CN103809114A - Power hedge testing apparatus for converter valves of modularized multi-level converter - Google Patents

Abstract

The invention relates to a power hedge testing apparatus for converter valves of a modularized multi-level converter, belonging to the technical field of power electronics and DC transmission. The device comprises a DC (Direct Current) power supply, converter valves, connecting reactors, a DC support capacitor and the like, wherein the lower end of a first converter valve and the upper end of a second converter valve are respectively connected to form a first bridge arm through a first connecting reactor and a second connecting reactor, and the lower end of a third converter valve and the upper end of a fourth converter valve are respectively connected to form a second bridge beam through a third connecting reactor and a fourth connecting reactor. Active power is controlled by the phase angular difference of the modulating strategy of the two converter bridge arms, and reactive power is controlled by the modulation ratio difference of the modulating strategy of the two converter bridge arms, so that the steady-state operation of the voltage and current stress set for the working of the converter valves can be tested. The power hedge testing apparatus is simple in circuit structure, and is capable of most accurately testing the steady-state operation of the tested converter valves.

Description

A kind of power of modularization multi-level converter converter valve test unit that liquidates

Technical field

The power that the present invention relates to a kind of modularization multi-level converter converter valve test unit that liquidates, belongs to power electronics and HVDC Transmission Technology field.

Background technology

Flexible DC power transmission has become the novel electric power transmission mode of being potential most at present.Due to modularization multi-level converter (Modular Multilevel Converter, hereinafter to be referred as MMC) there is public direct-current end, and have easy expansion, meritorious idle can decoupling zero control, outstanding, the switching device small loss and other features of harmonic characteristic, be very suitable for flexible DC power transmission system.Voltage and the capacity of flexible DC power transmission modularization multi-level converter are high; before cannot putting into operation at the scene, carry out overall test; therefore must effectively verify that converter valve is moved under declared working condition by equivalent test means time the electric current and voltage stress that can bear for a long time, and check converter valve press-fit and connect technique, control power supply, whether the design of the aspect such as control, protection, cooling, electromagnetic compatibility reached the requirement of technical standard.

Application number is that 201120310757.2 Chinese patent " the power ring test unit of flexible DC power transmission MMC valve Tests at Steady State " discloses a kind of test unit, realizes working voltage, electric current and the hot strength under actual operating mode by method equivalence in tested valve section of equivalent test.But this device needs charge power supply and two direct supplys of complementary energy power supply, and required direct supply is more, and need to be in running test by extra voltage balance control algorithm by the energy distribution of complementary energy power supply to the DC capacitor of all valve modules.Connection and the method for operation and being connected and the method for operation inconsistent in actual device of converter valve in hookup, causes test operation condition and actual operating mode still to have certain difference on the other hand, affects verification the verifying results.

Application number is that the Chinese patent " flexible DC power transmission MMC converter valve operating test device and test method " of 201310090549.X discloses a kind of test unit and test method, but these apparatus and method are also to need charge power supply and the multiple direct supplys of complementary energy power supply, and connection and the method for operation and being connected and the method for operation inconsistent in actual device of converter valve components in hookup, cause test operation condition and actual operating mode still to have certain difference, affect verification the verifying results.

Application number is that the Chinese patent " the back-to-back testing method of flexible DC power transmission MMC valve Tests at Steady State " of 201110244817.X discloses a kind of back-to-back testing method, the method is by jointly accessing same AC power by rectifying bridge arm and inverter bridge leg, the meritorious power supply itself of getting back to that power supply is sent, has reduced the requirement to power supply capacity.But this method need to make tested converter valve incoming transport power supply, in test process, also need to realize converter valve and be incorporated to the control algolithm of AC power, realize comparatively complicated.And because converter valve in test exists certain harmonic wave, easily used AC power is produced and disturbed, also higher to the capacity requirement of AC power.

Summary of the invention

The power that the object of the invention is the to propose a kind of modularization multi-level converter converter valve test unit that liquidates, make the circuit structure of steady-state operation equivalent test device of converter valve more simple, and liquidate and make direct supply that the loss of test unit run duration generation only need be provided by the power between converter valve, another object of the present invention is that electric current and voltage operating condition and actual operating mode that converter valve is born in hookup are also approaching, can carry out Tests at Steady State to tested converter valve the most exactly.

The power of modularization multi-level converter converter valve that the present invention the proposes test unit that liquidates, comprise direct supply, disconnector, charging by-pass switch, charging current limiter resistance, the first converter valve, the second converter valve, the 3rd converter valve, the 4th converter valve, first connect reactance, second and connect reactance, the 3rd connection reactance, the 4th connection reactance, the first DC support electric capacity and the second DC support electric capacity; The lower end of the first described converter valve and the upper end of the second converter valve are connected respectively reactance and link together and form the first brachium pontis with second by the first connection reactance, two tie points that connect reactance form the ac output end of the first brachium pontis; The lower end of the 3rd described converter valve and the upper end of the 4th converter valve are connected reactance by the 3rd respectively and are connected reactance with the 4th and link together and form the second brachium pontis, the tie point of two connection reactance forms the ac output end of the second brachium pontis, and the ac output end of the first brachium pontis is connected with the ac output end of the second brachium pontis; The positive pole of described direct supply is connected mutually with disconnector, described charging current limiter resistance is parallel with one another with charging by-pass switch, one end of parallel circuit is connected with the series circuit of direct supply and disconnector, and the upper end of the positive pole of the other end of parallel circuit and the first DC support electric capacity, the upper end of the first converter valve and the 3rd converter valve interconnects; The lower end of the negative pole of the negative pole of described direct supply and the second DC support electric capacity, the lower end of the second converter valve and the 4th converter valve interconnects, ground connection after the negative pole of the first DC support electric capacity is connected with the positive pole of the second DC support electric capacity; Described the first converter valve, the second converter valve, the 3rd converter valve and the 4th converter valve comprise respectively the first semiconductor switch, the second semiconductor switch, the first diode, the second diode and DC capacitor, collector, the negative electrode of the first diode and the positive pole of DC capacitor of the first described semiconductor switch interconnect, and the collector of the emitter of the first semiconductor switch, the anode of the first diode, the second semiconductor switch, the negative electrode of the second diode interconnect the upper end of rear formation converter valve; Emitter, the anode of the second diode and the negative pole of DC capacitor of the second semiconductor switch interconnects the lower end of rear formation converter valve.

The power of modularization multi-level converter converter valve that the present invention proposes its advantage of test unit that liquidates is: adopt the steady-state operation power of the modularization multi-level converter converter valve that the present invention the proposes test unit that liquidates, its circuit structure is simple, only need to adopt a direct supply.Active power in process of the test and reactive power only liquidate mobile between two brachium pontis, the loss that direct supply only need provide test unit run duration to produce.The wiring of tested converter valve in hookup and the method for operation and the wiring in actual device and the method for operation are in full accord, the electric current and voltage operating condition bearing and actual operating mode are also approaching, can carry out Tests at Steady State to tested converter valve the most exactly.In test run, only need amplitude and the phase place of simple open loop control change of current brachium pontis output voltage, do not need extra being incorporated into the power networks control and voltage all and control.

Accompanying drawing explanation

Fig. 1 is the liquidate circuit diagram of test unit of the power of the modularization multi-level converter converter valve that proposes of the present invention.

Fig. 2 is the liquidate voltage and current oscillogram of test unit of the present invention.

Embodiment

The power of modularization multi-level converter converter valve that the present invention the proposes test unit that liquidates, its circuit diagram as shown in Figure 1, comprising:

Comprise direct supply E1, disconnector K1, charging by-pass switch K2, charging current limiter resistance R 1, the first converter valve, the second converter valve, the 3rd converter valve, the 4th converter valve, first connect reactance L1, second and connect reactance L2, the 3rd connection reactance L3, the 4th connection reactance L4, the first DC support capacitor C d1 and the second DC support capacitor C d2; The lower end of the first described converter valve and the upper end of the second converter valve are connected respectively reactance and link together and form the first brachium pontis with second by the first connection reactance, two tie points that connect reactance form the ac output end of the first brachium pontis; The lower end of the 3rd described converter valve and the upper end of the 4th converter valve are connected reactance by the 3rd respectively and are connected reactance with the 4th and link together and form the second brachium pontis, the tie point of two connection reactance forms the ac output end of the second brachium pontis, and the ac output end of the first brachium pontis is connected with the ac output end of the second brachium pontis;

The positive pole of described direct supply is connected mutually with disconnector, described charging current limiter resistance is parallel with one another with charging by-pass switch, one end of parallel circuit is connected with the series circuit of direct supply and disconnector, and the upper end of the positive pole of the other end of parallel circuit and the first DC support electric capacity, the upper end of the first converter valve and the 3rd converter valve interconnects;

The lower end of the negative pole of the negative pole of described direct supply and the second DC support electric capacity, the lower end of the second converter valve and the 4th converter valve interconnects, ground connection after the negative pole of the first DC support electric capacity is connected with the positive pole of the second DC support electric capacity;

Described the first converter valve, the second converter valve the 3rd converter valve, the 4th converter valve comprise respectively the first semiconductor switch S1, the second semiconductor switch S2, the first diode D1, the second diode D2, DC capacitor C1, collector, the negative electrode of the first diode and the positive pole of DC capacitor of the first described semiconductor switch interconnect, and the collector of the emitter of the first semiconductor switch, the anode of the first diode, the second semiconductor switch, the negative electrode of the second diode interconnect the upper end of rear formation converter valve; Emitter, the anode of the second diode and the negative pole of DC capacitor of the second semiconductor switch interconnects the lower end of rear formation converter valve.

Below in conjunction with accompanying drawing 1, introduce in detail the liquidate principle of work of test unit of the present invention.In the time that the power that uses modularization multi-level converter converter valve of the present invention liquidates test unit, first closed disconnector K1, direct supply E1 passes through charging current limiter resistance R 1 to converter valve capacitor charging; In the time that converter valve capacitance voltage reaches preset value, closed charging by-pass switch K2, converter valve capacitor charging is complete.In the time of steady-state operation, send the first brachium pontis trigger pulse according to certain modulation strategy, the amplitude that makes the first brachium pontis ac output end voltage-to-ground is V ₁, phase angle is δ ₁; Send the second brachium pontis trigger pulse according to certain modulation strategy, the amplitude that makes the second brachium pontis ac output end voltage-to-ground is V ₂, phase angle is δ ₂.

If the modulation ratio of the pulsewidth modulation reference wave of the first brachium pontis is M ₁, the first brachium pontis over the ground output voltage amplitude be:

$V_1=M_1\frac{U_d}{2}---\left(1\right)$

Wherein U _dfor the magnitude of voltage of direct supply E1.If the modulation ratio of the pulsewidth modulation reference wave of the second brachium pontis is M ₂, phasing degree is δ ₂, the output voltage amplitude over the ground of the second change of current brachium pontis is:

${\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="HDA0000459916240000011.png"\; state="\{\{state\}\}">V</figure-callout>}}_2=M_2\frac{U_d}{2}---\left(2\right)$

Electric current phasor between the first brachium pontis and the second brachium pontis is:

$I=\frac{V_1-V_2\cos ({\mathrm{\&delta;}}_1-{\mathrm{\&delta;}}_2)-{\mathrm{<figure-callout\; id="2"\; label="jV"\; filenames="HDA0000459916240000011.png"\; state="\{\{state\}\}">jV</figure-callout>}}_2\sin ({\mathrm{\&delta;}}_1-{\mathrm{\&delta;}}_2)}{\mathrm{jX}}=\frac{V_2\sin ({\mathrm{\&delta;}}_1-{\mathrm{\&delta;}}_2)}{X}-j\frac{V_1-V_2\cos ({\mathrm{\&delta;}}_1-{\mathrm{\&delta;}}_2)}{X}---\left(3\right)$

Wherein X=2 π f ₁l,f ₁for electrical network work frequency, L is the inductance value that connects reactance L1, L2, L3 and L4.

Can calculate the active power that flows to the second brachium pontis by the first brachium pontis is:

$P=\frac{V_1}{\sqrt{2}}\frac{V_2({\mathrm{\&delta;}}_1-{\mathrm{\&delta;}}_2)}{\sqrt{2}X}=\frac{V_1{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="HDA0000459916240000011.png"\; state="\{\{state\}\}">V</figure-callout>}}_2\sin ({\mathrm{\&delta;}}_1-{\mathrm{\&delta;}}_2)}{2X}---\left(4\right)$

By formula (1) and formula (2) substitution formula (4), can obtain

$P=\frac{M_1{M}_2{\mathrm{<figure-callout\; id="2"\; label="U\; d"\; filenames="HDA0000459916240000011.png"\; state="\{\{state\}\}">U</figure-callout>}}_d^{}}{8X}\sin ({\mathrm{\&delta;}}_1-{\mathrm{\&delta;}}_2)---\left(5\right)$

The reactive power that is flowed to the second brachium pontis by the first brachium pontis is:

$Q=\frac{V_1}{\sqrt{2}}\frac{V_1-V_1\cos ({\mathrm{\&delta;}}_1-{\mathrm{\&delta;}}_2)}{\sqrt{2}X}=\frac{{V_1^{2}V}_1{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="HDA0000459916240000011.png"\; state="\{\{state\}\}">V</figure-callout>}}_2\cos ({\mathrm{\&delta;}}_1-{\mathrm{\&delta;}}_2)}{2X}---\left(6\right)$

Due to δ ₁and δ ₂between phase angle poor smaller, therefore can be similar to formula (6) is written as

$Q\&ap;\frac{V_1^2-V_1{\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="HDA0000459916240000011.png"\; state="\{\{state\}\}">V</figure-callout>}}_2}{2X}=\frac{V_1(V_1-V_2)}{2X}---\left(7\right)$

By formula (1) and formula (2) substitution formula (7), can obtain

$Q\&ap;\frac{M_1{\mathrm{<figure-callout\; id="2"\; label="U\; d"\; filenames="HDA0000459916240000011.png"\; state="\{\{state\}\}">U</figure-callout>}}_d^{}}{8X}(M_1-M_2)---\left(8\right)$

Through type (5) and formula (8) can obtain, only need amplitude and the phasing degree of simple open loop control the first brachium pontis and the second brachium pontis modulation strategy, wherein amplitude is modulation ratio control by modulation strategy, just can control active-power P and reactive power Q mobile between the first brachium pontis and the second brachium pontis.Active-power P can pass through the poor control of phase angle of two brachium pontis modulation strategies, and reactive power Q can pass through the modulation ratio control of two brachium pontis modulation strategies.Like this, can make each converter valve work in the voltage and current stress of setting, carry out the test of steady state operating condition.Its voltage and current oscillogram as shown in Figure 2.

According to the principle of power-balance, in the time carrying out steady state operating condition test, active power and reactive power only liquidate mobile between the first brachium pontis and the second brachium pontis, can't flow in direct supply, therefore direct supply only need be provided by the loss that provides DC voltage and converter valve to produce in the time that steady-state operation is tested, and required power is very little.

The mode of connection and its wiring in actual module multilevel converter of converter valve in proving installation of the present invention

Mode is consistent with operation logic, and the electric current and voltage operating mode in actual device is also consistent to the electric current and voltage operating mode of bearing when therefore their operation is tested with it, can realize the equivalent test that approaches the most actual operating mode.

Claims (1)

1. the power of the modularization multi-level converter converter valve test unit that liquidates, it is characterized in that this device comprises direct supply, disconnector, charging by-pass switch, charging current limiter resistance, the first converter valve, the second converter valve, the 3rd converter valve, the 4th converter valve, first connect reactance, second and connect reactance, the 3rd connection reactance, the 4th connection reactance, the first DC support electric capacity and the second DC support electric capacity; The lower end of the first described converter valve and the upper end of the second converter valve are connected respectively reactance and link together and form the first brachium pontis with second by the first connection reactance, two tie points that connect reactance form the ac output end of the first brachium pontis; The lower end of the 3rd described converter valve and the upper end of the 4th converter valve are connected reactance by the 3rd respectively and are connected reactance with the 4th and link together and form the second brachium pontis, the tie point of two connection reactance forms the ac output end of the second brachium pontis, and the ac output end of the first brachium pontis is connected with the ac output end of the second brachium pontis; The positive pole of described direct supply is connected mutually with disconnector, described charging current limiter resistance is parallel with one another with charging by-pass switch, one end of parallel circuit is connected with the series circuit of direct supply and disconnector, and the upper end of the positive pole of the other end of parallel circuit and the first DC support electric capacity, the upper end of the first converter valve and the 3rd converter valve interconnects; The lower end of the negative pole of the negative pole of described direct supply and the second DC support electric capacity, the lower end of the second converter valve and the 4th converter valve interconnects, ground connection after the negative pole of the first DC support electric capacity is connected with the positive pole of the second DC support electric capacity; Described the first converter valve, the second converter valve, the 3rd converter valve and the 4th converter valve comprise respectively the first semiconductor switch, the second semiconductor switch, the first diode, the second diode and DC capacitor, collector, the negative electrode of the first diode and the positive pole of DC capacitor of the first described semiconductor switch interconnect, and the collector of the emitter of the first semiconductor switch, the anode of the first diode, the second semiconductor switch, the negative electrode of the second diode interconnect the upper end of rear formation converter valve; Emitter, the anode of the second diode and the negative pole of DC capacitor of the second semiconductor switch interconnects the lower end of rear formation converter valve.

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