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A multi-scale power system modeling methodology for the integrative simulation of electromagnetic and electromechanical transients is introduced, implemented and validated. It makes use of frequency-adaptive simulation of transients (FAST) in which the shift frequency appears as a new parameter in addition to the time step size. For fast electromagnetic transients, tracking of instantaneous waveforms...
The failure of several transmission capacitor banks prompted The United Illuminating Company to perform an engineering study to evaluate the transient recovery voltage capabilities of existing 123-kV, oil-filled capacitor bank circuit breakers at the East Shore 115-kV substation. The study determined if the transient recovery voltage capability of existing bus and capacitor bank circuit breakers is...
Notwithstanding the positive environmental impact, the increasing penetration of Distributed Generation (DG) units connected to the distribution network raises new topics concerning the expected response of these during outages. Grid disturbances especially at the transmission level can cause the unwanted disconnection of large amounts of DG, leading to undesired power imbalances causing line overloadings...
This paper presents a model which can be used to simulate the load acceptance behavior of a diesel generating set. Unlike traditional thermal plants, generating sets (gen-sets) are often expected to undergo large rapid changes in load. A gen-set with a low inertia will naturally be more susceptible to changes in speed. This problem is compounded with the introduction of turbocharged engines. Although...
This paper presents an early warning and preventive control system for dynamic security, which has been used in several provincial power grids in China. The framework and the main modules of the proposed system are introduced. The system architecture is based on a Multi-agent system which is developed by our team. The modules like on-line contingency assessment, total transfer capacity evaluation,...
This paper presents a mathematical model to simulate and analyze electromagnetic transients in transmission lines using a mono-phase representation of these lines comparing results models with and without frequency influence in longitudinal parameters. For this, π circuits and state variables are used for composing a linear system that is solved through iterative numeric routines. This routine is...
The detailed dynamic modeling of pumped storage hydro-plants for system dynamic studies is revisited in this paper. Both rigid and elastic dynamic models for different water tunnel penstock configurations are presented. During the generating mode, the system is modeled following the conventional modeling method for hydro-turbines. During the pumping mode, the system is modeled using the pump head-flow...
Harmonic and interharmonic studies have become a relevant topic as the number of nonlinear elements and electronic devices connected to power systems networks is constantly increasing. This paper presents a methodology for the modeling of single-phase transmission lines interfaced with nonlinear loads. It is intended for transient analysis and special emphasis is put on the harmonic and interharmonic...
This paper presents a single-ended traveling wave based fault location method for power transmission systems where overhead lines are combined with underground cables. Bewley diagrams are used to determine the traveling wave patterns. The proposed method utilizes Discrete Wavelet Transform (DWT) to extract the transient information from the recorded voltage signals. The squares of the wavelet transform...
This paper presents a new, importantly improved, approach to Global Transient Stability-Constrained Optimal Power Flow (TSC-OPF). The main practical difficulty of global TSC-OPF has always been the huge dimension of its resulting optimization problem, since all the different approaches of this type reported in the literature require discretizing and including part of the time-domain simulation as...
In this paper a power system's reduced order model is presented which is evaluated by simple calculations through data taken out from the steady state analysis. This type of equivalent is useful, especially where preserving a portion of an electrical region is relevant. The external network is reduced to a few boundary buses where equivalent generators are located. From the internal network point...
The Multi-Area Thévenin Equivalent algorithm (MATE) partitions a network into a number of subnetworks connected by links. The solution proceeds in two stages: first the subnetworks are solved independently, with the links open, and then the system formed by the links is solved with the subnetworks represented by their Thévenin equivalents as seen from the link nodes. In this paper, an overview of...
Hitherto, the voltage stability of the Long Island Power Authority (LIPA) system has been evaluated utilizing steady-state power flow programs. However, time domain simulations of LIPA system demonstrated significant differences in post-disturbance voltage recovery of transmission system voltages between models with static and complex load compositions. This is mainly due to the predominant residential...
To avoid the mal-operation of transformer differential protection when external fault occurs with current transformer (CT) saturation, a new algorithm based on the mathematical morphology is put forward in this paper. Unlike the conventional Time Differential Method, the new algorithm only needs detecting the instant of fault occurring, while the instant of differential current appearance is no more...
In this paper signal processing tools are used to uncover common and unique characteristics of faults resulting from animal contacts, tree contacts and lightning. For each fault type a large number of voltage and current waveform data sets measured at monitoring stations on distribution systems are analyzed. The characteristics include but are not limited to the presence of impulse-like oscillations,...
Simulation tools for analysis and design of distribution systems with distributed resources (DR) must include modeling capabilities for representing the various DR technologies. Since distribution systems were not designed for the inclusion of DR, most distribution software packages were not designed for the analysis of systems with embedded generation either. Present distribution tools can efficiently...
This paper proposes a scheme based on the embedding theorem to locate and classify the transient disturbances in power system signals. The disturbance signals are transformed to the phase space, where the normal part of the signal and the disturbance form two waveforms that can be distinguished from each other, and the location and classification are based on the information obtained from the embedded...
The state-transition matrix of the κ-th order Taylor approximation to the dynamic phasor and its first derivatives leads to a plurality of state-space representations to approach the bandpass signal model of a power oscillation. With these truncated signal models, the Kalman filter algorithm can be applied to their state vectors in order to find observers able to estimate the dynamic phasor and its...
On November 2008 the Danish government decided that all Danish transmission lines with a rated voltage equal to and below 150kV must be put underground, in order to reduce the visual pollution caused by Overhead Lines. This decision will lead to a massive use of underground cables in the Danish Network, and force a change in the approach used until now when planning, analyzing and operating electrical...
The integration of distributed generation transforms current distribution networks from vertically operated to horizontally operated. This transition leads to problems related to protection coordination. In the future, new protection philosophies should be applied which guarantee the increase of the during-fault distributed generation availability. The paper presents a protection scheme based on fault...
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