CN103543306B - Voltage falling generator and control method thereof for low voltage crossing test - Google Patents

Abstract

Present invention provide for voltage falling generator and the control method thereof of low voltage crossing test, voltage falling generator is connected with parallel network power generation unit by step-up transformer；Voltage falling generator includes by-pass switch S₁, short switch S₂, ground connection stacked switch S₃, ground connection combination reactance X_pReactance X is combined with current limliting_S；Step-up transformer high-pressure side is Y connection, and step-up transformer combines reactance X by current limliting_SIt is connected with electrical network, by-pass switch S₁Reactance X is combined with current limliting_SIn parallel；Step-up transformer, short switch S₂, ground connection combination reactance X_pWith ground connection stacked switch S₃Series connection, step-up transformer high-pressure side neutral point and ground connection stacked switch S₃Ground connection after the other end is connected.The present invention can simulate as three-phase symmetrical fall, the various line voltage fault types such as single-phase earthing, two phase ground, line to line fault, realize with 5% electrical network rated voltage as step-length, fall the line voltage simulated failure that the degree of depth uniformly falls the degree of depth from the gamut 20 kinds of 0% to 100% electrical network rated voltage and fall.

Description

Voltage falling generator and control method thereof for low voltage crossing test

Technical field

The present invention relates to the detection device of a kind of photovoltaic combining inverter detection field, in particular to one is for low electricity Pressure passes through voltage falling generator and the control method thereof of test.

Background technology

Along with photovoltaic industry fast development, photovoltaic generation proportion in electrical network constantly increases.If occurred at electrical network When fault causes Voltage Drop, Large Copacity parallel network power generation unit can not maintain voltage and the frequency of electrical network, will be to power train System stability produces significant impact.Photovoltaic combining inverter is as the core component of big-and-middle-sized photovoltaic plant, it is necessary to possess low electricity Pressure ride-through capability.Detection device must be had grid-connected for detecting accordingly, as photovoltaic combining inverter testing laboratory Whether inverter has low voltage ride-through capability.

Low voltage crossing detection device is realized by voltage falling generator.Voltage falling generator scheme has 3 at present Class: impedance dividing potential drop form, transformer-type and Technics of Power Electronic Conversion form.Realize based on impedance dividing potential drop form and transformer-type Voltage falling generator belong to passive voltage drop generator, wherein based on impedance partial pressure type scheme reactor to grid side Dividing potential drop, controls the Voltage Drop degree of depth by adjusting reactor parameter, and energy realistic simulation electric network fault phenomenon, in Practical Project Easily implementing, reliability is high, for the most common a kind of scheme；The voltage falling generator that transformer-type realizes is logical Crossing and carry centre tapped transformer to realize, but volume of transformer and weight are very big, not readily portable, technics comparing is multiple simultaneously Miscellaneous.In addition, the voltage falling generator that electrically-based electronics variation realizes is active voltage drop generator, form Flexibly, the most powerful, but for high-power photovoltaic synchronization electricity generation system, use power electronic devices cost high, control Complexity, reliability is the highest, and during device opposing electric network fault itself, voltage, rush of current are limited in one's ability simultaneously.

In the relevant series of the wind power integration electrical network of international standard, it has been specified that employing passive reactance device ground short circuit Or phase fault carrys out simulating grid fault." pressure, high pressure, the generator unit of supergrid and systems technology directive/guide in access " TR3 explicitly points out, enters with reference to the circuit diagram in IEEE61400-21 " measurement of grid-connected blower fan quality of power supply characteristic and assessment " Row low voltage crossing, as shown in Figure 1:

Wherein impedance Z₁It is referred to as current-limiting reactor, impact on higher level's electrical network when being used to limit short circuit；Z₁Often in parallel There is by-pass switch.Z₂Be referred to as short-circuit reactance device, the amplitude fallen as required is to regulate Z₂Size.By closing a switch, S comes Simulating grid Voltage Drop, switch S should be able to time of closed and disconnected exactly, available mechanical chopper or power electronics device Part realizes.

GB GB/T19964 " photo-voltaic power generation station accesses power system technology regulation " also regulation low voltage crossing detection device Preferably using passive reactance device simulating grid Voltage Drop as shown in Figure 1, detection device should meet claimed below:

(1) device should be able to simulate that three-phase symmetric voltage falls, voltage between phases falls and falls with single-phase voltage；

(2) current-limiting reactor and short-circuit reactance device all should be adjustable, can produce the Voltage Drop of different depth；Detection should be at least Choose 5 and fall a little, wherein should comprise 0% rated voltage and 20%Un falls a little, other each points should (20%～50%) Un, (50% ～75%) Un, all there is distribution in tri-intervals of (75%～90%) Un, and choose when falling according to curve requirement in GB/T19964 Between；

(4) three-phase symmetrical capacity of short circuit should be more than 3 times of tested photovoltaic DC-to-AC converter capacity；

(5) switch S should use mechanical chopper or electronic power switch；

(6) Voltage Drop time and recovery time should be less than 20ms；

(7) Voltage Drop amplitude tolerance is that ± 5%, wherein 0% and 20% fall point voltage to fall amplitude tolerance is+5%, such as figure Shown in the low voltage crossing detection device Voltage Drop amplitude tolerance schematic diagram that 2 GB/T19964 specify.

In above-mentioned GB GB/T19964, the low voltage crossing curve of regulation is as shown in Figure 3, it is stipulated that when grid-connected point voltage is at this Time in LVRT calibration curve profile and area above, photovoltaic combining inverter must assure that and is uninterruptedly incorporated into the power networks；Otherwise, then permit Permitted photovoltaic combining inverter to stop generating electricity by way of merging two or more grid systems.Relative to national grid standard Q/GDW617-2011, " photovoltaic plant accesses electricity for it Network technology specifies ", it is critical only that increase defines no-voltage and passes through, and between 0% to 20%, voltage ride-through has to last for 125ms； It addition, it is+5% that 0% and 20% zero load fall point voltage to be fallen amplitude tolerance, other zero load is fallen point voltage and is fallen amplitude tolerance and is ±5%。

The low voltage crossing test of existing photovoltaic combining inverter can realize 20% to 90% fall in depth bounds 5 Fall the Voltage Drop of the degree of depth, such as 90%, 80%, 60%, 40% and 20%, it is adaptable to national grid standard Q/GDW617-2011 " light Overhead utility accesses electric power network technique regulation ".But do not possess no-voltage ride-through capability, and cannot further specification to can simulated implementation The quantity of the grid voltage sags degree of depth and precision.

Therefore, how to realize, based on impedance manner, the voltage falling generator that 0% to 100% gamut high-accuracy voltage falls Design become, with research and development, the key that low voltage crossing test regulation is implemented smoothly.

It addition, the voltage falling generator being currently used for the test of photovoltaic combining inverter low voltage crossing the most all obtains basis Concrete three-phase power grid voltage grade U and electrical network internal driving a carry out design and the reactance of each three-phase reactor of topological structure The calculating of value, as designed a set of topological structure for the three phase network of 10kV, and calculates the reactance value of three-phase reactor accordingly Size；If designing a set of topological structure again for the electrical network of 35kV, and calculate reactance value big of three-phase reactor accordingly Little；Even if it addition, line voltage grade is the same, if electrical network internal driving differs greatly, also must re-start topological structure and The calculating of the reactance value of three-phase reactor, correspondingly the control logic of internal each switch also must be changed.

Therefore, to be how a for electrical network internal driving, electric pressure is the three phase network of U, proposes a kind of general being used for The voltage falling generator method for designing of photovoltaic combining inverter low voltage crossing test also becomes this kind of voltage falling generator Another is crucial.

Summary of the invention

For overcoming above-mentioned the deficiencies in the prior art, the present invention provides a kind of Voltage Drop for low voltage crossing test to send out Raw device and control method thereof, be a for electrical network internal driving, and electric pressure is the three phase network of U, it is possible to simulation is such as three-phase symmetrical Fall, the various line voltage fault types such as single-phase earthing, two phase ground, line to line fault, and can realize with the 5% specified electricity of electrical network Pressure is step-length, falls the degree of depth and uniformly falls the line voltage simulation of the degree of depth from the gamut 20 kinds of 0% to 100% electrical network rated voltage Fault is fallen.

Realizing the solution that above-mentioned purpose used is:

A kind of voltage falling generator for low voltage crossing test, described voltage falling generator is by boosting transformation Device is connected with parallel network power generation unit；It thes improvement is that:

Described voltage falling generator includes by-pass switch S₁, short switch S₂, ground connection stacked switch S₃, ground connection combination electricity Anti-X_pReactance X is combined with current limliting_S；

Described step-up transformer high-pressure side is Y connection, and described step-up transformer combines reactance X by described current limliting_SWith electricity Net connects, described by-pass switch S₁Reactance X is combined with described current limliting_SIn parallel；Described step-up transformer, described short switch S₂, institute State ground connection combination reactance X_pWith described ground connection stacked switch S₃Series connection, the high-pressure side neutral point of described step-up transformer connects with described Ground stacked switch S₃The other end is total to ground connection after being connected.

Further, described current limliting combination reactance X_SCurrent limliting combination reactance one and current limliting combination reactance two including series connection；

The combination reactance one of described current limliting includes the three-phase reactor X of parallel connection₁With three-phase breaker K₁；

The combination reactance two of described current limliting includes the three-phase reactor X of parallel connection₂、X₃、X₄、X₅, three-phase reactor X₂With X₃、X₃With X₄、X₄With X₅Respectively by three-phase breaker K between two ends₂With K₄、K₅With K₇、K₈With K₁₀Connect；

Described current limliting combination reactance one and three-phase reactor X₂With three-phase breaker K₄The end that is connected connects, described electrical network and three Phase reactor X₅With three-phase breaker K₈The end that is connected connects；

Described three-phase reactor X₂With three-phase breaker K₄The other end respectively with three-phase breaker K₃Two ends are connected；

Described three-phase reactor X₃With three-phase breaker K₇The other end respectively with three-phase breaker K₆Two ends are connected；

Described three-phase reactor X₄With three-phase breaker K₁₀The other end respectively with three-phase breaker K₉Two ends are connected.

Further, described ground connection combination reactance X_pGround connection combination reactance one and ground connection combination reactance two including series connection；

The combination reactance one of described ground connection includes the three-phase reactor X of parallel connection₆With three-phase breaker K₁₁；

The combination reactance two of described ground connection includes the three-phase reactor X of parallel connection₇、X₈、X₉、X₁₀, three-phase reactor X₇With X₈、X₈With X₉、X₉With X₁₀Respectively by three-phase breaker K between two ends₁₂With K₁₄、K₁₅With K₁₇、K₁₈With K₂₀Connect；

Described ground connection combination reactance one and three-phase reactor X₇With three-phase breaker K₁₄The end that is connected connects, and described ground connection is combined Switch S₃Single-phase circuit breaker side and three-phase reactor X₁₀With three-phase breaker K₁₈The end that is connected connects；

Described three-phase reactor X₇With three-phase breaker K₁₄The other end respectively with three-phase breaker K₁₃Two ends are connected；

Described three-phase reactor X₈With three-phase breaker K₁₇The other end respectively with three-phase breaker K₁₆Two ends are connected；

Described three-phase reactor X₉With three-phase breaker K₂₀The other end respectively with three-phase breaker K₁₉Two ends are connected.

Further, described parallel network power generation unit includes photovoltaic array and the photovoltaic combining inverter being connected, described Photovoltaic combining inverter is connected with described step-up transformer；

Described ground connection stacked switch S₃Single-phase circuit breaker group and earthed switch N including series connection；Described single-phase circuit breaker group Including the in parallel single-phase circuit breaker controlling three-phase electricity respectively；Described earthed switch N is three-phase breaker.

Further, described current limliting combination reactance X_SReactance X is combined with described ground connection_pThe reactance value of middle three-phase reactor divides It is not:

$\left\{\begin{array}{c}{X}_6=X_1=a\\ X_7=X_2=2a\\ X_8=X_3=3a\\ X_9=X_4=6a\\ X_{10}=X_5=7a\end{array}\right.$

Wherein, X₁For the three-phase reactor in current limliting combination reactance one；X₆For the three-phase reactor in ground connection combination reactance one Device, X₂、X₃、X₄、X₅It is respectively current limliting combination reactance X_SThree-phase reactor；X₇、X₈、X₉、X₁₀It is respectively ground connection combination reactance X_p's Three-phase reactor；A is electrical network internal driving.

Further, described voltage falling generator is by changing ground connection stacked switch S₃In three described single-phase open circuits Device and the on off state of described earthed switch N, simulation produces various types of line voltage faults.

Further, described voltage falling generator is by changing current limliting combination reactance X_SReactance X is combined with ground connection_pIn each The connection in series-parallel combination of three-phase reactor, changes current limliting combination reactance X_SReactance X is combined with ground connection_pReactance value size, it is achieved With 5% electrical network rated voltage as step-length, from 0% to 100% electrical network rated voltage gamut Voltage Drop.

A kind of control method being applied to voltage falling generator, it thes improvement is that: described method includes following step Rapid:

I, measurement three-phase power grid voltage grade U and electrical network internal driving a；

II, set up voltage falling generator, and determine that current limliting combines reactance X_SReactance X is combined with ground connection_pMiddle three-phase reactor Reactance value size；

III, when photovoltaic combining inverter normally works, close by-pass switch S₁, disconnect short switch S₂, wait low electricity Pressure passes through detection；

IV, low voltage crossing detect, and select ground connection stacked switch S₃The combination of breaker in middle, the event of simulating grid voltage Barrier；

The current percentage h dropping to rated voltage set of V, basis selects current limliting combination reactance X_SWith ground connection combination electricity Anti-X_pIn switch combination mode；

VI, first disconnection by-pass switch S₁, at Guan Bi short switch S₂, grid-connected point voltage starts to fall；

After VII, grid-connected point voltage fall certain time, first disconnect short switch S₂, it is closed again by-pass switch S₁, and Site voltage starts to recover, and returns to step III.

Further, in described step II, as following formula determines that current limliting combines reactance X_SReactance X is combined with ground connection_pMiddle three-phase electricity The reactance value size of anti-device:

$\left\{\begin{array}{c}{X}_6=X_1=a\\ X_7=X_2=2a\\ X_8=X_3=3a\\ X_9=X_4=6a\\ X_{10}=X_5=7a\end{array}\right.$

In formula, X₁For the three-phase reactor in current limliting combination reactance one；X₆For the three-phase reactor in ground connection combination reactance one Device, X₂、X₃、X₄、X₅It is respectively current limliting combination reactance X_SThree-phase reactor；X₇、X₈、X₉、X₁₀It is respectively ground connection combination reactance X_p's Three-phase reactor；A is electrical network internal driving.

Compared with prior art, the method have the advantages that

(1) voltage falling generator and the corresponding control method thereof of the present invention can carry out Voltage Drop for different electrical networks and send out The General design of raw device.For concrete a certain three phase network, the present invention only need to know the three phase network electricity of this three phase network Pressure grade U and electrical network internal driving a, determine the reactance value X of each three-phase reactor₁、X₂、X₃……X₁₀Reactance value parameter, and press Quickly designing capacity of short circuit according to topological structure isAnd capacity can be suitable for be less thanPhotovoltaic combining inverter carry out The voltage falling generator of various electric network fault type low voltage crossings test.

(2) voltage falling generator and the corresponding control method thereof of the present invention can realize 20 including no-voltage is passed through Kind of Voltage Drop uniform depth and be at equal intervals 5% Voltage Drop." photo-voltaic power generation station accesses electric power to meet GB GB/T19964 Systems technology specifies " middle regulation " should at least choose 5 and fall a little, wherein should comprise 0% rated voltage and 20%Un falls by detection Point, other each points should all have distribution at (20%～50%) Un, (50%～75%) Un, (75%～90%) Un in tri-intervals ",

(3) voltage falling generator and the corresponding control method thereof of the present invention only needs simple according to each three-phase reactor determined The reactance value X of device₁、X₂、X₃……X₁₀Reactance value parameter, inquiry current limliting combination reactance X_SReactance X is combined with ground connection_pSwitch Combination, can realize with 5% electrical network rated voltage as step-length, FR totally 20 kinds from 0% to 100% electrical network rated voltage The line voltage simulated failure of Voltage Drop uniform depth is fallen, and can fully meet this GB GB/T19964 to grid-connected inverse Become the requirement of device low voltage crossing detection.

(4) voltage falling generator and the corresponding control method thereof of the present invention realizes photovoltaic combining inverter low voltage crossing Test, it is ensured that the stability of power system, significant.

(5) voltage falling generator of the present invention and corresponding control method thereof can simulate as three-phase symmetrical fall, single-phase The various line voltage fault types such as ground connection, two phase ground, line to line fault.Due to the ground connection group in described voltage falling generator Combination switch S₃Use three single-phase circuit breaker N_A、N_B、N_CSimulation three phase network is the most short-circuit；Use a three-phase breaker N simulation Electrical network whether ground connection, therefore by changing N_A、N_B、N_CAnd the on off state of N, generation various types of electrical networks electricity can be simulated Pressure fault, and for each of concrete line voltage fault type, again can be simply by selecting current limliting combination reactance X_S Reactance X is combined with ground connection_pSwitch combination mode obtain lower 20 kinds of every kind of line voltage fault type and fall the degree of depth.

Accompanying drawing explanation

Fig. 1 is low voltage crossing detection device schematic diagram in TR3 standard；

Fig. 2 is the low voltage crossing detection device Voltage Drop amplitude tolerance schematic diagram that GB GB/T19964 specifies；

Fig. 3 is the low voltage crossing curve synoptic diagram that GB GB/T19964 specifies；

Fig. 4 is voltage falling generator topology diagram.

Detailed description of the invention

Below in conjunction with the accompanying drawings the detailed description of the invention of the present invention is described in further detail.

Voltage falling generator for low voltage crossing test

Voltage falling generator is connected with parallel network power generation unit by step-up transformer；Voltage falling generator includes By-pass switch S₁, short switch S₂, ground connection stacked switch S₃, ground connection combination reactance X_pReactance X is combined with current limliting_S；Step-up transformer Reactance X is combined by current limliting_SIt is connected with electrical network, by-pass switch S₁Reactance X is combined with current limliting_SIn parallel；Step-up transformer, short circuit are left Close S₂, ground connection combination reactance X_pWith ground connection stacked switch S₃Series connection, ground connection stacked switch S₃Other end ground connection.Step-up transformer is high Pressure side is Y connection, and its neutral point and S₃After the other end is connected altogether.

Current limliting combination reactance X_SCurrent limliting combination reactance one and current limliting combination reactance two including series connection；Current limliting combination reactance one Including three-phase reactor in parallel and three-phase breaker；Current limliting combination reactance two includes the three-phase reactor X of parallel connection₂、X₃、X₄、 X₅, three-phase reactor X₂With X₃、X₃With X₄、X₄With X₅Respectively by three-phase breaker K between two ends₂With K₄、K₅With K₇、K₈With K₁₀Even Connect；Current limliting combination reactance one and three-phase reactor X₂With three-phase breaker K₄The end that is connected connects, electrical network and three-phase reactor X₅With three Phase breaker K₈The end that is connected connects；Three-phase reactor X₂With three-phase breaker K₄The other end respectively with three-phase breaker K₃Two ends It is connected；Three-phase reactor X₃With three-phase breaker K₇The other end respectively with three-phase breaker K₆Two ends are connected；Three-phase reactor X₄ With three-phase breaker K₁₀The other end respectively with three-phase breaker K₉Two ends are connected.

Ground connection combination reactance X_pGround connection combination reactance one and ground connection combination reactance two including series connection；Ground connection combination reactance one Including three-phase reactor in parallel and three-phase breaker；Ground connection combination reactance two includes the three-phase reactor X of parallel connection₇、X₈、X₉、 X₁₀, three-phase reactor X₇With X₈、X₈With X₉、X₉With X₁₀Respectively by three-phase breaker K between two ends₁₂With K₁₄、K₁₅With K₁₇、K₁₈ With K₂₀Connect；Ground connection combination reactance one and three-phase reactor X₇With three-phase breaker K₁₄The end that is connected connects, ground connection stacked switch S₃ Single-phase circuit breaker side and three-phase reactor X₁₀With three-phase breaker K₁₈The end that is connected connects；Three-phase reactor X₇And three-phase breaker K₁₄The other end respectively with three-phase breaker K₁₃Two ends are connected；Three-phase reactor X₈With three-phase breaker K₁₇The other end respectively With three-phase breaker K₁₆Two ends are connected；Three-phase reactor X₉With three-phase breaker K₂₀The other end respectively with three-phase breaker K₁₉ Two ends are connected.

As shown in Figure 4, Fig. 4 is the voltage falling generator topology diagram of the present invention；This voltage falling generator passes through Step-up transformer is connected with parallel network power generation unit；This voltage falling generator includes by-pass switch S₁, short switch S₂, connect Ground stacked switch S₃, ground connection combination reactance X_pReactance X is combined with current limliting_S。

Step-up transformer combines reactance X with current limliting_SSeries connection, current limliting combination reactance X_SThe other end is connected with electrical network, by-pass switch S₁Reactance X is combined with current limliting_SIn parallel；Step-up transformer, short switch S₂, ground connection combination reactance X_pWith ground connection stacked switch S₃String Connection, ground connection stacked switch S₃Other end ground connection；By-pass switch S₁Reactance X is combined with current limliting_SIn parallel.

Current limliting combination reactance X_SCurrent limliting combination reactance one and current limliting combination reactance two including series connection.Current limliting combination reactance one Including three-phase reactor X in parallel₁With three-phase breaker K₁；Current limliting combination reactance two includes three-phase reactor X₂、X₃、X₄、X₅With The three-phase breaker K being connected with three-phase reactor two ends respectively₂With K₄、K₅With K₇、K₈With K₁₀, and respectively with three-phase reactor X₂With Three-phase breaker K₄The other end, three-phase reactor X₃With three-phase breaker K₇The other end, three-phase reactor X₄And three-phase break Device K₁₀The other end connect three-phase breaker K₃, three-phase breaker K₆, three-phase breaker K₉。

Ground connection combination reactance X_pGround connection combination reactance one and ground connection combination reactance two including series connection；Ground connection combination reactance one Including three-phase reactor X in parallel₆With three-phase breaker K₁₁；Ground connection combination reactance two includes three-phase reactor X₇、X₈、X₉、X₁₀With The three-phase breaker K being connected with three-phase reactor two ends respectively₁₂With K₁₄、K₁₅With K₁₇、K₁₈With K₂₀, and respectively with three-phase reactor X₇With three-phase breaker K₁₄The other end, three-phase reactor X₈With three-phase breaker K₁₇The other end, three-phase reactor X₉With three Phase breaker K₂₀The other end connect three-phase breaker K₁₃, three-phase breaker K₁₆, three-phase breaker K₁₉。

Ground connection stacked switch S₃Including earthed switch N and single-phase circuit breaker N in parallel_A、N_B、N_C, control three-phase electricity respectively.

By-pass switch S₁, short switch S₂, ground connection stacked switch S₃In earthed switch N and current limliting combination reactance and connecing Ground combination reactance X_pBreaker in middle K₁、K₂、K₃、K₄、K₅……K₂₀It is three-phase breaker, ground connection stacked switch S₃In N_A、N_B、N_C For single-phase circuit breaker, current limliting combination reactance X_SReactance X is combined with ground connection_pIn three-phase reactor X₁、X₂、X₃、X₄、X₅……X₁₀For Three-phase reactor.

As by-pass switch S₁During Guan Bi, the boosted change of photovoltaic combining inverter is connected directly to electrical network；By-pass switch S₁Disconnect Time, it is connected to electrical network after the boosted change of photovoltaic combining inverter and voltage falling generator.Voltage falling generator is by changing Ground connection stacked switch S₃In N_A、N_B、N_CAnd the on off state of earthed switch N, generation various types of electrical networks electricity can be simulated Pressure fault；By changing current limliting combination reactance X_SReactance X is combined with ground connection_pIn each three-phase reactor X₁、X₂、X₃、X₄、X₅……X₁₀ Connection in series-parallel combination, can change current limliting combination reactance X_SReactance X is combined with ground connection_pReactance value size, thus realize with 5% electrical network rated voltage is step-length, from 0% to 100% electrical network rated voltage gamut Voltage Drop.

Above-mentioned according to voltage falling generator by change ground connection stacked switch S₃In N_A、N_B、N_CAnd earthed switch N On off state, simulation produce various types of line voltage faults, ground connection stacked switch S₃Use three single-phase switch N_A、N_B、 N_CSimulation three phase network is the most short-circuit；Use a threephase switch N simulating grid whether ground connection, by above-mentioned various switch combinations The fault type produced is as shown in table 1 below, and table 1 is ground connection stacked switch breaker in middle combination table corresponding with fault type；

Combination	NA	NB	NC	N	Fault type
						1	Guan Bi	Disconnect	Disconnect	Guan Bi	A phase ground short circuit
2	Disconnect	Guan Bi	Disconnect	Guan Bi	B phase ground short circuit
						3	Disconnect	Disconnect	Guan Bi	Guan Bi	C phase ground short circuit
4	Guan Bi	Guan Bi	Disconnect	Disconnect	AB phase fault
						5	Disconnect	Guan Bi	Guan Bi	Disconnect	BC phase fault
6	Guan Bi	Disconnect	Guan Bi	Disconnect	CA phase fault
						7	Guan Bi	Guan Bi	Disconnect	Guan Bi	The alternate ground short circuit of AB
8	Disconnect	Guan Bi	Guan Bi	Guan Bi	The alternate ground short circuit of BC
						9	Guan Bi	Disconnect	Guan Bi	Guan Bi	The alternate ground short circuit of CA
10	Guan Bi	Guan Bi	Guan Bi	Open circuit	ABC three-phase shortcircuit
						11	Guan Bi	Guan Bi	Guan Bi	Guan Bi	The short circuit of ABC three-phase ground

Table 1

Control method for the voltage falling generator of low voltage crossing test

Present invention also offers a kind of voltage falling generator applied and test at photovoltaic combining inverter low voltage crossing Control method, voltage falling generator successively according to following steps realize line voltage fall with recover, including:

Step one, measurement three-phase power grid voltage grade U and electrical network internal driving a；

Step 2, the parameter of three-phase reactor of design voltage drop generator, determine that current limliting combines reactance X_SWith ground connection Combination reactance X_pReactance value size X of middle three-phase reactor₁、X₂、X₃、X₄、X₅……X₁₀, and according to topology knot as shown in Figure 1 Structure builds voltage falling generator；

When step 3, photovoltaic combining inverter normally work, by-pass switch S₁For closure state, short switch S₂For disconnecting State, waits low voltage crossing detection；

Step 4, when carry out low voltage crossing detection time, first according to line voltage fault type, according to above-mentioned table 1 institute Show and select the combination of each switch in ground connection stacked switch；Then according to shown in table 2, according to current set drop to specified The percentage h of voltage selects current limliting combination reactance X_SReactance X is combined with ground connection_pIn switch combination mode；

Step 5, first disconnection by-pass switch S₁, it is closed again short switch S₂, grid-connected point voltage starts to fall；

Step 6, grid-connected point voltage are according to GB GB/T19964 " photo-voltaic power generation station accesses power system technology regulation " institute After the low voltage crossing curve map of regulation falls certain time, first disconnect short switch S₂, it is closed again by-pass switch S₁, and Site voltage starts to recover, and returns to step 3.

Table 2 below is that difference falls each switch combination mode table in combination reactance and the ground connection combination reactance of depth limit stream:

Table 2

The design procedure of the parameter of the three-phase reactor of above-mentioned voltage falling generator is as follows:

Assuming that certain three-phase power grid voltage grade known is U, electrical network internal driving is a, owing to the most general Voltage Drop is sent out Capacity of short circuit is photovoltaic combining inverter capacity 3～5 times of raw device, if setting voltage drop generator capacity of short circuit S_vForThen this voltage falling generator is suitably adapted for capacity and is less thanPhotovoltaic combining inverter carry out low voltage crossing survey Examination.

Set current limliting combination reactance X_SReactance X is combined with ground connection_pReactance value be respectively X_S(i)、X_p(i), wherein i=1,2, 3 ... 20, represent 20 kinds fallen from 0% to 100% electrical network rated voltage gamut and fall the degree of depth, then have:

$S_v=\frac{U^2}{X_P\left(i\right)+X_S\left(i\right)+a}=\frac{U^2}{20a}---\left(1\right)$

Based on impedance voltage divider principle, Voltage Drop is represented by rated voltage percentage h:

$h=5\%(i-1)=\frac{X_P\left(i\right)}{X_P\left(i\right)+X_S\left(i\right)+a}---\left(2\right)$

Such as following formula (3), (4), obtain 20 groups of current limliting combination reactance X according to formula (1), (2)_SReactance X is combined with ground connection_pElectricity Anti-value is to (X_S(i)、X_p(i)), i.e.

$X_S\left(i\right)=\frac{{\mathrm{iU}}^2}{20S_v}=\mathrm{ia}---\left(3\right)$

$X_P\left(i\right)=(1-\frac{i}{20})\frac{U^2}{S_v}-a=(19-i)a---\left(4\right)$

Reactance X is combined for current limliting_S, as switch K₁Guan Bi, i.e. switchs K₁By three-phase reactor X₁During bypass, three-phase reactor Device X₂、X₃、X₄、X₅By regulation switch K₂、K₃、K₄、K₅、K₆、K₇、K₈、K₉And K₁₀On off operating mode can produce 40 kinds of equivalent reactances Value X:

X(1)=X₂；X(2)=X₃；X(3)=X₄；X(4)=X₅；

X(5)=X₂+X₃；X(6)=X₂+X₄；X(7)=X₂+X₅；

X(8)=X₃+X₄；X(9)=X₃+X₅；X(10)=X₄+X₅；

X(11)=1/(1/X₂+1/X₃)；X(12)=1/(1/X₂+1/X₄)；

X(13)=1/(1/X₂+1/X₅)；X(14)=1/(1/X₃+1/X₄)；

X(15)=1/(1/X₃+1/X₅)；X(16)=1/(1/X₄+1/X₅)；

X(17)=X₂+X₃+X₄；X(18)=X₂+X₃+X₅；

X(19)=X₂+X₄+X₅；X(20)=X₃+X₄+X₅；

X(21)=1/(1/X₂+1/X₃)+X₄；

X(22)=1/(1/X₂+1/X₃)+X₅；

X(23)=1/(1/X₂+1/X₄)+X₅；

X(24)=X₂+1/(1/X₃+1/X₄)；

X(25)=1/(1/X₃+1/X₄)+X₅；

X(26)=X₂+1/(1/X₄+1/X₅)；

X(27)=X₃+1/(1/X₄+1/X₅)；

X(28)=1/(1/X₂+1/X₃+1/X₄)；

X(29)=1/(1/X₂+1/X₃+1/X₅)；

X(30)=1/(1/X₂+1/X₄+1/X₅)；

X(31)=1/(1/X₃+1/X₄+1/X₅)；

X(32)=1/(1/X₂+1/X₃)+X₄+X₅；

X(33)=X₂+1/(1/X₃+1/X₄)+X₅；

X(34)=X₂+X₃+1/(1/X₄+1/X₅)；

X(35)=1/(1/X₂+1/X₃+1/X₄)+X₅；

X(36)=X₂+1/(1/X₃+1/X₄+1/X₅)；

X(37)=1/(1/X₂+1/X₃)+1/(1/X₄+1/X₅)；

X(38)=X₂+X₃+X₄+X₅；

X(39)=1/(1/X₂+1/X₃+1/X₄+1/X₅)；

X(40)=0；

As switch K₁Disconnect, i.e. three-phase reactor X₁When series connection puts in circuit, current limliting combination reactance X_SEquivalent reactance value X is further added by 40 kinds, it may be assumed that

X (40+n)=X (n)+X₁(n=1,2......40) (5)

Therefore, current limliting combination reactance X_SAltogether can produce 80 kinds of reactance value X (1), X (2), X (3) ... X (80).

Convenient for design, ground connection combination reactance X_pReactance X is combined with current limliting_SThe parameter of topological structure and three-phase reactor It is identical, it may be assumed that

$\left\{\begin{array}{c}{X}_6=X_1\\ X_7=X_2\\ X_8=X_3\\ X_9=X_4\\ X_{10}=X_5\end{array}\right.---\left(6\right)$

From formula (6), ground connection combination reactance X_pAlso reactance X can be combined with current limliting_SEqually, altogether can produce 80 to finish Exactly the same reactance value X (1), X (2), X (3) ... X (80).

Current limliting combination reactance X can be obtained according to formula (3), (4), (5), (6)_SReactance X is combined with ground connection_pMiddle three-phase reactor One group of feasible solution of reactance value:

$\left\{\begin{array}{c}{X}_6=X_1=a\\ X_7=X_2=2a\\ X_8=X_3=3a\\ X_9=X_4=6a\\ X_{10}=X_5=7a\end{array}\right.---\left(7\right)$

Finally should be noted that: above example is merely to illustrate the technical scheme of the application rather than to its protection domain Restriction, although being described in detail the application with reference to above-described embodiment, those of ordinary skill in the field should Understand: those skilled in the art read the application after still can to application detailed description of the invention carry out all changes, amendment or Person's equivalent, but these changes, amendment or equivalent, all within the claims that application is awaited the reply.

Claims (7)

1., for a voltage falling generator for low voltage crossing test, described voltage falling generator passes through step-up transformer It is connected with parallel network power generation unit；It is characterized in that:

Described voltage falling generator includes by-pass switch S₁, short switch S₂, ground connection stacked switch S₃, ground connection combination reactance X_pWith Current limliting combination reactance X_S；

Described step-up transformer high-pressure side is Y connection, and described step-up transformer combines reactance X by described current limliting_SWith electrical network even Connect, described by-pass switch S₁Reactance X is combined with described current limliting_SIn parallel；Described step-up transformer, described short switch S₂Connect described in, Ground combination reactance X_pWith described ground connection stacked switch S₃Series connection, the high-pressure side neutral point of described step-up transformer and described ground connection group Combination switch S₃The other end is total to ground connection after being connected；

Described current limliting combination reactance X_SCurrent limliting combination reactance one and current limliting combination reactance two including series connection；

The combination reactance one of described current limliting includes the three-phase reactor X of parallel connection₁With three-phase breaker K₁；

The combination reactance two of described current limliting includes the three-phase reactor X of parallel connection₂、X₃、X₄、X₅, three-phase reactor X₂With X₃、X₃With X₄、X₄ With X₅Respectively by three-phase breaker K between two ends₂With K₄、K₅With K₇、K₈With K₁₀Connect；

Described current limliting combination reactance one and three-phase reactor X₂With three-phase breaker K₄The end that is connected connects, described electrical network and three-phase electricity Anti-device X₅With three-phase breaker K₈The end that is connected connects；

Described three-phase reactor X₂With three-phase breaker K₄The other end respectively with three-phase breaker K₃Two ends are connected；

Described three-phase reactor X₃With three-phase breaker K₇The other end respectively with three-phase breaker K₆Two ends are connected；

Described three-phase reactor X₄With three-phase breaker K₁₀The other end respectively with three-phase breaker K₉Two ends are connected；

Described ground connection combination reactance X_pGround connection combination reactance one and ground connection combination reactance two including series connection；

The combination reactance one of described ground connection includes the three-phase reactor X of parallel connection₆With three-phase breaker K₁₁；

The combination reactance two of described ground connection includes the three-phase reactor X of parallel connection₇、X₈、X₉、X₁₀, three-phase reactor X₇With X₈、X₈With X₉、X₉ With X₁₀Respectively by three-phase breaker K between two ends₁₂With K₁₄、K₁₅With K₁₇、K₁₈With K₂₀Connect；

Described ground connection combination reactance one and three-phase reactor X₇With three-phase breaker K₁₄The end that is connected connects, described ground connection stacked switch S₃Single-phase circuit breaker side and three-phase reactor X₁₀With three-phase breaker K₁₈The end that is connected connects；

Described three-phase reactor X₇With three-phase breaker K₁₄The other end respectively with three-phase breaker K₁₃Two ends are connected；

Described three-phase reactor X₈With three-phase breaker K₁₇The other end respectively with three-phase breaker K₁₆Two ends are connected；

Described three-phase reactor X₉With three-phase breaker K₂₀The other end respectively with three-phase breaker K₁₉Two ends are connected.

A kind of voltage falling generator for low voltage crossing test, it is characterised in that: described Parallel network power generation unit includes photovoltaic array and the photovoltaic combining inverter being connected, described photovoltaic combining inverter and described liter Pressure transformer is connected；

Described ground connection stacked switch S₃Single-phase circuit breaker group and earthed switch N including series connection；Described single-phase circuit breaker group includes also The single-phase circuit breaker controlling three-phase electricity respectively of connection；Described earthed switch N is three-phase breaker.

3. a kind of voltage falling generator for low voltage crossing test as described in any one of claim 1-2, its feature It is: described current limliting combination reactance X_SReactance X is combined with described ground connection_pThe reactance value of middle three-phase reactor is respectively as follows:

Wherein, X₁For the three-phase reactor in current limliting combination reactance one；X₆For the three-phase reactor in ground connection combination reactance one, X₂、 X₃、X₄、X₅It is respectively current limliting combination reactance X_SThree-phase reactor；X₇、X₈、X₉、X₁₀It is respectively ground connection combination reactance X_pThree-phase Reactor；A is electrical network internal driving.

A kind of voltage falling generator for low voltage crossing test, it is characterised in that: described Voltage falling generator is by changing ground connection stacked switch S₃In three described single-phase circuit breakers and the opening of described earthed switch N Off status, simulation produces various types of line voltage faults.

A kind of voltage falling generator for low voltage crossing test, it is characterised in that: described Voltage falling generator is by changing current limliting combination reactance X_SReactance X is combined with ground connection_pIn each three-phase reactor connection in series-parallel combination Mode, changes current limliting combination reactance X_SReactance X is combined with ground connection_pReactance value size, it is achieved with 5% electrical network rated voltage as step Long, from 0% to 100% electrical network rated voltage gamut Voltage Drop.

6. the control method being applied to voltage falling generator according to claim 1, it is characterised in that: described side Method comprises the following steps:

I, measurement three-phase power grid voltage grade U and electrical network internal driving a；

II, set up voltage falling generator, and determine that current limliting combines reactance X_SReactance X is combined with ground connection_pThe electricity of middle three-phase reactor Anti-value size；

III, when photovoltaic combining inverter normally works, close by-pass switch S₁, disconnect short switch S₂, wait that low-voltage is worn More detection；

IV, low voltage crossing detect, and select ground connection stacked switch S₃The combination of breaker in middle, simulating grid voltage failure；

The current percentage h dropping to rated voltage set of V, basis selects current limliting combination reactance X_SReactance X is combined with ground connection_p In switch combination mode；

VI, first disconnection by-pass switch S₁, it is closed again short switch S₂, grid-connected point voltage starts to fall；

After VII, grid-connected point voltage fall certain time, first disconnect short switch S₂, it is closed again by-pass switch S₁, and site Voltage starts to recover, and returns to step III.

A kind of control method being applied to voltage falling generator according to claim 1, It is characterized in that: in described step II, as following formula determines that current limliting combines reactance X_SReactance X is combined with ground connection_pMiddle three-phase reactor Reactance value size:

In formula, X₁For the three-phase reactor in current limliting combination reactance one；X₆For the three-phase reactor in ground connection combination reactance one, X₂、 X₃、X₄、X₅It is respectively current limliting combination reactance X_SThree-phase reactor；X₇、X₈、X₉、X₁₀It is respectively ground connection combination reactance X_pThree-phase Reactor；A is electrical network internal driving.