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This letter proposes a mass-matrix differential-algebraic equation (DAE) formulation for transient stability simulation. This formulation has two prominent advantages: compatible with a multitude of implicit DAE solvers and can be conveniently implemented based on the traditional formulation, for example, by separating the parameters in denominators into the diagonals of the mass matrix. It also allows reducing the dynamics using null time constants. Benchmark studies are presented on the time and accuracy of 17 implicit solvers for the proposed formulation using the Kundur's two-area system and a 2,000 bus system.

In this paper, we present a controller synthesis approach for wind turbine generators (WTG) and energy storage systems with metric temporal logic (MTL) specifications, with provable probabilistic guarantees in the stochastic environment of wind power generation. The MTL specifications are requirements for the grid frequency deviations, WTG rotor speed variations and the power flow constraints at different lines. We present the stochastic control bisimulation function, which bounds the divergence of the trajectories of a switched stochastic control system and the switched nominal control system in a probabilistic fashion.We first design a feedforward controller by solving an optimization problem for the nominal trajectory of the deterministic control system with robustness against initial state variations and stochastic uncertainties. Then we generate a feedback control law from the data of the simulated trajectories. We implement our control method on both a four-bus system and a nine-bus system, and test the effectiveness of the method with a generation loss disturbance. We also test the advantage of the feedback controller over the feedforward controller when unexpected disturbance occurs.

This paper exploits the availability of frequency disturbance recorder (FDR) measurements and knowledge of the underlying operational data from the Nigerian National Power System to develop a model capable of reproducing the most important characteristics of one of the many collapses in the Nigerian grid during the last recent years. The collapse investigated in this paper was captured on December 2nd , 2006, with an FDR unit installed at Abubakar Tafawa Balewa University (ATBU). Using operational information from the National Control Center (NCC) at Osogbo, three models representing the Nigerian power system were developed to capture the most relevant dynamics of the grid during the cascading failure. These models include both detailed representations of the different network components, as well as average frequency dynamics only. Comprehensive simulation results show how the models are capable of representing the most important features of the collapse of the system, and hence, their continuous improvement through model validation may allow their use in the development of load shedding mechanisms which are needed for mitigating cascading failures in the Nigerian system. QC 20120207

Synchrophasor technology is relatively new to many utility companies as they plan for its introduction as part of their smart grid infrastructure investment. A first question that arises in planning for synchrophasor technology use is where should we place the phasor measurement units (PMUs)? Because synchrophasor data can be used in a variety of applications, the placement of PMUs should be driven by the intended applications, which may have varying data needs and differing PMU siting considerations. This white paper intends to provide information on and be a resource for such PMU placement issues, using recently developed PMU placement documents from various power grid operators and from applications described in technical papers. This white paper offers some guidelines for designers and users of the synchrophasor systems to decide where to place new PMUs. The paper addresses the information requirements of power system applications under all conditions (normal, alert, emergency, restorative) and across all time horizons (monitoring, protection, control, operation, planning). As many PMU placement documents are already available, the main sections of this document will be quite brief. Some expanded details on the guidelines can be found in the appendices. QC 20120210

The successful deployment of Smart Grids at the transmission level will largely depend on the development and implementation of synchronized phasor measurement data-based applications and on the continuous improvement of the information and communication infrastructures supporting them. During the last decade several phasor measurement unit (PMU) data applications, that will potentially enable Smart Transmission Grids (STGs), have been proposed. In this paper we provide an overview on two of these applications, devoted to PMU-only state estimation, and modal analysis, as well as work related to developing some supporting IT infrastructure. Rather than discussing details of applications, this paper aims to give highlights of the relevant features of these applications in the context of STGs, and outlines additional research efforts necessary for phasing in these tools into practical use. QC 20120202

QC 20120126

This paper reports on an ongoing research effort between researchers in North America and Africa on the study of the dynamics of loosely regulated and rapidly growing power systems, with focus on the Nigerian power network. A description of the implementation of Virginia Tech’s FDR (Frequency Disturbance Recorder) at Bauchi, Nigeria is provided. We discuss the nature of the frequency dynamics observed throughout multiple hours of a day in Nigeria and other power systems. To cater to the loosely regulated nature of the system frequency in Nigeria, we propose an appropriate method for signal conditioning which prepares the data for ambient analysis. Parametric and nonparametric block processing techniques are applied to prolonged frequency recordings ranging from 8 to 19 hours, and estimates of modal frequencies and damping are obtained by computing power spectrum densities and applying a mode meter algorithm to the ambient data. The estimated modes from ambient analysis are in agreement with other studies based on power system models. QC 20120203

Frequency is one of the most important measures of the status of a power system, especially for weak and smallscale po systems. Therefore, frequency monitoring is a desirable practice to ensure reliability and provide data for analysis. This paper reports the joint work between Rensselaer Polytechnic Institute (RPI) and Abubakar Tafawa Balewa University (ATBU) to study frequency dynamics of small power systems. We describe the Frequency Disturbance Recorder (FDR) implementation experience at ATBU, Bauchi, Nigeria, and present analysis on the digital recordings provided by the FDR installed at this location. A proposal for a university-based FNET for Nigeria’s power system is also presented. Such monitoring system will allow further investigations on the Nigerian system dynamics and will enhance the understanding of dynamics and control of weak small-scale power systems. Qc 20120203