RU2281543C1 - Reactive power uniform distribution apparatus - Google Patents

Abstract

FIELD: systems for uniform distribution of reactive power between connected in parallel voltage sources.

SUBSTANCE: apparatus is designed for uniform distribution of reactive power between connected for parallel operation voltage sources having voltage regulators of those voltage sources with the same number of inlet terminals of each voltage regulator. Apparatus includes several groups of windings of differentiating induction measuring transducers (one for each voltage source); number of said groups is equal to number of inlet terminals of each voltage regulator. Each winding of any group is coupled inductively with one of load-current conductors of said power sources that are connected to inlet terminals of voltage regulators of said sources. Load current conductors which are inductively coupled with windings of the same group are connected between similar-polarity terminals of said voltage sources and one of common buses connected with load. Apparatus includes in addition (one for each group of windings) parallel-operation transformers. Each transformer is connected with windings only of one group and it has the same turn number in all windings. Primary windings of said transformers are connected to windings related to first (driving) power source having voltage regulator whose inlet terminals are connected to outlet terminals of said source. Each secondary winding of any transformer is connected between inlet terminal of voltage regulator of other (driven) voltage source and back end terminal of winding inductively coupled with current conductor of said source. Lead end terminal of said winding is connected to such outlet terminal of voltage source that is connected with said current conductor. Voltage sources with different nominal currents are used with windings whose mutual inductance with load electric current conductors have voltages inversely proportional to nominal currents of voltage sources.

EFFECT: improved quality parameters of produced electric energy.

2 cl, 1 dwg

Description

A device for uniform distribution of reactive power relates to the field of electrical engineering and can be used to evenly distribute reactive power between voltage sources connected for parallel operation, for example, synchronous generators equipped with voltage regulators of these sources, by regulating the EMF of all simultaneously working voltage sources, except for one leading , as a function of the deviation of their reactive currents from the reactive current of the leading voltage source.

A device is known for uniform distribution of reactive power between voltage sources connected for parallel operation, comprising, for each voltage source, a current transformer included in one of the phases of the voltage source, the secondary winding of which is connected to the midpoint of the primary winding of the parallel transformer and the midpoint of two series-connected the first and second resistors, which have the same resistance and are the load of this winding. The secondary winding of the parallel transformer is connected in series with the input terminals of the voltage source voltage regulator to the other two phases of this voltage source. Due to this feature of the primary winding of the parallel transformer, the current of the current transformer is divided into two equal parts that pass through the first and second resistors. If the voltage source operates autonomously, the voltages of the primary and secondary windings of the parallel transformer are practically zero, since the voltage drop at the first and second resistors is equal in absolute value and opposite in direction. As a result, the external characteristic of the voltage source is astatic, the voltage of this voltage source does not depend on the current of its load. In parallel operation of voltage sources, all second resistors are connected in parallel. On the first resistors of each voltage source, a voltage proportional to the load current of this voltage source drops, and on all second resistors the voltage is the same and proportional to the average current of all voltage sources. If the reactive current of a voltage source is greater than the average reactive current of all voltage sources, then the increased voltage supplied to the input of the voltage regulator of this voltage source leads to a decrease in the EMF of this voltage source and thereby to a decrease in its reactive current. If the reactive current of any voltage source is less than the average reactive current of all voltage sources, then the reduced voltage supplied to the input of the voltage regulator of this voltage source leads to an increase in the EMF of this voltage source and thereby to an increase in its reactive current. As a result, the voltage on the common buses of voltage sources remains unchanged when the total reactive load changes, and the reactive powers of all voltage sources are almost equal if the transformation ratios of the current transformers of all these voltage sources are equal. For different capacities of voltage sources, transformers with different current transformation ratios of these sources are used so that at the same relative values of the load currents of the voltage sources, the voltage drop across the first resistors is the same. In this case, the relative values of the reactive power of the voltage sources included in the parallel operation are aligned [1, pp. 105-107].

This device has a disadvantage that is caused by the use of a current transformer and consists in the large mass and dimensions of this current transformer and resistors connected to the primary winding of the parallel operation transformers.

From this drawback there is a free device for uniform distribution of reactive power between voltage sources connected for parallel operation, equipped with voltage regulators of these voltage sources, known as a current stabilization device, closest in technical essence to the claimed device and selected as a prototype. It consists of as many groups of coils of differentiating measuring current transducers, one for each voltage source, how many input terminals each regulator has. Moreover, each of the coils of any group of coils is inductively connected to one of the group of those load current conductors that are connected to the voltage regulators of these voltage sources. These coils are connected respectively to the output terminals of the voltage sources and the input terminals of the voltage regulators of these voltage sources. In the device, the voltage of the voltage source supplied to the voltage regulator is the sum of the phase voltage of the source and the voltage on the coils. Since the last voltages are much less than the voltage of the voltage source, only those components of the voltage on the coils that are proportional to the reactive current of the voltage source matter. The voltage regulator keeps the voltage at its input terminals constant by acting on the voltage source. The voltage of the voltage source depends on the reactive component of the load current [2]. In this device, in comparison with the analogue, the dimensions and dimensions are reduced due to the use of differentiating current measuring transducers instead of current transformers and installation rheostats.

The disadvantage of the prototype is to change the load voltage under the influence of its reactive current, as a result of which the quality of the generated electric energy is deteriorated.

The problem to which the invention is directed, is to improve the quality of the electrical energy obtained by regulating the voltage of voltage sources according to the astatic characteristic.

In the proposed device, the voltage of the voltage sources does not depend on changes in the power factor of the load.

The technical result that is achieved when solving the problem is expressed in the possibility of equalizing the reactive power of the voltage sources connected for parallel operation, as well as maintaining such voltage on the common buses, to which the load is connected, which practically does not depend on the load current.

To solve this problem, a device for uniform distribution of reactive power between voltage sources connected for parallel operation, equipped with voltage regulators of these voltage sources, with the same number of input terminals for each voltage regulator, containing as many groups of coils of differentiating induction measuring transducers, one for each voltage source how many input terminals each regulator has, each coil of any coil group inductively connected to one of the load conductors of the voltage sources mentioned above, which are connected to the input terminals of the voltage regulators of these voltage sources, characterized in that those load current conductors of the voltage sources that are inductively connected to the coils of the same group are connected between the same terminals of these voltage sources and one of the common buses to which the load is connected, are introduced into the device, one per group of the mentioned coils, parallel transformers, each of which rykh is connected to coils of only one group and has the same number of turns at all windings, and the primary windings of these transformers are connected to coils belonging to the first, leading, voltage source, the input terminals of the voltage regulator of which are connected to the output terminals of this voltage source, and each of the secondary windings of any transformer is connected between the input terminal of the voltage regulator of another, slave, voltage source and the end of the coil, which is inductively connected to the current lead of this source voltage, and the beginning of this coil is connected to the output terminal of this voltage source, to which the specified current lead is connected.

In addition, the device is characterized in that coils are used for voltage sources with different rated currents, the mutual inductances of which with the load current conductors have voltages inversely proportional to the rated currents of the voltage sources.

A comparative analysis of the features of the proposed solution and the characteristics of the analogue and prototype indicates its compliance with the criterion of "novelty."

Distinctive features of the proposed solution perform the following functional tasks:

The sign "... those current conductors of the load current of voltage sources that are inductively connected to the coils of one group are connected between the same terminals of these voltage sources and one of the common buses to which the load is connected ..." - allows you to connect voltage regulators to each input slave voltage sources such voltage, which depends on the currents of the same phases of the slave and master voltage sources.

The sign "... the transformers of parallel operation, each of which is connected to the coils of only one group and has the same number of turns for all windings ... are introduced into the device, one per group of coils mentioned above," - allows you to receive signals proportional to the difference in relative values load currents of the same phases of the driven and leading voltage sources.

The sign "... the primary windings of these transformers are connected to coils related to the first, leading, voltage source, the input terminals of the voltage regulator of which are connected to the output terminals of this voltage source ..." - allows you to support on common buses to which the load is connected, a voltage that is almost independent of the load current.

The sign "... each of the secondary windings of any transformer is connected between the input terminal of the voltage regulator of another, slave, voltage source and the end of the coil, which is inductively connected to the current lead of this voltage source ..." - allows you to align the reactive power of the voltage sources connected to the parallel operation .

The sign "... for voltage sources with different rated currents, coils are used, the mutual inductances of which with the load current conductors have voltages inversely proportional to the rated currents of voltage sources ..." - allows you to align the relative values of the reactive currents (in fractions of the rated current) of the included for parallel operation of voltage sources.

The proposed solution is illustrated in the drawing, which shows a functional diagram of a device for uniform distribution of reactive power in a three-phase design.

A device for uniform distribution of reactive power consists of transformers 1 of parallel operation and a group of coils of differentiating measuring current transducers (DIPT). In each group, one of the coils 2 is inductively connected to the current lead 3 of the load current of the leading voltage source 4. Other coils 5 of this group are inductively connected to the conductors 6 of the load current of the driven voltage sources 7. Each of the coils of any group of coils is inductively connected to one of the group of load current conductors that are connected between the same output terminals 8 and 9 of the leading 4 and 7 driven voltage sources, respectively, and one of the common buses 10 to which the load 11 is connected. Leading source 4 voltage is equipped with a voltage regulator 12 with input terminals 13, and the driven voltage sources 7 are equipped with voltage regulators 14 with input terminals 15. The number of input terminals 13 of the voltage regulator 12 of the leading source 4 voltage Nia input terminals 5 and 14 of voltage regulators each of the driven voltage sources 7 and identically equal to the number of groups containing the coils 2 and 5 diptih, and number of transformers 1 parallel operation. Each transformer 1 of parallel operation has a primary 16 and secondary 17 windings. All windings have the same number of turns. The primary winding 16 is connected to the coil 2 of the leading voltage source 4. The input terminals 13 of the voltage regulator 12 of the leading voltage source 4 are connected to the output terminals 8 of this voltage source. The beginning of the 18 secondary windings of 17 transformers 1 of parallel operation are connected to the ends of 19 coils 5 of the DIPT of the driven voltage sources 7, and the beginning of 20 coils 5 are connected to the output terminals 9 of the driven voltage sources 7. The ends 21 of the output windings 17 of the transformers 1 of parallel operation are connected to the input terminals 15 of the voltage regulators 14 of the driven voltage sources 7.

A device for uniform distribution of reactive power works as follows. The voltage of the leading voltage source 4 is supported by its voltage regulator 12 rated and equal to the open circuit voltage U ₁₀ . Open circuit voltage of the driven voltage sources 7 should be equal to U ₂₀ and equal to U ₁₀ . The voltage of the lead 4 and slave 7 voltage sources differs from the voltage on the common busbars 10 (load voltage) by small voltage drops in the sections of the conductors from the output terminals 8 and 9 to the common busbars 10. Phase input voltage of the voltage regulator 14 of the slave voltage source 7 with a sinusoidal shape voltages and currents of voltage sources of the leading 4 and slave 7 voltage sources is determined by the expression

where U ₂ is the phase voltage of the slave voltage source 7;

ω is the circular frequency;

I ₁ - current of the same phase of the leading voltage source 4;

I ₂ is the current of the same phase of the slave voltage source 7;

M - mutual inductance between the conductors 3 of the load current and the coils 2 DIPT.

We replace the product ω · M with the resistance X of the mutual induction of the 2 DIPT coils, then equation (1) takes the form

много меньше напряжения U₂ ведомого источника 7 напряжения, то справедливо следующее выражение:Since the voltage

much less than the voltage U _{2 of the} slave voltage source 7, the following expression is true:

where I _1p = I ₁ · sinφ ₁ and I _2p = I ₂ · sinφ ₂ - reactive currents of the leading 4 and the slave 7 voltage sources, respectively;

φ ₁ and φ ₂ are the angles between the voltage U ₁ and currents I ₁ and I _{2 of the} load of the master 4 and slave 7 voltage sources, respectively.

The voltage regulator 14 of the slave voltage source 7 maintains the voltage U _2in constant and equal to the voltage U ₂₀ = U _{10 of} this source when it is operating in stand-alone mode at idle. Therefore, the voltage of the slave voltage source 7 depends on the difference between the reactive load currents I _1p and I _2p :

If the reactive current I _{2p of the} slave voltage source 7 is less than the reactive current I _{1p of the} master voltage source 4, then the voltage U ₂ will increase, the reactive current of this voltage source will increase. And conversely, if the reactive current I _{2p of the} slave voltage source 7 is greater than the reactive current I _{1p of the} master voltage source 4, then the voltage U ₂ will decrease, the reactive current of this voltage source will decrease.

Thus, if the voltage regulators of all voltage sources have the same voltage U ₀ and the same resistance of the conductors from the output terminals 8 and 9 of the voltage sources to the common busbars 10, then the reactive currents of all the driven voltage sources 7 become equal to the reactive current of the leading voltage source 4.

At low resistances of the conductors from the output terminals 8 and 9 of the voltage sources to the common busbars 10, the voltage drops in these conductors can be neglected, then the voltage U ₂ of all the driven voltage sources 7 and the open circuit voltage U _{10 of the} leading voltage source 4 are the same, i.e.

With the equality of U ₂₀ = U _{10 it} turns out that I _1p = I _2p .

Information sources

1. Konstantinov V.N. Systems and devices for automation of ship electric power plants. - L .: Shipbuilding, 1988, p.105-107.

2. RF patent No. 2239224, MKI 7 G 05 F 1/20. Device for current stabilization of a voltage source.

Claims (2)

1. A device for uniform distribution of reactive power between voltage sources connected for parallel operation, equipped with voltage regulators of these voltage sources with the same number of input terminals for each voltage regulator, containing as many groups of coils of differentiating induction measuring transducers, one for each voltage source, as there is input terminals at each voltage regulator, and each of the coils of any group of coils is inductively connected one of the current conductors of the load current of the voltage sources that are connected to the input terminals of the voltage regulators of these voltage sources, characterized in that those current paths of the load of voltage sources that are inductively connected to the coils of the same group are connected between the same terminals of these voltage sources and one of common buses, to which the load is connected, are introduced into the device, one per group of the mentioned coils, transformers of parallel operation, each of which is connected to a cat ears of only one group and has the same number of turns for all windings, and the primary windings of these transformers are connected to coils belonging to the first, leading, voltage source, the input terminals of the voltage regulator of which are connected to the output terminals of this voltage source, and each of the secondary windings of any a transformer is connected between the input terminal of the voltage regulator of another, slave, voltage source and the end of the coil, which is inductively connected to the current lead of this voltage source, and achalo this coil is connected to the output terminal of the voltage source is connected to said conductor. 2. The device according to claim 1, characterized in that for voltage sources with different rated currents, coils are used, the mutual inductances of which with the load current conductors have voltages inversely proportional to the rated currents of the voltage sources.