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In this paper we present an algorithm for choosing optimal measurement points on the edges of a network of dynamic electrical oscillators such that the noise-corrupted electrical signals measured by sensors at that point can be used for generating the most accurate estimates for the network model. Assuming that the measured outputs are fed back to the network nodes to increase system damping we show...
Low frequency inter-area oscillation is a major problem in power system operation. If not damped, these oscillations prolong, grow, and decrease transmission capacity of the tie-lines, causing interruption in energy supply. Several methods for damping of these oscillations are reported in literature. The damping may be provided by appropriate control of different components in power system such as...
With the rapid development and interconnection of power systems, the low frequency oscillations(LFO) has become one of the serious factors threatening the power system stability. Thus, how to quickly locate the source of LFO and implement controller to suspend it, is an urgent task. The general approach to locate the sources of LFO is using the node contribution factor(NCF), which indicating the contribution...
Once the power system low frequency oscillation occurs, the operators desire to find out the dominant mode LFO so as to take measures to suspend it. This paper proposes an identification method for dominant mode of LFO based on Prony algorithm in wide-area measurement system (WAMS). The presented method contains three steps, the first step is preprocessing of Prony analysis result, the second step...
In large interconnected electric power systems, inter-area electromechanical oscillations may occur due to weak links among power systems. These oscillations involve power exchanges but also voltage and current oscillations that may cause tripping of lines or generators and thus lead to severe disturbances. Such oscillations have been (rarely) observed in the synchronous interconnected system of Continental...
ModeMeter techniques for real-time small-signal stability monitoring continue to mature, and more and more phasor measurements are available in power systems. It has come to the stage to bring modal information into real-time power system operation. This paper proposes to establish a procedure for Modal Analysis for Grid Operations (MANGO). Complementary to PSS and other traditional modulation-based...
Wide-area analysis and control of large-scale electric power systems are highly dependent on the idea of aggregation. For example, one often hears power system operators mentioning how `Northern Washington' oscillates against `Southern California' in response to various disturbance events. The main question here is whether we can analytically construct dynamic electromechanical models for these conceptual,...
Proper splitting controls are necessary to prevent large blackouts. Traditional relays cannot cope with or confirm out-of-step for severe instable situations of very fast power swings. Based on the wide area measurement system (WAMS), an adaptive framework for out-of-step splitting which makes use of remote communication to obtain quick and selectable disconnecting actions is proposed in the paper...
With the development of power grid interconnection, the low frequency oscillation is becoming more and more prominent which threats the stability of the system. It consists of local modes and inter-area modes, and the effectiveness of local PSS in damping inter-area modes is limited. Then the global power system stabilizer (GPSS) based on WAMS (Wide Area Measurement System) is proposed. First 3 problems...
The North American Frequency Monitoring Network (FNET) is a wide-area measurement system that monitors the North American Interconnections at distribution voltage level. A situational awareness system has been implemented on the server located at Virginia Tech to detect and analyze power system disturbances in near-real time. This paper demonstrates the viability of monitoring bulk transmission systems...
As the power system is interconnected with HVDC transmission, the power oscillation with low frequency appears in the AC transmission lines with weak damping. Due to the existence of the low frequency oscillation (LFO), the transmission power of AC lines is limited and the system angle stability is affected. In this paper, the low frequency oscillation (LFO) phenomena are introduced. By using the...
The frequency monitoring network (FNET) provides a low-cost, easily deployable method for wide-area monitoring. FNET has the capability to realize long term, high density and continuous monitoring of large interconnected power systems. In effect, there are potentials for ground-breaking research on wide-area monitoring and control. In this paper, low frequency oscillations in the Eastern Interconnection...
In this paper, the use of dynamic braking as a cost-effective measure for damping inter-area oscillations is considered. Proposed control scheme assumes possibility of multiple insertions of dynamic braking resistor triggered whenever the speed of equivalent one-machine infinite bus (OMIB) system exceeds predefined value or controlled based on commanded electrical power calculated from OMIB transformation...
Recent technological advances in the area of wide-area measurement systems (WAMS) has enabled the use of centre of inertia (COI) signals to improve the transient stability of large power systems. However there is an unavoidable delay involved before COI signals are received at generators. Conventional excitation control of generators is brought forward again to enhance power system stability with...
Under some circumstances, conventional power system stabilizers (PSS) suffer shortcomings and cannot enhance small-signal stability of the power systems especially when it comes to inter-area oscillation damping. This along with the advanced technology in phasor measurement units (PMUs) has lead to an increasing interest in developing global controllers using wide-area measurements to solve the deficiencies...
A method to analyze stability on a multi-machine power system was developed. For steady state estimation the phasor voltages and angles were used to calculate the frequency deviations. The calculated frequency deviations were then filtered by an FFT filter to extract the power oscillations. By linearly approximating a set of differential equations, the eigenvalues for the system were identified from...
Power system low frequency oscillations are detrimental to the stability and security of interconnected power networks. The recent advance in the wide area measurement system (WAMS) is driving power community to accept the notion of wide area monitoring and control. This paper proposes the placement of wide area PSSs and the selection of stabilizing signals based on improved residue matrices. Modal...
Wide-area measurement systems (WAMS) enable the monitoring of bulk power systems providing deep insight into system dynamics. The North American frequency monitoring network (FNET) takes GPS-synchronized wide-area measurements in a low-cost, easily deployable manner at the 120 V distribution level. A situational awareness system has been implemented on the server located at Virginia Tech to detect...
This paper first describes what kind of inter-area oscillations there exist in the Nordic power system and in what kind of situations they affect the power transfer capacity. The paper also describes the actions already taken in order to improve the damping of the oscillations and the efforts at online-monitoring of the damping level. The results of a two yearpsilas monitoring period imply that one...
When analyzing the electromechanical dynamic properties of power-system field-measurement data using signal processing techniques, it is often useful to identify and remove the slow trends within the data. This paper proposes an iterative non-linear trend identification algorithm. The proposed method adapts the upper and lower envelope idea proposed by empirical mode decomposition (EMD) method to...
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