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Low frequency electromechanical oscillations can pose a threat to the stability of power systems if not properly addressed. This paper proposes a novel methodology to damp these inter-area oscillations using loads, the demand side of the system. In the proposed methodology, loads are assigned to an aggregated cluster whose demand is modulated for oscillation damping. The load cluster control action is obtained from an optimal output feedback control (OOFC) strategy. The paper presents an extension to the regular OOFC formulation by imposing a constraint on the sum of the rows in the optimal gain matrix. This constraint is useful when the feedback signals are generator speeds. In this case, the sum of the rows of the optimal gain matrix is the droop gain of each load actuator. Time-domain simulations of a large-scale power system are used to demonstrate the efficacy of the proposed control algorithm. Two different cases are considered: a power imbalance and a line fault. The simulation results show that the proposed controllers successfully damp inter-area oscillations under different operating conditions and with different clustering for the events considered. In addition, the simulations illustrate the benefit of the proposed extension to the OOFC that enable load to provide a combination of droop control and small signal stability augmentation. [ABSTRACT FROM AUTHOR]

Homotopy analysis method (HAM) is a popular semi-analytical method used widely in applied sciences. It stands out from the rest of the semi-analytical methods as it provides a family of solutions to nonlinear equations, including ordinary differential equations (ODEs), partial differential equations, etc. The convergence characteristics of the solutions can be varied by changing an auxiliary parameter ($\hbar$) in HAM. The convergence region of solution of ODEs using HAM can be improved by applying it over multiple intervals of time, which is referred to as multi-stage HAM (MHAM). In this paper, MHAM models for the IEEE Model 2.2 synchronous machine, IEEE Type-1 excitation system, first-order governor and first-order turbine models have been developed. The applicability of MHAM for power system dynamic simulations has been investigated in this paper using seven widely used test systems ranging from 10 generators 39 bus systems to 4092 generators 13 659 bus systems. The effect of number of terms, $\hbar$ and the time step on the accuracy and stability of the solution has been studied. The effectiveness of MHAM has been compared with the modified Euler (ME) and midpoint Trapezoidal (TrapZ) methods. The accuracy of MHAM has been found to be comparable with ME and TrapZ methods for the values of $\hbar$ between $-$ 1.05 and $-$ 0.95. The best accuracy is obtained for $\hbar$ = $-$ 1.0, which is a special case of MHAM called multi-stage homotopy perturbation method (MHPM). In this paper, it is also shown that MHPM is equivalent to multi-stage adomian decomposition method, which has been recently explored for large power system simulations. [ABSTRACT FROM AUTHOR]

A continuous Online Monitoring System (OMS) for power system stability based on Phasor Measurements (PMU measurements) at all the generator buses is proposed in this paper. Unlike the state-of-the-art methods, the proposed OMS does not require information about fault clearance. This paper proposes a convolutional neural network, whose input is the heatmap representation of the measurements, for instability prediction. Through extensive simulations on standard IEEE 118-bus and IEEE 145-bus systems, the effectiveness of the proposed OMS is demonstrated under varying loading conditions, fault scenarios, topology changes, and generator parameter variations. Two different methods are also proposed to identify the set of critical generators that are most impacted in the unstable cases. [ABSTRACT FROM AUTHOR]

This paper describes the use of large electric grids in university electric power system courses. Since much actual power system information is not publicly available, the application of public domain synthetic grids developed by the authors is presented including a 2000-bus grid. Discussion of the educational applications utilized in a senior level class are given for power flow analysis and sensitivity, economic dispatch, contingency analysis, optimal power flow (OPF), security-constrained OPF, transient stability, and real-time dynamic operations. In each of these, the application of the large synthetic grids give students insights and experience with cases closer to actual power systems in complexity and size. [ABSTRACT FROM AUTHOR]

The paper proposes a new adaptive approach to power system model reduction for fast and accurate time-domain simulation. This new approach is a compromise between linear model reduction for faster simulation and nonlinear model reduction for better accuracy. During the simulation period, the approach adaptively switches among detailed and linearly or nonlinearly reduced models based on variations of the system state: it employs unreduced models for the fault-on period, uses weighted column norms of the admittance matrix to decide which functions to be linearized in power system differential-algebraic equations for large changes of the state, and adopts a linearly reduced model for small changes of the state. Two versions of the adaptive model reduction approach are introduced. The first version uses traditional power system partitioning where the model reduction is applied to a defined large external area in a power system and the other area defined as the study area keeps full detailed models. The second version applies the adaptive model reduction to the whole system. The paper also conducts comprehensive case studies comparing simulation results using the proposed adaptively reduced models with the linearly reduced model and coherency-based reduced model on the Northeast Power Coordinating Council 140-bus 48-machine system. [ABSTRACT FROM AUTHOR]

The motivation and training of a proficient and diverse pool of power engineers, system operators, and policymakers is an important challenge for the electric industry. Power system experts are increasingly in demand globally to facilitate transitions to more environmentally friendly energy systems. More generally, citizens with a basic understanding of load balancing and renewable energy sources are more effective partners in increasingly complex power economies and political decisions. To address the need for an accessible general introduction to power systems, we are developing Griddle, an educational video game that introduces secondary school students to the basics of power system design, scheduling, and operation. We describe the design of Griddle's gameplay and underlying simulation, improvements made in response to user feedback, alignment with emerging teaching standards, and a high school classroom evaluation (n = 178) of Griddle's significant transformative impact, with the goal of validating the game-based learning approach and sharing “lessons learned” with designers of related tools. We find that Griddle is effective at engaging students and presents evidence that it helps students integrate key concepts, and we identify areas where further development and study are needed. [ABSTRACT FROM AUTHOR]

To mitigate forced oscillation and avoid confusion with modal oscillation, fundamentals of forced oscillation in multimachine power system are investigated. First, the explicit formulation of the oscillation is formulated in terms of forced disturbances and system mode shapes. Then, forced oscillation amplitude, components and envelope are intensively studied. Consequently, measures for mitigating the oscillation are obtained. Forced oscillation can also be effectively detected and discriminated from modal oscillation by utilizing its uniqueness of components properties and envelope shapes. Study results of the 10-machine 39-bus New England test system and a real-life power system demonstrate the correctness of theoretical analyses and effectiveness of detection methods for forced oscillation. [ABSTRACT FROM AUTHOR]

This paper proposes a new approach for power system transient stability simulation, which is based on a semi-analytical solution (SAS) of power system differential-algebraic equations. In this paper, an SAS is derived using the Adomian decomposition method as a closed-form explicit function of symbolic variables such as time, the initial state, and other variables on system conditions and; hence, it can directly give a power system's dynamic trajectory being accurate for a certain time window. Unlike a traditional numerical integration based simulation approach, the proposed new approach offline derives an SAS and online evaluates the SAS by plugging in values of symbolic variables for a series of time windows making up the desired simulation period. This paper further studies the maximum length of the time window for an SAS being accurate and proposes a divergence indicator for simulation using adaptive time windows. Implementation of this new approach on parallel computers is also studied. The new approach is validated through contingency simulation of the IEEE 10-generator 39-bus system with detailed generator models. [ABSTRACT FROM AUTHOR]

The small-signal stability analysis of power systems concerns the critical modes as well as the modes associated with a physical meaning, e.g., the interarea oscillation modes for weakly connected systems and the modes sensitive to a particular parameter. As the order of the power-system state matrix increases, it becomes more difficult to determine these modes. In this paper, a method is proposed to compute the interarea oscillation modes of large-scale power systems. The deviation in the active power of the transmission section is selected to identify the interarea oscillation modes. Then, the two-sided Jacobi-Davidson method combined with this selection is employed to compute these modes. Participation factors are used to separate the electromechanical oscillation modes. Numerical tests show that the proposed method is valid and efficient. [ABSTRACT FROM PUBLISHER]

This paper presents a method to determine suitable countermeasures against emerging aperiodic small disturbance rotor angle (ASD) instability. The method utilizes stability indicators, computed in real time, to define a criterion for ASD stability. Sensitivities of these stability indicators are then determined and used to identify the most influential nodes for countermeasures. To increase the computational speed, only nodes visited by a self-propagating graph, rooted at the vulnerable generator, will have their sensitivities calculated. The steady state voltages after a given countermeasure are then determined, using a grid transformation coefficient (GTC) and a numerical, iterative solution to an equation system. The stability criteria can then be assessed to evaluate the sufficiency of a suggested countermeasure. The method is demonstrated on a synthetic 8-bus network and a 464-bus model of the Western Denmark transmission grid. The method successfully demonstrates its ability to efficiently identify and evaluate countermeasures for a large, practical system. [ABSTRACT FROM PUBLISHER]