Low Voltage Ride Through (LVRT) capability is essential for wind farms to avoid disconnection during low voltage and fault. In this study, both Voltage Behind Reactance (VBR) model and DQ model of Induction Generators (IGs) used in Fixed Speed Wind Turbines (FSWTs) are implemented and compared. Based on the appropriate model, a new method for enhancing Low Voltage Ride Through (LVRT) capability of FSWTs during balanced three-phase faults is proposed. This method is based on using a Synchronous Condenser (SC) with a Fuzzy Logic Controller (FLC). In order to have a good control of the system during the fault, the amount of injected reactive power produced by the SC is controlled through the FLC. Although using STATCOM is the most common method for LVRT capability enhancement in FSWTs, simulation results show that using the SC with the FLC in a three-phase fault leads to a better performance. Therefore, using the VBR model for the first time in FSWTs and suggesting the application of the SC with the FLC to improve LVRT capability are the novelties of this paper.

This paper studies the interest of the integration of battery energy storage with Static Synchronous Compensator (STATCOM) for improving the low voltage ride through capability (LVRT) of a fixed speed wind turbine connected to the grid. For this reason and by applying a grid fault, a comparison is made between integrating the SSSC, the STATCOM and the STATCOM with battery energy storage.The system with the aforementioned flexible alternating current transmission system (FACTS) systems is simulated using MATLAB/SIMSCAPE and the results show that the STATCOM with a battery is most efficient in terms of improving the LVRT of a fixed speed wind turbine.

Voltage security and congestion management are crucial issues in power systems, especially under heavily loaded conditions. In the new scheme of electricity restructuring, voltage security problems become even more serious. Due to the increase in stability margins, FACTS devices are the best option to mitigate voltage instability by reactive power management. The main purpose of this paper is to identify the optimal location and capacity of the Static Synchronous Compensator (STATCOM) to enhance voltage security and identify the capacity of a properly placed IPFC to manage transmission network congestion simultaneously. Artificial intelligence is implemented as a heuristic technique to this complicated constrained optimization problem. The proposed method demonstrates the improvement of the voltage security margin, as well as solving congestion management problems. Significant results through a modified IEEE 14-bus case study show the effectiveness of the proposed algorithm.

Nowadays, the Doubly-Fed Induction Generators (DFIGs) based Wind Turbines (WTs) are the dominant types of WTs connected to grid. Traditionally the back-to-back converters are used to control the DFIGs. In this paper, an Indirect Matrix Converter (IMC) is proposed to control the generator. Compared with back-to-back converters, IMCs have numerous advantages such as: higher level of robustness, reliability, reduced size and weight due to the absence of the bulky electrolytic capacitor. According to the recent grid codes it is required that the wind turbines remain connected to the grid during the grid faults and the following voltage dips. This feature is called Low Voltage Ride-Through (LVRT) capability. In this paper, the Linear Quadratic Regulator (LQR) controller is used for optimal control of the DFIG. The weighting matrices of the LQR are obtained by using the Genetic Algorithm (GA) technique. With the LQR controller the intention is to improve the LVRT capability of the DFIG wind turbines to satisfy the new LVRT requirements.Compared to the PI controller, the superiority of the LQR controller in improving the transient stability and LVRT performance of the DFIG wind turbines is shown. Simulation results confirm the efficiency of the proposed controller.

This paper presents a new intelligent algorithm, named binary real genetic algorithm (BRGA) to design parameters of PSS and STATCOM controller simultaneously. The proposed algorithm has a strong search capability and high speed convergence to find the global optimum points. The objective function used in this paper to be minimized is the time integral absolute error (ITAE). The objective will be minimizing the deviations of rotor speed (Dw) and the voltage of the bus in which STATCOM has been installed. The simulations are carried out on a two-area four-machine power system to show the superior performance of the proposed method, when compared with GA and PSO algorithms.

This paper demonstrates an enhancement of power quality in grid integrated systems with the help of the proposed control strategy for voltage source converter based active power filters. The Shunt Active Power filters (SAPF) are extensively utilized in modern grid integrated systems to diminish the power quality concerns associated with it. The SAPF is one of the various power filters, which has better dynamic performance. The SAPF requires an accurate control strategy that provides robust performance under source and loads unbalance conditions. The proposed control scheme is responsible for generating the gate signals to activate the operation of Voltage Source Converter (VSC) based Active Power Filter. Thus, the performance of mitigation of harmonics of source current principally depends on the adopted algorithm. The present paper represents a performance study of a control scheme to mitigate power quality issues in the grid integrated system. The proposed system is modelled and simulated in MATLAB-Simulink in Simpower system block set.

Land and resource developoment suitability is usually achieved by landscape capability analysis. But using land capability analysis in planning process is often restricted by budget and time limitations. A simple, yet effective capability analysis method is hence required, that can furnish planners reliable land zonning with the least data and time requirement. The Optimum Integration method (Formann, 1995) of land capability analysis, zonning and classification is one of these simple, yet effective methods.An addapttion of this method was used for a land-use planning project concerning touristic development of Kohkiloye-U-Boyer- Ahmad Province (Southern Iran). Successful achievement of foreseen planning objectives resulted in introducing this method for further possible uses in simillar cases. This environmental capability analysis method in land-use planning process offered both short-term management proposals and long-term planning strategies baseed on actual and preferred land capability and carrying capacity. Furthermore, proper site selection for implementation of pilot development projects was also achieved based on regional and local comparative advantages (and/or disadvantages) of concerning landscapes.