into account dependency of line outages on the geographical location, enables to obtain more accurate results as compared to classical Poisson and to hierarchical Poisson–Bayesian models.

An Adaptive TLS-ESPRIT Algorithm Based on an S-G Filter for Analysis of Low Frequency Oscillation in Wide Area Measurement Systems

In this paper, a two-stage mode identification algorithm including preprocessing and identification steps is introduced to solve the problems of measuring noise and inaccurate mode identification in the analysis of low-frequency oscillation (LFO) in a wide area measurement systems (WAMSs). S-G filter de-noising is utilized for the preprocessing. An adaptive total least squares-estimation of signal parameters via rotational invariance techniques (TLS-ESPRIT) algorithm with the order setting of the singular value accumulation percentage adjacency increment ratio (SVAPAIR) is utilized for the identifying stage. The S-G filter is used to mitigate the measuring of LFO noise of the system. Furthermore, the SVAPAIR is adopted to achieve an adaptive and precise determination of the LFO order, and then LFO parameters are extracted by the adaptive TLS-ESPRIT algorithm. The proposed algorithm has been tested and verified using the IEEE four-generator two-area system and the actual measured data of the LFO accident in the North American power grid. The simulation and experimental result showed that the proposed algorithm has better adaptability, anti-noise characteristic, and robustness compared to those of the conventional Prony, matrix pencil (MP), and TLS-ESPRIT algorithms.

Variable Loop Gain Using Excessive Regeneration Detection for a Delayed Wide-Area Control System

Excessive time delay in the implementation of a wide-area damping controller may lead to poor time-domain response or instability of an otherwise stable closed loop system. Careful monitoring of the controller output reveals the relative phase margin as it tends toward a vanishingly small value. Design and analysis of the excessive regeneration detector for system stability migration is presented. Details of degradation are followed by the description of a variable loop gain controller to ensure stability in the presence of significant delay, with nominal controller design developed using loop shaping theory. Linear and nonlinear stability of the system is assessed with the variable loop gain controller in place. Simulations of multiple disturbance environments and time delay conditions validate the developed theory using a detailed nonlinear model of the western North American power system. Finally, a GPS spoofing algorithm is employed to demonstrate the efficacy of the approach to a malicious phasor measurement unit attack.

Study on the balancing authority ACE limit standard of North American power grid

The control performance standard 2 (CPS2), once adopted in North American power grid, has some disadvantages, such as having insufficient evaluation time and ignoring the correlations between area control errors (ACEs). It was not suitable to restrain the tie‐line power flow and had been replaced by the balancing authority ACE limit (BAAL) standard. It is found that the design mechanism of BAAL standard is derived from reliability requirement. Its purpose is to restrict the duration of over‐limit frequency to be less than 30 min by managing the fluctuation of each ACE. The role of the new standard in co‐operation with control performance standard 1 (CPS1) is analyzed, and some of its technical characteristics, including short‐time operation security, setting dynamic ACE limit, and permitting the correlations between ACEs, are discussed. The simulation results indicate that even in the case where each area performance meets the requirements of CPS1 and CPS2, the short‐time frequency performance still cannot meet the requirement of operation security. BAAL standard co‐operating with CPS1 can not only restrict the standard deviation of frequency fluctuation over a long term but also maintain the short‐time frequency quality, which is beneficial for real‐time operation security and reliability. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Multivariable loop-shaping control design for stability augmentation and oscillation rejection in wide-area damping using HVDC

Two high-voltage DC (HVDC) transmission lines known as the Pacific DC Intertie and Intermountain DC line operate in the western North American Power System. These HVDC lines have the potential to be capable actuators in both single-input, single-output (SISO) and multivariable wide-area damping controllers. Implementation of a multivariable design is investigated and compared to two SISO controllers implemented simultaneously using these actuators. Control synthesis is executed using a robust multivariable auto-synthesis methods with modifications based on closed-loop behavior. Sensitivity weighting functions which result in controllers that emphasize feedback at troublesome frequencies while meeting prescribed bandwidth restrictions are applied. Performance criteria include transient responses to large contingency events and disturbance rejection. A forced oscillation is used to perturb the system at an eigenfrequency of interest to determine the effectiveness of each controller in rejecting oscillatory disturbances system-wide.