In this paper a novel concept of event triggering control (ETC) for effective resource utilization is proposed for dc microgrid. Matched uncertainty elimination is possible through sliding mode ...control (SMC) itself as addressed in the literatures. This paper proposes a new approach for suppression of both matched and unmatched uncertainties in grid connected and islanded mode through an integral disturbance observer (IDO) which is designed with super twisting SMC to provide dual filtering phenomena pertaining to system perturbations. The IDO facilitates control algorithm to manage effective event counts during disturbance conditions. The proposed controller is designed in order to regulate DC bus voltage and enhance the microgrid capability to perform stable operation in presence of uncertainties. Chattering free finite time convergent SMC is designed with super twisting reaching law to obtain robust behavior of dc microgrid. Results are compared with power rate reaching SMC, Nonlinear disturbance observer (NDO) based controller and PI controller. In the proposed work event triggering condition is designed first time under super twisting reaching law. Comparative assessment is accomplished in lieu of demonstrating the superior performance of event trigger SMC through MATLAB/Simulink and Typhoon based controller hardware in loop (CHIL) platform.
Offshore wind farm (OWF) is an emerging technology in the wind energy conversion system. These wind resources are abundant, stronger, and are more consistent in terms of their availability than ...land-based wind resources. As a matter of fact significantly higher energy production is achieved due to larger wind turbine ratings and stronger wind profiles.
This paper highlights the present scenario and challenges in development of offshore wind power. The challenges and opportunities that exist in the development stages of an offshore wind farm project, from exploration to erection and installation of wind turbines, construction of platforms and laying of sea cables, up to maintenance and de-commissioning, involving important technical aspects are addressed. An application of high voltage direct current (HVDC) transmission for integration of large scale offshore wind farm with onshore grid is attractive as compared to high voltage alternating current (HVAC) transmission system. To make the offshore wind farm feasible, reliable and secure, the different aspects in its planning, design and operation are also reviewed in this paper.
In this paper an extensive literature review on load–frequency control (LFC) problem in power system has been highlighted. The various configuration of power system models and control ...techniques/strategies that concerns to LFC issues have been addressed in conventional as well as distribution generation-based power systems. Further, investigations on LFC challenges incorporating storage devices BESS/SMES, FACTS devices, wind–diesel and PV systems etc have been discussed too.
Traveling wave (TW) based protection and fault localization requires high sampling frequency measurements (500 kHz - 1 MHz) and are non-compliant to the IEC 61869-9 measurement standards, which ...allows maximum sampling frequency of 96 kHz for DC application. This work proposes a novel low sampling frequency (50 kHz) TW based primary protection and real-time DC fault localization technique for multi terminal high voltage DC (MTDC) grid which is compliant with the aforementioned measurement standard. In the proposed MTDC protection scheme, a TW arrival time (TWAT) is estimated under low sampling frequency measurement using cascaded combination of modified mathematical morphology gradient (MMG), sobel operator and linear regression tool. Subsequently, the TWAT information at both DC link terminals is communicated via dedicated communication channel compliant to IEC-61850-9-2 standard. And if the TWAT difference between DC terminals is less than the TW propagation threshold for the protected DC line, then a DC trip signal is issued to the associated hybrid DC circuit breaker (HDCCB). For fast power system restoration, the same TWAT information is also used for real-time fault localization in the faulted DC line, which is also compliant with IEC 61869-9 measurement standards. Finally, the practical feasibility of the proposed algorithm is demonstrated through control hardware-in-loop testing with real-time digital simulation setup and TI TMS320F28379d digital signal processor card.
This article presents a unit protection scheme for bipolar dc microgrids, which is resilient to cyber attacks. The proposed method uses current measurement of both ends of the protected line segment ...for distinguishing the internal faults and cyber attacks. For any change in current, the disturbance index exceeds the threshold value, subsequently, the proposed protection algorithm is triggered. Being a bipolar dc system, the concept of symmetrical component decomposition is used to obtain the bias, unbalance, and balance components during an unbalance condition. The superimposed balance component of both ends of the line on a four-quadrant plane acts as a decisive discriminator between internal and external faults. The correct faulted pole is identified by analyzing the superimposed unbalanced component. By comparing the superimposed bias component with the local pole domain currents, the cyber attack is correctly identified. The proposed protection scheme is validated on a ring-type bipolar dc microgrid, simulated in real-time digital simulator, for different internal and external faults and cyber attacks. The performance of the proposed method is tested for various conditions, including the detection of internal and external high resistance faults, fault type classification, change in load, distinguishing between different faults, and cyber attacks. A comparative assessment of the proposed method with the available techniques confirms its strength.
► Paper presents study on isolated hybrid DG system to improve frequency deviation. ► Study is addressed for DG system connected with storage units; SMES or UC. ► Results demonstrate minimum ...frequency deviation achieved by proposed controller with use of UC.
This paper presents a study on isolated hybrid distributed generation (DG) system for improving the frequency deviation profile. The hybrid DG system consists of wind turbine generator (WTG), diesel engine generator (DEG), aqua-electrolyzer (AE), fuel cell (FC) along with energy storage units. The frequency control problem is addressed for DG system connected with superconducting magnetic energy storage (SMES) or ultra-capacitor (UC). The particle swarm optimization (PSO) based loop shaping of H-infinity controller is used and compared with those obtained by genetic algorithm (GA) to minimize the frequency deviation. The frequency stabilizing performance is analyzed under different disturbances. Also, the controller robustness in terms of system parameter uncertainties is tested for changes in parameter up to ±30% from its nominal value. The results demonstrate minimum frequency deviation as achieved by proposed controller with use of UC in hybrid DG system.
Time–frequency-based differential scheme is proposed for microgrid protection using non-stationary signal analysis. The non-stationary signal processing algorithm Hilbert–Huang Transform (HHT) have ...been implemented for the protection objective and the comparative assessment with that of S-transform, differential current is carried out in order to demonstrate the reliability of the proposed protection scheme with different case studies. The series of simulation results demonstrates the efficacy of HHT, than that of S-transform in some critical cases such as high impedance fault where accurate detection is a challenge. The configuration of the microgrid test model has been developed in PSCAD with different distributed generation such as photovoltaic and wind generation system penetrated at different buses. Thus, it is found that the HHT scheme is quite reliable and efficient for fault detection objective.
► We aim to minimize the deviation of frequency in an integrated energy resources like offshore wind, photovoltaic (PV), fuel cell (FC) and diesel engine generator (DEG) along with the energy storage ...elements like flywheel energy storage system (FESS) and battery energy storage system (BESS). ► Further ultracapacitor (UC) as an alternative energy storage element and proportional-integral (PI) controller is addressed in order to achieve improvements in the deviation of frequency profiles. ► A comparative assessment of frequency deviation for different hybrid systems is also carried out in the presence of high voltage direct current (HVDC) link and high voltage alternating current (HVAC) line. ► In the study both qualitative and quantitative analysis reflects the improvements in frequency deviation profiles with use of ultracapacitor (UC) as energy storage element.
The large band variation in the wind speed and unpredictable solar radiation causes remarkable fluctuations of output power in offshore wind and photovoltaic system respectively, which leads to large deviation in the system frequency. In this context, to minimize the deviation in frequency, this paper presents integration of different energy resources like offshore wind, photovoltaic (PV), fuel cell (FC) and diesel engine generator (DEG) along with the energy storage elements like flywheel energy storage system (FESS) and battery energy storage system (BESS). Further ultracapacitor (UC) as an alternative energy storage element and proportional–integral (PI) controller is addressed in order to achieve improvements in the deviation of frequency profiles. A comparative assessment of frequency deviation for different hybrid systems is also carried out in the presence of high-voltage direct current (HVDC) link and high-voltage alternating current (HVAC) line. Frequency deviation for different isolated hybrid systems are presented graphically as well as in terms of integral square error (ISE). Both qualitative and quantitative analysis reflects the improvements in frequency deviation profiles with use of ultracapacitor (UC) as energy storage element.
Islanding or nonislanding events in grid-connected distributed generation bring along a typical distinguishable transient signature in its frequency profile. This demarcation leads to the development ...of a new islanding protection approach, which is based on the estimation of frequency waveform parameter (transient's frequency) by Matrix pencil (MP) method. To demonstrate the efficacy of the proposed MP method, four critical scenarios are considered in this paper for covering all possible disturbance events. These events are also compared along with a discrete wavelet transform (DWT) based islanding detection method in simulations as well as in RT-LAB-based real-time environment. It is noteworthy to mention that the proposed MP method has been found to have a positive edge over the DWT-based method in terms of robustness and chances of misidentification.
In this paper, islanding detection in a hybrid distributed generation (DG) system is analyzed by the use of hyperbolic S-transform (HST), timetime transform, and mathematical morphology methods. The ...merits of these methods are thoroughly compared against commonly adopted wavelet transform (WT) and S-transform (ST) techniques, as a new contribution to earlier studies. The hybrid DG system consists of photovoltaic and wind energy systems connected to the grid within the IEEE 30-bus system. Negative sequence component of the voltage signal is extracted at the point of common coupling and passed through the above-mentioned techniques. The efficacy of the proposed methods is also compared by an energy-based technique with proper threshold selection to accurately detect the islanding phenomena. Further, to augment the accuracy of the result, the classification is done using support vector machine (SVM) to distinguish islanding from other power quality (PQ) disturbances. The results demonstrate effective performance and feasibility of the proposed techniques for islanding detection under both noise-free and noisy environments, and also in the presence of harmonics.
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