Quick-response protection system against electric shock in distributed generation systems

Abstract

The peculiarities of the operation of distributed generation systems lead to a change in the requirements for the reliability and safety of the power distribution systems in which they are integrated. To meet the increased requirements, continuous monitoring of the insulation parameters (active resistance and capacitance to ground) is often used with operating artificial non-industrial frequency operational signals introduced into the network. In the case of a sudden touch, such a system is not effective, since the response time of the protection device, which consists of the signal processing time and the operating of the actuator, is crucially important. For the used operational signals with a frequency of 100 and 200 Hz, the processing time using the Fourier transform is 10 ms for 100 Hz and 5 ms for 200 Hz. Considering that the response time of the fastest actuators (based on vacuum switches) is from 3 to 7 ms, this is a rather significant period of time. To develop an effective resolver system, the capabilities of the Matlab environment were used to determine the most successful design of an analog prototype (Butterworth, Bessel, Chebyshev and Cauer of 6 th order) for an operational signal with a frequency of 200 Hz. As a result, the processing time was established, which varies widely from 3.5 to 19 ms. Taking into account the known indicators, namely the frequency and number of operational signals, a signal processing system was developed using the vector-matrix analysis method. As a result of modeling the processing characteristics of functional signals (at a sampling rate of 1 kHz), the system quick-response was 3 ms, with the possibility of its further decrease as its productiveness increases.