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The fast development of renewable energies leads to an increase in the power electronics penetration in transmission systems. This is particularly true if one considers a 100% renewable energies power system, where wind and solar photovoltaic energies, which make most of the renewable energies connections today, are connected to the grid through power electronics converters. Because power electronics-based generators and synchronous machines-based generators have very different dynamic behaviours, some approximations usually used to run transient simulations of transmission systems might not be optimal for future grids. The systematic use of the phasor approximation applied to the power lines, implemented in most of the Transient Simulation Programs, is indeed not relevant any more. To avoid the use of Electromagnetic Transient simulations, that are resource-demanding and time-consuming, this paper presents a novel Model Order Reduction technique for large grids with a high penetration of power electronic devices. Compared to the classical phasor approximation, this event-based state residualization approximation allows accurate transient simulations and at the same time an optimal reduction of the number of the system’s state variables depending on the observed variables, the considered events and the tolerated approximation error. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to dynamic phasor-based transient stability simulation. The proposed method is based on the modified nodal analysis (MNA) approach to circuit simulation, which is used to construct continuous differential-algebraic equations (DAEs). The proposed method makes use of the stamp technique, which makes it possible to construct a general purpose MNA-based simulator. Stamp-based models for common power system components are derived in this work. A new MNA-based synchronous machine model is presented, which represents machines as nonlinear inductances instead of subtransient equivalents. The resultant continuous DAEs are numerically solved using the general purpose variable step and variable order library IDA. Simulation results from the IEEE 68 bus test system, a real 400 bus power system, and the IEEE 39 bus test system with an embedded HVdc transmission system demonstrate that the proposed method is suitable for large ac networks with power electronic devices. The results demonstrate good agreement between the proposed method and electromagnetic transient (EMT) simulation. The results also demonstrate that the proposed method is fast and scalable with CPU times that are up to 200 times faster than EMT simulation. [ABSTRACT FROM AUTHOR]

In transient stability simulators such as PSS/E, the bus frequency is estimated using a window of (positive-sequence) phasor angle measurements. A digital filter is often used to account for the filtering effect in actual measurement devices and to eliminate sudden changes during frequency computations. Although transient stability simulators label the filtered angle derivative as the “frequency,” the frequency provided by such programs does not match actual measurements reported by phasor measurement units (PMUs), which makes it difficult to gauge the validity of studies (e.g., wide-area event detection and control applications) that are based on such simulations. In this paper, we implement a frequency computation method directly using positive phasor angles provided by simulators. The proposed method is tested on two systems extensively and validated against the measurements of an actual PMU. The improved frequency measurements closely match PMU responses. Cross-validation results also suggest the method may be used for other systems without conducting full time-domain simulations. [ABSTRACT FROM AUTHOR]

The reliability of power systems with high penetration of renewables, a fast response mechanism, and precise decision-making scheme is more important than ever. This study presented a novel scheme that utilizes the predicted frequency nadir after a generation trip event to initiate necessary ancillary services such as fast spinning reserve units, energy storage units, and demand responses to restore the frequency back to the secure operating range. The proposed scheme coordinates Under-Frequency Load Shedding (UFLS) with ancillary services in the sense that the unnecessary load shedding can be avoided. By using the proposed scheme, the system becomes more resilient against disturbances, and the actions of load shedding are minimized. In this scheme, the frequency data is captured by phasor measurement units (PMUs), and a frequency nadir prediction algorithm is proposed. We demonstrate the effectiveness of the proposed scheme by using 1700-bus power system simulations and realistic frequency data from real generation trip events captured by a laboratory micro-phasor measurement unit (μPMU). [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]

Interarea power oscillation damping enhancement in large interconnected power systems is often accomplished using supplementary controls at the synchronous machines involved and with the use of flexible ac transmission system devices. The power system literature has demonstrated that wide area signals could be more effective than the local signals for these controllers. In some cases where phasor measurement units are used, all the required control signals may not be available. To alleviate these cases, control signals are obtained using estimated signals from a “dynamic state estimator,” and a robust supplementary controller is deployed. In this paper, the cited strategy is illustrated using a static var compensator. The feasibility of the proposed method has been demonstrated on the IEEE 50-generator test system. [ABSTRACT FROM AUTHOR]

To solve the following problem: the action speed of protection based on a phasor is restricted by the length of the filtering algorithm time window and the vulnerability to false data, a new pilot protection principle for transmission lines based on waveform similarity is proposed in this paper. By comparing the discrete point sets of current sampling values, a waveform similarity-based algorithm called the Hausdorff distance distinguishes the difference between both side currents of a protected transmission line, realizing fast identification, and removal of the fault. Based on the characteristics of the algorithm, setting methods and protection criterion are discussed. Finally, an improved Hausdorff distance algorithm is proposed to cope with false data. The effectiveness and advantages of the proposed algorithm are validated with theoretical analysis and extensive simulation test results. [ABSTRACT FROM PUBLISHER]

This paper presents a new approach in adaptive out-of-step (OOS) protection settings in power systems in real time. The proposed method uses extended equal area criterion (EEAC) to determine the critical clearing time and critical clearing angle of the system, which are vital information for the OOS protection setting calculation. The dynamic model parameters and the coherency groups of the system for EEAC analysis are determined in real time to ensure that the newly calculated settings suit with the prevalent system operating condition. The effectiveness of the method is demonstrated in simulated data from a 16-machine 68-bus system model. [ABSTRACT FROM PUBLISHER]

Phasor measurement units (PMUs) are the key components in modern wide-area monitoring, protection, and control systems. This paper addresses the development of a PMU model in the Alternative Transients Program/Electromagnetic Transients Program. The performance of the proposed PMU model is assessed during normal and abnormal operating conditions using an ideal source test circuit and the New England 10-machine 39-bus test power system. [ABSTRACT FROM PUBLISHER]