A New Methodology for Probabilistic Short-Circuit Evaluation With Applications in Power Quality Analysis

Bordalo, U.A.; Rodrigues, A.B.; Silva, Maria da Guia da

doi:10.1109/tpwrs.2006.873055

Cited by 21 publications

(9 citation statements)

References 12 publications

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“…SARFI is calculated by real measured data and/or simulated data using probability approaches. 14,16,17 The number of voltage sag events is signifi cantly changed from system to system. The results of 15 surveys have been presented in CIGRE report, 14 which are related to MV, HV and EHV systems.…”

Section: Introductionmentioning

confidence: 99%

Investigation of voltage sag impact on wind turbine tower vibrations

2008

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To study the effect of voltage sag on the mechanical vibration of a wind turbine structure, a detailed model that considers the combined electrical, mechanical and aerodynamic aspects of the wind turbine must be used. A drawback of many previously published works in the area of wind turbine simulation is that they study either a very simple mechanical model with a detailed electrical model or vice versa. Therefore, the interactions between electrical and mechanical components are not accurately taken into account. In this paper, three simulation programs-TurbSim, FAST and Simulink-are used to model the wind, mechanical and electrical parts of a wind turbine and its controllers in detail. Simulation results obtained from the model are used to observe the interaction of all three factors affecting the operation of a wind turbine system. The focus of the paper is on the effect of the voltage sag on tower vibration, considering different power system characteristics (i.e. short circuit level and X/R ratio), mechanical parameter (i.e. mechanical tower damping) and wind turbine operating conditions.To study the vibration in a wind turbine structure, it is important to calculate the blade aerodynamic forces since they can cause vibration in the mechanical structure and infi uence the generated torque (power). In this research, the mechanical torque, the defl ection and velocities of the mechanical structure are calculated based on the aerodynamic forces for each part of the blades. The effects of the blade defl ection and velocities on blade aerodynamic forces are accounted for. These subjects have not been considered in previous works, which have mainly studied the problems from electrical point of view. [3][4][5][6][7] In this paper, it will be shown that a combination of three different simulation packages, namely TurbSim, FAST and Simulink, can be used to model the electrical and mechanical aspects of a wind turbine in detail. The simulation environment is used to study the voltage sag impact on wind turbine tower vibration under different conditions. The results obtained from the model are discussed, and conclusions are made about the interaction of all three aspects of a wind turbine system in response to a voltage sag. Voltage Sag OccurrenceVoltage sag (also known as voltage dip) is reduction for a short duration (between 0.5 cycle and 1 min) in the RMS voltage because of the short circuits, overloads or starting of large motors, and transformer energizing. Disturbances that last less than 0.5 cycle are commonly called 'low-frequency transients'; voltage reductions that last longer than 1 min are commonly called 'undervoltage'. 8 In spite of the short duration of voltage sags, such events can cause serious problems for a wide range of equipment such as process-control equipment, computers, adjustable-speed drives and wind turbines. 3,4,[9][10][11] Voltage sags are of a stochastic nature as most of them are caused by remote short-circuit faults occurring in transmission and distribution systems and involving sever...

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Section: Introductionmentioning

confidence: 99%

Investigation of voltage sag impact on wind turbine tower vibrations

2008

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“…Since the topology of the distribution system is usually either radial or weakly meshed, the Thevenin equivalent circuit is also solved by the backward and forward sweep (BFSW) method [3]. To synthesize the stochastic variation in the SCC, in [4], the probabilistic simulations (e.g., Monte Carlo simulations) are performed. In [5,6], the decomposition method of the bus impedance matrices to bus-current-injection to branch-current (BIBC), and branch-current to bus-voltage (BCBV) matrices, which were originally proposed for power-flow calculation, are also applied to the SCC calculation.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Unbalanced Impedance Loads on the Short-Circuit Current

Kim

2018

Energies

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Conventional short-circuit studies often neglect the load current because the short-circuit current (SCC) flowing from generators is much greater than the SCC that is affected by various loading conditions. As distributed or clustered loads that are unbalanced in phases are connected to the grid, they can also change the magnitude and phase angle of the SCC, despite their small capacities. Thus, the objective of this study is to present algorithms that are able to analyze such an impedance unbalanced load. For this purpose, this study initially derives an SCC model of the unbalanced impedance load in phases. Since the proposed SCC model requires the pre-fault voltage, it uses a power-flow analysis algorithm that iteratively calculates the current that is to be injected and the pre-fault voltage, using the bus impedance matrix. Then, the proposed SCC calculation algorithm transforms the unbalanced loads into equivalent impedances, using the pre-fault voltage, and adds them to sequence networks as input data, using the proposed SCC model. The proposed algorithms are verified in various case studies. As a result, the proposed SCC calculation algorithms are more accurate, because they do not neglect unbalanced loads.

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“…The probabilistic methods have also been applied in power quality studies associated with voltage sags [5]- [12]. These applications are based on two methods: analytical [5], [6], [7], [9], [11] and Monte Carlo Simulation (MCS) [8], [10], [12]. The probabilistic assessment of voltage sags through the analytical method is usually based in two techniques: critical distances [5], [6] and fault positions [9].…”

Section: Introductionmentioning

confidence: 99%

“…These techniques are based on the proposed approach in [13] to evaluate post-fault voltages due to short circuits along lines. On the other hand, the application of Monte Carlo Simulation in the probabilistic voltage sag assessment has been based on state space representation, that is, non-sequential MCS [10], [12]. The computational effort of the analytical approaches to carry out a probabilistic analysis of voltage sags is usually lower than the one associated with MCS.…”

Section: Introductionmentioning

confidence: 99%

Probabilistic assessment of the impact of wind power generation on voltage sags in composite systems

Baptista

Rodrigues

Silva

2014

2014 Power Systems Computation Conference

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This paper presents a methodology to assess the impact of wind power generation on the voltage sags in generation and transmission composite systems. The proposed methodology is based on probabilistic techniques to model uncertainties associated with fault scenarios and wind speed fluctuations. The probabilistic technique used to represent the uncertainties is the non-sequential Monte Carlo Simulation. The voltage sags resulting from fault scenarios were evaluated using symmetrical components technique. The combination of these two techniques was used to estimate the nodal and systemic indices associated with the frequency of voltage sags. The proposed methodology to evaluate these indices was tested on the IEEE Reliability test system of 24 buses. The tests results demonstrate that the wind generation has a significant impact on the frequency indices related to voltage sags.

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A New Methodology for Probabilistic Short-Circuit Evaluation With Applications in Power Quality Analysis

Cited by 21 publications

References 12 publications

Investigation of voltage sag impact on wind turbine tower vibrations

Investigation of voltage sag impact on wind turbine tower vibrations

The Effect of Unbalanced Impedance Loads on the Short-Circuit Current

Probabilistic assessment of the impact of wind power generation on voltage sags in composite systems

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