CN202210679U - Controllable transformer dynamic power flow control device - Google Patents

Abstract

A controllable transformer dynamic power flow control device is provided. The device is composed of a controllable transformer, a power unit, a measurement and control module, a bypass switch, an input voltage transformer, an output voltage transformer and an output current transformer. The dynamic power flow control method is as follows, through utilizing an electronic power switch which can be rapidly turned on/off, the on/off of a tap joint of the input side (primary side) of the controllable transformer can be controlled, in pulse width modulation signals of the electronic power switch of the controllable transformer, direct current signals are injected into double frequency multiplication signals, through changing amplitude of the direct current signal, and amplitude and initial phase of the double frequency multiplication signals of the pulse width modulation signals, phase and amplitude of output voltage of the controllable transformer can be changed, adjusting of active power and reactive power can be realized, and as break-over of the tap joint of the controllable transformer can be controlled, dynamic power flow of an power network can be adjusted and controlled. The device is low in cost and high in control reliability of dynamic power flow.

Description

The dynamic power flow control device of controllable transformer

Technical field

The utility model relates to the dynamic power flow control device of flexible transmission technical field, particularly a kind of controllable transformer.

Background technology

Modern power systems is characteristics with big unit, superhigh pressure, long distance, heavy load, is a typical strong nonlinearity, higher-dimension, dynamically big system.Use along with the interconnected and various new equipments of large-scale power system; Make generating, transmission of electricity more economical, also increased simultaneously the scale and the complexity of electric power system efficiently; Add the generally use of quick response excitation system and the introducing of Electricity Market Competition mechanism, operation of power networks also greatly increases in the possibility at stability limit edge.Therefore, the flexibility of operation of power networks, trend controllability and grid stability become the problem that more and more presses for solution.In addition,,, improve the operation and the economic benefit of system, improve competitiveness so that reduce operating cost to greatest extent because the restriction of factors such as environmental protection, land use presses for and utilizes existing electric power transmission network to carry more electric power.But, because the commercial operations of saturated and grid company in transmission of electricity corridor, rely on and build new transmission line and increase the transmission capacity more and more difficult that costs dearly, will become.

Therefore, the demand that produced of the transmission system operating pressure of 21 century may be summarized to be following 3 aspects:

(1) increase ability to transmit electricity: thus because the increase of electricity consumption makes the transmission of electric energy demand increase, the situation of line construction reduction makes the requirement that improves ability to transmit electricity more outstanding on the other hand.

(2) keep system stability: serious power system accident causes severe impairment can for the social life in the vast service area; Like interruption of communication, cut off the water and electricity supply, communication paralysis, financial circulation are damaged, the precise machining process process is impaired, computerized information is lost etc., directly influences user's normal electricity consumption.Therefore, how in the compelled more electric power of longer distances of electric power system, still can keep the stability of a system, just become another vital task of management and running personnel.

(3) optimize the system operation: the change frequency that changes the power delivery that is determined with electricity market because of service conditions increases fast, and system controls and becomes more complicated, need the trend of total system be optimized.This optimization need be taken all factors into consideration the situation of overall situation operation in increasing area.In addition; Electricity market requirement system through specific " a contract path " go to control flow of power to; Control has the higher ability of controlling to trend to require electrical network; And this is difficult to accomplish in AC transmission system, because wherein the electric power in each " path " all is by the decision of the electrical characteristic of other all power transmission lines.

Flexible AC transmitting system (the Flexible Alternate Current Transmission System that arises at the historic moment to the demand; FACTS) technology, fundamentally changed ac grid system basically only rely in the past mechanical type, at a slow speed, be interrupted and the situation of coarse control and optimisation technique measure.The FACTS device is voltage, impedance and the phase angle on the control transmission line simultaneously or selectively, realize meritorious and reactive power flow control, for ac grid system provides rapidly, continuously and accurate control and the ability of optimizing trend.Under the prerequisite that does not change system's power generation mode and network topology structure, can utilize the FACTS device to improve the stability of system, improve the ability to transmit electricity of system, and alleviate the clogged conditions of system to a certain extent.

Though present FACTS technology has above many advantages,, also have significant limitation: FACTS unit engineering cost is high, applies difficulty; There is ill-effect between FACTS and power equipment and other controllers; The loss of FACTS device self is big; The complicated control structure of FACTS device and to the requirement of corresponding auxiliary devices such as communications facility has proposed more strict requirement to the operation and the control of electrical network; The additional problem that plant failure is brought; Stability of a system problem that the series connection access causes or the like makes its application in electrical network receive very big restriction.

Summary of the invention

To the problems referred to above, the purpose of the utility model provides a kind of dynamic power flow control device of controllable transformer, and the trend adjusting of raising electric power system, ability to transmit electricity, the stability of a system, reliability etc. make China's electrical network really become strong intelligent grid.

The technical solution of the utility model is following:

A kind of dynamic power flow control device of controllable transformer, it is characterized in that this device formation comprises: controllable transformer, power cell, measurement and control module, by-pass switch, input voltage instrument transformer, output voltage instrument transformer and output current transformer constitute:

The former limit of described controllable transformer comprises major joint and plus tapping head minus tapping head;

Described power cell is made up of first group power, second group power, filter inductance and filter capacitor; Described first group power of this power cell and second group power constitute by 2 insulated gate bipolar transistor differential concatenations; One end of described first group power and second group power connects the plus tapping head and the minus tapping head on the former limit of described controllable transformer respectively; One end of the described filter inductance of another termination of described first group power and second group power; The described input power supply of another termination of this filter inductance; Described filter capacitor is connected between the plus tapping head and minus tapping head on the former limit of described controllable transformer, and the control end of described first group power and second group power links to each other with the corresponding controling end of control module with described measurement;

Described by-pass switch is connected between the major joint and input power supply on the former limit of described controllable transformer;

One side of described input voltage instrument transformer links to each other with the former limit of controllable transformer input voltage main circuit, and voltage signal output end links to each other with the voltage signal input port of control module with described measurement;

Described output voltage instrument transformer, a side links to each other with controllable transformer secondary output voltage main circuit, and voltage signal output end links to each other with the voltage signal input port of control module with described measurement;

Described output current transformer is serially connected in the output main circuit of controllable transformer, and its current signal output end links to each other with the current signal input port of control module with described measurement;

Described measurement links to each other with described first group power and the control end of second group power and the control end of described by-pass switch of described power cell respectively with the control signal output ends of control module, and this measurement links to each other with host computer with control module.

Described measurement and control module are digital signal processor, single-chip microcomputer or computer.

Described first group power and second group power are respectively integral gate change transistor, gate turn-on thyristor, metal-oxide half field effect transistor or other electronic power switches.

The control principle of its power and the index of modulation is derived as follows:

IGBT pulse-width signal D is:

In the following formula, 0≤D≤1, K ₀Be direct current signal amplitude, K ₂Be two frequency-doubled signal amplitudes, ω ₀Be electrical network input voltage fundamental frequency,

Be two frequency-doubled signal initial phase angles;

If controllable transformer input voltage V _InFor:

V _in＝V ₁sin(ω ₀t) (2)

In the following formula, V ₁Peak value for controllable transformer;

If the positive and negative tap no-load voltage ratio of controllable transformer is respectively (1+N) and (1-N), then controllable transformer output voltage V _OutFor:

$V_{\mathrm{out}}=V_{\mathrm{in}}*(\frac{1-D}{1+N}+\frac{D}{1-N})---\left(3\right)$

So, the controllable transformer output voltage V _OutFor:

In the following formula, the 1st on equality the right is the fundamental component of output voltage, wherein, $A=\frac{1+N-2{\mathrm{NK}}_0}{1-{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HDA0000090695800000012.png"\; state="\{\{state\}\}">N</figure-callout>}}^2},$ $B=\frac{{\mathrm{<figure-callout\; id="2"\; label="NK"\; filenames="HDA0000090695800000012.png"\; state="\{\{state\}\}">NK</figure-callout>}}_2}{1-{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HDA0000090695800000012.png"\; state="\{\{state\}\}">N</figure-callout>}}^2};$

Therefore; The initial phase angle theta of the amplitude

of controllable transformer output voltage fundamental component is relevant with the amplitude and the initial phase angle thereof of IGBT pulse-width modulation direct current signal amplitude, two frequency-doubled signals, and its relation is:

Therefore, the initial phase angle of controllable transformer output voltage fundamental component

amplitude

output voltage fundamental component

does

Generally speaking, N is less for controllable transformer tap no-load voltage ratio, 0≤N≤0.15; And 0≤K ₀≤0.5,0≤K ₂≤0.5,

Therefore, output voltage fundamental component

Initial phase angle depend primarily on the amplitude K of IGBT pulse-width modulation two frequency-doubled signals ₂And initial phase angle

Because the N quadratic term can be ignored in 0≤N≤0.15 therefore; So

Following formula shows K ₂Right

Influence less, controllable transformer output voltage fundamental component amplitude

Depend primarily on direct current signal amplitude K in the IGBT pulse-width signal ₀

Suppose that electrical network 1 links to each other with transmission line to electrical network 2 transmissions of electricity through controllable transformer, reactance is j ω L between electrical network 1 and the electrical network 2, and electrical network 2 bus terminal voltages do

V _{Electrical network 2}=V ₂Sin (ω ₀T+ α) (8)

Then the relation of the active power P of controllable transformer place transmission line and reactive power Q and controllable transformer output voltage is following:

$P=\frac{V_2{\mathrm{<figure-callout\; id="1"\; label="V\; outM"\; filenames="HDA0000090695800000012.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{outM}}^{}}{\mathrm{\&omega;L}}\sin (\mathrm{\&alpha;}-\mathrm{\&theta;})---\left(9\right)$

$Q=\frac{{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="HDA0000090695800000012.png"\; state="\{\{state\}\}">V</figure-callout>}}_2^2-V_2{\mathrm{<figure-callout\; id="1"\; label="V\; outM"\; filenames="HDA0000090695800000012.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{outM}}^{}\cos (\mathrm{\&alpha;}-\mathrm{\&theta;})}{\mathrm{\&omega;L}}---\left(10\right)$

In the above-mentioned formula, active power, reactive power, voltage equivalent all adopt per unit value to calculate voltage magnitude V ₂All near 1.0.Can find out that from (9), (10) two formulas active power P is main relevant with the initial phase angle theta of controllable transformer output voltage fundamental component, the then main and controllable transformer output voltage fundamental component amplitude of reactive power Q

Relevant; That is the amplitude K of main and IGBT pulse-width modulation two frequency-doubled signals of transmission line active power P, ₂And initial phase angle

Relevant, direct current signal amplitude K in the then main and IGBT pulse-width signal of reactive power Q ₀Relevant.

Therefore, through to two frequency-doubled signal amplitude K in the IGBT pulse-width signal ₂With the initial phase angle

With direct current signal amplitude K ₀Adjusting realized the adjusting of active power and reactive power; Because the tap conducting of controllable transformer is controlled; The power tube IGBT capacity of control controllable transformer tap is merely the part of controllable transformer capacity; Thereby cost is low, thus the low cost of realization, the active power of high reliability and the control of reactive power.

The dynamic power flow control method of the controllable transformer that the utility model proposes is a kind ofly according to the electrical network demand active power and the reactive power of controllable transformer place transmission line to be controlled.Conducting and shutoff through IGBT control controllable transformer tap; In the pulse-width signal direct current signal of IGBT, inject two frequency-doubled signals; Through changing direct current signal amplitude and the amplitude and the initial phase of two frequency-doubled signals in the pulse-width signal, thereby phase place, the amplitude of controllable transformer output voltage have been changed.

The technique effect and the characteristics of the utility model are following:

1. power tube only needs the conducting of controllable transformer tap is controlled, thereby cost is low, has overcome the expensive problem of existing FACTS device;

2. usual controllable transformer can only be through regulating the control that its tap carries out voltage magnitude, and the utility model is through injecting two frequency-doubled signals to power tube IGBT pulse-width signal, thereby realized the skew of input voltage angle, realized the control of active power;

3. inject two frequency multiplication pulse-width signals and cause that main circuit produces triple-frequency harmonics, harmonic content is not high, also can be as required in addition filtering.

4. the power tube of controllable transformer tap also can be that other can turn-off fast, the switch of conducting.

Description of drawings

Fig. 1 is the dynamic power flow control sketch map of the utility model controllable transformer.

Fig. 2 is the structural representation of the dynamic power flow control device of the utility model controllable transformer.

Fig. 3 is the algorithm flow chart of the utility model dynamic power flow control.

Fig. 4 is the dynamic power flow phase control analogous diagram of the utility model controllable transformer.

Embodiment

Below in conjunction with embodiment and accompanying drawing the utility model is described further, but should limit the protection range of the utility model with this.

See also Fig. 2 earlier, Fig. 2 is the structural representation of the dynamic power flow control device of the utility model controllable transformer.Visible by figure, a kind of dynamic power flow control device of controllable transformer comprises: controllable transformer 1, power cell 2, measurement and control module 3, by-pass switch 4, input voltage instrument transformer 5, output voltage instrument transformer 6 and output current transformer 7 constitute:

The former limit of described controllable transformer 1 comprises major joint 12, plus tapping head 13 and minus tapping head 11;

Described power cell 2 is by the first group power S ₁, the second group power S ₂, filter inductance L _fWith filter capacitor C _fForm this power cell 2 described first group power S ₁With the second group power S ₂Constitute the described first group power S by 2 insulated gate bipolar transistor differential concatenations ₁With the second group power S ₂An end connect the plus tapping head 13 and minus tapping head 11 on described controllable transformer 1 former limit, the described first group power S respectively ₁With the second group power S ₂The described filter inductance L of another termination _fAn end, this filter inductance L _fThe described input power supply of another termination, described filter capacitor C _fBe connected between the plus tapping head 13 and minus tapping head 11 on described controllable transformer 1 former limit the described first group power S ₁With the second group power S ₂Control end link to each other with the corresponding controling end of described measurement with control module 3;

Described by-pass switch 4 is connected between the major joint 12 and input power supply on described controllable transformer 1 former limit; During power cell work, by-pass switch turn-offs, when power cell is deactivated, and the by-pass switch conducting.

One side of described input voltage instrument transformer 5 links to each other with the former limit of controllable transformer input voltage main circuit, and voltage signal output end links to each other with the voltage signal input port of control module 3 with described measurement;

Described output voltage instrument transformer 6, one sides link to each other with controllable transformer secondary output voltage main circuit, and voltage signal output end links to each other with the voltage signal input port of control module 3 with described measurement;

Described output current transformer 7 is serially connected in the output main circuit of controllable transformer, and its current signal output end links to each other with the current signal input port of control module 3 with described measurement;

The control signal output ends of described measurement and control module 3 respectively with the described first group power S of described power cell ₁With the second group power S ₂The control end of control end and described by-pass switch 4 link to each other, this measurement links to each other with host computer with control module 3.

Described measurement and control module 3 are digital signal processor, single-chip microcomputer or computer.

The described first group power S ₁With the second group power S ₂Be respectively integral gate change transistor (IGCT), gate turn-on thyristor (GTO), metal-oxide half field effect transistor (MOSFET) or other electronic power switches.

To system shown in Figure 1, as shown in Figure 3 based on the dynamic power flow Control work flow process of controllable transformer, utilize the dynamic power flow control device of above-mentioned controllable transformer to carry out electrical network dynamic power flow control method, this method comprises following concrete rapid:

1) initialization is carried out in 3 pairs of measurements of described measurement and control module and control, sends signal to by-pass switch 4 and turn-offs by-pass switch, receives the set-point Q of the given reactive power of host computer ₀Set-point P with active power ₀

2) described measurement and control module 3 receives the input voltage V that described input voltage instrument transformer 5, described output voltage instrument transformer 6 and described output current transformer 7 are imported respectively _In, output voltage V _Out, output current I, output voltage and output current angle β, receive distant place line voltage V _{Electrical network 2}Information and transmission line reactance value L:

V _{Electrical network 2}=V ₂Sin (ω ₀T+ α), V wherein ₂Be its amplitude, α is its phase angle;

Calculate active power P, the reactive power Q of actual measurement by following formula:

$P=\frac{1}{\sqrt{2}}{V}_{\mathrm{out}}I\cos \mathrm{\&beta;}$

$Q=\frac{1}{\sqrt{2}}{V}_{\mathrm{out}}I\sin \mathrm{\&beta;};$

3) according to active power P ₀And reactive power Q ₀,, calculate the output voltage phase angle theta and the output voltage amplitude V of controllable transformer according to following formula _Out:

$P_0=\frac{V_2{V}_{\mathrm{out}}}{{\mathrm{\&omega;}}_{0}L}\sin (\mathrm{\&alpha;}-\mathrm{\&theta;})$

$Q_0=\frac{{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="HDA0000090695800000012.png"\; state="\{\{state\}\}">V</figure-callout>}}_2^2-V_2{V}_{\mathrm{out}}\cos (\mathrm{\&alpha;}-\mathrm{\&theta;})}{{\mathrm{\&omega;}}_{0}L},$

Wherein: L is the reactance value of transmission line;

ω ₀Be 50 or the pairing angular frequency of 60Hz;

V ₂Be distant place line voltage V _{Electrical network 2}Amplitude;

4) calculate pulse width modulation duty D:

1., according to controllable transformer input voltage V _In, output voltage phase angle theta and amplitude V _Out, by the direct current signal COEFFICIENT K in the pulse-width signal of following formula calculating insulated gate bipolar transistor ₀, two frequency-doubled signal COEFFICIENT K ₂And initial phase

Wherein: V ₁Be controllable transformer input voltage V _InAmplitude, N is a controllable transformer tap no-load voltage ratio;

2., according to the direct current signal COEFFICIENT K ₀, two frequency-doubled signal COEFFICIENT K ₂And initial phase

According to following formula, calculate pulse width modulation duty D:

5) according to pulse width modulation duty D, to the conducting of insulated gate bipolar transistor pulse-width signal control insulated gate bipolar transistor;

6) repeating step 2) to 5), according to the pulse width modulation duty D that is obtained, the adjusting of the dynamic power flow of electrical network is controlled through the conducting realization of control insulated gate bipolar transistor.

Through dsp controller voltage, electric current are sampled; Calculate the active power and the reactive power of transmission line; According to host computer given active power and reactive power value; According to the initial phase angle and the amplitude of formula (9) and (10) calculating controllable transformer output voltage, calculate the DC component K in the corresponding IGBT pulse-width signal according to formula (5) and (6) ₀, two frequency-doubled signal amplitude K ₂With the initial phase angle

Thereby derive IGBT pulse-width signal D.Turn-off by-pass switch, the IGBT power tube is carried out conducting control by IGBT pulse-width signal D, the voltage that makes the phase deviation of the corresponding band of controllable transformer output, the high-frequency switching signal that produces during power tube IGBT work is by the filter circuit filtering.Difference through actual measurement active power and reactive power and set-point; Active power and reactive power are carried out closed-loop control; Regulate IGBT pulse-width signal D, make that actual measurement active power is consistent with set-point with reactive power, thereby the trend of transmission line is controlled.

IGBT when work be owing to comprise two frequency-doubled signals in its pulse-width signal, then in transmission line, produce triple-frequency harmonics, though harmonic content is little, also can be as required, in addition filtering, thus make that controllable transformer output voltage quality is higher.

Fig. 4 is N=0.15, K ₀=K ₂=0.5,

The time controllable transformer output voltage analogous diagram, V among the figure _Out1Be fundamental voltage output of voltage, V _InBe input supply voltage, V _Out3Be the contained triple-frequency harmonics of output voltage.From analogous diagram 4, found out the output voltage phase shift 4.25 the degree, output amplitude has increased by 2.3%, and harmonic content is not high.

When out of service, switch-off power pipe IGBT, the conducting by-pass switch is so dynamic power flow control is out of service.

Claims (3)

1. the dynamic power flow control device of a controllable transformer is characterized in that this device comprises that controllable transformer (1), power cell (2), measurement and control module (3), by-pass switch (4), input voltage instrument transformer (5), output voltage instrument transformer (6) and output current transformer (7) constitute:

The former limit of described controllable transformer (1) comprises major joint (12) and plus tapping head (13) minus tapping head (11);

Described power cell (2) is by the first group power (S ₁), the second group power (S ₂), filter inductance (L _f) and filter capacitor (C _f) form the described first group power (S of this power cell (2) ₁) and the second group power (S ₂) constitute the described first group power (S by 2 insulated gate bipolar transistor differential concatenations ₁) and the second group power (S ₂) an end connect the plus tapping head (13) and the minus tapping head (11) on the former limit of described controllable transformer (1), the described first group power (S respectively ₁) and the second group power (S ₂) the described filter inductance (L of another termination _f) an end, this filter inductance (L _f) the described input power supply of another termination, described filter capacitor (C _f) be connected between the plus tapping head (13) and minus tapping head (11) on the former limit of described controllable transformer (1) the described first group power (S ₁) and the second group power (S ₂) control end link to each other with the corresponding controling end of described measurement with control module (3);

Described by-pass switch (4) is connected between the major joint (12) and input power supply on the former limit of described controllable transformer (1);

One side of described input voltage instrument transformer (5) links to each other with the former limit of controllable transformer input voltage main circuit, and voltage signal output end links to each other with the voltage signal input port of described measurement with control module (3);

Described output voltage instrument transformer (6), a side links to each other with controllable transformer secondary output voltage main circuit, and voltage signal output end links to each other with the voltage signal input port of described measurement with control module (3);

Described output current transformer (7) is serially connected in the output main circuit of controllable transformer, and its current signal output end links to each other with the current signal input port of described measurement with control module (3);

The control signal output ends of described measurement and control module (3) respectively with the described first group power (S of described power cell ₁) and the second group power (S ₂) the control end of control end and described by-pass switch (4) link to each other, this measurement links to each other with host computer with control module (3).

2. the dynamic power flow control device of controllable transformer according to claim 1 is characterized in that described measurement and control module (3) are digital signal processor, single-chip microcomputer or computer.

3. the dynamic power flow control device of controllable transformer according to claim 1 is characterized in that the described first group power (S ₁) and the second group power (S ₂) be respectively integral gate change transistor, gate turn-on thyristor or metal-oxide half field effect transistor.

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