Method of load supply from n-phase power supply system (version 1)

FIELD: electricity.

SUBSTANCE: power required for supply of DC load is extracted with the help of a fully controllable n-phase WPM-rectifier of transistor type by means of balancing currents, at least from one phase, making a group of balanced phases, - so that the current that remained in each phase of the specified group picked by a non-balanced load, has a module value equal to either the one that has been previously determined or equal to the value of the current module in the reference phase, which has been previously selected from n-supplying phases of unbalanced system of power supply according to the condition of the maximum value of the current module.

EFFECT: increased efficiency of power usage by reduction of non-efficient losses in power flow caused by unbalance of phase currents.

1 dwg

 

The invention relates to energy and can be used to improve the efficiency of electric power in power systems, with the predominant active loads.

The known method (1) load voltage DC power from three-phase power systems, accepted as equivalent by unmanaged three-phase rectifier, the implementation of which, from its every phase, the energy is taken in almost equal amounts.

The known method (2) load voltage DC power from three-phase power supply system, adopted as a prototype, through controlled three-phase rectifier, the implementation of which, from its every phase, energy is extracted in the set, almost equal amounts. In case, if the system power is unbalanced, the known method is similar and prototype method does not allow to increase the efficiency of its electricity by reducing unproductive losses caused by non-symmetry phase currents.

The problem solved by the invention, the efficiency of energy use, by reducing unproductive losses caused by non-symmetry phase currents.

This is achieved by the fact that according to the proposed method, the power required to power is agrusti DC extract from at least one phase comprising the group simmetriyami phases, so that the remaining in each of the phases mentioned group - the current selected unbalanced load, would have had the unit rate, equal to, or predetermined, or equal to the value of the module of the current in the reference phase. While the reference phase is pre-determined from the n-supply phases unbalanced power supply system according to condition maximum value of the module current.

The drawing shows a diagram illustrating the essence of the claimed method. This introduced the following notation.

ES - feeding three-phase power supply system

1, 2, 3 sensors current phases a, b and C, respectively

4, 5, 6, 7, 8, 9 - fotokorrektsii chain

10, 11, 12 - bass -

13, 14, 15, 16, 17, 18 - blocks of determining the reference phase (Comparators)

19, 20, 21 - logical elements of the signal of the reference phase

22, 23, 24, 25, 26, 27 - blocks the signal simmetriyami phases

28, 29, 30 blocks the generation of control signals of the phases, a and b, respectively

31 three - phase fully-controlled PWM rectifier

32 - capacitive drive

33 - DC load

34 - unbalanced load system power supply

35, 36, 37, 38, 39, 40, 41, 42, 43 - half-wave rectifiers

44, 45, 46, 47, 48, 49 - blocks recovery phase modulating signal is corresponding simmetriyami phase

50 - unit assignments external phase of the regulatory impact

The essence of the claimed method disclosed in the example three-phase system. In the process of PTO unbalanced load in phases", and" power system are different modulo currents. This assumes that the relative phase angles are referred to the load or symmetric, or nearly symmetric, i.e. the variation of the phase angles is negligible. In accordance with the claimed method is determined by the phase at which the unbalanced load current flows with the largest module. In this case, it is assumed that this phase is the most overloaded shock, and it is defined as "reference" phase. Using a selection in the load DC - power from the other two underloaded phases, which is not a reference phase align the largest modules of the currents flowing in the individual phases of the power system. Thus, in the power system is balancing the relative modules phase currents. During this phase, from which the power to the DC load, defined as simmetriyami phase. The PTO from simmetriyami phases is carried out by fully controlled PWM rectifier transistor type, in the form of equivalent energy of a sequence of same-sex the situations, periodically repeating pulse-modulated current pulses, the length of which changes according to the law of change of the amount of recoverable balancing current. The control transistors is implemented by modulating the signal with predetermined characteristics. The use of transistors in the rectification currents, allows you to use their control properties relative to the last. Using a fully managed transistor PWM rectifier is selective current rectification, in predetermined quantities, determined by the control signal. Next, the extracted energy, having accumulated in a capacitive storage, used to power a DC load. It should be noted that if no symmetry currents in the power system are significant, and the load power constant current in comparison with it is very small, in accordance with the claimed method, the degree of balancing can be advanced through influencing the magnitude of the control of the modulating signal. In this case, by the above-mentioned effects on the magnitude of the modulating signals, which control phase selection balancing currents, the magnitude of the latter is limited.

The method is as follows. From the outputs of the sensors currents 1, 2, 3 signals proportional to the current is, taken from phase "a, b and C," unbalanced load 34, proinvestirovannye phase in blocks 10, 11 and 12, are received, respectively, to the inputs of the rectifiers 35, 38 and 40 where it is converted into a sequence of unipolar pulses. Next, you should note the following. When forming the modulating signals control the selection of balancing currents from simmetriyami phases, which is not a reference phase, a DC load, in accordance with the implementation of the claimed method, relative to the three-phase system, conventionally, there are formed three channel validation phases of the power system in conformity with the criterion "support phase". In each of the channels to be scanned signal, initially set as a reference, and proportional flowing in the test phase current, compares the signals of adjacent phases. In order arithmetic comparison module current in the assumed reference phase with the currents of adjacent phases, the latter is given to the reference phase by correcting at appropriate angles so that all the compared currents would be in-phase, i.e. the phase shift between them would be zero. If verified in accordance with the criterion of "reference" phase "And"out of it, arithmetically subtracted currents of phases "and". The latter are adjusted in phase, respectively, at 240 and 120 e. degrees, in the direction ol the constituent phase rotation. If verified in accordance with the criterion of "reference" phase "In", then it arithmetically subtracted currents of phases "a " and " C". The latter are adjusted in angle, respectively, 120 and 240 al. degrees. If verified in accordance with the criterion of "reference" phase "C", then it arithmetically subtracted currents of phases a and b". The latter are adjusted in angle, respectively, at 240 and 120 e. degrees. If the modules currents related, check with intended reference phase, the phase is less than the module current to the latter, the check phase, finally, is defined as a reference. If at least one of the modules currents adjacent to the scanned phase more module current last, the criterion of "reference phase" is checked the next phase "B", etc. After the phase reference is defined, in accordance with a specified algorithm, described below, are formed in the differential currents of the phases of the reference and corresponding simmetriyami, which after appropriate phase correction, and are modulating control signals corresponding phase PWM rectifier, whereby selection of balancing currents in predetermined quantities from simmetriyami phases. Phase correction differential signals should note the following. Formed as described above, a differential control signals to the STB the rum currents from simmetriyami phases, in phase relative to a reference phase, and they need to be adjusted in phase so that the control signal corresponding to a certain simmetriyami phase would be in-phase with respect thereto. So, before you go to the appropriate control inputs PWM rectifier formed by the aforementioned differential signals are adjusted to the appropriate angles. For example, the signal phases "and"formed as a differential relative to the reference signal phase "A"are shifted respectively by the angles: 120 and 240 al. degrees.

Thus, the outputs of blocks 35, 38 and 40, formed of a sequence of pulses, are received respectively in the first group of inputs of the blocks determine the reference phase: 13 and 16, 14 and 17, 15 and 18, to a second group of inputs which receive signals from the outputs of the rectifiers 36 and 37, 39 and 43, 41 and 42, the input of which receives signals proportional to the currents of the respective phases, and converted as described above (adjusted phase). The resulting signals are used, including for determining the phase current having the greatest amplitude (reference phase). The process of determining the reference phase, i.e. the phase with the highest module voltage, as follows. The input unit 13 receives the sequence of unipolar impul the owls of current from the outputs of the rectifiers 35 and 37, proportional respectively: proinvestirovanno current phase "A", and, sdvinuta 240 e. degrees, the current phase. The input unit 16 receives the sequence of unipolar pulses from the outputs of the rectifiers 35 and 36, respectively proportional: proinvestirovanno current phase "A", and, sdvinuta 120 e. degrees, current phase "C". Thus, the output units 13 and 16, which you can use Comparators, there are a sequence of unipolar pulses, proportional, respectively, the arithmetic difference of the currents of phases a and b" and "a and C". In case if a module current in phase "A" more modules of the currents in phases "b and C", phase "A" is determined as a reference, and the signs of the pulses in the above-mentioned sequences of positive and coincide. In this case, the output of logic element 19, which implements the logical function "And"formed a logical unit, otherwise - formed logical zero. In the latter case, automatically, by blocks 14, 17, 20, or 15, 18, 21, is alternately checking for compliance with the criterion of "reference" phases "and". If the module current in phase "In the" more modules of the currents in phases a and C, then the support is determined by the phase "B", and a logical unit is formed at the output of the logic gate signal of the reference phase 20. In case the, if the module is current in phase "With the" more modules of the currents in phases a and b", the reference is determined by the phase "C", and a logical unit is formed at the output of the logic gate signal of the reference phase 21. At the same time, in blocks of signal simmetriyami phases 22 and 23 are formed a signal proportional to the arithmetic difference of the currents of phases a and b" and "a and C", respectively. In the blocks 24 and 25, 26 and 27, are formed a signal proportional to the arithmetic difference of the currents, respectively phases, a and b, C, and C, a and C, In". Each of the blocks 22, 23, 24, 25, 26, 27 has a lock, which receives the signal block of said blocks corresponding to the signal of logical zero, in accordance with the logic of the implementation of the proposed method coming, respectively, from the outputs of blocks 19, 20 and 21. If the selected reference phase "A", only the output of block 19, a signal is generated as a logical unit, which signal the resolution of the blocks 22 and 23, and, while their outputs are signals proportional to the arithmetic difference of the currents of phases a and b" and "a and C", respectively. The outputs of blocks 20 and 21 present the signal of logical zero, which signals the lock, respectively, pairs of blocks: 24, 25, 26, 27, and all outputs mentioned pairs of blocks signals are absent. If f is a "But" is not defined, as a reference, the output of block 19, is a logical zero, the blocking work units 22 and 23. The blocks 28, 29, 30 are blocks the formation of modulating signals for controlling the respective phases of three-phase, fully controlled PWM rectifier 31, and can be made in the form of analog mixers, with the possibility of a specified control values of summed signals. Only on one of their inputs the blocks 28, 29, 30, there is always a signal. This can be explained as follows. For example, the reference phase is "And". Then on one of the inputs of the block 28, there is a signal coming from the output unit 23 that is proportional to the arithmetic difference of the signals of phases a and C, at the other input the signal coming from the output of the block 25 is missing, since the latter is blocked by a signal generated as described above, due to the fact that the phase "B" is not defined as a reference. If defined as a reference phase, the output of block 28, a signal proportional to the arithmetic difference of the currents in phases "and". If the same reference is defined phase "C", the output unit 28, the signal is absent, since the input unit 28, which outputs the blocks 23 and 25 are blocked by blocking blocks 23 and 25, a signal of logical zero, as described above. The process of forming the modulating si the channels for simmetriyami phases, if as a reference - defined phase "or"similar to those described. By means of recovery blocks phase of the modulating signal- 44, 45, 46, 47, 48, 49, the signals generated arithmetic subtraction of signals proportional to the current corresponding simmetriyami and reference phases are adjusted at angles corresponding to the phase angle between the current reference and the corresponding simmetriyami phase, the direct alternation of phases (three-phase system, this angle is equal to 120 El. degrees). If modulation of the control signals, are formed to control phase PWM rectifier "and", relative to the reference phase "A"modulation of the signal generated by block 22, by arithmetic subtraction of signals proportional to the reference phase "A" and simmetriyami phase "B", through block 45 is adjusted to 120 El. degrees; a modulating signal generated by the block 23, by arithmetic subtraction of signals proportional to the reference phase "A" and simmetriyami phase "C"is adjusted by block 44 240 e. degrees. If the modulating signals are generated to control the phase PWM rectifier - "a and C", in relation to the reference phase "B" (for the case if the phase "B" is defined as a reference), the modulating signal generated by block 24, by arithmetic is about subtracting the signals, proportional to the reference phase and simmetriyami phase "A"through block 48 is adjusted to 240 al. C;

the modulating signal generated by the block 25 by arithmetic subtraction of signals proportional to the reference phase and simmetriyami phase "C"is adjusted by block 46 120 e. degrees. If the modulating signals are generated for phases a and b", in relation to the reference phase "C" (for case, if the phase "C" is defined as a reference), the modulating signal generated by the block 27 by arithmetic subtraction of signals proportional to the reference phase and simmetriyami phase "A", through a block 47 is adjusted to 120 El. degrees; a modulating signal generated by block 26, by arithmetic subtraction of signals proportional to the reference phase and simmetriyami phase "B"is adjusted by block 49 240 e. degrees. As can be seen from the interaction logic blocks through which implements the claimed method, the modulating signal is only present on the control inputs three-phase fully-controlled PWM rectifier 31, which correspond symmetricaly phases: as applied to a three phase system there are two of them. In the third entry corresponding to the reference phase signal is absent. It should be noted that the group is a rotary unit job external phase regulatory impacts 50 depicted in explaining the claimed method - scheme, in the form of reference signals for each phase of the power system, form a more limiting effect on the quantity formed modulating control signals corresponding phase PWM rectifier, for the case of, if not the symmetry of the currents in the power system are significant, and the load power constant current in comparison with it is small. However, in accordance with the claimed method, the degree of balancing is set to advanced, through the impact on the value of the control of the modulating signal (decrease)to stabilize at the specified level. The block 50 may be constructed on the principle of the device forming the set of reference voltages, by comparison with which specify the magnitude of the modulating signals generated respectively for phases, a and b blocks 28, 29, 30. The management of the quantities mentioned baseband signals provide additional control inputs arranged in the above-mentioned blocks.

Thus, remaining in each of simmetriyami phase current has a value of modulus equal or predetermined by block 50, or equal to the value of the module of the current in the reference phase. The block 50 may be missing if initially it is planned that the current level is different in each of simmetriyami phases, must have a unit equal to the unit of current in the reference phase. After retrieval from simmetriyami phases, energy balancing currents accumulated in the capacitive storage 32, and is then used to power a DC load 33.

Thus, the sequence of actions carried out in accordance with the stated method of increasing the efficiency of electricity achieved by the fact that the power required to power a DC load, extract the at least one phase comprising the group simmetriyami phases, so that the remaining in each of the phases mentioned group - the current selected unbalanced load, would have had the unit rate, equal to, or predetermined, or equal to the value of the module of the current in the reference phase. While the reference phase is pre-selected from n-supply phases unbalanced power supply system according to condition maximum value of the module current.

SOURCES of INFORMATION

1. Zabrodin US Industrial electronics: Textbook for universities. [Text] / Zabrodin US): the High. HQ., 1982, s.

2. Zabrodin US Industrial electronics: Textbook for universities. [Text] / Zabrodin US): the High. HQ., 1982, s.

Method of feeding a DC load from an n-phase unbalanced power supply system, characterized in that the power is required to power a DC load, extract by balancing the currents of the at least one phase comprising the group simmetriyami phase, so remaining in each of the phases mentioned group current would be the unit rate equal to either a predetermined or equal to the value of the module of the current in the reference phase, which, in turn, pre-determined from the n-supply phases unbalanced power supply system according to condition maximum value of the module current, and the power of groups currents simmetriyami phase is extracted through a fully managed n-phase PWM rectifier transistor type, each phase is managed, the generated baseband signals, in the form of equivalent power sequence unipolar, recurrent pulse-modulated current pulses, the duration of which is formed according to the law of change of the envelope extracted from the corresponding simmetriyami phase power system balancing current, and the envelope of each of the balancing currents formed by the aforementioned respective baseband signal, which, in turn, form a proportion of either the arithmetic difference of the currents - current reference phase current and the corresponding simmetriyami phase; or referred to the arithmetic difference of the currents, limited to a predetermined value.



 

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