Program Topic: Renewables Integration & Optimization – Wind

T1-1Thursday 08:20-09:40

08:20 A Dump Load-Less Standalone Wind Energy Conversion System Supplying a Generic Load

Zuher Alnasir (University of Waterloo, Canada); Mehrdad Kazerani (University of Waterloo, Canada)

A current-source inverter-based standalone wind energy conversion system has been recently proposed for low power applications. In this paper, the system is modified by removing the dump load and avoiding the surplus power generation by curtailment of wind power. The generator-side converter is used to control the shaft speed, allowing extraction of maximum available wind power in normal mode of operation, and to regulate DC-link current, allowing curtailment of wind power when it is not possible to absorb maximum available power by the storage system and the load. In order to verify successful operation of the system under a wide range of load types, a reduced-order generic load model, that is suitable for both balanced and unbalanced load conditions, is developed and tested with the system. The current-source inverter is used to control positive- and negative-sequence voltage components separately. The operation of the modified system is investigated and verified under variable wind and load conditions.

08:40 Dynamic Frequency Support with DFIG Wind Turbines – A System Study

Denis Mende (Fraunhofer IWES, Germany); Tobias Hennig (Fraunhofer IWES, Germany); Alev Akbulut (Fraunhofer IWES, Germany); Holger Becker (Fraunhofer IWES, Germany); Lutz Hofmann (Leibniz Universität Hannover, Germany)

Frequency control in interconnected electrical power systems is nowadays realized using the networks’ conventional power plants. With the ongoing changes in power systems worldwide the share of these conventional power plants is decreasing while renewable resources such as wind power and photovoltaics are increasing their share continuously. Up to now a contribution of renewable sources on primary frequency control is not realized in interconnected power systems. This paper describes possibilities to support the frequency of power systems using wind turbines with enhanced active power functionalities such as primary frequency control and synthetic inertia. The effects of these functionalities were analyzed in the IEEE 39 bus system. Different simulations with an implementation in a doubly fed induction generator wind turbine model show promising results. The frequency behavior of a 50 % penetrated system with standard wind power plants shows unfavorable frequency behavior compared to the original system, whereas a system with additional frequency supporting functionalities by wind power plants improves the frequency behavior significantly.

09:00 Inertia Support During Variable Wind Conditions

Mattias Persson (Chalmers University of Technology, Sweden); Peiyuan Chen (Chalmers University of Technology, Sweden); Ola Carlson (Chalmers University of Technology, Sweden)

Wind variations are important to consider while designing inertia support strategies. One model has been evaluated but the findings should reflect issues with several control strategies utilizing a fixed support pattern. Wind variability is shown to be at the worst around 0.5 m/s for second to second evaluations, drastic changes can occur in wind speed if considering longer durations of inertia support, such as 30~s. An improved inertia control algorithm has been presented allowing a stable delivery of inertia support from variable speed wind turbines (VSWT) realistic wind conditions. The controller improves the previously presented algorithm and is proving good performance when subjected to realistic wind data. The impact of the utilized wind speed filter is described and its impact on the simulation found to be of great importance.

09:20 Low Voltage Ride-Through Enhancement in DFIG-Based Wind Turbine

Ehsan Gatavi (Western Sydney University, Australia); Ali Hellany (Western Sydney University, Australia); Mahmood Nagrial (Western Sydney University, Australia); Jamal Rizk (Western Sydney University, Australia)

Wind farms are regarded as large-scale power plants with interconnected systems, where all systems interact with each other to improve the efficiency of the plant and thus enhance the quality of the output power. However, the conventional centralized controller is inappropriate for such plants. Accordingly, the plant-wise controller is an alternative solution to be plant-wise decentralized, by designing the separate local controller of each subsystem. Moreover, voltage stability plays a significant role to preserve the Doubly Fed Induction Generator (DFIG) based Wind Farms (WF) connected to the grid, which is known as Low-Voltage-Ride-Through (LVRT), in the period of fault appearance. This paper describes a critical review on the existing control methods of the DFIG-based WTs, and also presents the significance of the LVRT capacity improvement to enhance the power quality and guarantee the plant-wise stability during the grid faults.

T2-1Thursday 11:00-12:20

11:00 Statistical Evaluation Study for Different Wind Speed Distribution Functions Using Goodness of Fit Tests

Abdulaziz Almutairi (University of Waterloo, Canada); Mohmmed Nassar (University of Waterloo, Canada); Magdy Salama (University of Waterloo, Canada)

Modeling wind generation for use in many power system applications requires a massive database of historical wind speeds so that the stochastic nature of the wind at a particular site can be accurately captured. The alternative is to use reliable estimates of a probability distribution function (PDF) that can preserve the variable characteristics of wind speed and generate the desired synthetic data. This paper presents a statistical evaluation study for different collections of PDFs in order to find the best model to precisely reflect the variable characteristics of the wind at a particular site. The most commonly used PDFs, along with some advanced PDFs, have been verified against the observed wind data based on consideration of two well-known goodness of fit statistical tests. A further case study is conducted in order to evaluate the impact of sample size on the selection of the best-fit PDFs. From a variety of candidate PDFs, the results indicate that the Generalized Logistic and Dagum distributions are the PDFs that best maintain the main characteristics of the observed wind data.

11:20 Effect of Wind Turbine Parameters on Optimal DG Placement in Power Distribution Systems

Majed Alotaibi (University of Waterloo, Canada); Abdulaziz Almutairi (University of Waterloo, Canada); Magdy Salama (University of Waterloo, Canada)

The notion of the “smart grid” has led stakeholders in the power industry to promote more efficient technologies to the network. Distribution systems are a favorite place to host most of these technologies including Renewable-based distributed generation (DG). Wind Turbine Generators (WTGs) in particular have proved their usefulness for supplying a fair portion of power demand; however, the power output of WTGs is mainly dependent on the stochastic nature of the site’s wind speed in addition to the design parameters of WTGs. Furthermore, WTGs can only be suitably utilized when their capacities and locations are optimized in such a way to achieve certain goals. In this paper, the effect of wind generator design parameters, namely cut-in, cut-out, and rated wind speeds, on the problems of sizing and siting WTGs-based DGs is addressed. The probabilistic optimization model is used to minimize the system’s annual energy losses, and the results reveal that the design parameters of WTGs must be carefully selected due to their strong effect on system losses and DG locations and capacities.

11:40 Comparison of Wind Turbine Probabilistic Model with Negative Model in Economic Dispatch Problem Using Differential Evolution (DE)

Zakareya Hasan (Dalhousie University, Canada); Mohamed El-Hawary (Dalhousie University, Canada)

This paper use differential evolution to do a comparison between two wind turbine cost models used in solving the economic dispatch problem. The models of interest are: The probabilistic model and the negative load model. These models will be used to solve the economic dispatch problem with and without the valve point effect considering different constrains such as generators capacity, ramp rate limit, and prohibited operation zones. Three test systems with different constraints will be used to select the best cost model for the wind turbine

12:00 Unit Commitment Incorporating Wind Energy by BBO and GA

Zakareya Hasan (Dalhousie University, Canada); Mohamed El-Hawary (Dalhousie University, Canada)

This paper proposes biogeography based optimization (BBO) algorithm and genetic algorithm (GA) to solve the unit commitment problem incorporating the wind energy (UCIW) uncertainty. Unit commitment (UC) problem is mainly finding the minimum cost schedule to a set of generators by turning each one either on or off over a given time horizon to meet the demand load and satisfy different operational constraints. There are many constraints in unit commitment problem such as spinning reserve, minimum up/down, crew, must run and fuel constraints. In this paper, BBO and GA are used to solve the UCIW problem for four and six generator system, then a comparison will be done between the results of both algorithms with other algorithms in literature if possible. And if not the comparison will be between the two algorithms only.