CN105281410A

CN105281410A - Working method of switch cabinet for electric power system

Info

Publication number: CN105281410A
Application number: CN201510891041.9A
Authority: CN
Inventors: 不公告发明人
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-04-15
Filing date: 2013-04-15
Publication date: 2016-01-27
Also published as: CN105322574A; CN103166310B; CN105429188A; CN105515177A; CN105515176A; CN105529819A; CN105322575A; CN105375618A; CN103166310A

Abstract

The invention relates to a working method of a switch cabinet for an electric power system. The switch cabinet comprises a direct current voltage module which is suitable for producing direct current voltage output, and the direct current voltage module takes power from a bus bar end of the switch cabinet. The direct current voltage module comprises a mutual inductor, a charging management unit and a direct current voltage output unit, wherein the mutual inductor is suitable for taking power from the bus bar end of the switch cabinet and is connected with a rectifier filter unit; the charging management unit is suitable for controlling charging and discharging of a storage battery. According to the working method of the switch cabinet for the electric power system, the direct current voltage module which is arranged inside provides corresponding direct current voltage so as to meet normal work of relevant instruments and meters in the switch cabinet; an MCU unit is used for controlling charging and discharging, an over charging phenomenon of the storage battery is avoided, the service life of the storage battery is prolonged effectively, power required for normal work of the instruments and meters during power failure maintenance is provided by the storage battery, and a power supply is not required to be connected externally.

Description

The method of work of electric power system switch cubicle

Technical field

The invention belongs to electric power project engineering field, particularly relate to a kind of in establish switch cubicle and the method for work thereof of supply module.

Background technology

In electric power system, ring main unit is used in a large number in electric power system, but without AC/220V power supply in ring main unit, cause many electrical instrumentations cannot normal power supply, great majority all use CT (CurrentTransformer, current transformer) power taking is as Power supply, and once primary current is too small, CT electricity taking coil to instrument normal power supply, cannot make instrument cisco unity malfunction, display, set-up function all cannot use, and give operation, overhaul and bring unnecessary trouble; More cannot drive the work of pertinent instruments, instrument, such as: cable head temperature on-Line Monitor Device and misoperation prevention locking device for ring main unit.A kind of switch cubicle power supply unit is provided so necessary, to solve the Related Technical Issues of the power supply run into when power-off is overhauled, namely, DC power supply is provided, detect with the illumination of satisfied scene and misoperation prevention locking device for ring main unit unblock, cable head temperature, and facilitate field service to operate, on the basis that direct voltage is provided, produce alternating current to meet the needs of specific occasion to alternating voltage.

Summary of the invention

The technical problem that the present invention first will solve is to provide a kind of method of work being suitable for the switch cubicle of DC-voltage supply.

The technical problem that the present invention second will solve is on galvanic basis, generates three-phase alternating current.

In order to solve primary technical problem, the invention provides a kind of method of work of switch cubicle, switch cubicle comprises, and one is suitable for the direct voltage module producing direct voltage output, and this direct voltage module is from the bus end power taking of described switch cubicle.

Further, in order to when dump, also can provide instrument, instrument normal direct voltage, described direct voltage module comprises: the instrument transformer being suitable for the bus end power taking from described switch cubicle, this instrument transformer is connected with a rectification filtering unit, be suitable for Charge Management unit storage battery being carried out to charge/discharge control, direct voltage output unit; Wherein, described Charge Management unit comprises: voltage detection unit, and MCU unit is provided with the charging input end of the first switching tube, and this charging input end is connected with described rectification filtering unit output, is provided with the electric discharge output of second switch pipe; Described direct voltage output unit comprises: the first input channel be connected with described electric discharge output, and this first input channel is suitable for the accumulator DC pressure receiving the output of described Charge Management unit; The second input channel be connected with described rectification filtering unit output; First, second input channel described is connected with a DC voltage booster circuit respectively, and this DC voltage booster circuit is suitable for producing a corresponding VD according to the direct voltage of input; Described MCU unit is suitable for controlling described first switching tube, the second input channel conducting, and when described voltage detection unit is after detection charge in batteries, then controls described first switching tube and disconnect; When after described bus power-off, then control described second input channel disconnect, and second switch pipe, the first input channel conducting.Wherein, by described MCU unit to the control of the first switching tube, storage battery can be prevented to be in the state of overcharging.

Further, in order to solve the second technical problem, that is, solve the problem that individual instruments, instrument or specific occasion need AC power.

Switch cubicle of the present invention also comprises: a SVPWM converter unit, and this SVPWM converter unit is connected with the output of described direct voltage module.

Described SVPWM converter unit comprises: three-phase inverter, this three-phase inverter is controlled by a DSP, the DC side of this three-phase inverter, AC are respectively equipped with direct current, alternating voltage current detection circuit, and described direct current, alternating voltage current detection circuit are connected with described DSP;

The method of work of above-mentioned switch cubicle, comprise the method that this DSP produces SVPWM modulation signal, it comprises: set up a three-phase static coordinate system according to its axis, from direction respectively is I, II, III, IV, V, VI sector counterclockwise;

Required reference voltage vector relevant voltage vector T action time in each sector ₁, T ₂:

Wherein, N=3, N=1, N=5, N=4, N=6, N=2 corresponding I, II, III, IV, V, VI sector respectively; T _sbe a sampling period, V _a, V _bfor required reference voltage vector in three-phase static coordinate system projection on direction, V _dcfor DC bus-bar voltage.

T ₁, T ₂after assignment, also to judge it, work as T ₁+ T ₂>T _s, then T is got ₁=T ₁ts/ (T ₁+ T ₂), T ₂=T ₂ts/ (T ₁+ T ₂)

Finally, adopt DSP inside to have hardware to realize, as required, the SVPWM of five sections or seven segmentations can be selected.

Further, the method for described DSP generation SVPWM modulation signal also comprises:

Judge required reference voltage vector in the step of respective sectors, this step comprises:

If sector discriminant: N=A+2B+4C;

Wherein, V _a+ 2V _b> 0 A=1, otherwise A=0;

V _a-V _b> 0, then B=1, otherwise B=0;

2V _a+ V _b< 0, then C=1, otherwise C=0;

Judge according to above-mentioned formula the value determining corresponding A, B, C, substitute into described sector discriminant to obtain required reference voltage vector sector, place, that is, N=3, N=1, N=5, N=4, N=6, N=2 corresponding I, II, III, IV, V, VI sector respectively.

Compared with prior art, tool of the present invention has the following advantages: the direct voltage module of establishing in (1) the present invention passes through provides corresponding direct voltage to meet the normal work of pertinent instruments in switch cubicle, instrument; (2) by MCU unit controls charging and discharging, avoid the phenomenon occurring accumulator super-charge, effective prolonging service life of battery, and by storage battery to realize power-off maintenance time required instrument, instrument normally work, without the need at external power supply; (3) add SVPWM converter unit at DC output end, realize direct current and the conversion exchanged, the conversion between storage battery and three-phase alternating current, enriched voltage output class, also can solve under specific circumstances, the technical problem of three phase mains must be used; (4) modulator approach of SVPWM modulation signal of the present invention simplifies the calculating process of the modulator approach of traditional SVPWM modulation signal, has saved the computing time of DSP, has improve computational accuracy.

Accompanying drawing explanation

In order to make content of the present invention be more likely to be clearly understood, below basis specific embodiment and by reference to the accompanying drawings, the present invention is further detailed explanation, wherein

The circuit structure block diagram one of direct voltage module in Fig. 1 switch cubicle of the present invention;

The circuit structure block diagram two of direct voltage module in Fig. 2 switch cubicle of the present invention;

The circuit structure block diagram of direct voltage module and SVPWM converter unit in Fig. 3 switch cubicle of the present invention;

The circuit structure block diagram of Fig. 4 SVPWM converter unit of the present invention;

Fig. 5 voltage space-vector decomposition figure of the present invention;

Wherein, bus 1, instrument transformer 2.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in detail:

Embodiment 1

See Fig. 1, a kind of switch cubicle, comprises, and one is suitable for the direct voltage module producing direct voltage output, and this direct voltage module is from the bus 1 end power taking of described switch cubicle.

This direct voltage module can be the power supply of misoperation prevention locking device for ring main unit and cable head temperature on-Line Monitor Device; Wherein said misoperation prevention locking device for ring main unit adopts utility model patent " misoperation prevention locking device for ring main unit " Authorization Notice No. CN202196675.

This direct voltage module produces the direct voltage of 24V or 28V or 220V, also can control direct voltage output according to user.

Embodiment 2

The execution mode of the direct voltage module on embodiment 1 basis, as follows:

See Fig. 2, described direct voltage module comprises: the instrument transformer 2 being suitable for the bus 1 end power taking from described switch cubicle, and this instrument transformer 2 is connected with a rectification filtering unit, is suitable for Charge Management unit storage battery being carried out to charge/discharge control, direct voltage output unit;

Wherein, described Charge Management unit comprises: voltage detection unit, and MCU unit is provided with the charging input end of the first switching tube, and this charging input end is connected with described rectification filtering unit output, is provided with the electric discharge output of second switch pipe;

Described direct voltage output unit comprises: the first input channel be connected with described electric discharge output, and this first input channel is suitable for the accumulator DC pressure receiving the output of described Charge Management unit; The second input channel be connected with described rectification filtering unit output; First, second input channel described is connected with a DC voltage booster circuit respectively, and this DC voltage booster circuit is suitable for producing a corresponding VD according to the direct voltage of input;

Described MCU unit is suitable for controlling described first switching tube, the second input channel conducting, and when described voltage detection unit is after detection charge in batteries, then controls described first switching tube and disconnect; When after described bus power-off, then control described second input channel disconnect, and second switch pipe, the first input channel conducting.

Described DC voltage booster circuit kind is a lot, such as: application number 201210349199.X title: a kind of technical scheme of direct current-direct current voltage boost circuit.

On the basis of embodiment 1 or 2, the execution mode of SVPWM converter unit, as follows:

See Fig. 3, described switch cubicle also comprises: a SVPWM converter unit, and this SVPWM converter unit is connected with the output of described direct voltage module.

See Fig. 4, described SVPWM converter unit comprises: three-phase inverter, this three-phase inverter is controlled by a DSP, and the DC side of this three-phase inverter, AC are respectively equipped with direct current, alternating voltage current detection circuit, and described direct current, alternating voltage current detection circuit are connected with described DSP;

The method that this DSP produces SVPWM modulation signal comprises: see Fig. 5, set up a three-phase static coordinate system according to its axis, from direction respectively is I, II, III, IV, V, VI sector counterclockwise; Required reference voltage vector relevant voltage vector T action time in each sector ₁, T ₂:

Wherein, N=3, N=1, N=5, N=4, N=6, N=2 corresponding I, II, III, IV, V, VI sector respectively; T _sbe a sampling period, be the sampling period that described DSP gathers direct current, AC signal, V _a, V _bfor required reference voltage vector in three-phase static coordinate system projection on direction, V _dcfor DC bus-bar voltage.

T ₁, T ₂after assignment, also to judge it, work as T ₁+ T ₂>T _s, then T is got ₁=T ₁ts/ (T ₁+ T ₂), T ₂=T ₂ts/ (T ₁+ T ₂).

Finally, realized by dsp program.Wherein, as required, can select the SVPWM of five sections or seven segmentations, DSP can adopt the dsp chip of MC56F8346 or other models all can realize this modulation.

The method that described DSP produces SVPWM modulation signal also comprises:

If sector discriminant: N=A+2B+4C;

Wherein, V _a+ 2V _b> 0 A=1, otherwise A=0;

V _a-V _b> 0, then B=1, otherwise B=0;

2V _a+ V _b< 0, then C=1, otherwise C=0;

Wherein, three-phase inverter, two power tube synchronizations of its every phase brachium pontis only have a conducting, and have 8 kinds of on off states to exist like this, its fundamental space vector comprises the amplitude of six non-zero is (V _dcfor DC bus-bar voltage).By controlling fundamental space vectorial combination and action time, SVPWM is according to reference voltage vector carry out rotating operation.V ₁, V ₂, V ₃, V ₄, V ₅, V ₆represent vector respectively mould, namely have: V ₁=V ₂=V ₃=V ₄=V ₅=V ₆=(2/3) V _dc.

In the modulator approach of SVPWM modulation signal, three-phase system model needs to be transformed in two-phase rest frame:

[\begin{matrix} V_{a l f} \\ V_{b e t} \end{matrix}] = \frac{2}{3} \times [\begin{matrix} 1 & - \frac{1}{2} & - \frac{1}{2} \\ 0 & \frac{\sqrt{3}}{2} & - \frac{\sqrt{3}}{2} \end{matrix}] \times [\begin{matrix} V_{a} \\ V_{b} \\ V_{c} \end{matrix}]

(formula 1)

In formula, V _a, V _b, V _cfor space voltage vector in three-phase static coordinate system projection on direction, V _alf, V _betfor reference voltage vector at two phase coordinate systems projection on direction, V _sfor mould, then have:

V _alf=V _s* cos θ (formula 2)

V _bet=V _s* sin θ (formula 3)

Reference voltage vector adjacent fundamental space Vector modulation can be crossed obtain:

\overset{&RightArrow;}{V_{s}} = \frac{T_{k}}{T_{s}} \overset{&RightArrow;}{V_{k}} + \frac{T_{k + 1}}{T_{s}} {\overset{&RightArrow;}{V}}_{k + 1}

(formula 4)

In above formula, T _k, T _k+1for fundamental space vector at a sampling period T _sin action time.K is vector place sector number, and azimuth θ can be obtained by antitrigonometric function computing in two-phase rest frame.

Judge reference voltage vector sector, place, analyzes V _alf, V _betrelation, following rule can be obtained, namely judge inequality:

If V _bet> 0, then A=1, otherwise A=0;

If

\sqrt{3} * V_{a l f} - V_{b e t} > 0,

Then B=1, otherwise B=0;

If

\sqrt{3} * V_{a l f} + V_{b e t} < 0,

Then C=1, otherwise C=0;

N=A+2B+4C is differentiated by sector.

Easily know N=3, N=1, N=5, N=4, N=6, N=2 be corresponding I, II, III, IV, V, VI sector respectively.

Work as reference voltage vector when the Ith sector, fundamental space vector can calculate by through type action time:

V_{a l f} * T_{s} = V_{1} * T_{1} + \frac{1}{2} V_{2} * T_{2}

V_{b e t} * T_{s} = \frac{\sqrt{3}}{2} V_{2} * T_{2}

Can obtaining of solution:

T_{1} = \frac{\frac{3}{2} * V_{a l f} - \frac{\sqrt{3}}{2} * V_{b e t}}{V_{d c}} * T_{s}

T_{2} = \frac{\sqrt{3} * V_{b e t}}{V_{d c}} * T_{s}

(formula 5)

Work as reference voltage vector when the IIth sector,

T_{1} = \frac{\frac{\sqrt{3}}{2} * V_{b e t} + \frac{3}{2} * V_{a l f}}{V_{d c}} * T_{s}

T_{2} = \frac{\frac{\sqrt{3}}{2} * V_{b e t} - \frac{3}{2} * V_{a l f}}{V_{d c}} * T_{s}

(formula 6)

In like manner can deriving the voltage vector action time in other sector, all there is computing as above when needing the vector of synthesis to be positioned at each different sector.By being not difficult to find that they are combinations of some basic times to solving of each sector basic vector operate time.See Fig. 5, required reference voltage vector projection in three-phase static coordinate system is respectively V _a, V _b, V _c, then have

V_{a} + V_{b} + V_{c} = V s * c o s θ + V s * c o s (θ - \frac{2}{3} π) + V s * c o s (θ + \frac{2}{3} π) = 0

Formula (7) is obtained by formula (1) and formula (7)

(\begin{matrix} V_{a l f} \\ V_{b e t} \end{matrix}) = (\begin{matrix} 1 & 0 \\ \frac{\sqrt{3}}{3} & \frac{2}{3} \sqrt{3} \end{matrix}) \times (\begin{matrix} V_{a} \\ V_{b} \end{matrix})

Formula (8)

Obtain V _alfand V _betwith V _a, V _bcorresponding relation namely

V _alf＝1*V _a+0*V _b＝V _a

V_{b e t} = \frac{\sqrt{3}}{3} * V_{a} + \frac{2}{3} \sqrt{3} * V_{b}

Formula (9)

Judge required reference voltage vector sector, place, analyzes V _alf, V _betrelation, by V _alf, V _betuse V respectively _a, V _bjudge reference voltage vector sector, place, substitutes into above-mentioned judgement inequality by formula (9), obtains following rule:

If V _a+ 2V _b> 0 A=1, otherwise A=0;

V _a-V _b> 0, then B=1, otherwise B=0;

2V _a+ V _b< 0, then C=1, otherwise C=0;

According to the value calculating A, B, C, bring N=A+2B+4C into, to determine required reference voltage vector sector, place, that is, N=3, N=1, N=5, N=4, N=6, N=2 corresponding I, II, III, IV, V, VI sector respectively.

When required reference voltage vector when the Ith sector, fundamental space vector can pass through formula (5) and calculate action time, namely formula (9) is substituted into respectively,

T_{1} = \frac{\frac{3}{2} * V_{a l f} - \frac{\sqrt{3}}{2} * V_{b e t}}{V_{d c}} * T_{s} = \frac{V_{a} - V_{b}}{V_{d c}} * T_{s}

T_{2} = \frac{\sqrt{3} * V_{\det}}{V_{d c}} * T_{s} = \frac{2 V_{b} + V_{a}}{V_{d c}} * T_{s}

When required reference voltage vector when the IIth sector, formula (9) is substituted into formula (6) respectively,

T_{1} = \frac{\frac{\sqrt{3}}{2} * V_{b e t} + \frac{3}{2} * V_{a l f}}{V_{d c}} * T_{s} = \frac{2 V_{a} + V_{b}}{V_{d c}} * T_{s}

T_{2} = \frac{\frac{\sqrt{3}}{2} * V_{\det} - \frac{3}{2} * V_{a l f}}{V_{d c}} * T_{s} = \frac{V_{b} - V_{a}}{V_{d c}} * T_{s}

Wherein, T _sbe a sampling period, V _dcfor DC bus-bar voltage.

In like manner can derive the voltage vector action time in other sector, here not in repetition, conclusion is as shown in the table for action time:

As can be seen here, in the method for whole SVPWM modulation signal, without the need to using V _c, only need V _a, V _bcan modulation operation be met, optimize computing greatly, improve operation efficiency.

Obviously, above-described embodiment is only for example of the present invention is clearly described, and is not the restriction to embodiments of the present invention.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here exhaustive without the need to also giving all execution modes.And these belong to spirit institute's apparent change of extending out of the present invention or change and are still among protection scope of the present invention.

Claims

1. a method of work for switch cubicle, is characterized in that: switch cubicle comprises, and one is suitable for the direct voltage module producing direct voltage output, and this direct voltage module is from the bus end power taking of described switch cubicle;

Described direct voltage module comprises: the instrument transformer being suitable for the bus end power taking from described switch cubicle, and this instrument transformer is connected with a rectification filtering unit, is suitable for Charge Management unit storage battery being carried out to charge/discharge control, direct voltage output unit;

Described switch cubicle also comprises: a SVPWM converter unit, and this SVPWM converter unit is connected with the output of described direct voltage module;

The method that this DSP produces SVPWM modulation signal comprises: set up a three-phase static coordinate system according to its axis, from direction respectively is I, II, III, IV, V, VI sector counterclockwise;

Wherein, N=3, N=1, N=5, N=4, N=6, N=2 corresponding I, II, III, IV, V, VI sector respectively; T _sbe a sampling period, V _a, V _bfor required reference voltage vector in three-phase static coordinate system projection on direction, V _dcfor DC bus-bar voltage;

The method that described DSP produces SVPWM modulation signal also comprises:

If sector discriminant: N=A+2B+4C;

Wherein, V _a+ 2V _b> 0 A=1, otherwise A=0;

V _a-V _b> 0, then B=1, otherwise B=0;

2V _a+ V _b< 0, then C=1, otherwise C=0;

V _a, V _bsubstitute into above-mentioned formula respectively, to obtain the value of corresponding A, B, C, substitute into described sector discriminant to obtain required reference voltage vector sector, place, that is, N=3, N=1, N=5, N=4, N=6, N=2 corresponding I, II, III, IV, V, VI sector respectively.