CN1979185A - Novel high-pressure frequency variator low energy-consumption load testing method - Google Patents

Abstract

The invention relates to a new type high voltage converter low energy consumption loading test method that includes the following steps: connects power network bus to converter through transformer, and the output end of converter connecting to bus after connecting inductive load, connecting voltage transformer and current transformer between converter and inductive load; adjusting the output amplitude and phase of converter, testing the voltage of resistance from inductive load to find the minimum, altering output pulse or modulation signal of PLC to control system current and realizing working state test in different current working state unit, the system current would be sent to PLC through current transformer. The invention has the following advantages and effects: it could be realized without motor; the control would be easy to realize; the test system is safe and reliable; and the power consumption of the entire system is low.

Description

A kind of novel high-pressure frequency variator low energy-consumption load testing method

Technical field

The invention belongs to and exchange transmission speed system control technology field, specially refer to a kind of high-voltage variable-frequency and variable-speed system variator low energy-consumption load testing method.

Background technology

Develop rapidly along with modern industry, the application of high-tension motor more and more widely, it is the major impetus in the industrial and mining enterprises, in the large and medium-sized factories and miness of industries such as metallurgy, iron and steel, chemical industry, water treatment, need drag various high-power machinery equipment such as blower fan, pump class, compressor.Because traditional kinematic train is made up of " motor-work mechanism ", causes a large amount of wastes of the energy and the reduction of equipment life, therefore has energy-efficient high voltage converter by the extensively employing of modern kinematic train institute.In the high voltage converter production run, in order to examine the operation conditions of each each power model of unit, overall test before must dispatching from the factory, but because of its power too big, the test that directly is connected to the grid will cause a large amount of wastes of electric energy, and increased enterprise cost, how to carry out effectively, easy, low energy consumption test will seem extremely important.

Test method for high voltage converter mainly contains two kinds at present: the one, and " AC-DC-AC " AC drive experiment system, promptly power to asynchronous machine by high voltage converter, the coaxial drive Dyn. of asynchronous machine, Dyn. drives direct current motor again, the coaxial again drive three-phase synchronous AC generator of direct current motor sends electric energy and is fed back to electrical network, realizes the test of high voltage converter various characteristics therebetween by the exciting current of regulating each motor; The 2nd, " the two inverter-double motor " that proposes presented pilot system mutually recently, a certain asynchronous machine is wherein carried out the control of slip frequency, make it to be operated in generating state and change the size of generator torque, thereby reach the purpose that fictitious load changes by changing revolutional slip.Though above two kinds of schemes all can satisfy various testing requirementss, the pilot system complexity, wayward, reliability and security are lower, and cost is also bigger.

Summary of the invention

The objective of the invention is to overcome the problem of the deficiencies in the prior art and existence, a kind of low energy consumption, safety, Simple and Reliable high voltage converter load test method are proposed, this method with the test of high voltage converter in two sub-sections, one is the frequency converter function test, can directly drive unloaded motor and carry out; It two is the test frequency converter in allowing voltage range, by the ability of rated current operation.

The present invention is primarily aimed at a back test, need not motor in the process of the test, and device simplification and cost will be reduced greatly.

Basic ideas are by means of the reactive current method for generation, set up a kind of current testing method of frequency converter low energy consumption.Its technical scheme is: power distribution network bus 1 is connected frequency converters 3 through isolating transformer 2, again with bus 1 and connect, be connected voltage transformer (VT) 5, current transformer 6 between frequency converter 3 and resistance sense load 4 after the inverter output terminal series connection resistance sense load 4; Regulate the amplitude and the phase place of frequency converter output voltage, size and Orientation with control of conversion device output current, in order to find line voltage and unit output voltage phase place control signal of the same size fast, detect the voltage of resistance in the resistance sense load, find out its minimum value, output this moment is consistent with input AC size and phase place; Close a floodgate, the PLC (programmable logic controller (PLC)) in the frequency converter 3 is sent in the pressure drop that voltage transformer (VT) 5 detects resistance, the output pulse that changes PLC simultaneously is to adjust the output phase angle, the signal value minimum that measures up to voltage sensor, change the amplitude of modulation signal then, constantly detect resistance drop simultaneously up to the signal minimum that finds voltage sensor to measure once more, this moment frequency converter 3 the output voltage size, phase place with exchange the input basically identical, then by changing PLC output pulse or modulation signal, the control system electric current, thereby finish the test of the operation conditions of different electric current operating modes unit, system power is detected by current transformer 6 and sends into PLC and monitor.

Close a floodgate moment by load current-limiting resistance current limliting, combined floodgate preceding switch K1, K2, K3, K4, K5, K6 are off-state, the combined floodgate start-up course is opened for closing sky--and close K6--and close K1--and close K3--and K2--and close K5--and close K4, when normal operation, whether need disconnect K3 and in actual moving process, test definite.

Output current, voltage are detected and are exported pulse adjustment output phase angle and carries out different current conditions and full load conditions test with the electric current of regulating by IGBT (insulated gate bipolar transistor) by PLC, in order to guarantee not overvoltage of cell voltage, power cell should be adjusted into inductive load, output phase angular advance input phase angle makes power flow to mains side by cell side

Detect to finish the back uninstall process and be the disconnected K5 of the disconnected K3--of the disconnected K4--of the disconnected K2--of the disconnected K1--of disconnected K6--.

For safety test, the size that line voltage and frequency converter output voltage phase angle are looked the resistance sense load is selected in about 0 degree.

The present invention has proposed a kind of brand-new high voltage converter test method by the reactive current method for generation, the ability that the effective test frequency converter of energy moves by rated current in allowing voltage range, this method is broken away from the constraint of traditional experiment method, has the following advantages and good effect:

(1), in process of the test, need not motor by the reactive current method for generation;

(2) divide two steps with the high voltage converter test, make control simpler and easy;

(3) pilot system is simple, reliability, security, practicality height;

(4) the meritorious consumption of entire test has only the loss of frequency converter and the consumption of load current-limiting resistance, so energy consumption is low.

Description of drawings

Fig. 1 is the test principle figure of the annexation of high-pressure frequency variator low energy-consumption load testing system of the present invention and network system bus;

Fig. 2 is when considering single test, specific embodiments figure of the present invention;

Fig. 3 is an IGBT drive signal generating principle block diagram;

Fig. 4 is the isoboles of test principle figure of the present invention;

Fig. 5 In advance During a certain angle [alpha], system voltage electric current phasor figure;

Fig. 6 a Lag behind During a certain angle [alpha], and U _bCos α≤U _aThe time, system voltage electric current phasor figure;

Fig. 6 b Lag behind During a certain angle [alpha], and U _bCos α 〉=U _aThe time, system voltage electric current phasor figure;

Fig. 7 is for working as

In advance During the α angle, ignore the frequency converter loss after, system voltage electric current phasor figure.

Embodiment

Below in conjunction with accompanying drawing and unit embodiment principle of work of the present invention is described further.

Shown in Fig. 1 test principle figure of the present invention.Power distribution network bus 1 is through isolating transformer 2, connect frequency converter 3, after its output terminal series connection resistance sense load 4 again with bus 1 and connect, in order to find line voltage and unit output voltage phase place control signal of the same size fast, can determine by the voltage that detects resistance in the resistance sense load, because when output voltage size in unit is consistent with the input ac voltage sized phases with phase place, the meritorious consumption of system is 0 in theory, then resistance drop also should be 0 in theory, but owing to there is the frequency converter loss, resistance drop should be one and approach 0 value, in fact finds out its minimum value and illustrates that promptly output is consistent with input AC size and phase place.The PLC in the frequency converter 3 is sent in the pressure drop that the back voltage transformer (VT) 5 that closes a floodgate detects resistance, the output pulse that changes PLC simultaneously is to adjust the output phase angle, the signal value minimum that measures up to voltage transformer (VT), change the amplitude of modulation signal then, constantly detect resistance drop simultaneously up to the signal minimum that finds voltage sensor to measure once more, this moment the unit the output voltage size, phase place with exchange the input basically identical, get final product the control system electric current by changing PLC output pulse or modulation signal then, thereby finish the test of the operation conditions of different electric current operating modes unit, system power is detected by current transformer 6 and sends into PLC and monitor.

As shown in Figure 4, with high voltage converter one unit ac output end through resistance sense load series connection back and ac input end and connect, this moment, the frequency converter unit output voltage can be regarded a controllable voltage source (output voltage amplitude and phase place are all controlled) as, and pilot system is this controllable voltage source With electric network source

Be connected into the loop after the load of series connection resistance sense, establish $\mathrm{\Δ}\stackrel{\mathrm{\μ}}{U}=\stackrel{\mathrm{\μ}}{U_a}-\stackrel{\mathrm{\μ}}{U_b,}$ System power then $I=\mathrm{\ΔU}/\mathrm{j\ωL}$ (reactance), L is the inductance of air reactor in the formula.(1) regulates

Make

With

During same-phase, if U _aGreater than U _b, then Lag behind

90 °; If U _aLess than U _bThe time, In advance 90 °.(2) regulate

Make

In advance During a certain angle [alpha], phasor graph as shown in Figure 5 will Be decomposed into two vertical components

Then $\stackrel{\mathrm{\μ}}{P_{\mathrm{Ua}}}=-U_a{I}_{\mathrm{ax}}-j{U}_a{I}_{\mathrm{ay}},$ So the A of system (8 among Fig. 4) sends meritorious and perception is idle, load and the B of system (9 among Fig. 4) absorption is meritorious and perception is idle.(3) regulate Make

Lag behind

During a certain angle [alpha], phasor graph is respectively shown in Fig. 6 a, 6b.If U _bCos α≤U _a, shown in Fig. 6 a, have according to phasor graph: ${\stackrel{\mathrm{\μ}}{P}}_{\mathrm{Ua}}=U_a{I}_{\mathrm{ax}}-j{U}_a{I}_{\mathrm{ay}}=-(-U_a{I}_{\mathrm{ax}}+j{U}_a{I}_{\mathrm{ay}}),$ ${\stackrel{\mathrm{\μ}}{P}}_{\mathrm{Ub}}=-U_b{I}_{\mathrm{bx}}+j{U}_b{I}_{\mathrm{by}},$ So it is meritorious that the A of system this moment absorbs, it is idle to send perception, and that the B of system sends is meritorious, and it is idle to absorb perception; If U _bCos α 〉=U _a, shown in Fig. 6 b, have according to phasor graph: ${\stackrel{\mathrm{\μ}}{P}}_{\mathrm{Ua}}=U_a{I}_{\mathrm{ax}}+j{U}_a{I}_{\mathrm{ay}}=-(-U_a{I}_{\mathrm{ax}}-j{U}_a{I}_{\mathrm{ay}}),$ ${\stackrel{\mathrm{\μ}}{P}}_{\mathrm{Ub}}=-(U_b{I}_{\mathrm{bx}}+j{U}_b{I}_{\mathrm{by}}),$ So the A of system absorbs meritorious and perception is idle, and the B of system sends meritorious and perception is idle.

From above analysis as can be known: as long as suitably regulate the amplitude and the phase place of frequency converter output voltage, size and Orientation that promptly can control of conversion device output current.When the high voltage converter absorption was meritorious, the inverter direct-flow side capacitance voltage raise; When high voltage converter output was meritorious, the inverter direct-flow side capacitance voltage descended; The rising of capacitance voltage or reduction will be regulated the active current size, up to power supply output the loss of function compensating load equivalent resistance be arranged, and reach equilibrium state.Therefore, the resistive component of power supply output is the loss of complementation test system, can reach the low energy consumption test objective like this.

In fact With

Phase differential α its security control scope is arranged: 1) when

In advance During the α angle, ignore the frequency converter loss, phasor graph as shown in Figure 7, I is a load current, β is electric current and system voltage U _aBetween the phase place angle, γ is the angle of frequency converter output voltage and resistance sense load voltage, θ is the power-factor angle of load, dotted portion is represented the electric current and voltage phase magnitude relation of some time during the etching system power-balance.According to meritorious and reactive balance relation, can draw $U_b=\frac{U_a\cos (\mathrm{\θ}-\mathrm{\α})}{\cos \mathrm{\θ}}=U_a\left(\cos \mathrm{\α}(\tan \mathrm{\θ}-\tan \mathrm{\α})\right),$ This formula is got U with α for the variable differentiate _b'=U _a(cos α (tan θ-tan α)), because

Can not be excessive, otherwise can cause the DC side overvoltage, can draw α security control scope for (0, α _Max] and [α _Min,

), in the formula ${\mathrm{\α}}_{\max }=\mathrm{\θ}-\arccos \frac{U_b\cos \mathrm{\θ}}{U_a},$ ${\mathrm{\α}}_{\min }=\mathrm{\θ}+\arccos \frac{U_b\cos \mathrm{\θ}}{U_a},$ But when α exists

During interior the adjustment, Δ U is very big, and running current is bigger, and the range of adjustment of electric current is less, and is unavailable during the test of historical facts or anecdotes border; 2) when Lag behind During the α angle, ignore the frequency converter loss, reach according to meritorious and reactive balance relation Can not be too little (otherwise the dc capacitor voltage fluctuation is very big) the security control scope that can draw α equally be that α is very little, or α changes about 180 °-θ, the latter is same because Δ U is very big, the Current Regulation scope is too little, so can not use.In sum, no matter It is hysteresis or leading All should control α in greater than 0 several years scope, carrying out that can warranty test safety, behind the combined floodgate, because current-limiting resistance, system overcurrent can not occur, detects input end alternating voltage size and frequency by PLC, and output pulse adjustment output phase angle makes output voltage consistent with the input voltage sized phases, output voltage is 50Hz, 650VAC

When considering single test shown in the specific embodiments figure as Fig. 2.Load is closed a floodgate moment because system is in transient state process, the dash current that flows through IGBT may be very big, for safety test, close a floodgate moment by load current-limiting resistance current limliting, and the combined floodgate start-up course is closed sky for (state is that K1, K2, K3, K4, K5, K6 are off-state before closing a floodgate) and is opened--close K6--and close K1--and close K3--and K2--and close K5--close K4 (whether need disconnect K3 when normal operation test definite) in actual moving process.2.1 and 2.2 be transformer, 7 is current-limiting resistance, and 4.1 is the load current-limiting resistance, and 4.2 is air reactor.After test was finished, uninstall process was the disconnected K5 of the disconnected K3--of the disconnected K4--of the disconnected K2--of the disconnected K1--of disconnected K6--.

Shown in Fig. 3 IGBT drive signal generating principle block diagram.Clock module 3.1 provides required clock signal for each module of FPGA (field programmable gate array).PLC module 3.2 functions: a) to phase place, voltage increase and decrease pulse and phase place, voltage increase and decrease direction signal sampling filtering; B), comprise the leading or counting that lags behind after counting before the phase place reset, the phase place reset to phase place, potential pulse counting; C) current phase place and the magnitude of voltage of feedback.Phase shift block 3.3 is specified the phase shift size according to the fundamental signal and the PLC of electrical network sampling, and mobile baseband signal goes to trigger band carrier wave shape module then.Band carrier wave shape module 3.4 generates the pulse waveform of cycle and synchronized according to the phase shift fundamental signal.Debugging waveform module 3.5 generates and drives direct currents debugging and the pressure regulator required waveform that powers on that powers on.3.6 for control signal output, drive the IGBT in the test unit major loop 3.7, major loop 3.7 topological structures are single-phase full bridge voltage-type inverter bridge.

Embodiments of the invention, for power is 2000kW, electric pressure is the variator low energy-consumption load testing system of a certain unit of high voltage converter of 6kV.

1 is the input electrical network, and voltage is 380VAC, 50Hz, 2.1 be that 380/220 step-down becomes, 2.2 is 220/380 change of boosting, capacity is 50KVA, 7 are 200 ohm of employings, the unit current-limiting resistance of 600W, and 4.1 for adopting 50 ohm, the load current-limiting resistance of 2KW, 4.2 be air reactor, 5mH, band 1mH, 2mH, the static tap of 3mH.The DC voltage Hall element detects the pressure drop of load current-limiting resistance, input PLC, PLC is by constantly changing output pulse and modulation signal amplitude adjustment unit output phase angle and output voltage size, up to the minimum value that finds the pressure drop of load current-limiting resistance, thereby adjust control signal then gradually and realize the test of different electric current operating modes to change unit output voltage and input ac voltage phase differential, the electric current PLC that makes a gift to someone after the current Hall sensor monitors.System clock input (CLK) is 20MHZ; The output of TESTCLK (clock module pin) frequency-dividing clock, frequency 480KHz is used for the debugging module waveform and generates; The output of PHASECLK (clock module pin) frequency-dividing clock, frequency 120KHz is used for band and carries the generation of module waveform.

Claims (5)

1. novel high-pressure frequency variator low energy-consumption load testing method, it is characterized in that comprising the following steps: power distribution network bus (1) is connected frequency converter (3) through isolating transformer (2), again with bus (1) and connect, between frequency converter (3) and resistance sense load (4), be connected voltage transformer (VT) (5), current transformer (6) after the inverter output terminal series connection resistance sense load (4); Regulate the amplitude and the phase place of frequency converter output voltage, size and Orientation with control of conversion device output current, in order to find line voltage and unit output voltage phase place control signal of the same size fast, detect the voltage of resistance in the resistance sense load, find out its minimum value, output this moment is consistent with input AC size and phase place; Close a floodgate, the PLC (programmable logic controller (PLC)) in the frequency converter (3) is sent in the pressure drop of voltage transformer (VT) (5) detection resistance, the output pulse that changes PLC simultaneously is to adjust the output phase angle, the signal value minimum that measures up to voltage sensor, change the amplitude of modulation signal then, constantly detect resistance drop simultaneously up to the signal minimum that finds voltage sensor to measure once more, the output voltage size of frequency converter this moment (3), phase place with exchange the input basically identical, then by changing PLC output pulse or modulation signal, the control system electric current, thereby finish the test of the operation conditions of different electric current operating modes unit, system power is detected by current transformer (6) and sends into PLC and monitor.

2. novel high-pressure frequency variator low energy-consumption load testing method as claimed in claim 1, it is characterized in that: the moment of closing a floodgate is by load current-limiting resistance current limliting, combined floodgate preceding switch K1, K2, K3, K4, K5, K6 are off-state, the combined floodgate start-up course is opened for closing sky--and close K6--and close K1--and close K3--and K2--and close K5--and close K4, when normal operation, whether need disconnect K3 and in actual moving process, test definite.

3. novel high-pressure frequency variator low energy-consumption load testing method as claimed in claim 1, it is characterized in that: output current, voltage are detected and are exported pulse adjustment output phase angle and carries out different current conditions and full load conditions test with the electric current of regulating by IGBT (insulated gate bipolar transistor) by PLC, power cell is adjusted into inductive load, output phase angular advance input phase angle makes power flow to mains side by cell side

4. novel high-pressure frequency variator low energy-consumption load testing method as claimed in claim 1 is characterized in that: uninstall process is the disconnected K5 of the disconnected K3--of the disconnected K4--of the disconnected K2--of the disconnected K1--of disconnected K6--after the off-test.

5. novel high-pressure frequency variator low energy-consumption load testing method as claimed in claim 1 is characterized in that: the size that line voltage and frequency converter output voltage phase angle are looked the resistance sense load is selected in about 0 degree.

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