Analysis and performance evaluation of a distribution STATCOM forcompensating voltage fluctuations

Controller design of a STATCOM-based voltage compensator requires a valid analytical model of the system. If phasor algebra is used for modeling, it is difficult to accurately describe the STATCOM behavior during compensation of subcycle transients in the PCC voltage. In this paper, a small-signal model of the system, with a distribution line, is derived. Predictions based on frequency-domain analysis are made, which are validated by experimental results. This model, therefore, can be used for controller design where subcycle voltage transients are to be compensated. It is shown that the voltage controller, so designed, can accomplish voltage sag mitigation. A discussion on the design of DC bus voltage controller-and experimental results showing its performance-is also included     

A multi-band shunt hybrid active filter with reduced sensor count

A Shunt Hybrid Active Filter (SHAF) is an attractive option for realizing low-cost harmonic compensation solutions. This paper proposes a SHAF with multiple harmonic compensation capability using a single Voltage Source Inverter and reduced sensor count. This strategy is apt for harmonic filtering solutions where low cost is the exclusive priority. In this paper, a new estimation approach is proposed to obviate requirement of a large number of sensors. Multiple Synchronous Reference Frames (MSRF) and low pass filters are used to measure 5^th and 7^th harmonic components separately from load as well as filter currents. Individual current controllers are designed for the 5^th and 7^th harmonic currents. Control is realized in the synchronously rotating, orthogonal (dq) reference frame. Performance of the controller is validated through simulation, using realistic plant and controller models. Experimental results are provided to corroborate the analytical and simulation results.     

Solar PV lanterns with centralized charging system - a new concept for rural lighting in the developing nations

A new concept has been introduced for providing electric light to rural households through portable solar PV lanterns, charged regularly in a centralized charging shop located in the village and operated on a commercial basis by an entrepreneur. The technical feasibility of a charging shop for charging solar PV lanterns has been described in detail. The results of an actual field trial of the proposed system are also reported. Finally, the economic viability of the system is described.     

Smart Prediction and Monitoring of Waste Disposal System Using IoT and Cloud for IoT Based Smart Cities

One of the prominent applications of Internet of Things (IoT) in this digital era is the development of smart cities. In IoT based smart cities, the smart objects (devices) are connected with each other via internet as a backbone. The sensed data by the smart objects are transmitted to the sink for further processing using multi hop communication. The smart cities use the analyzed data to improve their infrastructure, public utilities and they enhance their services by using the IoT technology for the betterment of livelihood of the common people. For IoT based smart cities, waste collection is a prominent issue for municipalities that aim to achieve a clean environment. With a boom in population in urban areas, an increasing amount of waste is generated. A major issue of waste management system is the poor process used in waste collection and segregation. Public bins begin to overflow for a long period before the process of cleaning starts, which is resulting in an accumulation of bacteria causing bad odors and spreading of diseases. In order to overcome this issue, in this paper an IoT based smart predication and monitoring of waste disposal system is proposed which utilizes off-the-shelf components that can be mounted to a bin of any size and measure fill levels. An Arduino microcontroller is employed in the proposed model to interface the infrared (IR), ultraviolet (UV), weight sensors, and a Global Positioning System (GPS) module is used to monitor the status of bins at predetermined intervals. The proposed system transmits the data using the cluster network to the master module which is connected to the backend via Wi-Fi. As data is collected, an intelligent neural network algorithm namely Long Short-Term Memory (LSTM) is used which will intelligently learn and predict the upcoming wastage from waste generation patterns. Moreover, the proposed system uses Firebase Cloud Messaging to notify the appropriate people when the bins were full and needed to be emptied. The Firebase Cloud Messaging (FCM) JavaScript Application Programming Interface (API) is used to send notification messages in web apps in browsers that provide service work support. Hence, the proposed system is useful to the society by providing facilities to the governments for enforcing stricter regulations for waste disposal. Additional features such as automated calibration of bin height, a dynamic web data dashboard as well as collation of data into a distributed real-time firebase database are also provided in the proposed system.

     

Discontinuous conduction mode analysis of phase-modulated series resonant converter

This paper proposes an analytical approach to derive voltage gain for phase-modulated dc–dc series resonant converter (SRC) operating in discontinuous conduction mode (DCM). The conventional fundamental harmonic approximation technique is extended for a non-ideal series resonant tank to clarify the limitations of SRC operating in continuous conduction mode (CCM). The DCM analysis is described in a normalized form defining appropriate base quantities. The converter is analysed both in time and frequency domain to derive a non-linear algebraic function of diode rectifier extinction angle. The root of this function is numerically determined using MATLAB and used to predict the dc bus voltage. Analytical derivation of critical load resistance is discussed, which indicates the CCM–DCM boundary condition. Experimental results are presented to validate the analysis.     

Polymerization of ethylene using a SiO2–MgCl2 supported bis(cyclopentadienyl)zirconium(IV) or titanium(IV) dichloride catalyst

Silica supported MgCl₂–Cp₂MCl₂ (M = Ti or Zr) catalysts (Si–Mg–M) were prepared by deposition of a homogeneous solution of a metallocene and anhydrous magnesium chloride in tetrahydrofuran (THF) onto a high surface area silica (SiO₂). Catalyst thus prepared show higher polymerization activity when compared to metallocenes supported on either silica or magnesium chloride alone. The molecular weight and polydispersity of the poly(ethylene)s obtained from metallocenes supported on SiO₂–MgCl₂ were found to be higher and narrower, respectively, relative to silica or MgCl₂ supported metallocene catalysts. © 2002 Society of Chemical Industry     

Redefining the Game in Local Water Management Conflict: A Case Study

The article intends to bring a new perspective on conflict and cooperation analysis addressing a case study of Yoshino river weir conflict (Japan) by the use of drama theory approach. The confrontation arose when the Governmental agency proposed to remove and replace the old weir by a movable modern dam (kodazeki) to prevent future flooding. The Opposition group’s main arguments were that the new weir may not be as effective as compared to the cost of constructing the new renewal project and damage of water quality and ecosystem. Thus, both players are playing the game where their interests are different. Rather than adopting the conventional approach of modeling the conflict using game theory, we propose the alternative approach to describe how the situation evolved and how game can be changed in the context of player’s threats and promises. This also emphasizes that future can be created cooperatively by a group, rather than by way of confrontation in the conflict. This model may bring an effective methodological leverage in conflict and cooperation analysis where we can change the game.