CN204721231U - There is voltage swell and fall the power generator of function temporarily - Google Patents

Abstract

The utility model discloses a kind of power generator that there is voltage swell and fall function temporarily.At present based on the VSG of inverter control advanced, flexibly, multiple voltage fault can be simulated, but be seen in only having of report and realize falling temporarily of voltage.The utility model comprises step-up transformer, rectification unit, inversion unit, LC sine wave filter, IGBT drive and protection circuit, sample circuit and control unit; described inversion unit is three-phase PWM inverter, and described rectification unit is three-phase uncontrollable rectifier bridge.The utility model have can flexible, export accurately and advantage that dynamic response is fast, can the line voltage that specifies of Simulation with I EEEll59-1995 standard rise temporarily/phenomenon is fallen temporarily, the test requirements document that frequency converter high-low voltage passes through supportive device can be met, also may be used for the performance test of other Electrical and Electronic product under line voltage abnormal conditions and research.

Description

There is voltage swell and fall the power generator of function temporarily

Technical field

The utility model relates to a kind of power generator having voltage swell simultaneously and fall function temporarily, can the abnormal conditions of simulating grid voltage, can the line voltage that specifies of Simulation with I EEEll59-1995 standard rise temporarily/phenomenon is fallen temporarily, can be used for the test requirements document that frequency converter high-low voltage passes through supportive device, also may be used for the performance test of other Electrical and Electronic product under line voltage abnormal conditions and research.

Background technology

In actual electric network, the startup of extra-high voltage alternating current-direct current line fault, electricity grid oscillating, large-size machine and short circuit malfunction etc. can cause larger voltage dip; And the extensive anticlimax of load, the input etc. of large bulk capacitance compensator can cause the temporary liter of line voltage.The situation that this kind of line voltage rises temporarily/falls temporarily, often can cause the shutdown of power plant frequency converter, occurs on some key equipments, and then can make whole generating set chaser, cause serious threat to the stable operation of electric power system if shut down.This potential safety hazard has caused great attention in the industry, in order to solve the problem of this type of large turbine-generator set one class subsidiary engine frequency converter high-low voltage ride-through capability, need to develop the power supply of simulating grid voltage swell/fall temporarily, it is basis and the checking means that research and development frequency converter high-low pressure passes through support equipment.

At present, research both domestic and external mainly concentrates on the simulation of falling temporarily line voltage, i.e. voltage falling generator (Voltage Sag Generator, VSG), its implementation can be divided into 4 kinds: based on amplifier, based on hindrance, based on autotransformer and based on inverter.VSG based on amplifier realizes primarily of the power device being operated in linear amplification region, primary structure is changed by signal generator, A/D and power amplifier forms, it is abundanter that it has waveform, the feature that dynamic characteristic is good, but its power output is by the restriction of power amplifier; Based on the VSG structure of hindrance form, be exactly increase series and parallel part in equipment in simple terms, by controlling the time of reactor place in circuit, change the impedance of circuit, and then realizing the temporary change of output voltage, it controls simple, is convenient to realize, but its energy loss is large, and output accuracy is not high enough; Based on the VSG of autotransformer and full-control type electronic AC switch, primary structure is autotransformer, diverse location leading-out terminal connects electronic power switch, output loop, there is the features such as fast response time, efficiency are high, energy capable of bidirectional flowing, and the output of the voltage swell of any time/fall temporarily, irregular waveform can be realized, but it cannot produce the waveform of optional frequency and harmonic wave, voltage cannot regulate automatically.Studying many VSG so far, is the technology based on all kinds of electronic switch, and creates many technical schemes.VSG based on inverter controls advanced person, flexibly, can simulate multiple voltage fault, but research is less at present, is seen in only having of report and realizes falling temporarily of voltage.

Utility model content

Technical problem to be solved in the utility model overcomes the defect that above-mentioned prior art exists, and provides a kind of based on having voltage swell while three-phase PWM inverter and falling the power generator of function temporarily.

For this reason, the utility model adopts following technical scheme: have voltage swell and fall the power generator of function temporarily, it is characterized in that, it comprises step-up transformer, rectification unit, inversion unit, LC sine wave filter, IGBT drive and protection circuit, sample circuit and control unit;

The AC of described rectification unit is connected with the secondary of step-up transformer; The DC side of described inversion unit is connected with the DC side of rectification unit; The described input side of LC sine wave filter is connected with the AC of inversion unit, and the outlet side of LC sine wave filter is used for being connected with load end;

Described sample circuit comprises voltage hall sensor and current Hall transducer, and voltage hall sensor is arranged on the outlet side of LC sine wave filter, and current Hall transducer is arranged on the outlet side of inversion unit; The signal output part of voltage hall sensor is connected with control unit, and the signal output part of current Hall transducer is also connected with control unit; Described control unit take microcomputer as the control circuit of core, and its signal output part is connected with IGBT drive and protection circuit;

Described inversion unit is three-phase PWM inverter, and described rectification unit is three-phase uncontrollable rectifier bridge.

380V voltage is increased to 660V by described step-up transformer, for power generator provides the space of voltage swell.

Described inversion unit is by changing time of each switch conduction/shutoff, and realize the step-less adjustment of output voltage 0-540V scope, output frequency is fixed, so the line voltage that Simulation with I EEEll59-1995 standard specifies rise temporarily/phenomenon is fallen temporarily.

Described LC sine wave filter filtering can come from the HF switch harmonic wave of inversion unit, keeps amplitude and the phase invariant of fundamental frequency voltages simultaneously, ensures that output voltage sinusoidal waveform meets requirement of experiment.

Information from sample circuit processes by described control unit in real time, in conjunction with respective algorithms, by vector control, obtains the pulse signal controlling inversion unit switch conduction/shutoff, and then realizes the accurate control of output voltage.

Described control unit adopts TMS320F2812 to be the control circuit of core, adopts voltage close loop control strategy under dq coordinate system.

Operation principle of the present utility model is: by step-up transformer, 380V voltage is increased to 660V, carries out rectification output, for three-phase PWM inverter provides direct voltage by three-phase uncontrollable rectifier bridge.Three-phase PWM inverter output rated voltage is 50Hz/400V.Control to adopt vector control strategy to the PWM of inverter by control unit, adjustable output voltage amplitude, scope reaches as high as 0-660V in theory, reality is set in about 0-560V (high-voltage value is about 1.4 times of rated voltage) as required, period, holding frequency was constant, the phenomenon that realistic line voltage rises temporarily/falls temporarily, duration and the phase place of device generation transient voltage are adjustable arbitrarily.

Power generator of the present utility model, based on PWM modulation technology, have can flexible, export accurately and the feature such as dynamic response is fast.Requirement configuration according to actual tests fully tests power, the test requirements document that current power plant one class subsidiary engine frequency converter high-low voltage passes through supportive device can be met, and be applicable to other electrically and the performance test of electronic product under all kinds of line voltage fault and research.

Accompanying drawing explanation

Fig. 1 is main circuit structure schematic diagram of the present utility model.

Fig. 2 is inverter equivalent mathematical model (the wherein U of the utility model under dq coordinate system _dq, I _ldq, V _dqbe respectively output voltage, inductive current, three-phase alternating current side voltage vector under dq coordinate; V _dcfor DC bus-bar voltage; P _cfor the active power of uncontrollable rectifier end input direct-current side; P _ofor inverter active power of output; ω is output voltage angular frequency; C is DC side bus capacitor; S is Laplacian, and j is the imaginary unit of plural number).

Fig. 3 is the utility model voltage error transfer function Bode diagram.

Fig. 4 is the control principle drawing of the utility model inverter.

Fig. 5 be the utility model under different band carries situation, AC voltage is to output voltage G _v/U(s) transfer function Bode diagram.

Fig. 6-7 for the utility model voltage swell/fall temporarily waveform detail drawing (in Fig. 6, p=1 → 1.3; In Fig. 7, p=1 → 0.2).

Fig. 8 is the utility model voltage swell oscillogram (p=1.3, t=0.5s).

Fig. 9 is the utility model voltage dip oscillogram (p=0.5, t=1s).

Embodiment

Below in conjunction with Figure of description, the utility model is described in further detail.

With reference to Fig. 1, the utility model rises temporarily/fall the composed as follows of power generator temporarily: step-up transformer, three-phase uncontrollable rectifier bridge, three-phase PWM inverter, LC sine wave filter, IGBT drive and protection circuit, the sample circuit be made up of voltage hall sensor and current Hall transducer and take TMS320F2812 as the control circuit of core.

Electrical network 380V voltage is elevated to 660V by step-up transformer, and the AC of the uncontrollable rectifier bridge of three-phase is connected with the secondary of step-up transformer, becomes direct voltage to be about 890V ac voltage rectifier; The DC side of three-phase PWM inverter is connected with the DC side of three-phase uncontrollable rectifier bridge; LC sine wave filter input side is connected with the AC of three-phase PWM inverter, and LC sine wave filter outlet side is connected with load end; Voltage hall sensor is arranged on the outlet side of LC sine wave filter, and current Hall transducer is arranged on the outlet side of three-phase PWM inverter; The signal output part of voltage hall sensor is connected with the control circuit taking TMS320F2812 as core, and the signal output part of current Hall transducer is connected with the control circuit taking TMS320F2812 as core; Take TMS320F2812 as the control circuit of core, adopt voltage close loop control strategy (see Fig. 4) under dq coordinate system, its signal output part is connected with IGBT drive and protection circuit.

In the inverter shown in Fig. 1, if the inductance of three-phase reactor is equal with internal resistance, i.e. r=r _a=r _b=r _c, L=L _a=L _b=L _c, then with output voltage U _abcunder directed synchronous rotary dq coordinate system (being called for short dq coordinate system), inverter equivalent mathematical model is for shown in Fig. 2, and its mathematic(al) representation is for shown in formula (1).

$\left\{\begin{array}{c}L\frac{{\mathrm{dI}}_{Ld}}{dt}=U_d-{\mathrm{rI}}_{Ld}-{\mathrm{\ωLI}}_{Lq}-V_d\\ L\frac{{\mathrm{dI}}_{Lq}}{dt}=U_q-{\mathrm{rI}}_{Lq}+{\mathrm{\ωLI}}_{Ld}-V_q\\ {\mathrm{CV}}_{dc}\frac{{\mathrm{dV}}_{dc}}{dt}=P_o-P_c\end{array}\right.---\left(1\right)$

Wherein U _d, U _q, I _ld, I _lq, V _d, V _qbe respectively output voltage, inductive current, three-phase alternating current side voltage d, q axle component under dq coordinate; V _dcfor DC bus-bar voltage; P _cfor the active power of uncontrollable rectifier end input direct-current side; P _ofor inverter active power of output; T is the time; ω is output voltage angular frequency; C is DC side bus capacitor.

The active power that inverter exports is provided by front end rectifier bridge, and therefore the utility model mainly considers the control of inverter ac side.For guaranteeing the precision of system output voltage, the utility model adopts voltage close loop control strategy under dq coordinate system.At output voltage U _abcin directed dq coordinate system, output voltage d axle component is equal with output voltage synthetic vector amplitude, and q axle component is always zero.Then consider that three-phase symmetrical rises temporarily/falls temporarily, the Amplitude Ration that rear voltage and rated voltage synthetic vector rise/fall in definition temporarily is temporarily p, then d, q axle component of output voltage reference value for

$\left\{\begin{array}{c}{U}_d^{*}={\mathrm{pU}}_m\\ U_q^{*}=0\end{array}\right.---\left(2\right)$

Wherein, U _mfor the amplitude of rated output voltage synthetic vector.

Three-phase symmetrical rise temporarily/fall in fault temporarily, with it is all DC quantity.Then adopt conventional PI control device can carry out DAZ gene to voltage.The transfer function G of PI controller _pi(s) be:

$G_{pi}\left(s\right)=K_p+\frac{K_i}{s}---\left(3\right)$

Wherein K _pand K _ibe respectively proportional gain and the integration gain factor of controller; S is Laplacian.

Then according to formula (1), the AC voltage instruction under dq coordinate system for

$\left\{\begin{array}{c}{V}_d^{*}=G_{pi}\left(s\right)(U_d^{*}-U_d)-{\mathrm{\ωLI}}_{Lq}\\ V_q^{*}=G_{pi}\left(s\right)(U_q^{*}-U_q)+{\mathrm{\ωLI}}_{Ld}\end{array}\right.---\left(4\right)$

Wherein, ω LI _ld, ω LI _lqbe respectively d, q decoupler shaft compensation term.Then output voltage error transfer function is

$err\left(s\right)=(U_{dq}^{*}-U_{dq})=\frac{G_{pi}\left(s\right)}{1+G_{pi}\left(s\right)}---\left(5\right)$

From the Bode diagram of the transfer function of voltage error shown in Fig. 3, during stable state, output voltage error is very little, approximates zero.Namely the voltage close loop based on PI controls, and can realize controlling the high accuracy of inverter output voltage.

PWM inverter System Control Figure shown in Fig. 4 (in figure, I _la, I _lb, I _lcfor three-phase phase current, θ is phase angle, the θ of phase voltage ^*for given phase voltage fixed phase angle, e is the end of natural logrithm).First, to three-phase phase voltage U _a, U _b, U _csample, obtain output voltage d, q component-U by coordinate transform _d, U _q.U _d, U _qrespectively with reference voltage subtract each other, the error obtained, respectively through PI controller, obtains the output voltage instruction under dq coordinate system again will the voltage instruction under two-phase static coordinate is obtained by coordinate transform be the reference voltage of SVPWM modulation, finally obtain the pulse signal of control inverter switch conduction/shutoff.

Owing to adopting PWM modulation technology, inverter ac side voltage is by the harmonic wave containing larger switching frequency.Therefore, inverter ac side voltage through LC filter with filtering high-frequency harmonic, need improve system output voltage sine degree.Under the voltage effect of inverter ac side, the transfer function of system output voltage is

$G_{V/U}\left(s\right)=\frac{U\left(s\right)}{V\left(s\right)}=\frac{1}{{\mathrm{CLs}}^2+\frac{L}{R}s+1}---\left(6\right)$

Wherein, C is filtering capacitance; R is load resistor value.Under Figure 5 shows that different band carries situation, AC voltage is to output voltage G _v/U(s) transfer function Bode diagram.Wherein the parameter of LC is used consistent with experiment, is respectively 1.7mH and 50 μ F.As seen from the figure, no matter underloading or fully loaded transportation condition, LC filter circuit all can effectively filtering switch harmonic (4kHz) and other high order harmonic components, simultaneously basic amplitude and the phase invariant keeping fundamental frequency voltages.

In order to still rated power be exported under minimum voltage, need the current rating improving major loop device, if design rated voltage load current is I _n, when output minimum voltage is the rated voltage of P%, then power outputting section maximum output current needs: I _n/ P% (A), inverter here and filter inductance need to select component parameter by this.140% consideration that the maximum operating voltage exported is specified, i.e. 560V.

The utility model can according to microcomputer instruction, and temporary liter/depreciation and the time temporarily of any regulation output voltage, Fig. 6-9 is the actual measured drawing building device output voltage waveforms.

Claims (1)

1. have voltage swell and fall the power generator of function temporarily, it is characterized in that, it comprises step-up transformer, rectification unit, inversion unit, LC sine wave filter, IGBT drive and protection circuit, sample circuit and control unit;

The AC of described rectification unit is connected with the secondary of step-up transformer; The DC side of described inversion unit is connected with the DC side of rectification unit; The described input side of LC sine wave filter is connected with the AC of inversion unit, and the outlet side of LC sine wave filter is used for being connected with load end;

Described sample circuit comprises voltage hall sensor and current Hall transducer, and voltage hall sensor is arranged on the outlet side of LC sine wave filter, and current Hall transducer is arranged on the outlet side of inversion unit; The signal output part of voltage hall sensor is connected with control unit, and the signal output part of current Hall transducer is also connected with control unit; Described control unit take microcomputer as the control circuit of core, and its signal output part is connected with IGBT drive and protection circuit;

Described inversion unit is three-phase PWM inverter, and described rectification unit is three-phase uncontrollable rectifier bridge.