Now showing 1 - 9 of 9
  • Publication
    Comparison of bus frequency estimators for power system transient stability analysis
    The paper presents a study on the dynamic response of power system frequency control devices considering different approaches to estimate bus frequencies in power system simulators. The frequency signals considered in this paper are obtained based on the center of inertia, a commonly-used washout filter that approximates the derivative of the bus voltage phase angle, and a frequency divider formula developed by the authors. The dynamic behavior of frequency control devices such as thermostatically regulated loads is compared considering the three signals above. Different scenarios are discussed based on the IEEE 14-bus and New England 39-bus, 10-machine test systems.
      322Scopus© Citations 20
  • Publication
    Frequency Divider
    The paper proposes an approximated yet reliable formula to estimate the frequency at the buses of a transmission system. Such a formula is based on the solution of a steady-state boundary value problem where boundary conditions are given by synchronous machine rotor speeds and is intended for applications in transient stability analysis. The hypotheses and assumptions to define bus frequencies are duly discussed. The rationale behind the proposed frequency divider is first illustrated through a simple 3-bus system. Then the general formulation is duly presented and tested on two real-world networks, namely a 1,479-bus model of the all-island Irish system and a 21,177-bus model of the European transmission system.
      425Scopus© Citations 95
  • Publication
    Hardware-in-the-Loop Validation of the Frequency Divider Formula
    This paper validates a theoretical approach, namely, the frequency divider formula, recently proposed by the first and fourth authors to estimate local frequency variations based on the synchronous machine rotor speeds and on signals from phasor measurement units (PMUs). The validation is based on simulations performed in a Real-Time Digital Simulator with physical PMUs connected in the loop. The case study considers the well-known WSCC 3-machine, 9-bus test system. Simulation results show the high accuracy of the frequency divider formula to estimate the frequency at every bus of the network. Results also show that the frequency divider prevents the numerical issues due to fast variations of the voltage when measured by the PMU and indicate that such a formula can be utilized to test the fidelity of PMU implementations.
  • Publication
    Frequency Participation Factors
    This paper discusses two quantitative and complementary approaches to evaluate the participation of synchronous generators and interconnection buses on local bus frequency variations during electromechanical transients. Both approaches are based on the concept of frequency divider formula recently proposed by the authors on these transactions. A thorough comparison of the two approaches is provided considering several scenarios and three networks, namely the New England 39-bus test system, the all-island 1,479-bus Irish transmission system, and the ENTSO-E 21,177-bus transmission system.
      369Scopus© Citations 2
  • Publication
    Stochastic Transient Stability Analysis of Transmission Systems With Inclusion of Energy Storage Devices
    The letter provides a thorough stochastic analysis of the impact of energy storage systems on the transient stability of transmission grids. This impact is evaluated considering the combined effect of different energy storage technologies, fault clearing times, and network topologies. The latter concerns the relative positions of faults, storage devices, and synchronous machines. The case study consists of stochastic time-domain simulations carried out for the all-island, 1479-bus model of the Irish transmission system that includes a real-world hybrid storage device. Results lead to some nonintuitive conclusions.
      409Scopus© Citations 27
  • Publication
    Model-Agnostic Linear Estimation of Generator Rotor Speeds based on Phasor Measurement Units
    The paper focuses on the estimation of the rotor speeds of synchronous machines by means of phasor measurement units. This estimation is aimed at on-line monitoring of electro-mechanical transients and transient stability analysis. The proposed technique is based on the concept of frequency divider formula recently published by the first two authors in these Transactions. The dynamic state estimation is formally stated as a convex optimization problem and a thorough discussion of the sensitivity analysis of the optimal solution is provided. The case study considers a dynamic 1,479-bus model of the all-island Irish system and discusses the effect of bad data, noise and latency on the proposed estimation technique.
      360Scopus© Citations 13
  • Publication
    Comparison of different control strategies for energy storage devices
    This paper compares three control strategies for energy storage devices. Detailed formulations and implementation procedures of PI, sliding mode, and H-infinity controllers are presented and discussed. The dynamic performance of each control technique is also studied and compared. With this aim, the paper duly discusses a comprehensive case study based on the IEEE 14-bus test system with inclusion of a wind power plant and an energy storage device.
      271Scopus© Citations 10
  • Publication
    Modeling, Simulation, and Comparison of Control Techniques for Energy Storage Systems
    This paper describes the modeling and formulation of a variety of deterministic techniques for energy storage devices, namely the PI, H-infinity, and sliding mode controllers. These techniques are defined based on a general, yet detailed, energy storage device model, which is accurate for transient stability analysis. The paper also presents a thorough statistical comparison of the performance and robustness of the considered control techniques, using stochastic dynamic models and a variety of disturbances and scenarios. The case study is based on a 1479-bus model of the all-island Irish transmission system and an energy storage device actually installed in the system.
      708Scopus© Citations 38
  • Publication
    Impact of frequency estimation for VSC-based devices with primary frequency control
    This paper presents a comparison of the performance of frequency control devices considering different techniques to estimate the frequency deviation signal. We consider three estimation techniques, namely the center of inertia (COI), the frequency divider (FD) formula, and the phase-locked loop (PLL). The first two are based on the measurement of synchronous machine rotor angles and are virtually exact measures, while the latter is based on an electronic device and is affected by noise and numerical errors. The goal of the paper is first to define whether the PLL estimation is closer to the COI or to the FD. Then, the dynamic response of VSC-based wind power plants and energy storage systems providing primary frequency regulation is studied and compared using the three aforementioned signals. A comprehensive set of scenarios based on the WSCC 9-bus test system is presented in the case study.
      313Scopus© Citations 13