SU1317554A1 - Method of protection of d.c.sources - Google Patents

Abstract

The invention relates to electrical engineering, in particular to the protection of direct current sources. The purpose of the invention is to increase the reliability of the power supply by early detection of a source with reduced energy efficiency. This is achieved by periodically disconnecting the load with the switching device for a time sufficient to control the amount of reverse current and the operation of the protective devices. 3 il. ate 4

Description

The invention relates to electrical engineering and is intended for the protection of direct current sources operating in parallel on a common load from the flow of reverse currents in circuits where short-term load shedding is allowed.

The purpose of the invention is to improve the reliability of the power supply by early detection of a source with reduced energy efficiency.

The current, i, in the i-M damaged current source is reduced in magnitude with a decrease in the coefficient a (with a decrease in the emf). and when the critical value aa p is reached, the current / j is zero (/,) (curve 7 in fig. 3). With a further decrease in the -th to the damaged current source, the reverse current (-L) begins to flow and the damage to the current source becomes an electrical consumer. Recoil

15

FIG. 1 shows the circuit of the device 10 energy in the load is reduced by this, to implement the method in which in the load shedding (load 3 on

FIG. 1 and 2) leads to the flow of a reverse current source (-It) in the i -ro circuit of the damaged source even at а «1 (curve 8 in Fig. 3).

The value of acre and the magnitude of the reverse current (- //) also depend on the coefficient p, i.e., on the degree of reduction of the internal resistance Ri i-ro of the damaged current source. With decreasing steepness of curves

Laziness 2 is connected to a total load of 3. A 20 current change / increases (curves B in the circuit of each current source are set to 9 and 10 in Fig. 3).

If the load is not disconnected, then reverse current devices are used as protective devices; in fig. 2 shows a scheme for implementing a method in which fuses are used as protective devices; in fig. 3 - graphs of the current change in the circuit of the damaged current source.

Parallel connected sources of direct current 1 with internal resistances30

but the protective device 4, and in the load circuit - switching device 5 (Fig. 1).

When performing a device that implements the proposed method, according to scheme 25 of FIG. 2 fuses are used as protective devices 6.

When all current sources are in good condition, the energy yield to the load is maximum. If any current source 1 loses its efficiency, which is manifested in the reduction of its EMF and the value of internal resistance, then its energy output to the load begins to decrease.

FIG. Figure 3 shows the graphs of the change in the current / I in the gth damaged source of current with a decrease in the EMF, and a gnome. and internal resistance; Coefficients and Р: characterize the degree of EMF reduction, - and internal resistance

These current sources are disconnected by the protection device only when the reverse current reaches the setting value of the protection device operation.

According to the proposed method, the load 3 is periodically disconnected by the switching device 5 for a time sufficient to control the amount of reverse current and to activate the protection devices.

When the load is disconnected and there is a damaged current source, all other good current sources start working on the damaged current source as if on a load.

As a result, the reverse current in the circuit of the damaged current source immediately reaches the set point of the response of the protection device, which causes its operation and the disconnection of the damaged current source.

If a load outage occurred.

of iri-ip ro of the damaged source 40, the current sources are fully operational,

this does not reflect on their future performance.

Thus, periodic disconnection of the load from parallel-connected current sources reduces the accidental time of damaged current sources, significantly reduces energy losses, increasing the energy yield to the load, and increases the reliability of current sources by detecting the damaged source earlier with reduced energy efficiency. .

Claims (1)

Invention Formula The method is protected by DC sources connected in parallel to the common supply. Current /; in the i-ro circuit of the damaged current source is determined by the equation ,, Ei-Vg ...,  -R :, where K -f is the potential difference at the terminals a and b of the load (load 3 in Figs. 1 and 2), determined by the formula Va-6 P-1jI J, / R} + gjRj y 1 I 1 RL R) Rl 50 + R: " where EI and are the EMF and internal resistance of the operable sources to the PA, consisting in that of the counter current; Lied., - ,,,. -,., .. 0 g,, Ei and Ri - EMF and internal resistance of the damaged current source. reverse the current in each source and turn off the corresponding a damaged source by a protective device if the amount of reverse current in it The current, i, in the i-M damaged current source is reduced in magnitude with a decrease in the coefficient a (with a decrease in the emf). and when the critical value aa p is reached, the current / j is zero (/,) (curve 7 in fig. 3). With a further decrease in the -th to the damaged current source, the reverse current (-L) begins to flow and the damage to the current source becomes an electrical consumer. Recoil 0 five five These current sources are disconnected by the protection device only when the reverse current reaches the setting value of the protection device operation. According to the proposed method, the load 3 is periodically disconnected by the switching device 5 for a time sufficient to control the amount of reverse current and to activate the protection devices. When the load is disconnected and there is a damaged current source, all other good current sources start working on the damaged current source as if on a load. As a result, the reverse current in the circuit of the damaged current source immediately reaches the set point of the response of the protection device, which causes its operation and the disconnection of the damaged current source. If a load outage occurred.  An argument consisting of the fact that the counter- Lglo., ,,,. -,., .. 0 g,, reverse the current in each source and turn off the corresponding a damaged source by a protective device if the amount of reverse current in it exceeds a predetermined value, characterized in that, in order to increase the reliability of the power supply by early detection of a source with diminished energy output, the load is periodically disconnected for a time sufficient to control the amount of reverse current and act on our devices. Lv P 3 figure 1 b № П П P 2 FIG. 2 -li (abrasive (U2. J