Design and implementation of the monitoring and control systems for distribution transformer by using GSM network

This paper designs and implements the monitoring and control systems for tap changer of the distribution transformers by using GSM (global system for mobile) network. The proposed method comprises an embedded system which collects and processes the transformer parameters such as temperature, humidity, silicone gel color, Buchholz relay status, the status of input and output phases, the current flow in each phase and power of each phase. If the parameters exceed the permitted level, the system sends all parameters using the GSM modem through GSM network to the control center, and the center receives and processes them by the GSM modem, and then they are displayed on computer. Furthermore, some commands are sent from the center to change the tap changer position, denoting the transformer position and making report on the transformer parameters. Some advantages of this system can be denoted as extending the lifetime of the transformer, consumers, wires and facilities, no need to the operator, simplifying the troubleshooting in distribution network, balancing the loads and providing customers with proper service.     

On power tracking and alleviation by a new controller for fulfilment of the damping and performance requisites for a variable speed wind system: An optimal approach

This paper addresses a new control strategy for a variable wind energy conversion system. The proposed controller aims to regulate the output power tightly in response to the desired value changes and alleviate power oscillations against the disturbances, including wind speed variation and fluctuation of the voltage magnitude, as voltage sag and swell. For the sake of straightforward analysis, an effective and reduced representation for the wind system is developed. In addition to the proper performance, the controller seeks to adequately fulfilment the damping requirements, as though both damping and performance requisites are taken into account control policy. Consequently, the proposed approach focuses on optimal tuning based upon a performance index incorporated into linear quadratic (LQ) cost function, which is subjected to the performance constraints. To validate the controller role, multiple simulation tests are carried out including set point tracking, disturbance rejection against wind speed, voltage sag and swell. Simulation results verify the proposed method features a satisfactory performance and sufficient damping, meeting both aspirations of the power regulation and disturbance suppression.