CN105680710B - A kind of bridge arm current threshold value frequency reducing method applied to modularization multi-level converter - Google Patents
A kind of bridge arm current threshold value frequency reducing method applied to modularization multi-level converter Download PDFInfo
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- CN105680710B CN105680710B CN201510469831.8A CN201510469831A CN105680710B CN 105680710 B CN105680710 B CN 105680710B CN 201510469831 A CN201510469831 A CN 201510469831A CN 105680710 B CN105680710 B CN 105680710B
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Abstract
The invention discloses a kind of bridge arm current threshold value frequency reducing method applied to modularization multi-level converter, by detecting the size of bridge arm current value, judge the magnitude relationship of bridge arm current value and given threshold, select suitable submodule switching mode.When electric current is less than given threshold, the switching mode of low frequency is selected；When electric current is more than the switching mode of setting value selection high frequency.Reach the purpose of frequency reducing by such a method.In this way, effectively IGBT switching frequency can be controlled by the setting of threshold value within 50~150Hz, greatly reduces the loss of switching tube.Bridge arm current threshold value frequency reducing method is as shown in Figure of description 3.
Description
Technical field
The present invention relates to power electronics and custom power field, and in particular to one kind is applied to modularization multi-level converter
Bridge arm current threshold value frequency reducing method.
Background technology
（1）Relative to traditional flexible direct current power transmission system（Based on IGBT serial connection technologies）, changed based on modular multilevel
The flexible direct current power transmission system of device (modular multilevel converter, MMC) is flowed because its is simple in construction, is easy to
The features such as engineering construction, causes the extensive concern of domestic and international experts and scholars in recent years.
（2）At present, it is that the transverter damages compared to Traditional DC converter valve to restrict one of wide variety of principal elements of MMC
Consume larger, it is lost the main reason for big and is that MMC IGBT switching frequencies are higher, and with the raising of voltage class, son
Number of modules is significantly increased, and power consumption also can be bigger, influences the efficiency of current conversion station, it is therefore necessary to which research reduces the side of switching frequency
Method, to reduce the power consumption of current conversion station.
（3）In the research process for the frequency reducing technology that sharp weapon are changed for modular multilevel, many researchers indicate
The method for reducing switching frequency, Guan Minyuan, Xu Zheng et al. have set one group of bound near submodule rated capacity voltage, will be equal
Pressure algorithm emphasis be put on the submodule for surmounting bound, by it is out-of-limit to those and last moment put into or cut off
The capacitance voltage of submodule, a holding factor is multiplied by, keeps the size of the factor can effective control submodule by adjusting
The switching time, so as to reduce switching frequency.Sun Shixian, Tian Jie et al. are changed to NLM modulation algorithms, its general principle
It is to subtract each other modulating wave and the number of modules that last moment is put into, when the absolute value of difference is more than setting value A（0≤A≤0.5）
When, the number of modules currently put into will change accordingly：Or be the integer higher than modulating wave, or be the integer less than modulating wave.
The good controlling switch frequency of rational control and regulation value A cans.The holding factor of first method is needed according to different works
Condition is done many experiments and just can determine that, and bad regulation, and second method is similar to SPWM, is typically all very high voltage in engineering
Grade, so NLM algorithms are enough.
（4）The present invention devises a kind of effective IGBT frequency reducing sides according to capacitance voltage and the relation of bridge arm current
Method --- bridge arm current threshold value frequency reducing method, this method can be by setting bridge arm current threshold value to effectively reduce switching frequency, will
Switching frequency is controlled between 50-150Hz, greatly reduces the switching loss of submodule.
The content of the invention
（1）The invention provides a kind of bridge arm current threshold value frequency reducing method applied to modularization multi-level converter, the drop
Frequency method uses low frequency switching strategy by judging the size of bridge arm current, when within bridge arm current threshold range, in bridge arm
High frequency switching strategy is used when outside current threshold scope, so can effectively reduce IGBT switching frequency, reaches reduction damage
The purpose of consumption.
（2）A kind of bridge arm current threshold value frequency reducing method applied to modularization multi-level converter, the modular multilevel change
Stream device is made up of six bridge arms of three-phase, and each bridge arm is by coupling or non-coupled inductance and several identical submodules
Cascade is formed.Each submodule includes two IGBT, two backward diodeds and a DC capacitor composition, it is characterised in that
Described bridge arm current threshold value frequency reducing method comprises the following steps：
1) bound of bridge arm current, upper limit Iup, lower limit Ilow are set；Modulator approach is approached using nearest level
Modulation algorithm；
2) electric current of each bridge arm is gathered compared with the bridge arm current bound set, judges bridge arm current whether in threshold value
Within the scope of；
3) when bridge arm current is more than Ilow and when being less than Iup, the switching mode of submodule using part switching method,
The basic thought of the operation/cutting method is：Current switching module number and the last moment that modulation algorithm obtains are approached according to nearest level
Obtained switching module number does subtraction, then puts into or cut off two moment phases according to the size of the sense of current and capacitance voltage
The submodule number of difference；
4) when bridge arm current is less than Ilow or more than Iup, the switching mode of submodule uses amended part switching
Method, the basic thought of the operation/cutting method is：According to nearest level approach current switching module number that modulation algorithm obtains with
The switching module number that last moment obtains does subtraction, then puts into or cut off two according to the size of the sense of current and capacitance voltage
The submodule number of individual moment difference, meanwhile, then Nx submodule of more inputs, Nx submodule is cut off, 0 ＜ Nx ＜ N, N is bridge arm
Total number of modules, take Nx=l；
5) input that will be finally given and the instruction of the submodule of excision, translate into submodule up and down that two IGBT are most
Whole control signal.
Brief description of the drawings
The flexible DC power transmission basic structure of figure one
The bridge arm current threshold value of figure two is set
The bridge arm current threshold value frequency reducing method flow chart of figure three
After frequency reducing method of the figure four using the present invention, the voltage fluctuation of capacitor and IGBT switching frequencies of different threshold values
After frequency reducing method of the figure five using the present invention, the relativity of IGBT switching frequencies and voltage fluctuation of capacitor
Embodiment
（1）Below in conjunction with accompanying drawing and the embodiment of the example in detail present invention, but the present invention is not by the tool
Body example is limited.
（2）A kind of bridge arm current threshold value frequency reducing method applied to modularization multi-level converter, the modular multilevel change
Stream device is made up of six bridge arms of three-phase, and each bridge arm is by coupling or non-coupled inductance and several identical submodules
Cascade is formed.Each submodule includes two IGBT, two backward diodeds and a DC capacitor composition, the structure such as institute of figure one
Show, DC current and upper and lower bridge arm current direction are as shown in the figure.
（3）The bound of setting bridge arm current, upper limit Iup, lower limit Ilow, as shown in Figure 2.Modulator approach uses
Nearest level approaches modulation algorithm（NLM）.The electric current of each bridge arm is gathered compared with the bridge arm current bound set, judges bridge arm
Whether electric current is within threshold range.
（4）When bridge arm current is more than Ilow, less than Iup when, method that the switching mode of submodule uses part switching should
The basic thought of operation/cutting method is：The switching that the current switching module number obtained according to NLM modulator approaches obtains with last moment
Number of modules does subtraction, then puts into or cut off the submodule of two moment differences according to the size of the sense of current and capacitance voltage
Number.When bridge arm current is less than Ilow, more than Iup when, method that the switching mode of submodule uses amended part switching should
The basic thought of operation/cutting method is：The switching that the current switching module number obtained according to NLM modulator approaches obtains with last moment
Number of modules does subtraction, then puts into or cut off the submodule of two moment differences according to the size of the sense of current and capacitance voltage
Number, meanwhile, then Nx submodule of more inputs, Nx submodule is cut off, 0 ＜ Nx ＜ N, N is bridge arm submodule sum, takes Nx=l.Tool
Body flow chart is as shown in Figure 3.
（5）It was found from figure four, bridge arm current threshold value frequency reducing method is controlled by increasing bridge arm current threshold value, successfully will be average
Switching frequency is controlled in below 150Hz, if current threshold x settings are sufficiently large, switching frequency is minimum to can reach 50Hz.
（6）Figure four is simplified to the graph of a relation of voltage fluctuation of capacitor value and switching frequency by figure five, it can be seen that with
Bridge arm current threshold value x increase, switching frequency is in reduction trend, and switching loss can also reduce accordingly, but submodule is electric
Holding the fluctuation of magnitude of voltage can become big accordingly.This can cause the change of circulation waveform, change of converter valve output current wave etc.
Problem, therefore bridge arm current threshold value x size is reasonably selected according to requirement of engineering.Comparing rational system of selection is：Adjust
Save bridge arm current threshold value x, while the fluctuation range of detection sub-module capacitance voltage value, when fluctuation range is close to engineering allowed band
Maximum when, bridge arm current threshold value x now is most suitable value.
Claims (1)
1. a kind of bridge arm current threshold value frequency reducing method applied to modularization multi-level converter, the modularization multi-level converter by
Six bridge arms of three-phase are formed, and each bridge arm is by coupling or non-coupled inductance and several identical sub-module cascade structures
Into each submodule includes two IGBT, two backward diodeds and a DC capacitor composition, it is characterised in that described
Bridge arm current threshold value frequency reducing method comprises the following steps：
(1) bound of bridge arm current, upper limit Iup, lower limit Ilow are set；Modulator approach approaches tune using nearest level
Algorithm processed；
(2) electric current of each bridge arm is gathered compared with the bridge arm current bound set, judges bridge arm current whether in threshold range
Within；
(3) when bridge arm current is more than Ilow and is less than Iup, the switching mode of submodule is using the method for part switching, the throwing
The basic thought of blanking method is：The current switching module number that modulation algorithm obtains is approached according to nearest level to obtain with last moment
Switching module number do subtraction, then put into or cut off what two moment differed according to the size of the sense of current and capacitance voltage
Submodule number；
(4) when bridge arm current is less than Ilow or more than Iup, the switching mode of submodule is using amended part switching
Method, the basic thought of the operation/cutting method are：According to nearest level approach current switching module number that modulation algorithm obtains with it is upper
The switching module number that one moment obtained does subtraction, then puts into or cut off two according to the size of the sense of current and capacitance voltage
The submodule number of moment difference, meanwhile, then Nx submodule of more inputs, Nx submodule is cut off, 0 ＜ Nx ＜ N, N is bridge arm submodule
Block sum, takes Nx=l；
(5) input that will be finally given and the instruction of the submodule of excision, it is final that two IGBT up and down are translated into submodule
Control signal.
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| CN110365234B (en) * | 2019-06-20 | 2024-05-07 | 中电普瑞电力工程有限公司 | Modular multi-level converter valve submodule switching method and device |
| CN112134477B (en) * | 2020-09-14 | 2021-07-27 | 湖南大学 | Frequency reduction control method of modular multilevel converter with auxiliary sub-modules |
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| CN102594192A (en) * | 2010-11-30 | 2012-07-18 | 中国南方电网有限责任公司电网技术研究中心 | Step wave pulse width modulation method based on nonlinear programming |
| CN103427692A (en) * | 2013-07-30 | 2013-12-04 | 浙江大学 | Modular multilevel converter modulation method based on double queues |
| CN103683995A (en) * | 2013-09-25 | 2014-03-26 | 浙江大学 | A balanced control method for full bridge MMC capacitor voltages |
| CN103888003A (en) * | 2014-03-24 | 2014-06-25 | 浙江大学 | Sub-module layering voltage-sharing method of modularized multi-level current converter |
| CN104798296A (en) * | 2012-11-27 | 2015-07-22 | Abb技术有限公司 | A multilevel converter with cells being selected based on phase arm current |
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2015
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| CN102594192A (en) * | 2010-11-30 | 2012-07-18 | 中国南方电网有限责任公司电网技术研究中心 | Step wave pulse width modulation method based on nonlinear programming |
| CN104798296A (en) * | 2012-11-27 | 2015-07-22 | Abb技术有限公司 | A multilevel converter with cells being selected based on phase arm current |
| CN103427692A (en) * | 2013-07-30 | 2013-12-04 | 浙江大学 | Modular multilevel converter modulation method based on double queues |
| CN103683995A (en) * | 2013-09-25 | 2014-03-26 | 浙江大学 | A balanced control method for full bridge MMC capacitor voltages |
| CN103888003A (en) * | 2014-03-24 | 2014-06-25 | 浙江大学 | Sub-module layering voltage-sharing method of modularized multi-level current converter |
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| Modulation and Closed-Loop-Based DC Capacitor Voltage Control for MMC With Fundamental Switching Frequency;Sixing Du et al.;《IEEE TRANSACTIONS ON POWER ELECTRONICS》;20150131;第30卷(第1期);第327-338页 * |
| 一种优化的模块化多电平换流器电压均衡控制方法;屠卿瑞等;《电工技术学报》;20110531;第26卷(第5期);第15-20页 * |
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