SU161398A1 - - Google Patents

Description

The existing methods of compensating for the negative-sequence voltage when powering three-phase current consumers from the mains wire-ground provide symmetry for only one specific load.

The proposed method allows to obtain full voltage symmetry regardless of the magnitude and nature of the load. It consists in the fact that by introducing an additional three-phase adjustable inductive impedance, the total power factor of the inductive resistance and load equal to 0.5 is automatically maintained, then the additional single-phase capacitance connected in series with the network is proportional to the load resistance with a constant factor

/ T

proportionality, equal to.

In the drawing, illustrating the proposed method, a diagram is presented in which, for a complete compensation, the reverse sequence is strained, it is necessary to familiarize two-step automatic adjustment of parameters.

Automatic regulation of the excitation of a three-phase synchronous motor D

Neosmeiis provides the value of the equivalent power factor in the load-motor circuit

cos ф 0,5 const

(one)

After the first conditional completion, it is necessary to change the capacitance of the single-phase synchronous generator G by automatically adjusting its excitation;

W.E.

(2)

where ug is the conductivity of the circuit

load - engine; UA - capacitive conductivity of a single phase synchronous generator.

For the implementation of the conditional (1), an automatic circuit with a balanced relay, CPi is used. This relay has two windings. One winding receives a voltage from a phase-sensitive rectifying PV circuit connected via TI nGo transformers to current transformers nr. The phase-sensitive photoelectric rectifier is switched on by a half-wave diagram and creates in the right-hand coil of the CPi relay a current cos где, where f is const.

The second (; 1st) cover of the CP relay is connected to the DC circuit via a potentiometer Ri. The latter is configured so that when conditions are fulfilled (1), the CP contacts are in the neutral open position. If sozf 0,5, then current / uvlnchnts, the CPi relay closes the right pair of contacts. This will turn on the DC motor D-, which through the PI reducer will begin to change the resistance value Ro in the circuit of the excitation winding OBi of a three-phase synchronous motor. The motor D. will work until the CP coitacts are open, i.e., until condition (1) is fulfilled. If, 5, then the engine Da will begin to rotate to the other side, ensuring that condition (1) is met.

In the engine circuit D-motor, a relay of current PT is provided, which disconnects the second stage of regulation until condition (1) is fulfilled. Under condition (I), the current in the RT relay circuit does not leak, the relay closes the RT relay contact in the power supply circuit of engine D, which makes it possible to operate the second part of the circuit.

In the second part of the circuit, the automatic regulation of the excitation of a single-phase synchronous generator D is performed. For this purpose, a CPO relay is used, similar in design to a CP relay. The right winding of the CPO relay is powered by the current of the direct sequence of the OPNS private power transmission line. The left winding of the CPO relay is wrapped around the current from the current transformer TT of the stator circuit of a single-phase synchronous generator of the Apele CP, so that the condition (2) of the average contact of the CPz relay is in the neutral open position under the conditions (2). With an increase in the load of consumers, the conductivity of the direct current sequence increases. When the current in the right coil of the CP2 relay increases, it closes the right pair of contacts. In this case, the motor Da will be turned on, which, through the PZ reducer, will start to move the RS resistor in the excitation winding circuit of the single-phase synchronous generator A. The displacement of the slider takes place until condition (2) is fulfilled. In this case, the reverse sequence at the load terminals is zero.

To limit the movement of the rheostat engines and the h within certain limits, the circuit provides limit switches with contacts K. B and C H to stop the auxiliary DC motors.

Subject invention

The method of compensating negative sequence charging when powering three-phase current consumers from a network is one wire - ground, characterized in that, in order to obtain full symmetry conditions regardless of the size and nature of the load, by introducing an additional three-phase adjustable inductive resistance, a total power factor of inductive impedance and a load of 0.5 is then automatically adjusted inclusive in series with the network. itelnoe single phase capacitance proportional to the resistance load factor ieizmennym Proport / T

nationalities equal to