Method of automatic adjustment of currents of multi-phase system as to one of phases at combined power takeoff

FIELD: electricity.

SUBSTANCE: method consists in generation by means of additional power source to each of the rest (n-1) phases of currents, which are pre-formed so that in each adjustable (n-1) phase of the main n-phase network the geometrical sum of currents - generated to adjustable phase and with current of its load can be equal as to current modulus to the current equal to current in reference phase, and the angle formed with the current of the latter and with total current of adjustable phase following the reference one at forward sequence of phases, as well as between total currents of neighbouring (n-1) adjustable phases can be equal to electrical degrees. At that, power takeoff to the above additional power source is performed from combination of at least two minimum loaded phases which are pre-determined by the condition of decreasing asymmetry in adjustable n-phase system.

EFFECT: increasing quick operation, economy, simplifying the implementation and enlarging application range.

1 dwg

 

Way to relate to electrical engineering and can be used for balancing multi-phase and single-phase loads with time-varying parameters.

There is a method of automatic control of symmetry and three-phase voltage system (1), the implementation of which is the measurement and adjustment of the currents reverse sequence simmetriyami system. The method has similar shortcomings, lies in the complexity of its implementation, as well as low performance, due to the search method of tuning of the parameters.

There is a method of automatic balancing voltage submersible induction motor is implemented in the device (2)through which symmetrist the voltage at the terminals of the consumer by regulating the resistance of the power supply circuit of the individual phases. This method is closest to the technical nature of the claimed and is therefore adopted as a prototype. Known prototype method has drawbacks consisting in low efficiency, low performance, inability to use, the method for balancing group loads in its implementation.

The problem solved by the invention, the efficiency of the balancing multiphase systems by improving performance, increasing efficiency, simplifying is realizatsii and expand the scope of in the process of balancing.

This is achieved by using an additional n-phase of the power source of the asymmetric n-phase load symmetrist relative to any pre-selected phase, defining it as a reference. However, balancing each of the (n-1) phases is achieved by the generation of each of these currents, in which the pre-form module and phase angle so that in each phase the geometric sum mentioned currents, and currents, which currents of n-phase unbalanced load would be equal to the current reference phase, and the angle formed by the current past and current referred to the geometric sum of the currents simmetriyami phase, the next in the order for reference, the direct sequence of phases, as well as between the currents of geometric sums neighboring simmetriyami phase would be equal toalrrady. While the PTO in the above-mentioned additional source of power used to generate compensation currents unbalance, carried out by a combination of at least two of the least loaded phase, which is determined in advance.

The essence of the method is determined as follows. As you know, any n-phase system is symmetrical, if complex load its phases are equal, i.e. if it is equal to the currents of individual phases, and the phase angle between them is equal towhere n - to icesto phase system. Thus, on this basis, balancing the n-phase system can be achieved simmetria currents of individual phases relative to the current any of its phases. Since the load currents are parameters set by the load, the balancing can be achieved by geometrical addition of currents from an additional source of current or voltage so that the geometric sum generated from an additional source currents and load currents simmetriyami phase would be equal to a current reference phase, and the angle formed by the total current of the latter and the total current simmetriyami phase, which follows the reference, in a direct sequence of phases, as well as between the total currents of the adjacent (n-1) simmetriyami phases, would be equal toe. degrees. The effectiveness of using the claimed process in the transition from balancing three-phase loads to the compensation of one or a group of single-phase loads does not depend on properties of the latter, and is determined only by the capacity of an additional source of power. In the event of power from the combination of the least-loaded phases increases the degree of their balance, resulting in the efficiency of the balancing increases.

The drawing shows a diagram illustrating the essence of the proposed method. The diagram in the Eden following notation:

1 - the phase reference;

2 - unbalanced load;

3 - sensor current shape of the reference phase;

4,5 - sensors current shape simmetriyami phases;

6 - the first phase-shifting block;

7 - the second phase-shifting block;

8 - unit forming differential signals;

9 is an additional source of power;

10 - forming unit combination minimally loaded phases.

An example of the method considered in respect of the three-phase system. In this case arbitrarily as the reference phase selected by the phase "A". From the output of the sensor current shape of the support phase 3 signal proportional to the waveform of the current reference phase, enters the first phase-shifting unit 6. This block, in General, consists of (n-1) phase-shifting chains, each of which is a signal proportional to the current signal of the reference phase, in General, shifted respectively by the anglewhere m is the ordinal number of phase with the direct sequencing of phases, n is the number of phases in the system. For the case when the number of phases is equal to three, such phase-shifting of the two chains: one of the chains mentioned signal is shifted 120 respectively, and the other at 240 e. degrees, depending on the number of phases, for balancing which it will be used. From the output of block 6 signals proportional to the current reference and phase shifted by 120 and 240 is L. degrees, respectively, are received on the first group of inputs of the block forming differential signals 8, to a second group of inputs which receives signals proportional to the currents form loads simmetriyami phases formed in the sensor current shape simmetriyami phases 4 and 5, and proinvestiruem 180 El. degrees in the second phase-shifting block 7. In block formation of differential signals 8 signals to the first and second groups of inputs of the last pairs are compared:

the reference current signal, shifted by 120 e. degrees, compared with proinvestiruem 180 El. C signal proportional to the shape of the load current of phase "B"and the reference current signal, shifted by 240 e. degrees compared with proinvestiruem 180 El. C signal proportional to the current load phase "C". Thus, on the output unit 8 generates signals proportional to the vector difference of the signal of the reference phase signal and load simmetriyami phases. These two pairs of vector difference of the currents and are formed by the signals simmetriyami phases, the geometric sum which the load current of each of the respective phases and gives a current proportional to the current reference phase and the phase angle formed by the mentioned geometric sum of the current and the current reference phase, 120 e. degrees. Thus, m is obtained fully symmetric system generated signal currents, proportional to the currents simmetriyami three-phase relative to the current phase. From the output of the unit 8 the generated control signals are received by the control circuit of the additional power source 9 through which are served in simmetriyami phase. As an additional source of power may be used, for example, a system with dual energy conversion, including PWM - rectifier PWM inverter and containing an intermediate DC link. The additional power of the power source 9 is carried out by a combination of at least two phases, the choice of which is to block the formation of the combination of minimally loaded phases 10 thus, to reduce the asymmetry.

Thus, the sequence of actions performed in accordance with the claimed method, is balancing in the main n-phase network regarding any of its phases by means of an additional source of power, power is carried out by a combination of at least two minimally loaded phases. While improving the efficiency of balancing multiphase system using the inventive method is achieved by improving performance, increasing efficiency, simplifying the implementation and expansion of applications in the process when metribolone.

SOURCES of INFORMATION

1. AS the USSR № 244495, bull. No. 18, 13.10.1969, CL. 02J 3/26, 1969

2. AS the USSR № 562038, bull. No. 22, 14.07.1977, CL. 02J 3/26, 1977.

The method of balancing the main n-phase network, loaded linear asymmetric n-phase load, which symmetrist the load currents of the individual phases, characterized in that the main n-phase network pre-defined as a reference any of its phases, allocate it a signal proportional to the current it load, and with additional (n-1)-phase source of power is generated in each of the remaining (n-1) phase currents, pre-forming them in such a way that in each of simmetriyami (n-1) phases of the main n-phase network as a geometric sum of currents is generated in simmetrical phase current and its load would be equal to the current in the reference phase, and the angle formed by the last and current total current simmetriyami phase, which follows the reference with the direct sequence of phases, as well as between the total currents of the adjacent (n-1) simmetriyami phase would be equal toe. degrees, and the PTO in said additional n-phase source of power carried out by a combination of at least two, the least loaded phase, which is determined in advance by the reduction of asymmetry in simmetriyami n-phase system.



 

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