Coherency Identification in Large-Scale Power System Using Measured Data

2013 ◽  
Vol 448-453 ◽  
pp. 2428-2433
Author(s):  
Xiao Dong Li ◽  
Ji Nan Zhang ◽  
Peng Li ◽  
Hong Jie Jia ◽  
Tao Jiang
Keyword(s):  
Power System ◽  
Large Scale ◽  
Oscillation Mode ◽  
Projection Pursuit ◽  
Dimensional Subspace ◽  
Measured Data ◽  
Model Parameters ◽  
Low Dimensional ◽  
Real Time Identification ◽  
The Impact

This paper presents a new method to identify coherent generator groups in power system based on projection pursuit. Projection pursuit algorithm is introduced to model wide-area measured time series and analyses high-dimensional data in low-dimensional subspace. It could seek and extract key projection vectors reflecting generator coherent features and identify the coherency of generators according to projection directions of generators. The presented technique could realize real-time identification of coherent generators, in which grouping is based on measured data avoiding the impact of model parameters. It proves that the composition of principal components has corresponding relationship with system oscillation mode. Finally, China Southern Power Grid is used as testing system to verify the feasibility and effectiveness of the method.

Effect of Large-Scale Wind Power Integration on Inter-Area Oscillation of Power System

2014 ◽  
Vol 672-674 ◽  
pp. 227-232
Author(s):  
Xu Zhi Luo ◽  
Hai Feng Li ◽  
Hua Dong Sun ◽  
An Si Wang ◽  
De Zhi Chen
Keyword(s):  
Power Systems ◽  
Power System ◽  
Wind Power ◽  
Large Scale ◽  
Oscillation Mode ◽  
Equivalent Model ◽  
Synchronous Generators ◽  
Actual System ◽  
Oscillation Modes ◽  
The Impact

With the fast development of the wind power, security constraints of power systems have become the bottleneck of the acceptable capacity for wind power. The underdamping oscillation modes of the inter-area is an important aspect of the constraints. In this paper, an equivalent model of a power system with wind plants has been established, and the impact of the integration of the large-scale wind power on the inter-area oscillation modes has been studied based on the frequency-domain and time-domain simulations. The results indicate that the damping of inter-area oscillation mode can be enhanced by the replacement of synchronous generators (SGs) with the wind generators. The enhancing degree is up to the participation value of the SGs replaced. The conclusion has been verified by the actual system example of Xinjiang-Northwest grid. It can provide a reference for system programming and operation.

scholarly journals Neural Excursions from Low-Dimensional Manifold Structure Explain Intersubject Variation in Human Motor Learning

2021 ◽  
Author(s):  
Corson N Areshenkoff ◽  
Daniel J Gale ◽  
Joe Y Nashed ◽  
Dominic Standage ◽  
John Randall Flanagan ◽  
...  
Keyword(s):  
Motor Learning ◽  
Large Scale ◽  
Brain Activity ◽  
Dimensional Subspace ◽  
Learning Performance ◽  
Dimensional Manifold ◽  
Learning Abilities ◽  
Manifold Structure ◽  
Electrophysiological Studies ◽  
Low Dimensional

Humans vary greatly in their motor learning abilities, yet little is known about the neural mechanisms that underlie this variability. Recent neuroimaging and electrophysiological studies demonstrate that large-scale neural dynamics inhabit a low-dimensional subspace or manifold, and that learning is constrained by this intrinsic manifold architecture. Here we asked, using functional MRI, whether subject-level differences in neural excursion from manifold structure can explain differences in learning across participants. We had subjects perform a sensorimotor adaptation task in the MRI scanner on two consecutive days, allowing us to assess their learning performance across days, as well as continuously measure brain activity. We find that the overall neural excursion from manifold activity in both cognitive and sensorimotor brain networks is associated with differences in subjects' patterns of learning and relearning across days. These findings suggest that off-manifold activity provides an index of the relative engagement of different neural systems during learning, and that intersubject differences in patterns of learning and relearning across days are related to reconfiguration processes in cognitive and sensorimotor networks during learning.

The Influence on Reactive Voltage of Large Scale Wind Power Connected to Grid

2013 ◽  
Vol 380-384 ◽  
pp. 2972-2976
Author(s):  
Xiang Yu Lv ◽  
Tian Dong ◽  
Ye Yuan ◽  
De Xin Li ◽  
Xiao Juan Han
Keyword(s):  
Power System ◽  
Wind Power ◽  
Influencing Factors ◽  
Large Scale ◽  
Reactive Power ◽  
Wind Power Integration ◽  
Power Fluctuations ◽  
The Impact

Large scale wind power integration has influenced the safety of power system. Taking wind power integration in Jilin as example, the paper describes the influencing factors of large scale wind power integration on reactive power of the grid in detail firstly, then analyze the reactive voltage in four typical ways, and discuss the impact of the wind power fluctuations on the grid reactive voltage.

scholarly journals Assessing the Impact of DFIG Synthetic Inertia Provision on Power System Small-Signal Stability

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3440 ◽  
Author(s):  
Edgar Lucas ◽  
David Campos-Gaona ◽  
Olimpo Anaya-Lara
Keyword(s):  
Power System ◽  
Large Scale ◽  
Damping Ratio ◽  
System Stability ◽  
Electrical Network ◽  
Small Signal ◽  
Small Signal Stability ◽  
Signal Stability ◽  
Electromechanical Modes ◽  
The Impact

Synthetic inertia provision through the control of doubly-fed induction generator (DFIG) wind turbines is an effective means of providing frequency support to the wider electrical network. There are numerous control topologies to achieve this, many of which work by making modifications to the DFIG power controller and introducing additional loops to relate active power to electrical frequency. How these many controller designs compare to one-another in terms of their contribution to frequency response is a much studied topic, but perhaps less studied is their effect on the small-signal stability of the system. The concept of small-signal stability in the context of a power system is the ability to maintain synchronism when subjected to small disturbances, such as those associated with a change in load or a loss of generation. Amendments made to the control system of a large-scale wind farm will inevitably have an effect on the system as a whole, and by making a DFIG wind turbine behave more like a synchronous generator, which synthetic inertia provision does, may incur consequences relating to electromechanical oscillations between generating units. This work compares the implications of two prominent synthetic inertia controllers of varying complexity and their effect on small-signal stability. Eigenvalue analysis is conducted to highlight the key information relating to electromechanical modes between generators for the two control strategies, with a focus on how these affect the damping ratios. It is shown that as the synthetic inertia controller becomes both more complex and more effective, the damping ratio of the electromechanical modes is reduced, signifying a decreased system stability.

Impact of Large-Scale Integrated Wind Farms on the Small Signal Stability of Power System

2013 ◽  
Vol 805-806 ◽  
pp. 393-396
Author(s):  
Zhen Yu Xu ◽  
Zhen Qiao ◽  
Qian He ◽  
Xu Zhang ◽  
Jing Qi Su
Keyword(s):  
Power System ◽  
Large Scale ◽  
Power Grid ◽  
Wind Farms ◽  
Small Signal ◽  
Small Signal Stability ◽  
Direct Drive ◽  
Signal Model ◽  
Signal Stability ◽  
The Impact

With the penetration of wind energy is becoming higher and higher in power grid, it is very important to investigate the impact of wind generations on small signal stability. In this paper, a complete small signal model of wind turbine with direct-drive permanent magnet generator is built to study the impact of large-scale wind farms on the small signal stability of power system. By means of simulation and eigenvalue analysis, an actual power system is investigated, and the damping characteristic of power grid under different wind power penetration is discussed.

scholarly journals An efficient approach for limited-data chemical species tomography and its error bounds

2016 ◽  
Vol 472 (2187) ◽  
pp. 20150875 ◽  
Author(s):  
N. Polydorides ◽  
S.-A. Tsekenis ◽  
H. McCann ◽  
V.-D. A. Prat ◽  
P. Wright
Keyword(s):  
Chemical Species ◽  
Dimensional Subspace ◽  
Concentration Function ◽  
Reconstruction Method ◽  
Limited Data ◽  
Computationally Efficient ◽  
Data Errors ◽  
Low Dimensional ◽  
The Impact ◽  
Simple Flow

We present a computationally efficient reconstruction method for the limited-data chemical species tomography problem that incorporates projection of the unknown gas concentration function onto a low-dimensional subspace, and regularization using prior information obtained from a simple flow model. In this context, the contribution of this work is on the analysis of the projection-induced data errors and the calculation of bounds for the overall image error incorporating the impact of projection and regularization errors as well as measurement noise. As an extension to this methodology, we present a variant algorithm that preserves the positivity of the concentration image.

scholarly journals Two-stage battery recharge scheduling and vehicle-charger assignment policy for dynamic electric dial-a-ride services

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251582
Author(s):  
Tai-Yu Ma
Keyword(s):  
Large Scale ◽  
Waiting Times ◽  
Model Parameters ◽  
Two Stage ◽  
Charging Infrastructure ◽  
Solution Approach ◽  
Charging Station ◽  
Total Vehicle ◽  
Vehicle Charging ◽  
The Impact

Coordinating the charging scheduling of electric vehicles for dynamic dial-a-ride services is challenging considering charging queuing delays and stochastic customer demand. We propose a new two-stage solution approach to handle dynamic vehicle charging scheduling to minimize the costs of daily charging operations of the fleet. The approach comprises two components: daily vehicle charging scheduling and online vehicle–charger assignment. A new battery replenishment model is proposed to obtain the vehicle charging schedules by minimizing the costs of vehicle daily charging operations while satisfying vehicle driving needs to serve customers. In the second stage, an online vehicle–charger assignment model is developed to minimize the total vehicle idle time for charges by considering queuing delays at the level of chargers. An efficient Lagrangian relaxation algorithm is proposed to solve the large-scale vehicle-charger assignment problem with small optimality gaps. The approach is applied to a realistic dynamic dial-a-ride service case study in Luxembourg and compared with the nearest charging station charging policy and first-come-first-served minimum charging delay policy under different charging infrastructure scenarios. Our computational results show that the approach can achieve significant savings for the operator in terms of charging waiting times (–74.9%), charging times (–38.6%), and charged energy costs (–27.4%). A sensitivity analysis is conducted to evaluate the impact of the different model parameters, showing the scalability and robustness of the approach in a stochastic environment.

Research on Wind Power Fluctuation and its Impacts on Power System Frequency

2013 ◽  
Vol 291-294 ◽  
pp. 407-414 ◽  
Author(s):  
Guo Peng Zhou ◽  
Fu Feng Miao ◽  
Xi Sheng Tang ◽  
Tao Wu ◽  
Shan Ying Li ◽  
...  
Keyword(s):  
Power System ◽  
Wind Power ◽  
Large Scale ◽  
Wind Farms ◽  
Frequency Stability ◽  
Frequency Deviation ◽  
Intrinsic Mode Functions ◽  
Power Fluctuation ◽  
System Frequency ◽  
The Impact

The output power of wind farms has significant randomness and variability, which results in adverse impacts on power system frequency stability. This paper extracts wind power fluctuation feature with the HHT (Hilbert-Huang Transform) method. Firstly, the original wind power data was decomposed into several IMFs (Intrinsic Mode Functions) and a tendency component by using the EMD (Empirical Mode Decomposition) method. Secondly, the instantaneous frequency of each IMF was calculated. On this basis, taking a WSCC 9-bus power system as benchmark, the impact on power system frequency caused by wind power fluctuation was simulated in a real-time simulation platform, and the key component which results in the frequency deviation was found. The simulation results validate the wind power fluctuation impacts on frequency deviation, underlying the following study on power system frequency stability under the situation of large-scale intermittent generation access into the grid.

Vulnerability Assessment and Analysis of Active Distribution Network Structure

2014 ◽  
Vol 568-570 ◽  
pp. 1843-1849
Author(s):  
Da Chuan Liu ◽  
Jian Hua Zhang ◽  
Dan Wang ◽  
Hai Nan Li ◽  
Bo Zeng
Keyword(s):  
Power System ◽  
Complex Network ◽  
Network Structure ◽  
Network Theory ◽  
Large Scale ◽  
Fossil Fuels ◽  
Distribution Network ◽  
Complex Network Theory ◽  
Active Distribution Network ◽  
The Impact

Owing to more and more people concern about environment issues and reduction of fossil fuels, a growing number of distributed generations (DGs) are being interconnected to the power system. The active distribution network (ADN) provides an effective way to achieve the large scale connection and efficient utilization of them. This paper analyzes the vulnerability performance of active distribution network quantitatively and discusses the impact of DGs on the distribution network transmission efficiency under different grid structure through the application of complex network theory in power system. The example results show that meshed network structure can effectively promoting the consumption of DG and verify the feasibility of applying complex network theory to the distribution network for vulnerability analysis.

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