Nicoleta Arghira

Embedded networked monitoring and control for renewable energy storage systems

Energy storage plays an important role in managing effectively the integration of distributed renewable energy generation within the electrical networks of the future. Pervasive monitoring and control of these systems makes growing use of information and communication technologies, which aim at secure and economic operation at various scales from microgrids to system-wide integration. Among these, low power wireless communication and computing embedded systems, in the main form of wireless sensor networks (WSN), have become a robust solution. Through hardware and software architectures, along with appropriate mechanisms e.g. for data collection and aggregation, wireless communication protocols and standards, they represent a valid solution in assuring continuous and reliable operation. The paper introduces a cyber-physical framework for renewable storage systems monitoring and control and discusses the application of wireless sensor networks to densely instrument such deployments. A hardware-in-the-loop type structure is designed which allows both testing various types of real storage systems, as well as more complex simulated models derived from large scale applications. We argue that the specific advantages brought forward by the advances in WSN technology can be put to efficient use for local distributed intelligence and control. Experimental data collected is analyzed in order to achieve an insight into the characteristics of the proposed solution.

Fuzzy decision support system for solar tracking optimization

This paper presents the design and implementation of a fuzzy decision support system for control of photovoltaic panel movement in order to improve the availability of solar energy and the systems total efficiency. The designed algorithm is implemented on a solar tracking experimental platform using a fuzzy logic control strategy. It makes use of measured values for radiation from appropriate sensors and assures command of the platforms two positioning motors. The solution was developed as a virtual instrument, using a graphical programming environment. This allows for fast deployment, versatility and scalability.

Forecasting Energy Consumption in Dwellings

Energy consumption is a major issue nowadays. The importance of forecasting energy consumption from end-user to power system operator becomes more obvious than ever. The consumption in the residential sector represents a significant percentage in the total electricity demand in Europe and all over the world and it is expected to grow. So, the prediction of energy consumption becomes a key component in the management (e.g. power flow) of the electrical grid. This paper presents different methods for prediction of energy consumption of electrical appliances used in dwellings. A stochastic approach is used since forecasting the consumption for a single appliance is more difficult that predicting the overall consumption. Different basic predictors are presented and a stochastic predictor is proposed and tested according to a prediction precision criterion. The enhancement of forecast precision is done by segmentation and aggregation of data. Several experiments are conducted for different appliances in the house and the results are discussed.

Distributed Generation Influence on Smart Distribution Grids

Abstract This paper presents a methodology for choosing the best location of a distributed generation (DG) unit in a distribution grid considering the short-circuit current values. The optimum position into the grid is searched according to the minimum short circuit current. A three bus network was used in order to test the methodology and a real distribution network in Romania was proposed.

Load frequency regulation in power systems

This paper focuses on load frequency regulation, as a major function of automatic generation control (AGC) in the context of a versatile power system structure, environmental constrains and emerging new uncertainties. Generation units models are determined in order to build a control diagram used for load dispatch. The optimal parameters for the secondary controller were determined using a gradient descent algorithm.

Process Control Simulator using programmable controller technology

The simulation of physical processes represents a modern and efficient direction for multifunctional testing platforms. This paper will present a Process Control Simulator and its applications in system simulation. The Process Control Simulator can be used for students training as well as for the conception, simulation and improvement of control schemes in modern technologies. The simulation of industrial processes reduces the cost and the amount of time needed for deploying the system. The various types of applications, with different complexity factors, are associated with several functional masks. The Process Control Simulator uses a simulation block and a microcontroller for all the applications with different replaceable masks according to the desired application.

Temperature control of a greenhouse heated by renewable energy sources

The paper proposes a system developed to provide heat for a greenhouse using parabolic trough collectors (GHPTC). The GHPTC control system has the goal to maintain the temperature inside the greenhouse at a desired level, with the actuating variable the flow of the conducting fluid through collector pipes. Considering this aspect, the proposed model takes into account as an output variable the internal temperature of the greenhouse as it influences directly the growth of the plants. The GHTPC model consists of two individual parts: the greenhouse model and the collectors model. Both were validated using real data, considering the maxim error between the real and simulated data on a period of one day. A nonlinear and linear model were deducted for the complex GHPTC system. Based on the linearized model, a PID controller was tuned and used to control the internal temperature in the greenhouse. The control method is suited for the system according to the obtained stationary and transient response performances.

Generation Units Models for Load Dispatch Simulator

Abstract This paper presents aspects regarding Load Frequency Control (LFC) in the Romanian Power System, which, considering its characteristics, is a large system. Load Frequency Control keeps the balance of the power generation and consumption in a control area in order to maintain an acceptable system frequency. Time models for hydro and thermal generation units used by LFC in the Romanian Power System are presented in the paper. These models were obtained using experimental data provided from the system (step response tests). The model parameters were determined using an experimental identification procedure based on the Trust Region Algorithm. Finally, we proposed and tested a simulation diagram for modelling the load dispatch.

A fuzzy PLC control system for a servomechanism

Abstract This paper presents a case study on a practical implementation of a fuzzy-PLC system for a servomechanism. The method presented achieves smooth fuzzy control, that can be easily implemented in a PLC system. The speed of the servomechanism is controlled.

PV Panel - Wind Turbine Hybrid System Modelling

The work proposes a hybrid system framework consisting of several solar panels and wind turbines, in order to supply the electricity need for small communities. The photovoltaic (PV) model considers as an output variable the active power obtained from the PV panel, which is directly influenced by the solar radiation measurements during a day. Based on wind speed, the output variable for the wind turbine model is the active power produced by the wind turbine. Both models were validated by computing the maximum relative error on a period of one day and the results showed a modelling error of 1.2 % for the wind turbine, respectively 6% for the PV panel. Also, a hybrid PV-wind turbine system architecture is proposed in order to minimize the consumer supply from the national grid.