High Wind Potential Research Articles

Forecasting the probability of commercial wind power development in lagging countries

There is significant under-utilization of wind energy resources, particularly in countries that have high wind potential. From the 67 highest wind potential countries, 39 have installed less than 500 ​MW of wind power capacity, while the remaining countries have an average installed capacity of 20,596 ​MW. In the lagging countries, there is significant potential for sustainable value creation, however large investment gaps need to be closed. Entering a new market for wind power Original Equipment Manufacturers is complex and requires a prediction of the future market size. Quantitative research to promote wind power internationalization is scarce. The objective of this paper is therefore to estimate the market size by predicting the probability of commercial wind development in the lagging countries. The purpose is to help the Original Equipment Manufacturers in their market entry decisions. The second purpose is to provide an example how to reduce risk required to close the Sustainable Development Goals financing gap. Using a binary logistic regression model based on technological path creation theory, the probability for the 39 lagging countries to enter the wind power commercialization stage was predicted. Results show that 12 of the lagging countries have a high probability to commercialize wind energy. A new simulation-based approach was presented to stimulate wind power market entry. The prediction of adoption probability proves useful to reduce risk required to close the financing gap to achieve the Sustainable Development Goals. • 58% of highest wind potential countries did not reach commercial wind exploitation. • Novel method to estimate probability to enter commercialization stage is presented. • 4 different wind industry market entry and development strategies are proposed. • The developed method de-risks wind power market entry, reduces SDG financing gap. • Simulation-based approach to stimulate wind industry market entry is presented.

Potential assessment of renewable energy resources and their power plant capacities in Iran

AbstractToday, most developed and developing countries utilize renewable energy to meet their needs. The use of renewable energy prevents environmental pollution. A concern of the governments is to deal with environmental pollution. In this paper, the types of renewable energy used in electricity generation in Iran have been studied. Studies show that during the last 20 years, 1.5% of the amount of electricity produced in Iran is supplied by renewable energy. Iran also has a much greater potential for utilizing renewable energy. By 2020, Iran has a potential of 42000 MW use of renewable energies. However, the capacity of renewable power stations constructed in Iran is 800 MW. Different regions of Iran have high wind, solar and geothermal energy potential, which unfortunately has not been used enough to meet industrial needs.

Design, dynamic simulation, and optimal size selection of a hybrid solar/wind and battery-based system for off-grid energy supply

Remote energy systems are applicable, especially in critical circumstances like earthquakes, floods, etc. Besides, renewable energy systems are suitable energy sources in remote areas. Therefore, Due to high solar and wind potential and its location as an earthquake-prone, a solar-wind energy system for a remote application on a Conex is presented in this study. Considered wind turbines have power production of 1 kW and 3 kW. PV panels have an efficiency of about 20%. This Conex has 12 m2 of the area and resides three to five people and supplies 520 W power consumption of equipment except for the HVAC unit. A considered lifetime of the Conex is 20 years. The considered capacity of batteries is about 100–200 Ah. Six cities are selected as representatives of the six major climate types in Iran. The studied system is optimized for each city. The heating and cooling demand of Conex in cities are specified using TRNSYS software. The heat pump's electricity requirement as a cooling and heating unit with COP of four, lighting (20 W), laptops (140 W), and refrigerators (360 W) is calculated for Conex in each city. Mixed-integer linear programming is employed to optimize an off-grid renewable energy system to supply this electricity demand. The system's total cost, which includes the initial and O&M cost of PV panels and wind turbines, and the capital and replacement cost of the batteries together with the loss of power supply probability during a year, are considered two objective functions. The interest rate is assumed to be 15%. Achieved results show that Iran's solar and wind potential can balance the required load of the Conex with a probability of power outage as low as 1% of a year. However, there is a variance in the cost of the required renewable energy system for supplying Conex power consumption for different climate zones: in the Mediterranean region, the system costs 500–5000 $ as the most expensive one, and in the hot coastal dry region, it costs 900 $-2000 $ as the most cost-efficient region. Finally, results show that wind turbines can be cost-effective energy suppliers for most considered climates, especially considering O&M costs. This study can fill the gap of requiring off-grid temporary portable residences in different climates after disasters, which destroy buildings. Therefore, the lack of these temporary residences can be supplied without adding greenhouse gases to the environment, which reduces greenhouse emissions and electrical grid dependence of the building sector.

Арктическая ветродизельная электростанция с интеллектуальной системой автоматического управления

The main problem faced in supplying power to remote consumers is that there are high logistical costs of delivering fuel and equipment for diesel power plants, poor density of transport infrastructure and, as a consequence, a high cost of fuel. There are also high operating costs at diesel power plants and specific fuel consumption; in addition, there is no monitoring and control automation. In view of a high wind potential of the Arctic territories, energy complexes and systems can be effectively modernized and constructed on the basis of modular wind-diesel power plants with an intelligent control system. A concept of and hardware solutions for an intelligent automatic control system are proposed, the use of which makes it possible to maximize the amount of electricity generated by renewable sources owing to dynamically redistributing the power between the hybrid energy complex components and, as a result, to minimize fuel consumption. An analysis of a controlled wind-diesel power plant has shown that by using an intelligent automatic control system, forecasting the electricity generation by a wind power plant, and arranging storage battery operation in a cyclic mode, it becomes possible to effectively cover the load schedule of an autonomous consumer and increase the extent of diesel fuel substitution by up to 60 % or more.

Optimal Capacity and Location Wind Turbine to Minimize Power Losses Using NSGA-II

Voltage deviations and power losses in the distribution network can be handled in various ways, such as adding diesel power plants and wind turbines. Adaut Village, Tanimbar Islands Regency, Maluku Province has installed a diesel power plant with a capacity of 1,200 kW, while the average hourly electricity load is 374.9 kW. Adaut Village has high wind potential that can be used for distributed generations namely wind turbine (WT). WT can be used to improve power quality in terms of power losses and voltage deviations. In adding WT, the capacity and location must be determined to get good power quality in terms of power loss and voltage deviation. The research applied an optimization technique for determining the capacity and location of WT using non-dominated sorting genetic algorithm II (NSGAII) with an objective function of power losses and voltage deviation. In addition, the economic aspects of the power plant were calculated using the levelized cost of energy (LCOE). The research used scenarios based on the number of WT installed. The best results were obtained in scenario IV or 4 WT with 1.38 kW on Bus 2, 422.43 kW on Bus 15, 834.33 kW on Bus 30, and 380.81 kW on Bus 31 which could reduce power losses by 80% with an LCOE value of Rp7,113.15/kWh. The addition of the WT could also increase the voltage profile to close to 1 pu, which means it can minimize the voltage deviation in the distribution network.

Optimal site selection for wind energy: a case study

ABSTRACT Renewable energy sources (RES) have gained attraction in recent years. The optimal site selection problem is one of the most important problems in the area of RES. In this study, the optimum site selection problem for wind energy, which is one of the RES types, is discussed. Eighty-one provinces in Turkey are evaluated using the Pareto diagram and the provinces with high potential wind energy are obtained. Long-term electricity consumption estimates are performed for the 13 provinces using ARIMA and Time Series Analysis methods. Also, in the article, an integrated optimum site selection problem in GAMS 23.5 software is modeled by the predicted future energy demand. As a result of the study, the total 41 installation decisions are made for the strategic optimal site selection decision between 2021 and 2025 years. Minimizing the total cost proposed as an objective function of the developed mathematical programming model, the total cost is found as 52526500 currency unit. It is seen that the decision to install the power plant is mostly made for Balıkesir, Çanakkale and İzmir, and the number of plants for the provinces are 6, 6 and 5, respectively. The computational results show that the developed model produces effective solutions and minimizes the total cost by focusing on strategic optimal site decisions. According to the sensitivity analysis results, increasing the percentage of use in wind energy approximately 4–5% from 3.5% in total percentage will reduce the total cost by approximately 3.62%.

Performance Enhancement of Proposed Namaacha Wind Farm by Minimising Losses Due to the Wake Effect: A Mozambican Case Study

District of Namaacha in Maputo Province of Mozambique presents a high wind potential, with an average wind speed of around 7.5 m/s and huge open fields that are favourable to the installation of wind farms. However, in order to make better use of the wind potential, it is necessary to evaluate the operating conditions of the turbines and guide the independent power producers (IPPs) on how to efficiently use wind power. The investigation of the wind farm operating conditions is justified by the fact that the implementation of wind power systems is quite expensive, and therefore, it is imperative to find alternatives to reduce power losses and improve energy production. Taking into account the power needs in Mozambique, this project applied hybrid optimisation of multiple energy resources (HOMER) to size the capacity of the wind farm and the number of turbines that guarantee an adequate supply of power. Moreover, considering the topographic conditions of the site and the operational parameters of the turbines, the system advisor model (SAM) was applied to evaluate the performance of the Vestas V82-1.65 horizontal axis turbines and the system’s power output as a result of the wake effect. For any wind farm, it is evident that wind turbines’ wake effects significantly reduce the performance of wind farms. The paper seeks to design and examine the proper layout for practical placements of wind generators. Firstly, a survey on the Namaacha’s electricity demand was carried out in order to obtain the district’s daily load profile required to size the wind farm’s capacity. Secondly, with the previous knowledge that the operation of wind farms is affected by wake losses, different wake effect models applied by SAM were examined and the Eddy–Viscosity model was selected to perform the analysis. Three distinct layouts result from SAM optimisation, and the best one is recommended for wind turbines installation for maximising wind to energy generation. Although it is understood that the wake effect occurs on any wind farm, it is observed that wake losses can be minimised through the proper design of the wind generators’ placement layout. Therefore, any wind farm project should, from its layout, examine the optimal wind farm arrangement, which will depend on the wind speed, wind direction, turbine hub height, and other topographical characteristics of the area. In that context, considering the topographic and climate features of Mozambique, the study brings novelty in the way wind farms should be placed in the district and wake losses minimised. The study is based on a real assumption that the project can be implemented in the district, and thus, considering the wind farm’s capacity, the district’s energy needs could be met. The optimal transversal and longitudinal distances between turbines recommended are 8Do and 10Do, respectively, arranged according to layout 1, with wake losses of about 1.7%, land utilisation of about 6.46 Km2, and power output estimated at 71.844 GWh per year.

Benefits of Energy Storage Systems for Small-Scale Wind Farm Development in Latvia

Abstract The paper covers the main aspects and restrictions on siting small-scale wind farms in Latvia and benefits of using energy storage systems with small-scale wind farms. The restrictions of siting have been analysed. Grid connection restrictions are addressed as the main issues for small-scale wind farm development in Latvia. Two small-scale wind farm models with similar properties have been made and analysed within the framework of the research. The paper proposes the idea for maximising the production of small-scale wind farm in a small area site with high wind potential.

Hybrid Photovoltaic-Wind Microgrid With Battery Storage for Rural Electrification: A Case Study in Perú

Microgrids are autonomous systems that generate, distribute, store, and manage energy. This type of energy solution has the potential to supply energy to remote communities since they can integrate solar, wind, and back-up diesel generation. These systems are potentially beneficial in Peru, where there are approximately 1.5 million people without access to electricity. This paper studies the technical aspects of the implementation, operation, and social impact of a hybrid microgrid installed in Laguna Grande, Ica, Peru, a rural fishing community composed of about 35 families who have lived in this remote location for more than 40 years without access to electricity. The design of the microgrid comprised three main stages: assessment, sizing, and social management. According to resource assessment, this location has a very high wind potential with an average of 8 m/s and annual average irradiation of 6 kWh/m2/day. The microgrid was designed based on interviews with members of the community on energy use, social-economic aspects, and factors such as expected growth and available funds. The construction followed a participatory approach, involving the community in specific stages of the project. This hybrid microgrid is composed of a 6 kWp photovoltaic system and two wind turbines of 3 kW each. It has two coupled 4 kW inverters that deliver power to a 230 V AC distribution line to which all the community loads are connected. Energy is stored using a VRLA 800 Ah, 48 V battery bank, which is designed to work at 50% DOD. The installed microgrid has proven very effective in supplying the average daily demand of 23 kWh at an almost steady power of 1–1.2 kW. During almost 2 years of monitoring, it has presented a 10% loss of load due to peak increases in demand, technical problems, and occasional low solar and wind resources. PV/wind integration is very important since approximately 60% of the energy demand is nocturnal. The CAPEX of the project reached USD 36,000.00, obtaining a cost of energy levelized cost of energy of 0.267 USD per kWh. The project has a useful life of 20 years, with battery renewal every 3 years and wind turbines and electronics every 10.

Statistical study of wind speed variations by Weibull parameters for Socotra Island, Yemen

According to the International Energy Agency (IEA-2013), Electricity alone does not create all the conditions for socioeconomic growth, but it is obviously essential to meet basic human needs and facilitate the development of economic activities. For the isolated areas with high wind potential and the island suffering from the electrification problems, the prospective solution is the use of renewable energies, especially wind energy. The present paper deals with a detailed statistical study on wind energy, its parameters, and variables on Socotra Island in Yemen, where that island is isolated from the main electricity grid in addition to the difficulty of providing electrical energy to this region in light of conditions in which Yemen has been living in recent times. The simulation results prove that the mean wind speed can reach a value ranging from 8.36 to 10.36 m/s, which is a large and enough speed to generate electricity using turbine farms. Based on the k and c Weibull parameters, the maximum probability at speeds 3 and 4 m/s is 0,052, while a value of 0,085 at speed 7 m/s is given by Rayleight distribution. Every result proved that Yemen has a good wind energy potential can utilize it for electrical energy production, and that strengthens the planning of economical wind turbines capacity for electricity production in the region.

Estimation of wind speed and energy potential by atmospheric model for day-ahead market and wind power plants in Turkey

The requirement for energy has expanded day by day due to excessive consumption, developing technology, and population growth, especially after the Industrial Revolution. Since the investments for promoting renewable energy sources, The Turkish energy sector has been progressing in the way of renewable energy. This inevitable change in the energy sector and variable power generation values in wind energy directly affect the energy markets. Accompanying with the structural transformation of the energy sector, Turkey had launched the Day-Ahead electricity marketing system in December 2011. The price per megawatt-hour is determined on the open market by the supply and demand. Hatay province was selected in this study because of its highest wind potential. Temperature and wind speed values, observed in Hatay Samandağı for October 2019, were determined. The data was configured with The Weather Research and Forecasting Model. The results indicate that the wind speed at high altitudes could reach above 7 meters per second on Turkey’s eastern Mediterranean coast, Hatay. The results were compared with the real-time data, and the error rates were determined. In the selected region, the electrical energy values generated using the model results were calculated the day before.

An Optimization Framework for Solving Integrated Planning and Scheduling Problems for Dense Energy Carriers

Abstract Due to rapid population growth, the global demand of energy and water resources are accelerating. Simultaneously, there is a global trend to transition to renewable energy systems. Recently, researchers have begun to investigate how green dense energy carriers (DECs) can be apart of this transition. In this work, we present an optimization framework for solving large-scale supply chain problems and we apply it to explore the economic and environmental impacts of DECs. Specifically, we look at utilizing DECs to transport renewable energy produced in areas with high solar and wind potentials to regions with low renewable potential. To reduce the computational burden of the large-scale optimization problem, we have developed a greedy randomized adaptive search procedure (GRASP). The GRASP leverages the linear programming (LP) relaxation of the problem to generate feasible solutions. We have found that the GRASP is able to reduce the computational time by approximately two orders of magnitude as compared to a commercial grade mixed-integer linear programming (MILP) solver ran out-of-the-box on large-scale instances.

Assessment of wind and hydropower potential of Bukhara region

This article presents a methodology for assessing the gross, technical and economic potential in the territory of the Bukhara region. Locations with high wind and hydropower potential were identified in the region, and the introduction of wind and micro-hydroelectric power plants was analyzed. According to the results of the study, the importance of wind and hydropower in the development of the socio-economic sphere of remote areas of the Bukhara region was studied.

Early development of a shaftless horizontal axis wind turbine for generating electricity from air discharged from ventilation systems

The air discharged from ventilation systems is a high potential wind resource for generating electricity in countries where wind speed is unreliable or weak, such as in Thailand. The air discharged from ventilation systems produces consistent and high-speed wind when benchmarked against natural wind. However, the limitations of conventional wind turbines are that they have negative impacts on the ventilation system and are inconvenient to install in many areas. The innovative shaftless horizontal axis wind turbine (SHWT) introduced in this article has been designed to close the gap between the wind source and the conventional wind turbines in this process. The concept design shows how it could be mounted next to sources of waste wind, requiring only a small space for installation. An open hole is provided to enable airflow to be discharged into the environment. This SHWT has high market potential for utilizing man-made wind to generate electricity from an alternative source which supports sustainable energy development. The purpose of this study is to demonstrate the concept design of a prototype SHWT used for energy recovery from the discharged air of a ventilation system. How the rotor and stator design of the SHWT optimize wind turbine performance and minimize the negative effects on the ventilation system efficiency are also addressed in this study. The performance of the SHWT is demonstrated in a lab-scale test using the type of propeller fan that is generally applied in many sectors in Thailand. The results showed that the SHWT was successful in generating electricity and produced minimal negative effects on the ventilation system's performance. The maximum power output of the prototype SHWT is 7.4 W at a rotational speed of 1644 rpm using eight sets of magnets and 5.1 m/s wind speed. The maximum wind turbine efficiency is 51%. However, it still requires further optimization to enhance the SHWT performance.

Multi‐criteria analysis and Geographic Information Systems methods for wind turbine siting in a North Aegean island

AbstractThe need for energy independence of small remoted islands, promote the exploration of renewable energy sources. Greek islands have rich wind potential and subsequently, the attention is being drawn to the use of wind turbines to meet their energy needs. However, the optimal location of wind turbines installation is the basis for the exploitation of high wind potential in combination with the current legislation framework. This paper presents a combined use of Multi‐Criteria Decision‐Making (MCDM) and Geographic Information Systems (GIS) for the evaluation of eligible sites for wind turbine installation in North Aegean island, in Greece. Criteria weights are estimated for three scenarios using the Analytic Hierarchy Process (AHP) for the illustration of the impact on the final design. The minimum distance from the main settlement of the island constitutes an extra constraint for the investigation of the capability of installing wind farms with the lowest possible energy losses due to power transmission via cables. In all scenarios, the prohibited zone corresponds to 27.9% of the total area of the island. Also, sites with high wind potential can be combined with lower altitudes and can give even more suitable locations for installation, reducing, thus, the installation cost. Economic‐oriented scenario appears to combine both low cost and larger surface area for installation. A sensitivity analysis is performed, for determining the impact of the criteria on the suitability of a site. It seems that new suitability maps are affected greater by the type of the chosen criterion rather than the weight.

Platform Optimization and Cost Analysis in a Floating Offshore Wind Farm

Floating offshore wind represents a new frontier of renewable energies. The absence of a fixed structure allows exploiting wind potential in deep seas, like the Atlantic Ocean and Mediterranean Sea, characterized by high availability and wind potential. However, a floating offshore wind system, which includes an offshore turbine, floating platform, moorings, anchors, and electrical system, requires very high capital investments: one of the most relevant cost items is the floating substructure. This work focuses on the choice of a floating platform that minimizes the global weight, in order to reduce the material cost, but ensuring buoyancy and static stability. Subsequently, the optimized platform is used to define a wind farm located near the island of Pantelleria, Italy in order to meet the island’s electricity needs. A sensitivity analysis to estimate the Levelized Cost Of Energy is presented, analyzing the parameters that influence it most, like Capacity Factor, Weighted Average Capital Cost (WACC) and number of wind turbines.

Analysis levelized cost of energy from the perspective of an power purchase agreements for airborne wind power technology

With the need to diversify the national electric matrix to expand the generation capacity, the searches for new technologies capable of contributing to supply the national demand are fundamental. In this sense, the development of wind energy technology, but specifically high-altitude wind energy using wired airfoils, is an attractive possibility, given the high national wind potential. This research aimed to analyze the cost models used in the literature to assess the leveled cost of energy (LCOE) from the perspective of an power purchase agreements (PPAs) and to simulate the leveled cost of energy for a wind farm with the innovative technology of wired airfoils. For this, we chose two cities Fortaleza (CE) and Florianópolis (SC) to carry out the simulations. The wind farms are identical, with the same number of wind turbines, the parameters that have been modified are, the amount of energy supplied by each of the scenarios, to visualize the influence of the capacity factor of each scenario within the real and nominal LCOE and the PPA real and nominal after 20 years of analysis. As wind energy is not a constant source of supply, the simulation considered the limits of energy delivery that are above or below the minimum limit of energy delivery. The results demonstrated economic viability in almost all scenarios, with greater attractiveness for scenarios with an increase in the capacity factor. When financial parameters such as federal and state charges are varied downwards, all scenarios investigated are attractive to development with an IRR greater than the reference value.

Dynamic rating assists cost-effective expansion of wind farms by utilizing the hidden capacity of transformers

Dynamic rating of power transmission devices is a technology that allows better equipment utilization through real-time monitoring of the weather conditions and the load. Dynamic rating of transformers is a fairly new technology if compared to the dynamic rating of power lines, and has a high potential for significantly improving component utilization while lowering investment costs on installing new transformers.The following work investigates how to utilize already operational transformers, which are used for wind farm connection, for expanding wind generation capacity. Also, this paper shows improvements that dynamic transformer rating can bring to both power grid operators and wind farm owners by exploring the economic benefits of expanding wind parks without investing in new power transformers. Connecting additional wind turbines at sites with high wind potential after the wind park is already in exploitation can assist in lowering electricity price and provide a possibility of less risky investment in the wind energy sector. This paper uses transformer thermal modelling and wind farm expansion techniques such as convolution method and product method to investigate to which extent existing wind farms can be expanded using already installed transformer units.Five transformer locations and nine units are studied for finding the potential of dynamic transformer rating for network expansion applications. The analysis shows that the optimal expansion of wind power from a generator perspective is around 30% to 50%, although, it can be limited further by network restrictions. A possibility to use a large component, such as power transformer, closer to its full potential can provide material and cost savings for building new devices and decrease investment costs on manufacturing, transportation and installation of new units. Dynamic rating of power transformers can also increase the socio-economic benefits of renewable energy by lowering electricity price from renewables and incentivize an increased share of green power in electricity markets.

Experimental investigation of a wind to thermal energy hydraulic system

Abstract In EU households, heating and hot water alone account for 79% of total final energy use (192.5 Mtoe) [ 1 ]. The development of smart technologies to cover the heating requirements of the building sector constitutes a major challenge of the EU scientific community. Wind to thermal energy technologies, although they have been investigated thoroughly since the 50’s, did not gain much interest in the recent years. This study aims to analyse a novel wind to thermal energy conversion system, which could potentially be used in the EU building sector, in regions with high wind potential and increased requirements for space heating. The rationale of the proposed solution is based on a hydraulic system and the heat produced mainly due to friction losses of this system. The main idea behind the system is that the energy required to drive the hydraulic pump will be directly provided by a wind turbine. For the investigation of the proposed system, a scale-down test facility, which simulates the performance of the proposed system, was developed and operated at the Kaunas University of Technology. The wind turbine was simulated with the use of an electric motor with variable rotational frequency. Flow control valves were used both as the main energy converter of mechanical energy of the hydraulic fluid to heat as well as to regulate the load of the hydraulic pump. The optimal working conditions of the experimental set-up were defined in terms of the maximum thermal power delivered. The results of the research were summarized by empirical equations, which can be used for further development of the proposed hydraulic system. The study concluded that under optimal conditions, the system may reach an overall efficiency of 58.8%, which is comparable to efficiencies delivered by solar thermal systems for space heating in regions with increased solar potential (EU Mediterranean countries).

Assessing wind energy potential of Turkey via vectoral map of prevailing wind and mean wind of Turkey

In this study, the most detailed prevailing wind and average wind velocity maps of Turkey on a topographical layer were prepared in terms of the wind energy potential. Thus, the areas with high wind potential have also been investigated in detail, and the wind areas with high wind power potential that have not been studied before were determined. Then, comparisons were made with Turkish Wind Potential Atlas (REPA) prepared by the General Directorate of Renewable Energy (GDRE) operating under the Ministry of Energy and Natural Resources. The number of Automatic Weather Observation Stations (AWOS) installation by Turkish Meteorological Service (TMS) highly increased after 2012. Therefore, the composite vectoral topographical maps were well-prepared with using average wind velocity (m/s) data belong to 1207 stations and prevailing wind velocity (m/s) belongs to 1198 stations measured by AWOSs for the period 2012–2018. Climatologically, the strongest winds blow during the summer months, while the weakest winds blow during the autumn months in Turkey. However, the winds at 50 m are weaker in summer months than winter months according to the REPA. Also, higher wind potentials were calculated in selected areas than REPA. For example, it is shown that the Aksaray province has wind potential where REPA shows zero potential and the western parts of Datca have one of the highest wind potentials calculated in Turkey. Therefore, it is concluded that REPA should be updated using the higher numbers of measured station data as much as possible.