CN1832289A - Neutral line harmonic current control device and its control method - Google Patents
Neutral line harmonic current control device and its control method Download PDFInfo
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Abstract
本发明公开了一种中性线谐波电流治理装置及其控制方法，涉及电力系统电能质量控制技术。本装置是在三相四线电力系统1和非线性负载8之间，依次串联有指令电流运算电路2、控制电路3、驱动电路4、单相桥式逆变器5、隔离变压器6；在单相桥式逆变器5和非线性负载8之间连接有三相不可控桥式整流电路7。主要优点：1)由于隔离变压器6特殊的拓扑结构，使单相桥式逆变器5无需承受电力系统1工频电压，所以本装置结构简单，易于实现，且成本低；2)采用有源器件，补偿效果好，经济可靠；3)三相四线电力系统1补偿过程中不增加任何新的畸变分量；适用于对低压三相四线电力系统1—主要为商业、建筑、民用电力系统—进行中性线上谐波电流的治理。The invention discloses a neutral line harmonic current control device and a control method thereof, and relates to power system power quality control technology. This device is between the three-phase four-wire power system 1 and the non-linear load 8, and the command current calculation circuit 2, the control circuit 3, the drive circuit 4, the single-phase bridge inverter 5, and the isolation transformer 6 are serially connected in series; A three-phase uncontrollable bridge rectifier circuit 7 is connected between the single-phase bridge inverter 5 and the nonlinear load 8 . Main advantages: 1) Due to the special topological structure of the isolation transformer 6, the single-phase bridge inverter 5 does not need to withstand the power frequency voltage of the power system 1, so the structure of the device is simple, easy to implement, and low in cost; 2) It adopts active 3) Three-phase four-wire power system 1 does not add any new distortion components during the compensation process; it is suitable for low-voltage three-phase four-wire power system 1—mainly commercial, building, and civil power systems - Control the harmonic current on the neutral line.
Description
Technical field
The present invention relates to the electric power quality control technology, relate in particular to a kind of efficient, low withstand voltage neutral harmonic electric current controlling device and control method thereof.
Background technology
Mains by harmonics has caused electric network pollution and sinusoidal voltage wave distortion, makes the power supply equipment of electric power system many anomalies and fault occur, and situation is on the rise.In today increasingly mature, be an important topic of current power department for harmonic wave control to Harmonious Waves in Power Systems generation, detection and research on standard thereof.
With regard to the neutral line of distribution system, because the existence of fluorescent lamp, desk lamp with dimmer switch, computer even load, the harmonic wave in the electric power system makes the voltage of electrical network and current waveform distort, and can produce a large amount of odd harmonics, wherein the content of 3 subharmonic is bigger, can reach 40%.In the three-phase distribution circuit, the integer harmonics of 3 on the phase line can stack on the neutral line, makes the current value of the neutral line may surpass electric current on the phase line.
The neutral harmonic electric current that this is very big will produce adverse influence for load.Increasing single-phase load becomes very important to the humorous unbalanced influence that involves between the three-phase that electrical network produces.The accident that neutral line current causes also has report in China.
Therefore, at present just seem extremely important for the improvement of the electric power system neutral harmonic of skyscraper.Especially for as key sectors such as dispatching of power netwoks building, public security control buildings, the reliability of its power supply just requires very high.But these departments itself are again the units that nonlinear-load is concentrated, and therefore just are necessary to carry out the work that neutral harmonic is administered, to prevent the power failure accident.
Traditional neutral harmonic improvement method has passive filter and two kinds of methods of active filter.
1, passive filter method
As tortuous transformer filtering method, this method has following characteristics:
1) harmonic wave cancellation ability depends on the comparison of filter and system impedance size, and general harmonic filtration ability can only reach 50%.
2) owing to want cancellation zero sequence high order harmonic component, volume of transformer is bigger.
3) owing to require filter bigger to impedance of fundamental frequency, harmonic impedance is less, makes the transformer device structure complexity, the manufacturing process complexity; Therefore increased the capacity of system.
2, active filter method
By detecting the electric current on the actual neutral line, the Control current generating means produces an opposite electric current and offsets with it, thereby reaches the purpose of electric current on the compensation neutral line.Compare with passive filter, the active filter method has more advantage:
1) because active filter adopts the closed loop Detection ﹠ Controling, the filter compensation ability is improved greatly, can be up to 80 ~ 95%;
2) control is difficult for causing the filter overload flexibly;
3) power frequency presents high impedance, and harmonic wave presents Low ESR;
4) can not produce voltage disturbance;
5) because active filter adopts the electronic power switch device, consumption active power is very little during harmonic compensation, the efficient height.
Traditional active filter that is applicable to neutral harmonic improvement method is based on the bridge-type voltage source type inverter of three-phase and four-line, and two kinds of four phase current transformers and 3-phase power converters are arranged.Four phase current transformers are to add the 4th pair of brachium pontis on the basis of phase three-wire three bridge-type inverter, are specifically designed to the compensation of neutral current, and required like this power electronic device just increases; And 3-phase power converter with four mutually the difference of current transformer maximum be with three pairs of brachium pontis compensation three-phase currents, the neutral line links to each other with DC side bus mid point provides the neutral line current passage, the sort circuit structure needs 6 electronic power switch devices, and main circuit directly is connected with system, in order to reach compensation effect, dc voltage requires than higher.So just increased the switching loss of power electronic device, and too high du/dt and di/dt make that also the electromagnetic interference of device is more serious.Integrate, adopt the bridge-type voltage source type inverter of three-phase and four-line carry out neutral harmonic improvement have high input, control complexity, poor reliability.
Summary of the invention
The objective of the invention is to overcome the problem and shortage that prior art exists, a kind of neutral harmonic electric current controlling device and control method thereof are provided, thereby pollution is carried out dynamically administering in real time to neutral harmonic, and the neutral current of infield is met the requirements.
The object of the present invention is achieved like this:
1, device
As Fig. 1, this device is made up of three-phase and four-line electric power system 1, instruction current computing circuit 2, control circuit 3, drive circuit 4, single-phase bridge type inverter 5, isolating transformer 6, the uncontrollable bridge rectifier 7 of three-phase, nonlinear load 8;
Its annexation is: between three-phase and four-line electric power system 1 and nonlinear load 8, be in series with instruction current computing circuit 2, control circuit 3, drive circuit 4, single-phase bridge type inverter 5, isolating transformer 6 successively; Between single-phase bridge type inverter 5 and nonlinear load 8, be connected with the uncontrollable bridge rectifier 7 of three-phase.
Described instruction current computing circuit 2 is a kind of modules of gathering the voltage and current signal of three-phase and four-line electric power system 1 and separating harmonic signal, claims that the harmonic signal that separates is an instruction current.
Described control circuit 3 is a kind of drive controlling functional blocks, according to producing corresponding drive signal by instruction current computing circuit 2 gained instruction current control Driver Circuit 4.
Described drive circuit 4 is a kind of drive-pulse generators, and the control of controlled circuit 3 produces required switch drive drive waveform power cell switch closure.
Described single-phase bridge type inverter 5 is a kind of power unit modules, injects the harmonic current of required compensation to three-phase and four-line electric power system 1.
Described isolating transformer 6 is a kind of by three interconnected three-phase transformers of forming of single-phase transformer, plays buffer action.
The uncontrollable bridge rectifier 7 of described three-phase is a kind of rectification modules, provides single-phase bridge type inverter 5 dc voltages, plays through-put power.
The operation principle of this device is:
The electric current of three-phase and four-line electric power system 1 is passed through the command signal that instruction current computing circuit 2 calculates offset current, and this signal produces by control circuit 3 and answers pulse-width modulation (PWM) the signal V of compensation rate
i, obtain drive signal V through drive circuit 4
OutDirectly pass to the gate pole of single-phase bridge type inverter 5, single-phase bridge type inverter 5 produces offset current and returns bus by isolating transformer 6, thereby reaches the compensation of neutral current.Single-phase bridge type inverter 5 DC side provide power supply by the uncontrollable bridge rectifier 7 of three-phase, and this rectification circuit can not produce additional Zero-pharse harmonic electric current to system.
Single-phase bridge type inverter 5, its output links to each other with three-phase and four-line electric power system 1 by isolating transformer 6.The former limit of isolating transformer 6 is Y
0Connection, secondary are open-delta connection.Single-phase bridge type inverter 5, DC side provides power supply by the uncontrollable bridge rectifier 7 of three-phase, and this rectification circuit can not produce additional Zero-pharse harmonic electric current to three-phase and four-line electric power system 1, promptly can not produce additional harmonic current on the neutral line.Single-phase bridge type inverter 5 is zero with the instantaneous power of three-phase and four-line electric power system 1 exchange during compensation zero sequence harmonic current.The fluctuation of dc voltage is mainly by the switching loss of switching device, the asymmetric electric current of compensation be connected the inductive energy storage effect and produce, for dc voltage stability at certain level, can realize by selecting suitable electric capacity.
2, control method
As Fig. 1, Fig. 3,
Make i
* cBe the neutral line instruction current that should compensate, promptly instruction current computing circuit 2 isolated neutral harmonic electric current from three-phase and four-line electric power system 1 also is the harmonic current that single-phase bridge type inverter 5 must compensate;
i
cBe the single-phase bridge type inverter 5 actual offset currents that produce;
i
eBe error current;
Error current i
e=i
* c-i
c, the proportional integral in control circuit 3 (PI) control, the triangular carrier that its output and control circuit 3 produce relatively obtains a kind of igbt (IGBT) gate pole control signal V of single-phase bridge type inverter 5
iThrough the drive circuit 4 gate electrode drive signals V that gets back
Out, single-phase bridge type inverter 5 sends offset current i under this drive signal control
c, inject electric power system 1 by isolating transformer 6, reach the purpose of compensation neutral harmonic.
The present invention has the following advantages and good effect:
1),, be easy to realize, and cost is low so this apparatus structure is simple because the special topological structure of isolating transformer 6 makes single-phase bridge type inverter 5 need not to bear electric power system 1 power-frequency voltage;
2) adopt active device, compensation effect is good, economic and reliable;
3) do not increase any new allocation of distortion in electric power system 1 compensation process;
4) in time domain, calculate the current compensation component, clear physics conception, fast operation has been realized the compensation compatibility of goals;
5) the automaticity height is easy and simple to handle, is easy to safeguard.
The present invention is applicable to that to low pressure three-phase and four-line electric power system 1---being mainly commerce, building, civilian power system---carry out the improvement of harmonic current on the neutral line.
Description of drawings
Fig. 1 is this apparatus structure block diagram;
Fig. 2 is the control method block diagram;
Fig. 3 is single-phase bridge type inverter and electric power system connection diagram;
Fig. 4 drives the interface circuit of IGBT and control, drive pulse waveform figure for M57962L;
Wherein:
The electric power system of 1-three-phase and four-line; 2-instruction current computing circuit;
The 3-control circuit; The 4-drive circuit;
The 5-single-phase bridge type inverter; The 6-isolating transformer;
The uncontrollable bridge rectifier of 7-three-phase; The 8-nonlinear load.
V
i-IGBT gate pole control signal; V
Out-IGBT gate electrode drive signals
Embodiment
The present invention is further described below in conjunction with drawings and Examples.
1, device
1) drive circuit 4 employing mixing integrated drive electronics M57962L are core devices.
2) the controlled inverter of single-phase full bridge that single-phase bridge type inverter 5 is by 4 switching devices---igbt (IGBT)---forms injects the harmonic current of required compensation to electric power system 1.
3) single-phase bridge type inverter 5 and electric power system 1 connection diagram as shown in Figure 3, establish:
u
a, u
b, u
cBe the three-phase voltage of electric power system 1,
L
SBe the equivalent inductance of system 1,
u
dBe dc voltage,
i
c *Be instruction current, i.e. the harmonic current that electric power system 1 must compensate.
Isolating transformer 6 is that 1: 1 single-phase transformer constitutes by three no-load voltage ratios, and its secondary winding order end to end is connected between the bridge circuit of single-phase bridge type inverter 5, and its former limit winding is Y
0Connection links to each other with electric power system 1.
The fundamental voltage of symmetry is zero after the voltage stack of secondary winding induction, and zero sequence subharmonic voltage and unbalance voltage are non-vanishing in the voltage stack back of secondary winding induction.Like this, be dc voltage u at opening part voltage
dBe mainly zero sequence subharmonic voltage and unbalance voltage, so single-phase bridge type inverter 5 has avoided bearing fundamental voltage, dc voltage u
dCan be very low, thus the loss of switching device can be reduced, and can not increase the electric current that single-phase bridge type inverter 5 bears.
Suppose the three-phase voltage u of system 1
a, u
b, u
cSymmetry, and transformer is that no-load voltage ratio is 1: 1 a ideal transformer, both ignored the internal resistance and the leakage inductance of transformer, and excitation reactance is infinite, then has:
In fact, transformer can not be ideal, and (1) formula is false at this moment, also contains first-harmonic symmetry current component in every phase current, shown in (2) formula:
i
a＝i
* c+I
m?sin(ωt+α)
i
b＝i
* c+I
m?sin(ωt+α-2π/3) (2)
i
c＝i
* c+I
m?sin(ωt+α+2π/3)
This fundamental current is an excitation current component, and following formula is still set up after the three-phase current addition:
Under the ideal transformer situation, the instantaneous power of system and single-phase bridge type inverter 5 exchanges is:
When disregarding single-phase bridge type inverter 5 switching device losses, the power of this exchange is mainly cushioned by single-phase bridge type inverter 5 dc bus capacitors equally.By (1) Shi Kede, the three-phase addition result of following formula is 0, can obtain:
Can obtain by (4) formula:
Wherein, U
dBe dc voltage mean value.The permission voltage change ratio is ε, then can in the hope of the dc bus capacitor amount be:
Wherein, i
G maxFor compensating the peak value of current in middle wire.
2, method
Adopt the ring PWM control mode that stagnates to produce the IGBT gate pole control signal V of single-phase bridge type inverter 5
i
The ring PWM control that stagnates is meant adopts the chain rate that stagnates to produce gate pole control signal pwm pulse than mode.As Fig. 2, the comparator that the proportional integral in the control circuit 3 (PI) is controlled and is connected in thereafter constitutes the comparator with hysteresis characteristic jointly, error current i
eAs the input of comparator, export the break-make of the switching device IGBT that controls single-phase bridge type inverter 5 by it with hysteresis characteristic.By ring width is the gate pole control signal pwm pulse V of the hysteresis comparator generation of 2 Δ I
iGet driving pulse V through drive circuit 4
OutThe break-make of the power device IGBT of control single-phase bridge type inverter 5, the offset current i that single-phase bridge type inverter 5 produces
cJust at i
c *-Δ I and
Scope in, the trace command current i of indentation
c *2 Δ I are wide for ring width, and then switching frequency is low, but tracking error is big; 2 Δ I are narrow for ring width, and then tracking error is little, but the switching frequency height, even surpass the tolerance frequency scope of switching device IGBT, and switching loss also increases thereupon, may cause burning switching device IGBT, and final ring width 2 Δ I will be determined by the experiment situation.
The ring PWM control that stagnates has following advantage:
1) hardware circuit is simple;
2) belong to real-time control mode, current response is fast.
3, embodiment
380V, a capacity are the low withstand voltage neutral line active filter of 5KVA.
The phase voltage of system is 110V, and harmonic source is the three-phase imbalance load, adopts three single phase rectifier circuits, the big inductance of DC side band; Single-phase bridge type inverter 5 dc bus capacitors are 1000 μ F, and dc voltage is provided through the uncontrollable bridge rectifier 7 of three-phase by step-down transformer.Single-phase bridge type inverter 5 is the single-phase bridge reactive inverters that adopt power model to constitute.Since integrated driving, protection and absorption circuit in the power model, so the whole test device volume is little, simple in structure.Control circuit 3 is a kernel control chip with the digital signal processor DSP chip TMS320LF2407A of company of Texas Instruments (TI), include 16 road A/D and sampling holder and three-phase PWM signal generation circuit, therefore adding some simple ancillary equipment just can realize functional requirement.The outer program data memory RAM of man-machine interface, sheet that comprises the Industrial PC Computer communication.
M57962L drives interface circuit figure such as Fig. 4 of IGBT, the IGBT gate pole control signal V that control circuit 3 sends
iConnect 13 pin of M57962L, V through the Transistor-Transistor Logic level reverse buffer
iWaveform shown in top right plot.The gate pole G of IGBT is through small resistor R
WLink to each other with 5 pin of M57962L, collector electrode C is through fast recovery diode D
1Link to each other with 1 pin of M57962L, radiation utmost point E links to each other with 4,6 pin of M57962L through two electric capacity of voltage regulation.IGBT gate-drive waveform V
OutCorresponding V
iShown in bottom-right graph, the positive driving voltage of output is+15V about, negative driving voltage is-10V.T wherein
PLHBe service time, t
rBe the collector current rise time, t
PHLBe the turn-off time, t
fIt is collector current fall time.M57962L inside has the saturation detection of moving back and protection link, can respond fast when overcurrent takes place but turn-offs IGBT at a slow speed, and provide fault-signal by optocoupler to control circuit 3, and powerful, versatility is good.
Claims (7)
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| Application Number | Priority Date | Filing Date | Title |
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| CNA200610018628XA CN1832289A (en) | 2006-03-24 | 2006-03-24 | Neutral line harmonic current control device and its control method |
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|---|---|---|---|
| CNA200610018628XA CN1832289A (en) | 2006-03-24 | 2006-03-24 | Neutral line harmonic current control device and its control method |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101872977A (en) * | 2010-06-28 | 2010-10-27 | 长沙理工大学 | Interaction between multi-harmonic sources and optimal control method of power quality in smart grid |
| CN102185510A (en) * | 2011-05-09 | 2011-09-14 | 张承臣 | Safety protective power system |
| CN102255326A (en) * | 2011-07-04 | 2011-11-23 | 胡继炜 | Method and system for balancing active power loads |
| CN102299517A (en) * | 2011-09-13 | 2011-12-28 | 河海大学常州校区 | Industrial harmonic-eliminating filtering energy-saving device and method |
| CN105932697A (en) * | 2016-05-27 | 2016-09-07 | 陕西科技大学 | Three-phase balance control device used for long-distance low-voltage power transmission and three-phase balance control method thereof |
| CN106159923A (en) * | 2016-08-30 | 2016-11-23 | 王伟刚 | Low voltage three-phase four line power active unbalance administer N line overcurrent protector |
| CN116961004A (en) * | 2023-07-24 | 2023-10-27 | 湖南电桥科技有限责任公司 | Intelligent power distribution network voltage adjusting method, system and readable storage medium |
-
2006
- 2006-03-24 CN CNA200610018628XA patent/CN1832289A/en active Pending
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101872977A (en) * | 2010-06-28 | 2010-10-27 | 长沙理工大学 | Interaction between multi-harmonic sources and optimal control method of power quality in smart grid |
| CN101872977B (en) * | 2010-06-28 | 2013-07-10 | 长沙理工大学 | Method for optimally controlling influences among harmonic sources and power quality of smart grid |
| CN102185510A (en) * | 2011-05-09 | 2011-09-14 | 张承臣 | Safety protective power system |
| WO2012151935A1 (en) * | 2011-05-09 | 2012-11-15 | 沈阳隆基电磁科技股份有限公司 | Safety protection-type power supply system |
| CN102185510B (en) * | 2011-05-09 | 2013-07-31 | 沈阳隆基电磁科技股份有限公司 | Safety protective power system |
| CN102255326A (en) * | 2011-07-04 | 2011-11-23 | 胡继炜 | Method and system for balancing active power loads |
| CN102299517A (en) * | 2011-09-13 | 2011-12-28 | 河海大学常州校区 | Industrial harmonic-eliminating filtering energy-saving device and method |
| CN102299517B (en) * | 2011-09-13 | 2013-04-24 | 河海大学常州校区 | Industrial harmonic-eliminating filtering energy-saving device and method |
| CN105932697A (en) * | 2016-05-27 | 2016-09-07 | 陕西科技大学 | Three-phase balance control device used for long-distance low-voltage power transmission and three-phase balance control method thereof |
| CN106159923A (en) * | 2016-08-30 | 2016-11-23 | 王伟刚 | Low voltage three-phase four line power active unbalance administer N line overcurrent protector |
| CN116961004A (en) * | 2023-07-24 | 2023-10-27 | 湖南电桥科技有限责任公司 | Intelligent power distribution network voltage adjusting method, system and readable storage medium |
| CN116961004B (en) * | 2023-07-24 | 2024-01-26 | 湖南电桥科技有限责任公司 | Intelligent power distribution network voltage adjusting method, system and readable storage medium |
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