Power Aware Hand-Held Human Machine Interface (HMI) For An Intelligent Electronic Device (IED)

Abstract

With the increasing control and automation functionalities of the systems, the monitoring and configuration of the control parameters are being important. To achieve these objectives the designer has to provide an interface between the inside of the system to the world outside. This interface takes the responsibilities of the link of communication between system and user. This governing interface is known as Human Machine Interface (HMI). The work presented, describes about the developed HMI module for a numerical relay. The protection relays of cutting edge technology not only serve as a protection unit but also work as the monitoring and communication units simultaneously. The numerical protection relays having both advanced functionalities of control and communication is called an Intelligent Electronic Device (IED). The HMI for an IED serves the purposes such as configuration of protection parameters, display of the measured values, storage of critical data and many more functionalities associated with it. The IED involved in the project is self-powered over current and earth fault protection relay. It is a CT powered numerical feeder protection relay, designed for the protection of utility and industrial power systems, where auxiliary power is not available or cannot be guaranteed. The additional HMI module is to be locally detached on the front panel of the IED and which will be dependent on it for its power needs. Therefore, the operation of the HMI module is optimized for the power consumption. The HMI module is an embedded system which consists of 32-bit ARM based microcontroller, keypad, display and external memory. The NXP made LPC2138 microcontroller is used for the whole digital activities in the module. The controller will accept the digital input through keypad, assign the parameters given by the user to the numerical relay and display the current values of the parameters inside the relay thereby providing the interactive user interface.