Emergency components – parameters that occur during any switching in the electrical system. They are one of the most informative values and are used in highly sensitive protection functions, for example, to implement blocking during swings.

There are a large number of implementations of emergency component filters. In this article, we consider the simplest implementation of this filter described in [1]. A more complex implementation, for example, is given in [2].

The output value of emergency component filter is determined by the expression

where * V* is the value of the observed value at a discrete time instant

*k*,

*N*is the value that determines the delay of the input signal for calculating the alarm component, usually taken to be a multiple of the value of the samples over the period of the network frequency.

The implementation of filter in Simulink is given in the attached file emer_components.mdl. The type of circuit is shown in Fig. 1.

Fig. 1. Implementation of the emergency components filter in Simulink

Test the resulting filter. For this we will use the circuit shown in Fig. 2. At the input of the filter, we apply a sinusoidal signal, the amplitude of which during the test is increased by 2 times.

Fig. 2. Scheme for testing filter in Simulink

In fig. 3 presents input signal and output signal of filter. We see that at the first moment (imitation of switching on) and at the time of increasing the amplitude of the input signal, the output value of the filter is not zero, while in the steady state, the output value of the filter is zero.

Fig. 3. Filter Test Results

So, we modeled and tested the simplest filter of emergency components. The filter outputs a nonzero value only at the time of switching.

**References**

- Shneyerson E.M. Tsifrovaya releynaya zashchita. – M.: Energoatomizdat, 2007.
- Kokoulin D.N., Shuin V.A. Issledovaniye algoritma ustroystva blokirovki releynoy zashchity pri kachaniyakh. – Vestnik IGEU, vyp. 1, 2012, s. 18-22.