Small Wind Farm Research Articles

Incorporation of fixed speed wind turbine generators in load flow analysis of distribution systems

Small scale wind farms are increasingly being integrated into distribution systems. This paper proposes a simple model of a fixed speed wind farm and incorporates that model into a standard load flow program of a distribution system. For each wind farm, the proposed model augments the size of the network by two buses that allow including all parameters of the generator. For a given wind speed, the mechanical power of the wind turbine is first determined from manufacturer's supplied data and then it is incorporated into one of the new buses as a negative load. This would allow evaluating the load flow results of the system using any standard load flow program without modifying the source codes of the program. The effectiveness of the proposed method is then evaluated on a simple system as well as on two distribution systems consisting of 33 and 69 buses.

The tidal energy potential of the Manukau Harbour, New Zealand

A renewable source of electricity generated near the demand in Auckland might help defer investment in grid infrastructure, avoid grid transmission losses and help achieve the target for renewable energy mix in New Zealand. The tidal energy at both ends of the entrance channel to the Manukau Harbour is calculated based on navigation chart current speed data. Calculation is done using the kinetic energy flux method, and a farm method calculation is used for comparison purposes.The peak current speeds are modest: 1.35 and 1.80m/s. These give estimated extracted electricity results of 7.2 and 7.9GWh/year for flux method and 13.3 and 11.2 GWh/year for farm method. This electricity could supply about 900–1400 New Zealand homes and is similar to the generation output of a small wind farm. Factors affecting feasibility for a future tidal energy project in the Manukau Harbour include New Zealand electricity demand changes, technology maturity, and environmental effects – especially on rare dolphins. The study concludes that the resource is sufficient to support a small-scale distributed generation project after technology costs reduce. A strong case is made for investment in another more detailed study in 2017.

An assessment of the optimal level of feed-in tariffs in Ukraine

In this work, an assessment of the optimal level of feed-in tariffs in Ukraine was carried out. One of the purposes of the study was to see whether the existing tariffs are sufficient for business operation and attractive to investors. Important assumptions on the economics of renewable energy projects were made. The results indicate that the current level of feed-in tariffs in Ukraine is sufficient for medium and large wind projects, rooftop solar power plants, rehabilitated small hydropower projects and biogas-derived electricity. Feed-in tariff rates are high enough to attract new investors and compensate for the high risk of doing business in Ukraine. If governmental policies aim to enhance power generation by households, the feed-in tariff rates should be differentiated from those for small wind farms and photovoltaic systems.

Residual Generator Fuzzy Identification for Wind Farm Fault Diagnosis

In the recent years the wind turbine industry has focused on optimising the cost of energy. One of the important factors in the achievement of this task consists of increasing the reliability of the wind turbines, which can be obtained using advanced fault detection and isolation strategies. Clearly, most faults are managed quite easily at a wind turbine control level. However, some faults are better dealt with at wind farm level, when the wind turbine is located in a wind farm. This paper aims at proposing a fault detection and isolation solution with application to a wind farm benchmark model. The considered benchmark includes a small wind farm of nine wind turbines, based on simple models of wind turbines, as well as the wind and interactions between wind turbines in the wind farm. The solution relies on a set of piecewise affine Takagi–Sugeno models, which are identified from the noisy measurements acquired from the simulated wind park. The design of the fault isolation strategy is also enhanced by the use of the proposed fuzzy approach. Finally, the wind park simulator is exploited for validating the achieved performances of the suggested methodology.

The role of NIMBY in opposing the siting of wind farms: evidence from Greece

This paper aims to assess the relative importance of a NIMBY (‘Not-In-My-Back-Yard’) stance on an individual's opposition to the siting of a wind farm vis-à-vis other predictors, such as perceived effects (costs, risks and benefits associated with the project), perceived fairness of the siting decision and societal trust. Data originate from two case studies, a small wind farm of just two wind turbines in southern Greece and a mega-project of 153 turbines on the Greek island of Lesvos (aggregate N = 334). We use structural equation modelling (SEM) for testing the theoretically-suggested relations between the various constructs. We find that NIMBY is not the most important predictor of opposition while it is strongly correlated with other predictors, such as the perceived unfairness of the siting decision as well as the risks and costs associated with the wind farm. These latter findings undermine the common-sense idea that wishing a wind farm out of one's vicinity (‘Not-In-My-Back-Yard’) is an example of mere ‘free-riding’. Since the fit of the SEM models was found to be moderate, we discuss the limitations of our study and the implications of our findings as well as suggesting pathways for future research.

Estimation of bird and bat mortality at wind‐power farms with superpopulation models

Summary Collision of birds and bats with turbines in utility‐scale wind farms is an increasing cause of concern. Carcass counts conducted to quantify the ‘take’ of protected species need to be corrected for carcass persistence probability (removal by scavengers and decay) and detection probability (searcher efficiency). These probabilities may vary with time since death, because of intrinsic changes in carcass properties with age and of heterogeneity (preferential removal of easy‐to‐detect carcasses). In this article, we describe the use of superpopulation capture–recapture models to perform the required corrections to the raw count data. We review how to make such models age specific and how to combine trial experiments with carcass searches in order to accommodate the fact that carcasses are stationary (which affects the detection process). We derive information about optimal sampling design (proportion of the turbines to sample, number of sampling occasions, interval between sampling occasions) and use simulations to illustrate the expected precision of mortality estimates. We analyse data from a small wind farm in New Jersey, in which we find the estimated number of fatalities to be twice the number of carcasses found. Synthesis and applications. Our approach to estimation of wind farm mortality based on data from carcass surveys is flexible and can accommodate a range of different sampling designs and biological hypotheses. Resulting mortality estimates can be used (1) to quantify the required amount of compensation actions, (2) to inform mortality projections for proposed wind development sites and (3) to inform decisions about management of existing wind farms.

Wind farm layout optimization using genetic algorithm with different hub height wind turbines

Layout optimization is one of the methods to increase wind farm’s utilization rate and power output. Previous researches have revealed that different hub height wind turbines may increase wind farm’s power output. However, few researches focus on optimizing a wind farm’s layout in a two-dimensional area using different hub height wind turbines. In this paper, the authors first investigate the effect of using different hub height wind turbines in a small wind farm on power output. Three different wind conditions are analyzed using nested genetic algorithm, where the results show that power output of the wind farm using different hub height wind turbines will be increased even when the total numbers of wind turbines are same. Different cost models are also taken into account in the analysis, and results show that different hub height wind turbines can also improve cost per unit power of a wind farm. At last, a large wind farm with commercial wind turbines is analyzed to further examine the benefits of using different hub height wind turbines in more realistic conditions.

Assessment of wind power Potential at Zeway, Central Rift Valley

Wind is one of the renewable resources in Zeway which is unexploited. This paper presents a number of issues related to the Assessment of wind energy resource based on 16 years longterm measured data of daily wind speed and direction, 3-hourly measured wind data at 10 m height, which are obtained from meteorological station and Analysis carried out By using Rayleigh stastical Analysis for wind data analysis and Matlab software used for data acquisition. This study indicates that Zeway, has energy potential available with the maximum and minimum average wind speed respectively, 4.9 m/s and 1.5 m/s and average wind power density also varies with maximum and minimum values respectively, 68.6 w/m and 0.0 w/m and the Results suggested that wind energy must be encouraged, promoted, invested, implemented, and demonstrated, but especially for small Wind farm. Key Wordswind speed and direction, Rayleigh probability density, power density, wind speed probability curve, Zeway.

A Design Fuzzy Logic Controller for a Permanent Magnet Wind Generator to Enhance the Dynamic Stability of Wind Farms

In this paper, a design fuzzy logic controller for a variable speed permanent magnet wind generator connected to a grid system through a LC-filter is proposed. A new current control method of grid side conversion is developed by integrating the fuzzy controller, in which both active and reactive power, delivered to a power grid system, is controlled effectively. The fuzzy logic controller is designed to adjust the gain parameters of the PI controllers under any operating conditions, so that the dynamic stability is enhanced. A new simple method, based on frequency response of the bode diagram, is proposed in the design of the fuzzy logic controller. To evaluate the controller system capabilities, simulation analyses are performed on a small wind farm model system including an induction wind generator connected to an infinite bus. The simulations have been performed using PSCAD/EMTDC. Simulation results show that the proposed control scheme is more effective for enhancing the stability of wind farms during temporary and permanent network disturbances and randomly fluctuating wind speed, compared with that of a conventional PI controller.

A new control strategy for small wind farm with capabilities of supplying required reactive power and transient stability improvement

Abstract This paper presents a new control strategy for a small scale wind farm which is composed of both fixed and variable speed wind turbine generator systems. Fixed speed wind generators (FSWGs) are largely dependent on reactive power, so they require large reactive power when a short circuit fault occurs in the power system. Otherwise the FSWGs become unstable and have to be disconnected from the power system. In this paper, a new wind farm topology is considered, where series connected fixed speed WTGs are installed with variable speed wind turbine (VSWT) driven by doubly fed induction generators (DFIGs). A new direct power control (DPC) strategy based on discrete space vector modulation (DSVM) technique is applied for DFIG-based wind turbine system. No extra power or current control loops are required, simplifying the system design and improving transient performance. Simulation results clearly show that the proposed topology is a cost effective solution and simplified system design to minimize voltage fluctuation of both fixed and variable speed WTGs as well as to improve the transient stability of the wind farm.

Systemic assessment and analysis of factors affect the reliability of a wind turbine

Nowadays, the availability of wind turbines usually approaches the 98%. The objective is to increase the turbines availability, by improving the wind turbine reliability especially for offshore plants. The wind turbines reliability is a pivotal factor in the successfully function of a wind power plant. High reliability can be achieved by understanding and minimizing the failures of the system. Maintenance planning could make maintenance more efficient and could lead to a reduction of failure events. In order to decide the most effective maintenance strategy, it should be identified the most critical components of the wind turbines, which are prone to failures. The maintenance strategy should take into both the reliability improvement and the reduction of maintenance cost. Moreover, it is essential to determine and record the main cause that provokes the failure event. The data logging and statistical processing of failure information could improve the reliability of the system components. A wind turbine is a complex power generating system consisting of several structural, electrical and mechanical components. Its efficiency depends largely on its reliability level. In the present study, the factors that affect the reliability of a wind turbine are presented, as well as the analytical way of calculating its reliability. The reliability analysis of the wind turbine is based on the systemic approach of the wind turbine subsystems, as its total reliability depends directly on the reliability of the subsystems. Moreover, it is based on a technical analysis of the reliability of complex systems. The model used is the Fault Tree Analysis (FTA), which is an identification method for probable causes of system failure. The relation of reliability, maintainability and availability is also presented and explained by the example of a small wind farm.

Presence of harbor porpoises near a pile driving site and modeling of cumulative acoustic effects.

The construction of the a small wind farm in the southern North Sea has just been completed. Possible effects on harbor porpoise (Phocoena phocoena) distribution and habitat use caused by the pile driving impulses emitted during the installation of the foundations for 12 offshore wind turbines (OWTs) were assessed by ship surveys, aerial surveys, and static acoustic monitoring (SAM). SAM data and sighting data revealed that during the pile driving activities for the construction of the transformer platform as well as for the first OWTs the presence of harbor porpoises decreased significantly. However, the number of porpoise detections by the SAM units increased during the pile driving activities toward the end of the construction period. Habituation, ecological parameters, and external effects are considered as potential reasons for this increased presence of harbor porpoises in the vicinity of the construction site. The cumulative acoustic energy received by the animals exposed to repeated pile driving i...

Incorporating Community Governance: Planning Sustainable Energy Security

Climate change has focussed global attention on reducing greenhouse gas (GHG) emissions, particularly through energy eficient technological innovation. In Australia energy policy incentives include increasing the contribution of renewable energy sources along with energy eficient behaviours. InWestern Australia an Energy Utility has embraced the principle of community engagement to inform corporate strategies toward sustainable green energy visions. This paper evaluates the process of citizen involvement in promoting community acceptance of green energy technologies at the community level. This qualitative study examines the role of community governance in planning the sustainable energy needs of regional communities. While it is promising to observe the emergence of lexible institutional responses to community energy visions, this energy governance network is a work in progress as it struggles to gain community consensus to site a small community-owned wind farm. To address community polarisation over the costs and beneits of community energy, attention must be paid to issues of inclusive representation along with mechanisms of accountability that assesses the social and economic impacts of green energy initiatives. This study highlights that an effective governance process would incorporate the principles of sustainability, procedural and distributive justice to enhance community transitions toward a more environmentally benign economy and electricity system.

Wind characteristics and mapping for power production in the Island of Lesvos, Greece

This study investigated the wind characteristics of the island of Lesvos, Greece, with the objective of providing the necessary data for identifying the wind power production capabilities of the island. Weather patterns were examined using weather data from four Remote Automatic Weather Stations. Specific tools were used to produce the necessary windroses, Weibull curves and charts that helped to understand the prevailing wind characteristics. By using the tools of Geographic Information Systems (GIS) and the Wind Atlas Analysis and Application Program (WAsP) as the basic calculation platform, a wind map was produced portraying the wind speeds that prevail at a height of 10 m above ground level. The results of the analysis were tested and evaluated with measurements from 15 wind turbine sites by creating six alternative scenarios. The optimum scenario was used to investigate the installation of a small wind farm with five wind turbines, of 3 MW total capacity.

A Variable Speed Wind Turbine Control Strategy to Meet Wind Farm Grid Code Requirements

This paper presents a new operational strategy for a small scale wind farm which is composed of both fixed and variable speed wind turbine generator systems (WTGS). Fixed speed wind generators suffer greatly from meeting the requirements of new wind farm grid code, because they are largely dependent on reactive power. Integration of flexible ac transmission systems (FACTS) devices is a solution to overcome that problem, though it definitely increases the overall cost. Therefore, in this paper, we focuses on a new wind farm topology, where series or parallel connected fixed speed WTGSs are installed with variable speed wind turbine (VSWT) driven permanent magnet synchronous generators (PMSG). VSWT-PMSG uses a fully controlled frequency converter for grid interfacing and it has abilities to control its reactive power as well as to provide maximum power to the grid. Suitable control strategy is developed in this paper for the multilevel frequency converter of VSWT-PMSG. A real grid code defined in the power system is considered to analyze the low voltage ride through (LVRT) characteristic of both fixed and variable speed WTGSs. Moreover, dynamic performance of the system is also evaluated using real wind speed data. Simulation results clearly show that the proposed topology can be a cost effective solution to augment the LVRT requirement as well as to minimize voltage fluctuation of both fixed and variable speed WTGSs.

Distributed small-scale wind in New Zealand: Advantages, barriers and policy support instruments

If future climate change goals being negotiated internationally are to have any chance of being achieved, developed countries need to undertake a major transition in their energy systems. This will require a rapid expansion of renewable energy generation, including wind electricity. Wind energy in New Zealand is commercially viable in many cases, yet opportunities for its exploitation are far from fully utilised. Many communities are showing resistance to wind farm developments, since large wind farms are often seen as intrusive. Building wind farms on a small scale may be a useful way of overcoming this problem. This study examines the pattern of recent wind industry development in New Zealand. It is argued that two key characteristics have emerged that are limiting the potential development of the industry: a trend towards large scale, leading to increased local opposition; and a small number of investors. Research methods include a review of international and local literature, and a rural mail survey questionnaire, with 338 respondents. We provide survey evidence that small wind farms, and community ownership of them, may be attractive to local communities, and that this point of advantage is helpful for the rapid expansion of wind generation in New Zealand.

Assessment of Condition Monitoring Techniques for Offshore Wind Farms

This paper discusses the results of an extensive investigation to assess the added value of various techniques of health monitoring to optimize the maintenance procedures of offshore wind farms. This investigation was done within the framework of the EU funded Condition Monitoring for Offshore Wind Farms (CONMOW) project, which was carried out from 2002 to 2007. A small wind farm of five turbines has been instrumented with several condition monitoring systems and also with the “traditional” measurement systems for measuring mechanical loads and power performance. Data from vibration and traditional measurements, together with data collected by the turbine’s system control and data acquisition (SCADA) systems, have been analyzed to assess (1) if failures can be determined from the different data sets; (2) if so, if they can be detected at an early stage and if their progress over time can be monitored; and (3) if criteria are available to assess the component’s health. Several data analysis methods and measurement configurations have been developed, applied, and tested. This paper first describes the use of condition monitoring if condition based maintenance is going to be applied instead of only scheduled and corrective maintenance. Second, the paper describes the CONMOW project and its major results, viz., the assessment of the usefulness and capabilities of condition monitoring systems, including algorithms for identifying early failures. Finally, the economic consequences of applying condition monitoring systems have been quantified and assessed.

Comparison of Wake Model Simulations with Offshore Wind Turbine Wake Profiles Measured by Sodar

Abstract This paper gives an evaluation of most of the commonly used models for predicting wind speed decrease (wake) downstream of a wind turbine. The evaluation is based on six experiments where free-stream and wake wind speed profiles were measured using a ship-mounted sodar at a small offshore wind farm. The experiments were conducted at varying distances between 1.7 and 7.4 rotor diameters downstream of the wind turbine. Evaluation of the models compares the predicted and observed velocity deficits at hub height. A new method of evaluation based on determining the cumulative momentum deficit over the profiles is described. Despite the apparent simplicity of the experiments, the models give a wide range of predictions. Overall, it is not possible to establish any of the models as having individually superior performance with respect to the measurements.

Analysis of state of MV distribution system before and after connection of small wind farm Ravna1

In the last two decades, the number of installed wind turbines has grown rapidly all over the world. This was due to the huge improvement in technology and increased interest in using wind energy as an important energy source in the future. Following this worldwide trend, the first small wind farm in Croatia named Ravna1 was installed on the Pag Island. To check its influence on local distribution network, power quality measurements have been made in different points in the network before and after the connection of the small wind farm. In parallel, simulation of the distribution network with its connection to 110 kV network was made, and power flow and voltage analysis were made for cases of network with and without wind farm connected. Analyses were made to check the influence of the connection of the wind park on the relatively weak island network, and were made with different power outputs of wind turbines. Calculated values of power flows and values of voltages in the network match very well with measured ones. Also, measurements show that connection of small wind farm does not affect power quality on the Pag Island distribution network.

An overview of marine renewables in the UK: a synopsis of Michael Hay's presentation

An overview of marine renewables in the UK: a synopsis of Michael Hay's presentation