Power System Small-signal Stability Analysis Research Articles

Modeling of Grid-Connected VSCs for Power System Small-Signal Stability Analysis in DC-Link Voltage Control Timescale

With the increasing use of voltage source converters (VSCs) in power electronics dominated power systems, oscillation phenomena in DC-link voltage control (DVC) timescale (around 10 Hz) among multiple VSCs have occurred. Several studies have tried to analyze these oscillation problems, but all associated with the single VSC situation. To consider the dynamic interactions between VSCs in DVC timescale, especially in the weak grid condition, this paper presents a small-signal model to understand VSC external characteristics based on motion equation concept also featured in synchronous generator (SG). Comparisons of time-domain simulation responses and eigenvalues show that the proposed model can hold the main behaviors of concern. The form of the model is very similar to the rotor motion equation in SG, with which power engineers have been very familiar. In addition, by establishing the relationship between the unbalanced powers and state variables of internal voltage (viz., VSC output voltage), the modeling idea introduced in this paper can be applied to other power electronic devices.

Forward and Backward Extended Prony (FBEP) Method for Power System Small-Signal Stability Analysis

The performance of the Forward and Backward Extended Prony (FBEP) method on power system small-signal stability analysis is investigated in this paper. The effectiveness of the FBEP method in identifying system eigenvalues from the output signal is validated by experiments on a test system model. Using a four-machine-two-area power system model the estimation of the dominant modes contained in oscillatory signals given by the FBEP method is compared with that given by the SVD-TLS method, Trudnowski's algorithm, and the Prony with stepwise regression method. The multi-signal analysis and sliding window analysis using the FBEP method are also studied.

Developing feedback model for power system dynamic sensitivity analysis

Summary Since sensitivity analysis provides information on changes of the system dynamics with respect to changes of system parameters, it has been long recognized as an important tool for power system small-signal stability analysis and controller designs. Sensitivity analysis is now much more important due to all the anticipated changes of future power systems, so more efficient and feasible methods are needed. The current sensitivity analysis methods are either simulation based or eigenvalue based. The eigenvalues and/or the time domain trajectories of the investigated system are solved for scenarios both before and after the parameter changes to evaluate the impacts of these changes on the system dynamics. However, both methods are actually numerically based, so often insufficient in fully revealing system physical characteristics. This paper analyzes the drawbacks of the available methods for analyzing the dynamic impacts of parameter changes in a power system and then develops a feedback-based model for sensitivity analysis. The model is easier to identify the dynamic interactions of components; meanwhile, it also offers a new perspective on sensitivity analysis from the frequency domain. Case studies of increasing complexity demonstrate fully that the application of the proposed method reveals new insights on power system dynamics that conventional methods could not do.

Application of PTP synchronized PMUs in power system small-signal stability analysis

Application of PTP synchronized PMUs in power system small-signal stability analysis

Modelling a grid-connected SOFC power plant into power systems for small-signal stability analysis and control

SUMMARY This paper presents a systematic procedure to establish mathematical models of a solid oxide fuel cell (SOFC) power plant integrated in a multi-machine power system for power system small-signal stability analysis and control. First, the paper describes comprehensively how a grid-connected SOFC power plant can be modeled into a multi-machine power system. The model established can be used for power system small-signal stability analysis. Second, a localized model of the grid-connected SOFC power plant is proposed. This localized model can be used for the design of a power system stabilizer attached to the SOFC power plant to improve power system small-signal stability. The design proposed is simple because establishment of the localized model does not need to obtain and validate the information of the entire multi-machine power system. In the paper, an example four-machine power system integrated with a SOFC power plant is presented. The example demonstrates the effectiveness of the stabilizer designed by the proposed method based on the localized model, which is confirmed by the modal computation and non-linear simulation. Copyright © 2012 John Wiley & Sons, Ltd.

Computing Rightmost Eigenvalues for Small-Signal Stability Assessment of Large-Scale Power Systems

Knowledge of the rightmost eigenvalues of system matrices is essential in power system small-signal stability analysis. Accurate and efficient computation of the rightmost eigenvalues, however, is a challenge, especially for large-scale descriptor systems. In this paper we present an algorithm, based on subspace accelerated Rayleigh quotient iteration (SARQI), for the automatic computation of the rightmost eigenvalues of large-scale (descriptor) system matrices. The effectiveness and robustness of the algorithm is illustrated by numerical experiments with realistic power system models, and we also show how SARQI can be used to compute eigenvalues closest to any damping ratio and repeated eigenvalues. The algorithm can be used for stability analysis in any other field of engineering.