D. K. Jain

Battery Energy Storage System for Power Conditioning of Renewable Energy Sources

Renewable energy sources such as wind, hydro, etc. are intermittent in nature. Generators connected to the local grid may lead to severe power quality problems. These issues are voltage dip while connection/ disconnection of the generator, uncertainty of supply, unbalanced and distorted power supply. In this paper, the power conditioning of micro hydro driven induction generator connected to the local grid using battery energy storage system (BESS) is simulated for voltage regulation, load leveling, harmonics elimination and power factor improvement

Average Absolute Frequency Deviation Value Based Active Islanding Detection Technique

An average absolute frequency deviation value based active islanding detection technique is proposed in this paper. The inverters classical q-axis current controller is modeled with a continuous periodic reference current of a small value. During the loss of mains, the islands frequency deviates with respect to the variation in the reference current; this is detected by making the use of an average absolute frequency deviation value. In case of a stable island formation, there is a small periodic frequency deviation owing to the small value of the periodic reference current, and the frequency deviation is so small that it falls inside the nondetection zone (NDZ) of the frequency relay. The main advantage of the proposed algorithm is that it detects the stable island formation but without forcing the island to lose its stable operation. In case of nonislanding switching events, which may transiently impose a significant deviation in the frequency, the possibility of false detection is eliminated by reconfirming the occurrence of islanding once it is suspected. The reference current is kept to a small value to limit the degradation of the power quality and the power factor. Computer simulation is done with MATLAB.

An Overview of Some Important Issues Related to Wind Energy Conversion System (WECS)

Wind power capacity has experienced tremendous growth in the past decade. There are many loads (such as remote villages, islands, ships etc) that are away from the main grid. They require stand-alone generator system (which can provide constant nominal voltage and frequency) to provide for their local electrification. This requirement has lead to widespread research on development of new technologies for stand-alone generators. Initially an overview of different existing generator technologies for grid connected operation is given. This paper presents the recent developments in wind energy conversion systems, their classifications, choice of generators and their social and environmental benefits , a review of the interconnection issues of distributed resources including wind power with electric power systems, hybrid power system and reports the developments of interconnection standards in Canada and IEEE.

Battery energy storage system for variable speed driven PMSG for wind energy conversion system

There are many loads such as remote villages, islands, etc. that are located far away from the main grid. These loads require stand-alone generating system, which can provide constant voltage and frequency for local electrification. Locally available wind power can be used in such off-grid systems. As the wind speed is variable, an AC-DC-AC conversion system is required to convert variable voltage and variable frequency power generation to constant voltage and constant frequency source. Further, as the wind power as well as load is variable there is a need of energy storage device that take care of the load mismatch. In this paper, a standalone wind energy conversion system (WECS) using a variable speed permanent magnet synchronous generator (PMSG) is proposed with a battery energy storage system.

Active ROCOF Relay for Islanding Detection

Intentional frequency perturbation by recently researched active islanding detection techniques for inverter based distributed generation (DG) define new threshold settings for the frequency relays. This innovation has enabled the modern frequency relays to operate inside the non-detection zone (NDZ) of the conventional frequency relays. However, the effect of such perturbation on the performance of the rate of change of frequency (ROCOF) relays has not been researched so far. This paper evaluates the performance of ROCOF relays under such perturbations for an inverter interfaced DG and proposes an algorithm along with the new threshold settings to enable it work under the NDZ. The proposed algorithm is able to differentiate between an islanding and a non-islanding event. The operating principle of relay is based on low frequency current injection through grid side voltage source converter (VSC) control of doubly fed induction generator (DFIG) and therefore, the relay is defined as “active ROCOF relay”. Simulations are done in MATLAB.

Advanced controlled series compensated self-excited induction generator

The dynamic reactive power (VAr) requirements limits the applications of self-excited induction generators (SEIG) because of poor voltage regulation even at constant speeds. Fixed and varying VAr compensators with conventional devices (such as synchronous condensers, shunt capacitors, series capacitors) have inherent problems like sluggish response, undue overvoltage, switching transients, sub-synchronous resonance, etc. In this paper, application of an advanced controlled series compensator (ACSC) for the voltage control of SEIG at different speeds is discussed. An ACSC-SEIG system is modeled and analysed. The theoretical results are supported with experimental results in order to establish the effectiveness of the proposed scheme.

Grid Voltage Control of Inverter Interfaced Wind Energy Conversion System (WECS)

In this paper the grid interconnection issues of AC-DC-AC inverter interfaced wind energy conversion system have been dealt. The power flow in context of load has now reversed in such local generating stations; the voltage rise at the point of common coupling (PCC) in the case of large scale wind farm is well known. The wind energy conversion system has to be taken out if the voltage exceeds beyond limit. Thus the capacity factor of the wind farm may be poor. In this case, the grid inverter can support the voltage at PCC by injecting reactive power along with the active power. The simulation results are given here for improving the voltage at PCC.

Battery Energy Storage System Based Power Conditioner for Improved Performance of Hybrid Power Generation

Hybrid power generation is typical in isolated power generation; especially in case of islands. Here, conventional source of energy, generally diesel generator, is combined with a local renewable source, wind energy system. In this paper, a detailed analysis of BESS based power conditioner has been carried out for a hybrid power generation. The optimum utilization of the diesel generator and power quality enhancement using soft-starting of induction generator has proposed.

Integration of embedded generation in local grid using STATCOM

The renewable sources of energy are being connected to the local distribution system/local grid leading to embedded generation. As these sources are intermittent in nature, they impose technical challenges in the power system operation which include power quality related problems of local grid. The performance of the system has to be evaluated while connecting these sources to the local distribution system/micro grid. In this paper, the application of STATCOM-based power quality conditioner for improving the performance of wind driven induction generator embedded to the local grid have been discussed. The modelling, control and analysis of the proposed STATCOM-based power quality conditioner have been given. The MATLAB Simulink-based system model has been used for the performance evaluation while connection of wind-driven induction generator to the local grid, its variable speed operation and unbalanced supply system. The STATCOM-based power quality conditioner has been found effective for the power quality improvement of the local grid.

Power quality evaluation in deregulated power system using matrix method

Power quality has emerged as a challenging area in the context of deregulation, wherein electricity distribution buyers and sellers carry out mutually agreed-upon exchanges. A market for active power and reactive power is installed in many places as a result of a deregulation process. However, the power-quality-related market is in the developing stage. For a given site, the power quality attributes have individual indices which have to be combined to give a suitability index so that the performance of the supply system may be evaluated at the point of common coupling. In this paper, a new technique based on the matrix method and permanents is proposed to quantify the power quality of a site. The proposed algorithm method is explained and illustrated with a sample problem on site evaluation and ranking.