Marine Current Farm Research Articles

Study on Dynamic analysis of Grid Interactive of offshore wind and Marine Current Farm

Abstract:-In day-to-day life due to growth of power demand worldwide. The use of conventional energy is increased and there is reduction in conventional resources. To fulfill the Demand, it is essential to increase the renewable resources like wind, tidal, solar etc. The energy which is sustainable means which is endless. The ocean has untapped energy resources in the form of tidal wave, geothermal, offshore wind etc. at different geographical locations.OWF combined with MCF, owing to their natural availability in close proximity, would become a new kind of integrated energy generation system in near future. Mainly there are TWO types of generators synchronous and asynchronous generator we use asynchronous generator because wind is not constant in offshore wind farm .There are FOUR types of generators used in offshore wind farm (OWF) which are named as:- Doubly fed induction generator (DFIG), Squirrel cage induction generator(SCIG) ,Wound-Rotor induction generator(WRIG) ,Permanent Magnet Synchronous generator (PMSG). And in our project, we have taken wind Energy as a source and our system is hybrid of offshore wind and marine-current farm connected to an onshore power grid via a high-voltage alternating current (HVAC) link. The performance of the studied offshore wind farm (OWF) is simulated by a doubly-fed induction generator (DFIG). DFIG system is a popular system in which the power electronic interface controls the rotor current to achieve the variable speed necessary for maximum energy capture in variable winds .while the operating characteristics of the studied marine current farm (MCF) are simulated by a squirrel-cage induction generator (SCIG).SCIG is attached to the wind turbine by means of a gearbox. The wind turbine is responsible for transforming wind power into kinetic energy .Both frequencydomain approach based on a linearized system model using Eigen value analysis and time-domain scheme based on a nonlinear system model subject to a disturbance condition are carried out. It can be concluded from the simulated steady-stated transient results that the proposed HVAC link can effectively stabilize the hybrid OWF and MCF under various disturbance conditions

Stability assessment and robust controller design of grid interactive offshore wind farm and marine current farm with STATCOM and BFCL

ABSTRACT In the context of larger renewable energy harnessing, combining offshore wind farm (OWF) and marine current farm (MCF) at the same location is often found suitable in terms of geographical conditions and economic reasons. However, stochastic nature of wind speed and marine current speed with increased penetration level significantly affects the system stability, grid voltage and raises some control and stability problem; furthermore, the parametric uncertainty of generators brings additional challenges under grid voltage distortion. Therefore, in this article, we present a consolidated application of STATCOM and BFCL in the context of stability assessment of integrated system. Consequently, a robust H∞ loop-shaping controller has been proposed in the presence of parametric uncertainties. In this context, optimizing controller performance with respect to the undesired parametric uncertainties and external disturbances has been proposed. The control effort is initiated by formulating the robust H∞ loop-shaping controller in the context of evaluating the controller parameters and gain with respect to desired robust stability margin. The efficacy of the proposed control scheme is measured through different case studies in real time digital simulation (RTDS) environment. The comparative analysis of simulation results demonstrates the effectiveness of the proposed control strategy in the context of integrated system stability and reliability.

Impact of STATCOM and BFCL on the performance of distance relay and its improvement by adaptive setting for grid‐interactive offshore wind and marine current farm

This study explores the impact of the dynamic impedance of static synchronous compensator (STATCOM) and bridge type fault current limiter (BFCL) on the performance of distance relay and its improvement by adaptive setting for Grid Interactive Offshore Wind and Marine-Current Farm. For assessments, analytical results are presented under different STATCOM settings, low voltage ride through (LVRT) condition, and different types of fault conditions. Moreover, the presence of STATCOM and BFCL significantly changes the apparent impedance characteristic of the studied system. It is also seen that the presence of STATCOM likely to induce an under reach and overreach problem of distance relay. Further, the LVRT capability is significantly affected as STATCOM supplies reactive power to offshore wind generators during a short circuit on the grid side. It is found that the grid integration of OWF and MCF with STATCOM and BFCL is likely to induce mis-coordination and subsequently deteriorate the performance of distance relay, leading to system security problems. Therefore, this study proposed an adaptive setting in order to eliminate the simultaneous influence upon the dynamic impedance due to incorporation of STATCOM and BFCL on the distance relay setting. The simulation results show the efficacy of the proposed adaptive setting.

Optimal Control Strategy for a Marine Current Farm Integrated with a Hybrid PV System/Offshore Wind/Battery Energy Storage System

This paper suggests an automated control technique constructed on the Multi-Objective Particle Swarm Optimization to enhance the operation of a wind farm, a marine power plant and a photovoltaic array with a battery energy storing system. due to changes in PV / wind / tide, and to boost the efficiency of offshore wind farms and marine power stations connected to the battery-powered storage system, with a view to smoothing power production, the aim of projected automatic control strategy is to minimize power fluctuations and voltage variations. The battery energy storage network was used with an optimized demand response strategy based on the real-time pricing model to improve stability and power efficiency, reduce the power fluctuations and variations in bus voltage and address renewable energy generation instability. The multi-objective particle swarm optimization-based energy management programming model would be used to minimize running costs, pollutant emissions, increase the demand response benefits of micro grid operators and, at the same time, meet the load demand constraints from customers of all sorts, such as domestic, commercial and industrial users.

Robust H∞ control for stability assessment in grid‐connected offshore wind and marine current hybrid system

The geographic suitability brings the offshore wind farm (OWF) and marine current farm (MCF) together with their aggregated power fed to grid simultaneously in most relevant energy harnessing infrastructures. However, stability assessment of the integrated system is a major concern due to the integration of stochastic and intermittent sources with parametric uncertainty. Bridge-type fault current limiter (BFCL) has consolidated their application for a suitable enhancement of stability margin for most modern supply systems. In this article, a detailed modelling of the integrated system is carried out in the presence of BFCL along with consideration of uncertainty as well. A robust H∞ controller design strategy for stability assessment of grid-connected OWF and MCF in the presence of parametric uncertainties is presented in this article. Linear matrix inequality (LMI) conditions are derived in the context of evaluating the robust controller gain with respect to desired robust stability margin. The efficacy of the controller design is compared with that of H∞ loop shaping and conventional P-I control through different case studies with simulation followed by real-time digital simulator (RTDS) validation.

Modified Thevenin‐based voltage instability indicator and load shedding approach for MCF connected network

Marine current farm (MCF) equipped with squirrel cage induction generators (SCIGs) influences on the voltage stability of the power network. Thevenin-based voltage instability risk indicator is a simple and local index that can be used for voltage instability prediction from a load or zero injection bus. This indicator is modified to evaluate the voltage stability from MCF bus. In addition, a Thevenin-power flow tracing-based load shedding approach is also presented for preventing voltage instability. The method compares two equivalent Thevenin impedances of the main network and MCF for total active and reactive power calculations. Then, the total values are used for load sharing and load shedding by power flow tracing algorithm. The proposed hybrid method is tested on IEEE 14-bus test system considering different contingencies. The results confirm the capability of the proposed indicator and load shedding approach in timely prediction and proper prevention of voltage instability problems, respectively.

Power system stability enhancement in the presence of renewable energy resources and HVDC lines based on predictive control strategy

The renewable energy resources are increasingly employed as new electric power sources. However, their stochastic and uncertain behavior negatively influences the power system stability. In this paper, a hybrid system composed of PMSG-based wind farm, marine-current farm, and PV has been used to supply the network’s load. These resources have been connected to a nine-bus power system through a line-commutated HVDC link. A new control method has been proposed to enhance the damping characteristics of power system. This method is based on Generalized Predictive Control (GPC) for design of inverter current regulator (ICR) of HVDC link. In this regard, the BAT search algorithm has been employed for obtaining the best solution for the GPC’s objective function. In order to demonstrate the effectiveness of the proposed GPC-BAT method, the simulations using eigenvalue analysis and root-loci technique are presented. For further investigating the efficiency of conducted approach, a PID controller has been designed for controlling the ICR of HVDC link, and the results have been compared with those of GPC-BAT method. The comparisons have been made through a three-phase short circuit fault on the multi-machine power system in MATLAB software. The evaluations clearly show the effectiveness and superiority of the proposed approach.

Power Quality Enhancement of Integrated Grid Connected Off-Shore Wind Farm and Marine Current Farm using Statcom

The objective of this paper is to enhance the Power Quality of Network joined Off-shore Wind Farm (OWF) and Marine Current Farm (MCF) under some non-linear conditions by help of a STATCOM and it is planned utilizing model control hypothesis to contribute powerful damping attributes. Here a PID and an ANN based damping controllers are designed and compared. The system is simulated without STATCOM first and then STATCOM with PID and ANN based controllers are used. The ANN based controller reduces the magnitude of the oscillations far better than the PID controller an also reduce the settling time of the system. From the simulation results we can conclude that the ANN based controller can effectively damp the oscillations than the PID controller and enhances the power quality.

Review of maturing multi-megawatt power electronic converter technologies and reliability modeling in the light of subsea applications

The increasing demand for establishing deep water enhanced oil recovery systems for subsea boosting, power generation, transmission from remote subsea marine current turbine farms, efficient power transmission and operation of subsea dredgers and mining machines requires subsea based power conversion, as the subsea pumps, compressors and turbines need to be operated at varying power and voltage levels. Even though techno-economic studies indicate the absolute need for locating the multi megawatt power electronic converters in subsea, the recorded failure-in-time data of multi megawatt capacity industrial standard power converters are not encouraging. Reliability is the key factor, as subsea breakdowns lead to huge production losses, and system retrieval for repair and maintenance is very costly and time consuming. This paper reviews the present technical maturity of a typical industry standard 6MW capacity 6.6kV 3-level voltage source inverter based power electronic frequency converter, and describes a reliability model in the light of their use in subsea environments. Reliability modeling is done for different possible configurations, with Mean Time Between Failure as the driver. The results presented can be directly used by the system designers to select a suitable configuration based on the Mean Time Between Failure requirements. The results obtained provide confidence that a suitably configured multi megawatt power converter, when used in an oil filled enclosure in a deep water environment, could have an MTBF of more than twenty years.

Comparative Stability Analysis of Offshore Wind and Marine-Current Farms Feeding Into a Power Grid Using HVDC Links and HVAC Line

This paper presents the comparative stability analyzed results of integration of a doubly fed induction generator-based offshore wind farm (OWF), a PMSG-based OWF, and a squirrel-cage induction generator-based marine-current farm (MCF) feeding into a power grid through a high-voltage alternating-current line and two high-voltage direct-current (HVDC) links. One of the HVDC links is based on a voltage-source converter (VSC) while the other is a multiterminal configuration that uses three VSCs at the converter station and a VSC at the inverter station. A power oscillation damping (POD) controller for the MT-HVDC system is designed, and the design steps include the selection for the POD controller based on the total effects on the remaining system. A frequency-domain approach based on a linearized system model using calculated eigenvalues and a time-domain scheme based on a nonlinear system model subject to disturbances are systematically performed to compare the damping characteristics contributed by the three transmission schemes. It can be concluded from the simulation results that the proposed MT-HVDC link is capable of rendering better damping characteristics to stabilize the integrated OWFs and MCF feeding into a power grid under a severe fault than the HVAC line and the VSC-HVDC link.

An Integrated Topology of Hybrid Marine Farm & Wind Farm

Abstract- Renewable energy has been playing an important role to meet power demand and ‘Green Energy’ market is getting bigger platform all over the world in the last few years. In order to meet the increasing demand of electricity and power, integration of renewable energy is getting highest priorities around the world. Wind is one of the most top growing renewable energy resources and it is the most environmental friendly, cost effective and safe among all renewable energy resources available. Another promising form of renewable energy is ocean energy which covers 70 % of the earth. Offshore Wind farm` (OWF) has already become very popular for large scale wind power integration with the onshore grid. Recently, marine current farm (MCF) is also showing good potential to become mainstream energy sources and already successfully commissioned in United Kingdom. An integration of wind and tidal energy represents a new-trend for large electric energy production using offshore wind generators and marine current generators, respectively. This work first focuses on the modeling of fixed speed IG based marine current farm and variable speed DFIG based wind farm. Detailed modeling and control scheme for the proposed system are demonstrated considering some realistic scenarios. The power system small signal stability analysis is also carried out by eigenvalue analysis for marine current generator topology, wind turbine generator topology and integrated topology. The relation between the modes and state variables are discussed in light of modal and sensitivity analyses. The results of theoretical analyses are verified by MATLAB/SIMULINK.

An analysis of subsynchronous resonance in hybrid marine current and wind farms with squirrel cage induction generator

Subsynchronous resonance (SSR) is a well-known phenomenon in series-compensated systems with synchronous generators. With the rapid growth of renewable energy systems, it is likely that with its integration to series-compensated system for the transmission of bulk power may lead to the problem of SSR. This paper conducts an analysis of SSR phenomena in the squirrel cage induction generator-based hybrid wind farm and marine current farm connected to series-compensated system with power variation due to the addition or removal of small turbine units. A dynamic model has been developed to analyse the induction generator effect and torsional interaction of SSR on the IEEE first bench mark model for SSR studies. The eigenvalue analysis was performed on the developed model with MATLAB and the time domain electro magnetic transient simulation performed on DiGSILENT Power Factory confirms the predicted results by the eigenvalue analysis.

Dynamic Stability Improvement of an Integrated Grid-Connected Offshore Wind Farm and Marine-Current Farm Using a STATCOM

This paper presents a control scheme based on a static synchronous compensator (STATCOM) to achieve both voltage control and damping enhancement of a grid-connected integrated 80-MW offshore wind farm (OWF) and 40-MW marine-current farm (MCF). The performance of the studied OWF is simulated by an equivalent doubly-fed induction generator (DFIG) driven by an equivalent wind turbine (WT) while an equivalent squirrel-cage rotor induction generator (SCIG) driven by an equivalent marine-current turbine (MCT) is employed to simulate the characteristics of the MCF. A damping controller of the STATCOM is designed by using modal control theory to contribute effective damping characteristics to the studied system under different operating conditions. A frequency-domain approach based on a linearized system model using eigenvalue techniques and a time-domain scheme based on a nonlinear system model subject to various disturbances are both employed to simulate the effectiveness of the proposed control scheme. It can be concluded from the simulated results that the proposed STATCOM joined with the designed damping controller is very effective to stabilize the studied system under disturbance conditions. The voltage fluctuations of the AC bus subject to the active-power variations of the studied system can also be effectively controlled by the proposed control scheme.

Dynamic stability improvement of an integrated offshore wind and marine-current farm using a flywheel energy-storage system

This study presents a control scheme using a flywheel energy-storage system (FESS) to simultaneously achieve power-fluctuation mitigation and dynamic-stability enhancement of an offshore wind farm (OWF) and marine-current farm (MCF) connected to a power grid. The performance of the studied OWF is simulated by an equivalent aggregated 80-MW doubly-fed induction generator (DFIG), while the characteristics of the studied MCF are simulated by an equivalent aggregated 40-MW squirrel-cage induction generator. A proportional–integral–derivative (PID) damping controller of the proposed FESS which is connected to the common AC bus of the OWF and MCF is designed by using modal control theory to contribute effective damping characteristics to the studied OWF and MCF under different operating conditions. A frequency-domain approach based on a linearised system model using eigenvalue analysis is performed. A time-domain scheme based on a non-linear system model subject to disturbance conditions is also carried out. It can be concluded from the simulation results that the proposed FESS combined with the designed PID damping controller can effectively stabilise the studied OWF and MCF under various disturbance conditions. The inherent power fluctuations injected to the power grid can also be effectively mitigated by the proposed control scheme.

Dynamic Stability Enhancement and Power Flow Control of a Hybrid Wind and Marine-Current Farm Using SMES

This paper presents a control scheme based on a superconducting magnetic energy storage (SMES) unit to achieve both power flow control and damping enhancement of a novel hybrid wind and marine-current farm (MCF) connected to a large power grid. The performance of the studied wind farm (WF) is simulated by an equivalent 80-MW induction generator (IG) while an equivalent 60-MW IG is employed to simulate the characteristics of the MCF. A damping controller for the SMES unit is designed by using modal control theory to contribute effective damping characteristics to the studied combined WF and MCF under different operating conditions. A frequency-domain approach based on a linearized system model using eigen techniques and a time-domain scheme based on a nonlinear system model subject to disturbance conditions are both employed to validate the effectiveness of the proposed control scheme. It can be concluded from the simulated results that the proposed SMES unit combined with the designed damping controller is very effective to stabilize the studied combined WF and MCF under various wind speeds. The inherent fluctuations of the injected active power and reactive power of the WF and MCF to the power grid can also be effectively controlled by the proposed control scheme.

Development of a hydraulic control mechanism for cyclic pitch marine current turbines

Tidal power generation by means of marine current farms is potentially a large renewable energy resource which could be harnessed in many coastal waters. Its availability is highly predictable in time, and the technology promises high energy conversion efficiency along with a relatively low impact on sea life due to its relatively small disturbance of natural tidal flows. A series of devices have so far been proposed and developed for the extraction and conversion of kinetic energy present in tidal flows into useful electrical power [1]. Designs include horizontal axis turbines, vertical axis turbines, and devices with oscillating lift surfaces. Up to date no technology has firmly established itself. This paper describes a novel hydraulic control mechanism designed for vertical-axis marine current turbines of the straight-bladed Darrieus type. It has been found to significantly improve turbine efficiency over conventional Darrieus turbines when operated at low blade tip-speed to tidal-flow-velocity ratios (TSR) and to give the turbine the ability to self-start reliably. The control mechanism enforces a cyclic pivoting motion on the turbine blades as they move around their circular flight-path. The movement of the pitch control is of sinusoidal shape and is continuously variable in amplitude. The blade actuation is powered by the turbine's own rotation and is implemented using a swash-plate mechanism in conjunction with a hydraulic circuit for every blade. For surface piercing turbines, this control mechanism may be remotely positioned in a dry nacelle above sea level. If the appropriate design is applied, this can offer access to the cyclic pitch control mechanism, gearbox and generator, even when the turbine is operational, promising lower maintenance and operating costs compared with submerged systems.