J. L. Munda

Viability and economic analysis of wind energy resource for power generation in Johannesburg, South Africa

In this study, wind characteristics and wind power potential of Johannesburg are investigated using 5-min average time series wind speed collected between 2005 and 2009 at anemometer height of 10 m. The statistical distribution that best fits the empirical wind speed data at the site of study is first determined based on the coefficient of determination and root mean square error criteria. The statistical parameters and wind power density based on this model are estimated for different months of the year using standard deviation method. Economic analyses of some wind turbines are also carried out. Some of the key results show that the site is only suitable for small wind turbines in a standalone application. A 10 kW wind turbine with cut-in wind speed of 3.5 m/s, rated wind speed of 9 m/s, and cut-out wind speed of 25 m/s seems most appropriate in Johannesburg with the lowest cost that varies from 0.25 to 0.33

A Statistical Analysis of Wind Distribution and Wind Power Potential in the Coastal Region of South Africa

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Effects of slot opening on the performance of a six phase squirrel cage induction machine using finite element and field analysis

This article investigates the wind characteristics and the wind power potential for electricity generation in the coastal regions of South Africa through the analysis of local wind regime of ten different sites. The data used consist of 10-min average time series wind speeds, temperatures, and standard deviation measured at anemometer height of 20 and 60 m for a period of 1 year. First, the statistical distribution model that best fits the empirical wind speed data in the areas of study is determined based on the coefficient of determination and root mean square error, which are used to test the goodness of fit. The parameters and the wind power density based on this model are estimated for each of the months and season of the year. For a realistic result in estimating the power density, the stochastic nature of the site air density based on the local temperature and the site altitude above the sea level is taken into consideration. The diurnal (day and night), electricity peak periods wind characteristic, and the turbulence intensity of the sites are calculated. The optimum wind speed, most probable wind speed and shear exponential which are important pieces of information in the selection of wind turbines are evaluated. Some of the key results show that at 60 m anemometer height, site WM05 has an exceptional wind power potential with annual power density of 694 W/m2, while site WM02 shows a poor wind power potential with annual power density of 216.29 W/m2.

Optimal reactive power control in transmission network with a large wind farm connection

The operational behavior of a six-phase, 2 poles and 36 stator slot squirrel cage induction machine is analyzed for the effects of stator slot openings in this paper. The study is carried out using the field analysis method and the finite element analysis (FEA) of the two dimensional commercially available finite element QuickField modeling Package. Experimental analysis is conducted on a 1.5 kW machine to validate the integrity of the theoretical method of the original opening slot. The FEA analysis is carried out for no-load (Magnetostatics) and loaded conditions (steady state AC Magnetics). The results show that decreasing the slot opening of the stator winding increases the performance of the machine.

Power sensitivity and algebraic technique for evaluation of penetration level of photovoltaic on DC link of VSC HVDC transmission

In a weak network where the reactive power capability is not able to satisfy the demand of wind farm based on squirrel-cage induction generator (SCIG), flexible AC transmission system such as static VAR compensator (SVC) is used. Traditionally, the SVC device and other network reactive power facilities are used in optimal way by the network operator, for optimal voltage profile and loss minimization, during different steady-state operations caused by wind resource changes. In this paper, the SVC reactive power reserve (SVC-RPR) is added to the problem as a third objective function to be maximized with the purpose of further compensation usage during dynamic operation. Particle swarm optimization (PSO) is used to optimize the search space of this multi-objective problem. The reactive power optimization scheme is tested in a MATLAB/R2010a based simulation model of Wale & Hale 6-bus system with wind farm integration. It is has been found that the conflict between the three objective functions causes the difficulty of achieving a sufficient SVC-RPR during high wind farm power generation, unless the SVC rating is designed in such away to be higher than the reactive power required by the total number of SCIG at full load.

Impact of variation of wind speed in a wind integrated power system

With the increased advent of VSC HVDC with long DC transmission link in power systems, situations have arisen and will be even more frequent in the future, where several distributed generation will be connected on the DC-link for more power transfer capability. As penetration level increases, there is need to predict the limit before violation of voltage and power instability on the DC transmission link and ensure that it does not interfere with the main VSC HVDC system control. In this paper, power sensitivity and algebraic technique is proposed to predict the maximum DG penetration that can be accepted at a particular location on the dc link of VSC HVDC transmission system before violation of voltage and power stability.

Economic analysis of a small scale wind turbine for power generation in Johannesburg

When large renewable energy sources (RES) are integrated into a power system, the dynamics and the operation of the network are affected. This paper studies the effect of variation in wind speed when a large wind power is integrated into the power system using fixed speed squirrel cage induction generator (SCIG). The wind farm is modelled with the commercially available software, PSCAD/EMTDC. Different scenarios are created to investigate how wind speed variability affects the operation of power system.

The impact of wind power on the transient stability of a power system using probabilistic approach

In this paper, the economic analysis of small scale wind turbines is studied based on the wind regime of Johannesburg for the purpose of electricity generation in a standalone application. Levelised energy cost method is employed to determine the cost of electricity from wind energy using 5-minute average time series wind speed data collected between 2005 and 2009 at anemometer height of 10m. The study is conducted for nine small scale commercially available wind turbines ranging from 1kW to 60kW. The result shows that a 10kW wind turbine with cut-in wind speed of 3.5m/s, rated wind speed of 9m/s, and cut-out wind speed of 25m/s seems most appropriate in Johannesburg with the lowest levelised cost of energy that varies from 0.25-0.33

Comparison of hot water draw models integrated within a statistical physically-based model for electrical demand of domestic water heater

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Dynamic and steady state performance of higher phase order (HPO) squirrel cage induction machine

Transient stability is a stochastic problem that is attracting a lot of attention in recent time. Traditionally, transient stability is evaluated using the deterministic method. This method is usually considered for a single contingency. However, the disturbances in a power system are stochastic in nature. The types of disturbance, its location and the time it is cleared are all random process. In this paper, the influence of wind power on these stochastic processes is analysed taking into consideration the wind power generator technology, wind generator location and the wind power penetration level.