Investigating Spatio-Temporal Variations of Groundwater Quality of Guilan Province using Geostatistical Method

Knowledge and awareness of temporal and spatial changes of quality parameters, especially salinity in groundwater and surface water resources and the preparation of zoning maps can be an important step in proper management and planning in the use of water resources. In this research, the trend of spatial and temporal changes of some groundwater quality parameters in Guilan province has been evaluated. Measurement data of some cations and anions sampled from 150 wells in September and March of 2011-2018 and water level data of 282 piezometric wells were collected. The zoning maps obtained by ordinary kriging method were examined. These maps show that in terms of quality parameters, groundwater resources in the central part of Gilan province have higher values ​​and in the growing season due to agricultural activities and fertilization, groundwater quality decreases. Effect of groundwater depth on the concentration of the parameters was assessed. According to the map of groundwater depth changes, the largest area of ​​Gilan province has a water level of 0.23 to 5.5 m. The results of classification of qualitative parameters show that in shallow groundwater depths the concentration of qualitative parameters increases

Robust Optimal Controller Design for Induction Generator Driven by Variable-Speed Wind Turbine with STATCOM Using Immune Algorithm

This paper presents the modelling, controller design and a steady-state analysis algorithm for a wind-driven induction generator system. An output feedback linear quadratic controller is designed for the static synchronous compensator (STATCOM) and the variable blade pitch in a wind energy conversion system (WECS) in order to reach the voltage and mechanical power control under both grid-connection and islanding conditions. A two-reference-frame model is proposed to decouple the STATCOM real and reactive power control loops for the output feedback controller. To ensure zero steady-state voltage errors for the output feedback controller, the integrals of load bus voltage deviation and dc-capacitor  voltage deviation are employed as the additional state variables. Pole-placement technique is used to determine a proper weighting matrix for the linear quadratic controller such that satisfactory damping characteristics can be achieved for the closed-loop system. Effects of various system disturbances on the dynamic performance have been simulated, and the results reveal that the proposed controller is effective in regulating the load voltage and stabilizing the generator rotating speed for the WECS either  connected with or disconnected from the power grid. In addition, proper steady-state operating points for an isolated induction generator can be determined by the proposed steady-state analysis algorithm. Constant output frequency control using the  derived steady-state characteristics of the isolated induction generator is then demonstrated in this paper