Active ROCOF Relay for Islanding Detection

Gupta, Pankaj; Bhatia, R.; Jain, Dinesh Kumar

doi:10.1109/tpwrd.2016.2540723

Cited by 159 publications

(78 citation statements)

References 33 publications

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“…From the above discussion, it is clear that the magnitude of the fault current in grid‐connected mode is higher than the fault current for the stand‐alone mode of operation. And, if the I P settings for both the modes are kept constant, then as per the inverse characteristics of the OCR, relay tripping time is more in stand‐alone mode as compared to grid‐connected mode . Because of this, components of the MG network are adversely affected that might lead to equipment failure.…”

Section: Resultsmentioning

confidence: 99%

“…This results in a significant change in the measured system parameters. Some important active IDTs are current injection‐based techniques, negative‐sequence current injection, average absolute frequency deviation, active ROCOF, and positive feedback based IDT for DGs . The main shortcomings of these methods are the power quality issues arising because of the injection of external disturbances.…”

Section: Introductionmentioning

confidence: 99%

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Design and verification of hardcore reconfigurable relay for islanding detection and subsequent mode adaptation of microgrid

Kumar

Pratap

2019

Int Trans Electr Energ Syst

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Summary Islanding detection is an important factor of the microgrid (MG) protection. Since an MG can work in two modes, ie, grid‐connected and stand‐alone/islanded mode, during any abnormality appearing in the upstream grid, the MG must be decoupled at the point of common coupling and made to operate in the islanded mode to sustain the critical loads. Because of this mode switching, it is necessary to change the pick up current settings of the overcurrent relays (OCRs) at the distributed generators (DGs) to accommodate the changes in the current levels. In this paper, a hardcore reconfigurable multifunctional relay is designed, which is used for the islanding detection as well as mode adaptation within the MG. A modular approach is used to implement the design, which is targeted on field‐programmable gate array (FPGA). Hardware description language, Verilog, is used to develop the optimized hardware. The relay has different submodules viz overcurrent, voltage unbalance, and rate of change of frequency (ROCOF) modules, which are controlled by a soft controller using a multiplexer. Hardware‐in‐loop (HIL) verification for various test cases under different power mismatches is performed on the Real Time Digital Simulator (RTDS) with FPGA setup. The results suggest that the proposed hardcore relay have the capability to identify the islanding event within permissible time and subsequently adapt to the mode of operation effectively.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Design and verification of hardcore reconfigurable relay for islanding detection and subsequent mode adaptation of microgrid

Kumar

Pratap

2019

Int Trans Electr Energ Syst

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“…The kinetic energy stored in the wind turbine may also significantly contribute to the frequency regulation during a black start process. The system ROCOF right after the load energization, taking into account an equivalent synchronous generator, can be written as

{\frac{df}{dt}|}_{t = 0^{+}} = \frac{- P_{load}}{2 H_{syn} S_{b}} f_{0},

where f is the system frequency (Hz), f 0 is the system nominal frequency (Hz), H syn is the inertia constant of the equivalent synchronous generator (W s/VA), S b is the power rating of the equivalent synchronous generator (VA), and P load is the active power of the energized load (W). The right side of 4 has a negative sign because a positive load variation results in a negative ROCOF .…”

Section: Operational Margin Of Wind Generation and Inertial Responsementioning

confidence: 99%

Auxiliary frequency controllers for the black start of stand-alone systems with predominance of wind generation

Bordignon

Oliveira

Lukasievicz

2018

Int Trans Electr Energ Syst

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Summary This paper proposes a novel control approach and supplementary controllers to support the black start of stand‐alone systems with predominance of wind generation based on fully rated converter. The main purpose of the proposed control approach is to provide auxiliary frequency control during the black start of stand‐alone systems. The proposed controllers, based on the signal of the system frequency error, are added to the grid‐side and generator‐side converters of the wind generation unit. One of the supplementary controllers, which act on the speed reference of the wind turbine, aims to extract kinetic energy from the wind turbine. The second supplementary controller aims to temporarily extract additional electrical energy from the DC link capacitor by acting on the typical control loops of the grid‐side converter. The energy extracted from the wind turbine and DC link capacitor is injected into the grid to quickly contribute to the frequency control during the black start of the system. The proposed controllers are coordinately designed by means of a genetic algorithm optimization technique which minimizes the deviations of the frequency and DC link voltage during the controller design process. The proposed operational and control approach has significantly improved the frequency nadir during the restoration process of the stand‐alone system.

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“…This problem has been studied using many methods, such as the autocorrelation function and maximum likelihood estimation [9][10][11][12][13]. For our method, the frequency deviation can be estimated using (6). Firstly, the frequency deviation can be accurately estimated using the phase of the signal spectrum.…”

Section: Performance Analysis Of the Frequency Deviation Estimationmentioning

confidence: 99%

“…Several fast and accurate frequency estimators have been previously proposed [4][5][6][7]. Without loss of generality, these frequency estimation algorithms mainly use discrete Fourier transform (DFT), maximum likelihood (ML), and phase estimation [4].…”

Section: Introductionmentioning

confidence: 99%

A Filter Structure for Arbitrary Re-Sampling Ratio Conversion of a Discrete Signal

Zhang¹,

Zhu

2017

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Abstract:In this report, we studied the sampling synchronization of a discrete signal in the receiver of a communication system and found that the frequency of the received signal usually exhibits some unpredictable deviations. We observed many harmonics caused by the frequency deviations of the discrete received signal. These findings indicate that signal sampling synchronization is an important research technique when using discrete Fourier transforms (DFT) to analyze the harmonics of discrete signals. We investigated the influence of these harmonics on the performance of signal sampling and studied the frequency estimation of the received signal. Based on the frequency estimation of the received signal, the sampling rate of the discrete signal was converted using a modified Farrow filter to achieve sampling synchronization for the received signal. The algorithm discussed here can be applied to sampling synchronization for monitoring and control systems. Finally, simulations and experimental results are presented.

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Active ROCOF Relay for Islanding Detection

Cited by 159 publications

References 33 publications

Design and verification of hardcore reconfigurable relay for islanding detection and subsequent mode adaptation of microgrid

Design and verification of hardcore reconfigurable relay for islanding detection and subsequent mode adaptation of microgrid

Auxiliary frequency controllers for the black start of stand-alone systems with predominance of wind generation

A Filter Structure for Arbitrary Re-Sampling Ratio Conversion of a Discrete Signal

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