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This paper presents a novel data-driven framework to aid in system state estimation when the power system is under unobservable false data injection attacks. The proposed framework dynamically detects and classifies false data injection attacks. Then, it retrieves the control signal using the acquired information. This process is accomplished in three main modules, with novel designs, for detection, classification, and control signal retrieval. The detection module monitors historical changes in phasor measurements and captures any deviation pattern caused by an attack on a complex plane. This approach can help to reveal characteristics of the attacks including the direction, magnitude, and ratio of the injected false data. Using this information, the signal retrieval module can easily recover the original control signal and remove the injected false data. Further information regarding the attack type can be obtained through the classifier module. The proposed ensemble learner is compatible with harsh learning conditions including the lack of labeled data, concept drift, concept evolution, recurring classes, and independence from external updates. The proposed novel classifier can dynamically learn from data and classify attacks under all these harsh learning conditions. The introduced framework is evaluated w.r.t. real-world data captured from the Central New York Power System. The obtained results indicate the efficacy and stability of the proposed framework. [ABSTRACT FROM AUTHOR]

Flexible ac Transmission Systems (FACTS) play an important role in improving the transfer capability and stability of a power system. In the application of voltage-sourced converter (VSC)-based FACTS controllers, it is important to study how a VSC impacts the flows in a power system. In this paper, we investigate this flow control problem using two sensitivity approaches, one using an injected voltage source formulation and the other an equivalent impedance formulation. The applications of sensitivity analysis for line active power redispatch and for new series VSC siting in a 1673-bus system are presented. Index Terms--Equivalent impedance, FACTS controllers, sensitivity analysis, voltage source model, voltage-sourced converter.

This article discusses how techniques from reinforcement learning (RL) can be exploited to transition to a model-free and scalable wide-area oscillation damping control of power grids. We present two control architectures with distinct features. Performing full-dimensional RL control designs for any practical grid would require an unacceptably long learning time and result in a dense communication architecture. Our designs avoid the curse of dimensionality by employing ideas from model reduction. The first design exploits time-scale separation in the generator electro-mechanical dynamics arising from coherent clustering, and learns a controller using both electro-mechanical and non-electro-mechanical states while compensating for the error in incorporating the latter through the RL loop. The second design presents an output-feedback approach enabled by a neuro-adaptive observer using measurements of only the generator frequencies. The controller exhibits an adaptive behavior that updates the control gains whenever there is a notable change in the loads. Theoretical guarantees for closed-loop stability and performance are provided for both designs. Numerical simulations are shown for the IEEE 68-bus power system model. [ABSTRACT FROM AUTHOR]

The article proposes a computationally efficient and robust method for estimating impulse or frequency response in the context of black-box multiple-input-multiple-output linear model identification of large power systems from simulations. The proposed approach is validated in conjunction with two realization algorithms – ERA method that is based on the established Ho-Kalman procedure for minimal realization, and the relatively new Loewner matrix based method. Practical aspects of identification in presence of numerical noise and nonlinearities are discussed. Study cases presented in the article include a linear model equivalent of a large-scale power system and the full-scale nonlinear transient model of the Eastern Interconnection. [ABSTRACT FROM AUTHOR]

Utilities today are facing unprecedented challenges due to more stringent regulations, environmental concerns, and a growing demand for reliable electricity. Meanwhile, according to U.S. Department of Energy?s statistics, 70% of the grid's transmission lines and power transformers are more than 25 years old. Without upgrades and enhancements, the grid will continue to age, increasing the risk of service interruptions and limiting the integration of renewable resources. It will also be severely challenged by the intermittency of supply and the uncertainty in load. [ABSTRACT FROM AUTHOR]

This study demonstrates the application of a wide-area control scheme based on multi-functional multi-band power system stabilisers (MF-MBPSS) in New York State grid for the purpose of system stability improvement. The aspects of oscillation damping, frequency and voltage closed-loop control are considered. The study describes useful techniques for placing and tuning of MF-MBPSSs based on simulation models and suitable techniques for very large power grids. The application of these concepts is demonstrated on a transient stability model of Eastern Interconnection. Results show a reduction of system frequency nadir during generation outages, significant improvement in damping of post-disturbance swings and capabilities to contribute to long-term voltage stability using only a modest amount of dynamic reactive power resources. [ABSTRACT FROM AUTHOR]

This paper applies a phasor-only state estimator (PSE) to a large power system consisting of two control regions, using synchrophasor data from 56 765/345/230 kV substations. Although the technique has been previously developed, this paper describes a topology processor to determine the redundant clusters of connected buses such that the PSE can be used in real time. This PSE allows corrections for phase biases, transformer taps, and current magnitude scaling. The ability to simultaneously solve the PSE for the two control regions is due to a PMU monitoring a tie-line between these two regions. The results show that with this method, the total vector errors of the measured voltage phasor data in these two control regions average to less than 0.5% under ambient conditions. The PSE also computes virtual phasor measurements on 70 buses that do not have PMUs, including large steam generator and wind-turbine generator substations. [ABSTRACT FROM AUTHOR]

This paper presents a new framework of identifying a series of cyber data attacks on power system synchrophasor measurements. We focus on detecting “unobservable” cyber data attacks that cannot be detected by any existing method that purely relies on measurements received at one time instant. Leveraging the approximate low-rank property of phasor measurement unit (PMU) data, we formulate the identification problem of successive unobservable cyber attacks as a matrix decomposition problem of a low-rank matrix plus a transformed column-sparse matrix. We propose a convex-optimization-based method and provide its theoretical guarantee in the data identification. Numerical experiments on actual PMU data from the Central New York power system and synthetic data are conducted to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

High-Voltage DC (HVdc) applications and flexible alternative current transmission systems (FACTSs) have been integrated in the Northeastern United States and Canada power grid for almost 30 years. The development of high-power, solid-state thyristor technology in the early 1970s contributed to the development and implementation of static var compensators (SVCs) to improve system stability and voltage control. The thyristor technology also enhanced HVdc back-to-back (BtB) applications for asynchronous ac interconnection. [ABSTRACT FROM PUBLISHER]

This paper presents a new framework of recovering missing synchrophasor measurements (erasures). Leveraging the approximate low-rank property of phasor measurement unit (PMU) data, we connect the problem of recovering PMU data erasures with recent advances in low-rank matrix completion methods. Since the existing analysis for matrix completion methods assumes an independent-erasure model that does not capture the correlations in PMU erasures, we propose two models to characterize the temporal and the channel correlations in PMU erasures and provide theoretical guarantees of a matrix completion method in recovering correlated erasures in both models. We also propose an online algorithm that can fill in the missing PMU measurements for real-time applications. Numerical experiments on actual PMU data are conducted to verify the effectiveness of the proposed methods. [ABSTRACT FROM PUBLISHER]

This paper investigates the concept of convertible static transmission controller (CSTC) using modular transformer converter (MTC) as the building block. The MTC is a bidirectional back-to-back ac/ac power conversion unit and the CSTC is a versatile transmission controller asset for dynamic power flow control and contingency management of the transmission grid. The proposed CSTC with new functions has several advantages compared to existing flexible ac transmission system controllers. System modularity for manufacturers and utilities/system operators using standard high power electronic systems is one of the advantages of this structure. In this paper, algebraic models of the CSTC are derived in two different operation modes (series-shunt and shunt-shunt connecting configurations). The proposed algebraic models are used to define the reference values for the CSTC converters based on the desired operating points for the meshed power system, the power transformers in particular. The dynamic performance of the CSTC with the proposed control structures and algebraic models will be investigated based on the PSCAD simulation. To prove the CSTC as a transmission asset and to verify the control structure and algorithm, ultrahigh fidelity controller hardware-in-the-loop testing has been conducted and comparative results will be presented. Finally, lab-scale experimental results are reported on the dynamic performance of the MTC-based CSTC. [ABSTRACT FROM AUTHOR]

Voltage-sourced converter (VSC)-based static synchronous compensators (STATCOMs) are used for voltage regulation in transmission and distribution systems. Unlike PWM-controlled STATCOMs, angle-controlled STATCOMs are switched at line frequency to limit the system losses. In recent years, angle-controlled STATCOMs have been deployed by utilities for the purpose of transmission system voltage regulation, voltage stability improvement, and increasing operational functionality. Despite the superior feature on voltage waveform quality and efficiency, the practical angle-controlled STATCOMs suffer from the over-current (and trips) and possible saturation of the interfacing transformers caused by negative sequence current during unbalanced conditions and faults in the utility. This paper specifically proposes a control structure to improve the angle-controlled STATCOMs performance under unbalanced conditions and faults. The main improvement is a substantial decrease in the negative sequence current and dc-link voltage oscillations under power system faults by the proposed control. This eliminates the need to redesign the STACOM power components to operate under fault current and dc-link voltage oscillations. The proposed control structure is designed based on adding appropriate oscillations to the conventional angle-controller output that is the control angle by which the VSC voltage vector leads/lags the line voltage vector. Since this control structure uses two angles for controlling the VSC output voltage, it is called dual angle control (DAC). PSCAD/EMTDC and experimental results verify the validity of the proposed control structure under unbalanced system conditions and faults. The experiments were conducted on a transient network analyzer, a unique hardware-based flexible ac transmission system simulator which was designed to study system faults and transients for a 2 × 100 MVA STATCOM field installation. [ABSTRACT FROM AUTHOR]

Validation and data quality improvement of phasor data through state estimation is the first step in ensuring that the synchrophasor data is useful for applications in monitoring, visualization, and control. This paper presents a phasor-measurement-based state estimator (PSE) for improving data consistency by identifying angle biases and current scaling errors in the phasor data using the augmented state vector approach. These errors can arise from issues with the Global Positioning Signal (GPS), timing circuits, instrument channels, and/or data channel scaling. The PSE is demonstrated using several sets of disturbance data from the Central New York Power System. The PSE can also provide estimates of line parameters and transformer tap ratios with sufficient measurement redundancy. Finally, the PSE allows the computation of interface power flows for disturbance and stability monitoring. [ABSTRACT FROM AUTHOR]

Dynamic regulation models for voltage-sourced converter (VSC) based flexible ac transmission system (FACTS) controllers are described in this paper. The dynamic models can then be used to analyze these FACTS controller's capability to improve the capability of a power transfer path. The contributions of this paper include showing that the benefits of FACTS controllers are proportional to the MVA ratings and the benefits of multiple FACTS controllers are cumulative. Furthermore, the coupling of dc buses allowing active power circulation between multiple VSC FACTS controllers may offer additional improvement in transfer capability. [ABSTRACT FROM AUTHOR]

Flexible ac Transmission Systems (FACTS) play an important role in improving the transfer capability and stability of a power system. In the application of voltage-sourced converter (VSC)-based FACTS controllers, it is important to study how a VSC impacts the flows in a power system. In this paper, we investigate this flow control problem using two sensitivity approaches, one using an injected voltage source formulation and the other an equivalent impedance formulation. The applications of sensitivity analysis for line active power redispatch and for new series VSC siting in a 1673-bus system are presented. [ABSTRACT FROM AUTHOR]