We propose novel line outage distribution factors under AC power flow (AC-LODF) for providing very efficient approximate post-outage power flow solution. The AC-LODF is derived by using holomorphic embedding (HE) approach, and the approximate post-outage power flow solution is obtained with Padé approximation (PA). Tests on IEEE 14-bus system, and Polish 2383-bus system verify that the proposed AC-LODF

Chance-constrained program (CCP) is a popular stochastic optimization method in power system planning, and operation problems. Conditional Value-at-Risk (CVaR) provides a convex approximation for chance constraints which are nonconvex. Although CCP assumes an exact empirical distribution, and the optimum of a stochastic programming model is thought to be sensitive in the designated probability distribution

Second-order generalized integrator (SOGI)-based phase-locked loops (PLLs)/frequency-locked loops (FLLs) are the most commonly used methods for grid synchronization. While the SOGI in these standard SOGI-PLLs/FLLs is adaptive to the estimated frequency, which results in the coupling between the SOGI and PLL/FLL, and this coupling brings about difficulties in stability analysis and parameter tuning

Phase-locked loop (PLL) control provides a typical synchronization mechanism for voltage-source converters (VSCs) integrated into strong grids. However, such a synchronization mechanism is hardly adaptive to the high-impedance weak grid neither to the islanded grid. In the scope of low-inertia weak grid issues, additional frequency control is conceived as an effective way for VSC-based devices to improve

In this work we address the problem of short-term load forecasting. We propose a generalization of the linear state-space model where the evolution of the state and the observation matrices is unknown. The proposed blind Kalman filter algorithm proceeds via alternating the estimation of these unknown matrices and the inference of the state, within the framework of expectation-maximization. A mini-batch

Despite it is essential to distribution network economics, computing energy loss for most major networks is still a tough task due to the absence of full monitoring. Assume the line current follows a normal distribution, the sum of its square is a linear combination of independent chi-square variables, which follows a generalized noncentral chi-square distribution. Based on this finding, we develop

Skewness can be used to identify the asymmetry introduced into a current stream by a High Impedance Fault (HIF). This letter introduces relative skewness as a superior computational approach for detecting HIF induced asymmetry changes in the feeder current. Relative skewness is defined as a measure of asymmetry in the stream with respect to the stream itself. The key highlight is the analysis of four

A novel concurrent control scheme of optimal re/active power regulation in a wind farm is proposed in this letter, of which the objective is to minimize the detrimental shortfall of active power during low-voltage-fault events. Distinguished from the existing works, the proposed control scheme incorporates an efficient optimization module into the wind turbine controllers. Specifically, it features

Recently, several authors have reported specific criteria to support the widely accepted use of a convex operational model for bulk energy storage in the formulation of power system operation and planning problems involving binary variables. Using two counterexamples, we show that this modeling simplification may give rise to impractical solutions featuring simultaneous charging and discharging, even

The letter proposes an algorithm for big data generation based on realistic selection of a set of contingencies for power systems described by undirected graphs. Every contingency is created by eliminating a certain number of elements in the system represented by graph edges. The number of elements as well as the distance between elements of the contingency is randomly selected according to a geometric

Presents closure discussion to the above named paper.

Presents the table of contents for this issue of the publication.

Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.

This letter introduces a novel approach to prevent ice formation on transmission lines during ice storms. First, weather forecast is used to calculate minimum currents needed to raise the conductor temperature above the freezing point. Then, a preventive unit commitment model is developed to enforce those minimum limits. Simulation studies are conducted on the three-area RTS-96 system. The results

The robust optimization based dynamic economic dispatch (DED) model has been extensively studied to address uncertainties of net loads induced by renewable energy resource variabilities and demand fluctuations. However, the robust DED model is computationally expensive, when solved by the column-and-constraint generation (CCG) approach that iterates between a master problem and a max-min subproblem

This letter presents a robust generalized correlation approach for monitoring of power system oscillatory modes. Due to the non-Gaussian nature of measurement noise, and presence of impulsive outliers, the wide-sense stationarity assumption of power system measurement data is violated even under ambient conditions thus limiting the effectiveness of conventional autocorrelation based approaches in mode

Distributed generators performing black start to form isolated microgrids offer a flexible and resilient solution to service restoration in distribution systems. Employing the dynamic microgrid concept, distributed generators can form isolated microgrids by changing their physical boundaries through smart switches and conventional circuit breakers. However, the flexibility of distributed generators

The synchronization instability in the presence of a fault is a main issue for the dynamic behavior and control of grid-feeding converters. In the literature, the synchronization stability assessment is carried out considering the dynamics of Phase-Locked Loops (PLL) but the transients of converter currents are neglected. The letter shows that such a simplification leads to inaccuracies and, thus,

This paper introduces quantum computing as a necessary and viable tool in addressing the needs of a modernized power grid. The application of quantum computing in enhancing physical security of the grid – an increasingly difficult problem to solve– is investigated. A comparative study based on mathematically proven computing performance measures shows the merits of the proposed method and further unveils

In this discussion, an analysis that the authors of the above name paper used the probable precision index ρ and made it to be greater than or equal to ρmin upon exit of forming clusters. This leads to the formation of clusters which are nearby to each order. In other words, border of one cluster is near to the border of other cluster. Indeed, any minor change in cluster data will lead to the major

Presents corrections to above named paper.

Presents corrections to above named paper.

Presents corrections to above named paper.

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal.

This page or pages intentionally left blank.

The legacy Optimal Power Flow (OPF) dispatch in electric power grids with high proliferation of renewables can be at risk due to the lack of awareness on major uncertainties, and sudden changes in renewable outputs. This may, in turn, result in conditions where transmission line power flows are significantly exceeded, and subsequent automatic protective actions take place. This letter presents a new

This letter proposes a novel technique for estimating the rate of change of frequency (RoCoF) of the center of inertia (CoI) in power systems. To offer a holistic picture of the system's frequency response, the proposed technique requires local frequency at the point of measurement, only. This enables the local estimation of active power deficit following a loss of generation (LoG) event, thus facilitating

Conventional load frequency control primarily relies on large synchronous generation units to ensure regulation of the system frequency. However, its performance deteriorates as the system parameters, including inertia and droop coefficients, deviate from original system design. This letter proposes an augmented load frequency control (ALFC) to ensure robust frequency regulation under diurnal variations

In this letter, we propose a tractable formulation and an efficient solution method for the Wasserstein-metric-based distributionally robust unit commitment (DRUC-dW) problem. First, a distance-based data aggregation method is introduced to hedge against the dimensionality issue arising from a huge volume of data. Then, we propose a novel cutting plane algorithm to solve the DRUC-dW problem much more

Different from voltage-source converter (VSC), reactive power absorption of line-commutated converters (LCCs) changes depending on DC voltage level. Therefore, the amount of AC voltage fluctuations at inverter side are different according to $I$ – $V$ droop constants in hybrid multi-terminal high-voltage direct current (MT-HVDC) system. This paper proposes a method for calculating the $I$ – $V$ droop

This letter proposes an efficient method for com-puting the delay-margins of large-scale power systems with single constant delay. The method computes the margin by identifying the minimal delay under which some eigenvalues are about to cross the imaginary axis from the left to the right half complex plane. Based on the Rekasius substitution, a new characterization for the crossing points is developed

This letter devises a Reachable Eigenanalysis ( ReachEigen ) theory as a formal method to analyze uncertain eigenvalues in power systems. ReachEigen computes the set of the possible spectra, taking into account the changes of both the system operating points and the characteristic equations caused by uncertainties. The innovation of ReachEigen lies in: 1) a Newton-iteration-based eigensolver which

Presents the table of contents for this issue of the publication.

Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.

Presents a list of reviewers who contributed to this publication in 2019. In addition, presents a listing of papers recognized for their high quality, 2017-2019.

High-level penetration of intermittent renewable energy sources has introduced significant uncertainties and variabilities into modern power systems. In order to rapidly and economically respond to the changes in power system operating state, this letter proposes a real-time optimal power flow (RT-OPF) approach using Lagrangian -based deep reinforcement learning (DRL) in continuous action domain. A

In this paper, detectability analysis is studied and extended to guide selection of measurements for the dynamic state estimation (DSE) of a synchronous machine. To make sure that the DSE converges, past studies suggested that enough measurements must be available to make the system observable. In this paper, the convergence condition is relaxed via detectability analysis to reduce the number of required

This letter presents an analytical closed-form expression that quantifies the contributions of nodal active- and reactive-power injections to total loss in a power system operating at sinusoidal steady state. We term this as the loss divider , since it is derived by leveraging the ubiquitous current divider law. The proposed loss divider innately embeds the dependence of system loss on both the network

Radiality constraints are involved in both distribution system restoration and reconfiguration problems. However, a set of widely used radiality constraints, i.e., the spanning tree (ST) constraints, has its limitations which have not been well recognized. In this letter, the limitation of the ST constraints is analyzed and an effective set of constraints, referred to as the single-commodity flow constraints

In energy-only electricity markets, the operational reserve demand curve is a scarcity pricing mechanism adopted to address the shortage of reserves and incentivize the generators. It is constructed based on the assumption of the normality of loss of load probability, which is estimated from reserve error data. In this Letter, the historical record of reserve error is collected and analyzed to test

In this letter, a new model to represent power system inertia distribution is derived first. Then, a specific online identification method is proposed to identify parameters of the model under normal operating conditions so that the system inertia distribution can be tracked in real-time. The effectiveness of the proposed model and identification method is validated in the IEEE 39-bus system.

This letter proposes an optimization-free technique to estimate the parameters of voltage dependent loads through the measurements of only the load active and reactive power consumption and frequency deviations at the load bus. The technique is shown to be a relevant consequence of the dependency of power flow equations on the bus voltage phase angles. The WSCC 9-bus and the IEEE 14-bus systems serve

In the literature, Bode plots and Nyquist diagrams are used extensively in stability analysis for admittance-based models. In this letter, we demonstrate that eigenvalues obtained from the total admittance lead to accurate prediction of stability while Bode plots and Nyquist diagrams show limitations. A voltage source converter with weak grid interconnection is used as an illustrative example to demonstrate

Presents corrections to author information for the above mentioned paper.

These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal.

This page or pages intentionally left blank.

High-voltage direct-current (HVDC) transmission systems have been rapidly developing, whereas they also become the crucial factors that affect the power system's stability. The repetitive commutation failures (RCF) of the HVDC link will put the sending-end power system at risk of transient instability, which greatly raises the demand of the system to enhance its ability to cope with such events. This

In the absence of demand-side bids for certain reliability products in the wholesale electricity markets, Independent System Operators (ISOs) traditionally use fixed demand requirements with penalty factors to clear the market. This approach does not allow proper tradeoffs between cost and reliability due to the inelasticity of the fixed requirements. Therefore, ISOs have been replacing the fixed requirements

Following Part I of this paper that reveals two distinct interpretations of demand curves and the corresponding different forms of the market clearing formulation, Part II of this paper analyzes the sequential and the iterative market clearing algorithms currently implemented in some markets. It is shown that these algorithms lead to socially sub-optimal solutions. The root cause of the problem is

This article presents a library of second-order models for synchronous machines that can be utilized in power system dynamic performance analysis and control design. The models have a similar structure to that of the so-called classical model in that they consist of two dynamic states, the power angle and the angular speed. However, unlike the classical model, they find applications beyond first swing

This paper proposes a multi-agent deep reinforcement learning-based approach for distribution system voltage regulation with high penetration of photovoltaics (PVs). The designed agents can learn the coordinated control strategies from historical data through the counter-training of local policy networks and centric critic networks. The learned strategies allow us to perform online coordinated control

With the increasing integration of distribution generations (DGs), active distribution networks (ADNs) need to address the new challenges in voltage control. Meanwhile, the traditional centralized method in reactive power optimization usually leads to a heavy computational burden for large-scale distribution networks. A distributed voltage control model with a novel network partitioning method is proposed

As significant amounts of renewable distributed generation (RDG) are installed in the power grid, it becomes increasingly important to plan RDG integration to maximize the utilization of renewable energy and mitigate unintended consequences, such as phase unbalance. One of the biggest challenges in RDG integration planning is the lack of sufficient information to characterize uncertainty (e.g., load

The real-time preventive control is particularly critical because the integration of renewable energy aggravates the random fluctuation of large power grid operating state. An online preventive control optimization method for static voltage stability is proposed based on the Thevenin equivalent parameter identification. According to the definition of the stability margin, its quantitative relationship

Electric power system state estimation is a vital part of real-time monitoring and management for power grid operations and control. With increased interest in the effects of geomagnetically induced currents (GICs) and effective mitigation strategies therein, similar tools that provide situational awareness during GMD events are increasingly necessary. Therefore, a GIC estimator is developed by relating

This article proposes a framework for stochastic eigenvalue analysis of electric power systems with a high penetration of inertialess renewable generation, focusing on the influential factors that affect the eigenvalue movement resulting from the inertia reduction. We analytically investigate the influence of the inertia and the variation in renewable generation on small-signal stability using stochastic

The implicit $\text{Z}_\text{bus}$ Gauss algorithm is revisited to empower the power flow analysis for microgrids with hierarchical control and frequency- and voltage- dependent loads. The contributions of the revisited Gauss (GRev) algorithm include: 1) a droop-based implicit $\text{Z}_\text{bus}$ Gauss microgrid algorithm which automatically incorporates the distributed energy resources (DERs)/load

The autonomous microgrid (MG) with multiple voltage source inverters (VSI) is operated in droop mode to share the load proportionally. These VSI controllers require higher droop constants if the feeder lines connecting the VSI to microgrid has a low X/R ratio. The higher droop gains and large loading conditions in the microgrid may exhibit instability with the low frequency power modes (LFPM). This

In this paper, the problem of optimal placement of virtual inertia is considered as a techno-economic problem from a frequency stability point of view. First, a data driven-based equivalent model of battery energy storage systems, as seen from the electrical system, is proposed. This experimentally validated model takes advantage of the energy storage system special attributes to contribute to inertial

Event-triggered control (ETC) is becoming increasingly popular in load frequency control (LFC) operation in power systems. So far, the existing literature has primarily focused on load disturbance rejection in face of communication delay without considering much on networked-induced measurement disturbances and messages sent. In this paper, we study the LFC operation as a problem of networked control