Camila S. Gehrke

Monitoring in Industrial Systems Using Wireless Sensor Network With Dynamic Power Management

The advances in wireless communication, microelectronics, digital electronics, and highly integrated electronics and the increasing need for more efficient controlled electric systems make the development of monitoring and supervisory control tools the object of study of many researchers. This paper proposes a digital system for energy usage evaluation, condition monitoring, diagnosis, and supervisory control for electric systems applying wireless sensor networks (WSNs) with dynamic power management (DPM). The system is based on two hardware topologies responsible for signal acquisition, processing, and transmission: intelligent sensor modules (ISMs) and remote data acquisition units (RDAUs). The gateway function of the wired network is carried out by remote servers (RSs) based on the Soekris architecture, which is responsible for receiving the data collected and transmitting it to the supervisory controller (SC). To extend the WSN lifetime, sensor nodes implement a DPM protocol. The basic characteristics of the presented system are the following: 1) easy implementation; 2) low-cost implementation; 3) easy implementation of redundant routines (security); 4) portability/versatility; and 5) extended network lifetime.

Smart Grid Infrastructure Using a Hybrid Network Architecture

Smart grid can be defined as a modern electric power grid infrastructure for improved efficiency, reliability and safety, with smooth integration of renewable and alternative energy sources through automated control and modern communications technologies. The increase need for more effective power electrical systems control turned the development of smart grids, the main object of study for many researchers. This paper proposes a digital system for condition monitoring, diagnosis and supervisory control applied to smart grids. The system is based on hybrid network architecture (HNA), consisting of a wired infrastructure, a wireless sensor network (WSN), a power line communications (PLC) and a controller area network (CAN). The system is based on three hardware topologies: remote data acquisition units (RDAUs), intelligent sensors modules (ISMs) and a PLC modem. The basic characteristics are: a) easy/low cost implementation, b) easy to set up by user, c) easy implementation of redundant routines (security), d) portability/versatility, and e) open system. To validate the developed system, it was implanted in one underground electric substation power distribution, characterized as an extremely hostile environment for supervisory control applications. In this application, the main challenge is to establish a communication system installed inside the substation with the outside (operations center-OC) considering that there are not commercial solutions appropriate to solve completely this problem.

Monitoring and Diagnosis in Industrial Systems Using Wireless Sensor Networks

Condition monitoring and diagnosis of industrial systems avoids unexpected failures and greatly improves system reliability and maintainability. Advances in wireless communication, microelectronics, digital electronics and highly integrated electronics in addition to the increasingly need for more efficient controlled electric systems, makes the development of monitoring and supervisory control tools object of study of many researchers. This paper proposes a digital system for energy usage evaluation, condition monitoring, diagnosis and supervisory control for electric systems applying wireless sensor networks (WSNs) connected to a wired infrastructure. The system is based on two hardware topologies responsible for the signal acquisition, processing and transmission: Intelligent Sensors Modules (ISMs) and Remote Data Acquisition Units (RDAUs). The gateway function of the wired network is carried out by Remote Servers (RSs) based on the AMD-Soekris NET4521 architecture, responsible for receiving the data collected and transmitting it to the Supervisory Controller (SCs) based on a PC Pentium IV architecture. The basic characteristics of the presented system are: (a) easy implementation, (b) low cost implementation, (c) easy implementation of redundant routines (security), and (d) portability/versatility.

Cooperative control for active power compensators allocated in distributed networks

This paper proposes cooperative control of multiple active filters based on voltage detection and Total Harmonic Distortion (THD) computation for improve power quality. The time changing of loads, shunt capacitors, faults or others occurs in real Electric Power Systems (EPS). This dynamic scenarios require a distributed control, which, more than one Active Power Line Conditioner (APLC) reduce, cooperatively, harmonics from all Points of Common Coupling (PCC)s in the EPS. The harmonic reduction should satisfy IEEE-519 norm, which regulated that the THD value should be under 5%.

Active Power Line Conditioner based on Modular Multilevel Cascade Converter - Double-Star Chopper-Cells

In this paper an Active Power Line Conditioner (APLC) is proposed based on a Modular Multilevel Cascade Converter (MMCC) - Double Star Chopper Cells (DSCC) topology. A higher-voltage, low-switching frequency IGBT converter is used to achieve harmonic minimization. Compared to the conventional APLC topology, the proposed approach employs lower DC-link voltage, lower voltage in the power devices, flexible output voltage level, fault protection, less prone to noise, loss reduction, among others features considered in this work. Experimental results show that the proposed active power filter topology is capable of minimizing load harmonics and compensating reactive power at the Point of Commom Coupling (PCC).

Evaluating APLCs placement in a power system based on real-time simulation

Optimal allocation of active power line conditioners (APLC)s for compensating dynamic load changing in power distribution networks is formulated and solved in the present work. The use of Matlab/Simulink environment is evaluated as an alternative to the traditional tools employed in power system analysis and design. The optimal allocation aim at reducing the total harmonic distortion to meet specific power quality requirements, e.g. the IEEE-519 Standard. The work also proposes the use a real-time simulation environment which allows one to test worst case load scenarios and undergo a pre-validation of the proposed solution under quasi-real operating conditions.

Unidirectional rectifier based on hybrid modular multilevel cascade converter — Double-star chopper-cells

In this paper a hybrid topology of Modular Multilevel Cascade Converter (MMCC) - Double-Star Chopper-Cells (DSCC) is proposed. This configuration is applied as a unidirectional controlled single-phase rectifier, wherein one of the converter legs is composed by diodes instead of the submodules (SMs) connections. In order to ensure the energy balance among the local SM capacitors, a voltage balancing control strategy is also presented. Besides, a grid current control strategy associated to a method that eliminates zero-crossing distortion caused by the diode leg is proposed, resulting in a power-factor correction (PFC) and a sinusoidal grid current. Experimental results are presented and allow validating the control strategies.

Smart control for active power generation, voltage level and harmonic content based on photovoltaic generators

Nowadays, to improve power quality and meet the energy demand, several studies point to the widespread use of Distributed Generation (DG) units equipped with power line conditionning capability. This work proposes a simplified structure and its related control system for Photovoltaic (PV) generation that embodies an Active Power Line Conditioner (APLC), allows harmonic minimization and active power injection to grid. Besides, it allows control of the grid voltage by using a Battery Energy Storage (BES) integrated to the system, which allows controlled bi-directional power flow. Simulation and pseudo-experimental results are presented to demonstrate the correctness of the methodology as well as the feasibility of the proposed distributed generation photovoltaic system and its related feedback control laws.

Controlling harmonics in electrical power systems for satisfying total and individual harmonic distortion constraints

The increase in the number of power electronic applications has led to harmonic pollution of the power grid. Harmonic resonance that can result in severe voltage distortion is a well documented problem. Several suppression techniques have been proposed to solve this problem. This paper proposes a technique to cooperatively operate multiple Active Power Line Conditioner (APLC) installed in the same Electric Power System (EPS) for minimizing the effect of harmonic pollution. The APLC operates as a tunable conductance for specific harmonic frequencies based on to the maximum desired harmonic voltage distortion. The proposed control is based on the reference Total Harmonic Distortion (THD) and Individual Harmonic Distortion (IHD) values specified by the IEEE Std 519-1992 recommendations. The damping conductance for each harmonic frequency can be adjusted separately and autonomously without any communication between the points of common coupling. Simulation and experimental results are used to demonstrate the correctness of the proposed approach as well as its feasibility.

Cooperative filters: Localization and injected current control

The present work discussthe localization and coordinated operationof active power filters installed ina distributionpower network. The localization problem is solved off-line for a given load variation scenario. The control of the current injected by the active power filter is solved on-line. In both cases the design solutions aim at reducing the total harmonic distortionbelow 5% and individual harmonic distortion below 3% to satisfy the IEEE-519 standard.