Grid integration of large scale fixed speed wind farm considering static voltage stability

This paper addresses the influence of integrating a large-scale wind farm on static voltage stability of a power system based on the factors such as, wind speed, wind farm interconnection bus, interconnection cable length and wind farm size. Using the continuation power flow method effects of each factor were analysed and an index is proposed to locate a large scale fixed speed wind farm in a power system

Prototype implementation of an islanding detection relay based on pattern classification of current and voltage transients

A prototype islanding detection relay, which uses decision tree classifier to categorize the transient generating events as ‘islanding’ or ‘non-islanding’ was implemented and tested. It consisted of two basic stages of signal processing to extract the required feature vectors for the classification. The first stage involved signal filtering and in the second stage signals were processed by rectifying, summing, and lowpass filtering to get the energy content in the three phases during a selected time-frame. A simple radial medium voltage distribution system having a single distributed generator was simulated in PSCAD/EMTDC to obtain the transient waveforms, and the performance of the relay was tested with signals generated using an RTP real-time waveform playback instrument. The experimental results showed high accuracy in detecting islanding events within a response time of less than two cycles. The proposed relay can be implemented with a very low cost and is simple in construction. Therefore, this could be an acceptable low cost substitute for the expensive and complex transfer trip schemes, which are commonly in use with the distributed generation. loads and distributed energy resources (DER) remains energized while isolated from the remainder of the utility system’ (IEEE, 2003). Unintentional islanding resultsin several safety and power quality' issues including abnormal variations in frequency and voltage, possibility of creating ungrounded systems, and potential safety hazards for repair crews. In formulating guidelines and/or rules for interconnecting DGs in the distribution systems, the most common practice is to adopt the IEEE standard 154 (IEEE, 2003). These otional practice standards have been developed with an underlying assumption that thepower system is radial. In the past, the power available from DGs was not essential to support the load on the system. Hence, the standards suggest to disconnect the DGs for any ‘significant’ fault (a fault that could require the protection to be provoked) on the distribution system and thus, maintaining the radial nature of the system. Consequently, the islanding detection relays are designed to avoid power islanding, and these relays are referred to as anti-islanding relays (Xu et al., 2004; Mahat et al., 2008). However, there is a change in the approach towards islanding with the initiatives on microgrids (Chowdhury et al., 2009; Lidula & Rajapakse, 2011). The performance of the power-islanding detection methods in a microgrid setup is more demanding as the microgrid is designed to operate as a stable power island. Many powerislanding detection methods in practice would find it difficult to meet the qualities demanded by micorgrids (Katiraei et al., 2005) without the use of expensive telecommunication facilities. Keywords: Active filters, decision tree classifica

Prototype implementation of an islanding detection relay based on pattern classification of current and voltage transients

A prototype islanding detection relay, which uses decision tree classifier to categorize the transient generating events as ‘islanding’ or ‘non-islanding’ was implemented and tested. It consisted of two basic stages of signal processing to extract the required feature vectors for the classification. The first stage involved signal filtering and in the second stage signals were processed by rectifying, summing, and lowpass filtering to get the energy content in the three phases during a selected time-frame. A simple radial medium voltage distribution system having a single distributed generator was simulated in PSCAD/EMTDC to obtain the transient waveforms, and the performance of the relay was tested with signals generated using an RTP real-time waveform playback instrument. The experimental results showed high accuracy in detecting islanding events within a response time of less than two cycles. The proposed relay can be implemented with a very low cost and is simple in construction. Therefore, this could be an acceptable low cost substitute for the expensive and complex transfer trip schemes, which are commonly in use with the distributed generation. loads and distributed energy resources (DER) remains energized while isolated from the remainder of the utility system’ (IEEE, 2003). Unintentional islanding resultsin several safety and power quality' issues including abnormal variations in frequency and voltage, possibility of creating ungrounded systems, and potential safety hazards for repair crews. In formulating guidelines and/or rules for interconnecting DGs in the distribution systems, the most common practice is to adopt the IEEE standard 154 (IEEE, 2003). These otional practice standards have been developed with an underlying assumption that thepower system is radial. In the past, the power available from DGs was not essential to support the load on the system. Hence, the standards suggest to disconnect the DGs for any ‘significant’ fault (a fault that could require the protection to be provoked) on the distribution system and thus, maintaining the radial nature of the system. Consequently, the islanding detection relays are designed to avoid power islanding, and these relays are referred to as anti-islanding relays (Xu et al., 2004; Mahat et al., 2008). However, there is a change in the approach towards islanding with the initiatives on microgrids (Chowdhury et al., 2009; Lidula & Rajapakse, 2011). The performance of the power-islanding detection methods in a microgrid setup is more demanding as the microgrid is designed to operate as a stable power island. Many powerislanding detection methods in practice would find it difficult to meet the qualities demanded by micorgrids (Katiraei et al., 2005) without the use of expensive telecommunication facilities. Keywords: Active filters, decision tree classifica

Implementation, Comparison and Application of an Average Simulation Model of a Wind Turbine Driven Doubly Fed Induction Generator

Wind turbine driven doubly-fed induction generators (DFIGs) are widely used in the wind power industry. With the increasing penetration of wind farms, analysis of their effect on power systems has become a critical requirement. This paper presents the modeling of wind turbine driven DFIGs using the conventional vector controls in a detailed model of a DFIG that represents power electronics (PE) converters with device level models and proposes an average model eliminating the PE converters. The PSCAD/EMTDC™ (4.6) electromagnetic transient simulation software is used to develop the detailed and the proposing average model of a DFIG. The comparison of the two models reveals that the designed average DFIG model is adequate for simulating and analyzing most of the transient conditions

ASEAN towards clean and sustainable energy: Potentials, utilization and barriers

This paper reports the outcome of the project on “Capacity building in formulating harmonized policy instruments for the promotion of Renewable Energy and Energy Efficiency in the ASEAN member countries”. With the growing concerns about green house gas (GHG) emission and consequent climate change, renewable energy sources have become more attractive option for electricity generation around the world. Studies have been made on the status of renewable energy potential and utilization, major barriers in promoting renewable energy in ASEAN countries, major energy policies to overcome barriers, and existing renewable energy and energy efficiency policies in ASEAN countries. Paper concludes that ASEAN has not utilized its renewable energy resources anywhere near to the potential. Analysis found that the key factor that has to be amended is “policies and regulations in renewable energy and energy efficiency” at both country level and regional level. But, ASEAN is not yet ready for the full harmonization of the policies. However, it recommends that, with the project outputs it is possible to focus on the specific policy instruments common to most of the member countries, such that it could use to augment ASEAN Plan of Action for Energy Cooperation (APAEC) initiatives

Microgrid Energy Management and Methods for Managing Forecast Uncertainties

The rising demand for electricity, economic benefits, and environmental pressures related to the use of fossil fuels are driving electricity generation mostly from renewable energy sources. One of the main challenges in renewable energy generation is uncertainty involved in forecasting because of the intermittent nature of renewable sources. The demand also varies according to the time of day, the season, the location, the climate, and the availability of resources. Microgrids offer a potential solution for the integration of small-scale renewable energy sources and loads along with energy storage systems and other non-renewable sources. However, intermittent generation and varying demand need to be matched to provide stable power to consumers. Therefore, it is crucial to design an energy management system to effectively manage the energy sources and supply loads for reliable and efficient operation. This paper reviews different techniques proposed in the literature to achieve the objectives of a microgrid energy management system. The benefits of existing energy management systems and their challenges are also discussed. The challenges associated with uncertainties and methods to overcome them are critically reviewed