Stability-constrained generation rescheduling using energy margin sensitivities

In this paper, a structure preserving energy margin (EM) sensitivity-based analysis is presented to determine the amount of preventive generation rescheduling to stabilize a transiently unstable power system. An expression using a simplified model is derived to relate the change in the EM to change in generation. Utilising this expression, two approaches for generation rescheduling are developed which are applicable to detailed model of power systems. The proposed methods are applied to the 10-machine New England power system and 16-machine power system with detailed power system models.IEE

Application of structure preserving energy margin sensitivity to determine the effectiveness of shunt and series FACTS devices

This paper presents a structure preserving energy margin sensitivity based analysis to determine the effectiveness of FACTS devices to improve transient stability of a power system. A structure preserving energy model, which retains the topology of the network is used to derive simple analytical expressions for improvement in energy margin due to series or shunt compensation. The expressions are in terms of current magnitude through a line for series compensation and voltage magnitude at a bus for shunt compensation. Therefore, these expressions are easy to interpret in the context of applying compensation at strategic locations. The proposed method is applied to a four-machine, ten-bus system and a ten-machine, 39-bus New England system, and its validity is demonstrated through time domain simulations both for a classical and detailed model with AVR for generators.IEE

Equivalence of Matrix Pencil and HTLS Ring-Down Electromechanical Mode Identification Algorithms

Matrix pencil and Hankel total least squares (HTLS) are two popular ring-down electro- mechanical mode identification algorithms. The appeal of these algorithms can be attributed to faster execution due to the non-iterative procedure of model order determination based on singular value decomposition of the data matrix. In this paper, these two algorithms are shown to be equivalent – the data matrix in one being the transpose of that in the other. Although this equivalence is proved in the context of power systems, it is valid for other areas of system identification as well. Further, the performance of these algorithms is examined as noise level in the signal increases, and it is shown that these work right down to an SNR of 1 dB provided the signal has only poorly damped modes

Determination of effectiveness of transient stability controls using reduced number of trajectory sensitivity computations

This paper presents a new approach for determining the effectiveness of preventive generation rescheduling and shunt/series compensation in improving transient stability using trajectory sensitivity (TS) method. It is shown that the effectiveness of changes in parameter values can be judged by evaluating the TS of certain variables with respect to clearing time. Therefore, the need to evaluate a host of sensitivities with respect to many parameters is obviated. This heuristic is motivated by the fact that for simple models and small changes, controllability of trajectories using certain parameters can be inferred from observability in certain output signals. An example of such a parameter and signal pair is shunt susceptance at a bus and the square of voltage at that bus, respectively. Case studies are carried out on a 10-machine 39-bus system with detailed models and 17-machine system to validate this method.IEE