DE3202323A1 - Circuit for preventing high surge loads - Google Patents

Abstract

The invention relates to the circuit for preventing high surge loads from power supply networks, as occur when a very large number of loads are switched on simultaneously during the transition to the night-time supply in a ripple-control system. According to the invention, the switching-on surge is prevented in that a switching-on delay is connected upstream of every load, whose delay duration is random within a predetermined maximum time period, and thus a gradual rise in the load at the power station is achieved.

Description

Circuit to avoid high shock loads.

Ripple control systems of power plants make sense to feed consumers, that are to be operated with cheaper night-time electricity, after switching from Automatically switch on day to night power. This simultaneous activation However, many consumers can put so much shock load on the network that they only use, for example can be carried out in districts, but not in large supply areas. These measures make such a ripple control system more difficult and expensive.

In addition, the customer structure can change in a relatively short period of time change so that further subdivisions are necessary. So one calculates e.g. with a significant worsening of the situation when heat pumps in larger Scope are used. While heaters are purely ohmic loads, Heat pumps due to the starting currents of the motors disproportionately high inrush currents appear.

The object of the invention is to avoid the power surges and thus also a subdivision of the service area into one after the other to be switched on to make smaller areas obsolete.

This is achieved according to the invention in that the electricity company emitted switch-on pulse only then switches on the consumer to be controlled, if the respective consumer has a periodic delay element its period has completed.

This ensures that the consumers are statistically distributed in be switched on in a time range of e.g. 5 or 10 minutes. Through the statistical Distribution is also achieved that not always the same consumer at the beginning and another is at the end of the switch-on period, but statistically distributed times switched on immediately or only with a slight delay and at other times with a significant delay will.

Figure 1 shows a simple circuit. 1 is an AND gate, that of the switch-on pulse of the electricity company and the periodic output pulse a monostable multivibrator 3 connected downstream of a frequency divider 2 is supplied. The frequency divider is in turn supplied by a deliberately unstable clock generator 4, e.g. a temperature-dependent one Oscillator driven with a frequency instability of e.g. 3-10.

By choosing the division factor of the frequency divider you can determine the maximum Set the delay value. The instability has the advantage that even after one Power shutdown relatively quickly ensured the statistical character of the expansion and any synchronization that may have occurred due to the restart of the Network after a short time disappeared again.

The AND gate 1 is followed by an RS flip-flop 5, which is from the Output of gate 1 is brought into the on position and thereby the downstream Amplifier 6 switches on relay 7, with which the consumer is switched on.

With the inverter 8, the ripple control signal is inverted and the second Gate 9 is supplied, which is also supplied with the output pulse of the monostable multivibrator. This gate 9 switches the RS flip-flop in the off position and also with statistical Delay.

Figure 2 shows some voltages in the circuit. Curve a is that of Electricity company coming control voltage with the switch-on jump from low to high. Curve b shows the periodic output pulses of the monoflop, which are random Have phase position to the switch-on jump of curve a. Curve c is the output voltage of gate 1. The RS flip-flop is switched over with the first pulse of this voltage. Curve d shows the output voltage of the flip-flop as a delayed switching pulse serves.

As you can see, the delay depends on the random phase position of the periodic impulses to the primary switch-on impulse.

A further simplification is possible by using the frequency divider omits and equals a clock oscillator with a period of about selects the maximum desired delay time. Since this may be frequency unstable, this can be implemented very cheaply.

Such a circuit according to the invention is so inexpensive that it can be without significant additional costs can and therefore also apply to the consumer can easily be required by law.

In further development of the invention can be for special cases, in which especially high demands are placed on the statistical character of the activation, a circuit with two oscillators of very different frequencies (e.g. one Frequency difference 1: 1000 or 1: 10000) are used in which the Switch-on pulse controls the counter from the high-frequency oscillator the low-frequency oscillator is switched and this the max.

Delay duration determined.

The high-frequency oscillator makes the counter very faster Repetition frequency "counted" up to its final value, so that its position at The arrival of the switch-on pulse certainly has a random value, too if there was a power failure just recently. After the switch-on pulse, the counter will from this random value from the low frequency oscillator to the End position clocked, when reached, the consumer is switched on. With the choice the frequency of the low-frequency oscillator can - if desired - the maximum Delay time can be set.

Of course, the arrangement according to the invention is also in the Switching on the energy supply of entire factory halls at the start of work makes sense. This is such a special case in which claims are made of statistical character must be switched on because the power supply has been switched on immediately beforehand was missing.

Claims (1)

Claim S circuit to avoid high impact loads on power supply networks when switching on a large number of consumers, characterized in that that the activation of each consumer by an upstream delay circuit is delayed, the delay time depending on chance, but a predetermined one Does not exceed the maximum value. Claim 2: Circuit according to Claim 1, in particular in the case of power supply networks with ripple control systems, characterized in that the one sent by the electricity company Switch-on impulse only then does the consumer to be controlled (night-time heating or Heat pump) switches on if there is a periodic delay element at the respective consumer (e.g. an oscillator) has completed its period. Claim 3: Circuit according to Claim 2, characterized in that a counter controlled by an oscillator as a periodic delay element and the total period of this counter of the maximum desired delay is equivalent to. Claim 4: Circuit according to Claim 1 to 3, characterized in that that the counter is optionally controlled by two oscillators with very different frequencies where the low frequency oscillator determines the maximum delay time, and by the switch-on pulse of the counter from the control by the high-frequency Oscillator switched to control by the low-frequency oscillator will.