Dorina Purcaru

Equipment for monitoring and analysis of transient electrical events in power system

Many power quality problems are generated by various electrical events (faults, disturbances, etc.). This paper presents the PC-08/104 equipment for monitoring and analysis of transient electrical events in power systems. It is a programmable electronic module which runs according to the signals provided by the transducers that take over the process parameters. PC-08/104 performs the acquisition of analog and digital inputs, local data storage, monitoring and processing, data transfer to an IBM-PC compatible computer and communication with the process server in a distributed data acquisition system. The program which runs on an IBM-PC compatible computer contains three sections: Monitoring (configuring all settable parameters of the equipment), Analysis (visualization of the input signals waveforms and the computation of several characteristic values) and Manager (management of records and archives). PC-08/104 provides an excellent tool to analyse the performance of the power system before, during and after a network disturbance situation. Some experimental results obtained using this equipment in energetic system are also presented in the paper.

Aspects Regarding the Configuration of a Functional Node in a Distributed Data Acquisition System, Based on PC/104 Compatible Modules

This paper presents a practical approach for a distributed data acquisition system organized on several levels, with functions distributed in functional nodes. A field bus allows the communication between all programmable electronic modules for data acquisition (first level) and the process server (second level); the last one is a data processing and monitoring equipment which also represents the process server in a computer network with many clients. The electronic equipment for monitoring and recording analog and digital inputs (i.e. a functional node from the first level of the distributed data acquisition system) is described in detail. This equipment is organized around the PC/104 central unit and performs four main functions: acquisition, configuration, local monitoring and communication. The experimental results, corresponding to the Server application, are also presented and discussed in this paper.

Data Acquisition and Processing Method Adequate for High Speed Transient Electrical Events

Many programmable electronic modules for data acquisition and processing can be found in power systems. To monitor and record different specific high speed transient events in energetic systems, an adequate data acquisition and processing method is required. This paper deals with such method and its application in data acquisition for implementation of complex protection functions. The acquisition routine for analog and digital channels, detailed acquisition and storing process for analog and digital values, storing and calculation method for acquired digital and analog values are all presented. The proposed method is adequate for many and various practical applications which require high speed data acquisition systems.

PC104 Interface Recommended for High Speed Data Acquisition Systems

The interface presented in this paper is recommended for high speed data acquisition systems; it performs a synchronized sampling of all common-mode or differential analog inputs with a high sampling rate. This is a low cost interface, entirely controlled by the PC104 CPU. Programmable electronic modules that contain such PC104 interfaces can be found running in the energetic system from Romania; these dedicated equipments perform the analog and digital signal acquisition for monitoring and recording different specific transient events. Some experimental results obtained using the disturbance monitoring device PC-08/104 are also presented in this paper.

Aspects about the conversion of geothermal energy into electricity in the north west of Romania

Based on a synthetic analysis of the groundwater thermality in the Upper Pannonian and the geothermal potential of the NW region of Romania, the article presents an analysis of the conversion of geothermal energy into electricity. This analysis was made in terms of the thermodynamic calculations necessary for the design of the geothermal power plants based on Kalina Thermodynamic Cycle, as well as from an experimental point of view, the influence of the external factors (the ambient temperature) on the quantity of electricity produced under the same conditions of flow and the temperature of the geothermal water was revealed.

Testing and monitoring ultrasonic sensors for engineering education on electronic measurements

Accurate training on electronic measurements can be obtained while experimenting with real sensors, electronic circuits and equipments. The paper presents an experimental system that allows the study and testing for two ultrasonic sensors, the remote programming for one of them and the monitoring of switching output for each sensor. A programmable logic controller performs the sensor remote programming and monitoring. The guideline for studying, testing and monitoring the ultrasonic sensors helps students to select, comprehend and apply information from datasheets and catalogs, use the previously acquired theoretical knowledge, understand the sensor connection to the programmable logic controller for implementing the sensor remote programming and monitoring. The engineering undergraduates acquire new practical skills using ultrasonic sensors and programmable logic controller, analogue and digital circuits and other devices. The experimental system presented in this paper has been proved very useful in academic study for experimental training on electronic measurements.

System for remote control and monitoring using optical fiber and GSM communication for loadbreak cutouts

The loadbreak cutout control is most often performed from the zonal load dispatcher level. The system presented in this paper performs the remote control and permanent monitoring of some loadbreak cutouts which run on a 20kV power line. The monitoring and control is directly carried out by the zonal load dispatcher. This remote control alternative provides more operativity and safety in decision making for the load dispatcher. The hardware components of this control system are installed in the dispetchers control center and in the electric switch boxes of the loadbreak cutouts, respectively. The physical communication support for sending information between the dispatcher and the cutouts is the optical fiber and the Global System for Mobile Communications (GSM) network. On the control center server a customized software application is installed, ensuring the user (dispatcher) interface while monitoring the cutouts status and performing commands, choosing the communication support (GSM or optical fiber) etc. The monitoring and remote control system enables all features for Supervisory Control and Data Acquisition (SCADA) integration. The application is hardware and software configurable, giving the posibility of monitoring more loadbreak cutouts. The system is currently operational in Romanian hydropower plants.

Signal processing and generating unit for power system simulator

A wide variety of protection relays evaluate the state of plants in high power systems and react properly. The power system simulator presented in this paper is designed to test complex protection relays. This equipment performs the simulation of typical events without using excessive automated functions, with very low costs. The paper focuses on signal processing and generation unit which contains two embedded systems, a multifunctional interface and a digital to analog conversion block. Signal processing and generating unit performs the digital generation of sinusoidal waveform and provides to the power amplifier block eight sinusoidal signals with amplitudes and phase shifts fitting the power system simulator settings. Some experimental results confirm the advantages and utility of this power system simulator.

Contributions to Hydrogenerator Protection when its Running in the Motor Regime is Detected

The paper presents a modern solution for the hydrogenerator protection implementation when its running in the motor regime is detected. Such protection function implementation is performed by a digital equipment organized around an embedded system. This equipment must be connected (locally or remote) to a computer for the configuration of the protection function and the set of the characteristic parameters. The digital equipment also performs the monitoring and display of several characteristic parameters of the hydrogenerator and allows obtaining very useful records for the post-failure analysis. The presented solution is successfully used in hydropower plants, as the results obtained in real conditions of hydrogenerator operation confirm it.

Hydrogenerator loss of excitation protection function implemented with a digital equipment organized around a PC/104 central unit

Protections for generators have been studied by many researchers in recent years. This paper shows how to implement the hydrogenerator loss of excitation protection function using a programmable electronic module organized around a PC/104 central unit. This equipment samples the currents and voltages of all three phases, the homopolar current and homopolar voltage, performs data processing, allows both the threshold setting of the monitored parameters and protection function implementation and commands, if necessary, the hydrogenerator disconnecting. Some experimental results are also presented and discussed at the end of the paper.