Despite improving various technical indices such as operation and voltage profile, the integration of synchronous distributed generations (SDGs) may lead to the loss of protection coordination in the distribution netw...
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Despite improving various technical indices such as operation and voltage profile, the integration of synchronous distributed generations (SDGs) may lead to the loss of protection coordination in the distribution network (DN). To tackle the problem, this paper presents a multi-objective siting and sizing of SDGs on DN considering operation, economic and protection coordination indices simultaneously. The proposed scheme is structured in the framework of a four-objective optimization problem, which aims to minimize the energy losses, the worst voltage security index (VSI), planning cost of SDGs and the protection index (PI) (the deviation of coordination time interval). Therefore, it is constrained to power flow equations, VSI, and protection coordination of overcurrent relays (OCRs). Then, the Pareto optimization based on the method of the weighted functions summation obtains an integrated single-objective problem for the proposed scheme. Next, a hybrid evolutionary algorithm formed by merging particle swarm optimization (PSO) and crow search algorithm (CSA) is incorporated to achieve the optimal solution with unique response approximate conditions. Eventually, the suggested scheme is applied on distribution portion of IEEE 30-bus ring and IEEE 69-bus radial DN and numerical results confirm the efficient performance of SDG planning in terms of technical indicators and protective devices coordination.
Frequency-based relays, commonly used for islanding detection of synchronous distributed generation (SDG), may either have large non-detection zones (NDZs) or wrongly operate for non-islanding disturbances unless they...
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Frequency-based relays, commonly used for islanding detection of synchronous distributed generation (SDG), may either have large non-detection zones (NDZs) or wrongly operate for non-islanding disturbances unless they are efficiently adjusted. Trial and error simulation-based methods, employing application region (AR) and/or power imbalance AR (PIAR), are presented in the literature to adjust these relays for quick islanding detection without false trips. However, the associated settings are not optimal and finding them is time-consuming. In this study, an approach utilising particle swarm optimisation algorithm is proposed to adjust a rate of change of frequency (ROCOF) relay, one of the most effective relays in SDG islanding detection. The proposed approach needs a set of analytical formulas for determining the ROCOF relay performance curve and NDZ as well as AR and PIAR. These formulas are developed to be employed in the relay adjustment. By applying the developed analytical formulas to the optimisation-based approach, the ROCOF relay is adjusted fast and systematically. It is shown that while the performance of the relay adjusted by the proposed approach is close to the one with setting obtained by corresponding trial and error-based method, the latter is much more time-consuming than the former.
Penetration of distributed generators (DGs) has continued to grow rapidly into power grids and is one of the indispensable aspects of the future smart grid. If a part of the system becomes islanded, DGs should effecti...
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ISBN:
(纸本)9781538644782
Penetration of distributed generators (DGs) has continued to grow rapidly into power grids and is one of the indispensable aspects of the future smart grid. If a part of the system becomes islanded, DGs should effectively continue to control the islanded power system without degradation of power quality, and otherwise the DGs should be disconnected as soon as they have no adverse impact on the islanded grid. Therefore, the islanding should be detected timely in order to disconnect the DG or change control strategy of the DG. This paper proposes a passive islanding detection method for synchronous DGs based on pattern recognition of signal trajectory. The proposed algorithm provides an accurate islanding detection for future smart grid using intelligent relays. The islanding situation can be discriminated from grid-connected disturbances even when the generation and load are closely matched in the island. The performance of the proposed method has been investigated using PSCAD/EMTDC time-domain simulations in different scenarios.
High impedance fault (HIF) is problematic in various distribution systems, specially in rural distribution feeders. The fault current of HIF is with low magnitude, non-linear, asymmetrical and random, therefore extrac...
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ISBN:
(纸本)9781509040001
High impedance fault (HIF) is problematic in various distribution systems, specially in rural distribution feeders. The fault current of HIF is with low magnitude, non-linear, asymmetrical and random, therefore extracting useful detection features from HIF current and voltage is the key to solve this issue. This paper experiments with 246 conventional electrical features and their combinations and proposes an effective feature set (EFS) via a feature ranking algorithm utilizing simple signal processing technique of discrete Fourier transform and Kalman filter estimation. This EFS is tested in six types of distribution systems and exhibits a promising detection performance in terms of accuracy, dependability and security once a proper pattern recognition classifier is determined. Besides conventional batch learning algorithms, the proposed detection method demonstrates a significant performance in online machine learning environment. Therefore it shows the potential of processing instantaneous signals and updating its prediction model adaptively to detect more HIFs in future smart grid.
Islanding Protection is a fundamental function of any distributedgeneration Interconnection Protection package. This article illustrates how intelligent relays can be used to address DG islanding detection issues spa...
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ISBN:
(纸本)9781467327299
Islanding Protection is a fundamental function of any distributedgeneration Interconnection Protection package. This article illustrates how intelligent relays can be used to address DG islanding detection issues spawned by the presence of more than one synchronous generator on a distribution feeder. The analysis assumes the existence of high-speed distribution feeder reclosing. The developed methodology is illustrated and results are provided for many system operating cases. The performance of intelligent relays is compared with the performance of currently used islanding protective devices on each generator.
Nowadays, penetration of DG resources into the power systems due to their advantages is rapidly increasing. Islanding performance is one of the most disadvantages of using DGs, which should be considered, because this...
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Nowadays, penetration of DG resources into the power systems due to their advantages is rapidly increasing. Islanding performance is one of the most disadvantages of using DGs, which should be considered, because this option may lead to negative effects on the protection, performance, and operation management of distributed systems implementation. An island must be detected in less than 2sec based on IEEE STD 1547-2003 standard, and DG resources must be disconnected from distribution network immediately. In this paper, a novel hybrid algorithm to identify the islanding has been proposed based on the passive parameters (ROCOV and ROCORP) and capacitor bank connection strategy. In the incompatibility conditions of the large-scale power, by combining two parameters i.e. ROCOV and ROCORP and investigating their changes, the islanding is carefully and quickly identified. This strategy is completely verified in the mismatch conditions of small-scale power by applying the capacitor bank connection strategy. The presented approach is tested on two case studies and the detailed results were completely reported. As it was shown, the proposed approach is able to distinguish between islanding and the other events.
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