Islanding detection scheme based on morphological wavelets

Abstract: Unintentional islanding is one of the serious concerns to be addressed when interfacing a distributed generation source, as it causes damage to the equipment and personnel. Many algorithms have been proposed for islanding detection in the literature which are classified into local methods (passive, active and hybrid), communication-based methods, and methods employing signal processing and classifiers techniques. Out of which, passive islanding detection methods have been mostly adopted in practice since they have an edge over other islanding detection methods (IDMs) such as there is no degradation of power quality as in active methods and are simple to implement and cheap as compared to communication-based methods. Therefore, in this paper, an attempt has been made to systematically put forward a detailed review of islanding detection methods exclusively with a passive approach. This review provides an insight into passive parameters (which are islanding detection indicators) considered by various researchers and their performance with respect to detection time (also known as run-on-time), non-detection zone, performance in a noisy environment exclusively for passive schemes employing signal processing techniques, difficulty level and process of selecting threshold value(s). Additionally, this review provides a brief account on the future role of passive schemes and also passive IDMs incorporating ride-through requirements in compliance with recent interconnection standards.

Abstract: Distributed Generation (DG) reduces the amount of energy lost in transmitting electricity because the electricity is generated very near where it is used. This book introduces systematic and transparent methods for quantifying the impact of DG on the power grid. It emphasizes systematic and transparent calculation methods, allowing for a quantification of the amount of DG that can be integrated at a certain location of the grid or in the grid as a whole. It also provides an overview of the different energy sources, with emphasis on wind power, solar power and combined heat and power in the power grid.

Abstract: Transformations morphologiques, morphologie euclidienne, erosion et notions derivees, ouvertures et fermetures, amincissements et epaississements

Abstract: This report describes the various methods and circuits that have been developed to detect an islanding condition for photovoltaic applications and presents three methods that have been developed to test those methods and circuits. Passive methods for detecting an islanding condition basically monitor parameters such as voltage and frequency and/or their characteristics and cause the inverter to cease converting power when there is sufficient transition from normal specified conditions. Active methods for detecting the island introduce deliberate changes or disturbances to the connected circuit and then monitor the response to determine if the utility grid with its stable frequency, voltage and impedance is still connected. If the small perturbation is able to affect the parameters of the load connection within prescribed requirements, the active circuit causes the inverter to cease power conversion and delivery of power to the loads. The methods not resident in the inverter are generally controlled by the utility or have communications between the inverter and the utility to affect an inverter shut down when necessary. This report also describes several test methods that may be used for determining whether the anti-islanding method is effective. The test circuits and methodologies used in the U.S. have been chosenmore » to limit the number of tests by measuring the reaction of a single or small number of inverters under a set of consensus-based worst-case conditions.« less

Abstract: Islanding detection is a mandatory feature for grid-connected inverters. The effectiveness of passive islanding detection methods (IDMs) is usually demonstrated by means of nondetection zones (NDZs) represented in a power mismatch space (/spl Delta/P versus /spl Delta/Q). Active frequency drifting IDMs have been shown to provide improved performance but their theoretical NDZ cannot be described in the /spl Delta/P versus /spl Delta/Q space for a general RLC load. This paper shows that a load parameter space based on the values of the quality factor and resonant frequency of the local load (Q/sub f/ versus f/sub 0/) can be used in these cases. It employs a single curve to represent the NDZ of frequency drifting IDMs for any RLC loads. Equations that represent NDZs of three common active IDMs in the Q/sub f/ versus f/sub 0/ load parameter space are derived and it is shown that the slip mode frequency shift and the Sandia frequency shift IDMs can be designed to guarantee islanding detection for equivalent RLC loads with a quality factor smaller than a design value. The accuracy of the NDZs is verified with simulation and experimental results.

Abstract: Islanding of a utility-interactive photovoltaic (UIPV) system occurs if the UIPV system continues to power a section of the utility system after that section has been disconnected from the utility source. Since islanding creates hazards for personnel and equipment, UIPV systems are required to detect and prevent it. It is desirable to have a simplified method of determining which islanding detection methods (IDMs) are most effective. In this paper, a previously described method for finding the nondetection zones (NDZs) of IDMs is experimentally verified. This method is used to determine the NDZs of several common IDMs. These results indicate that, of the IDMs discussed in this paper: (1) Sandia Frequency Shift (SFS) is most effective; and (2) the worst-case loads are low-power loads that are near resonance at the line frequency and have a large capacitance and small inductance (a high value of the quality factor Q).