CN111224589B - Common-mode voltage control method for double-fed motor converter system - Google Patents
Common-mode voltage control method for double-fed motor converter system Download PDFInfo
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- CN111224589B CN111224589B CN202010100851.9A CN202010100851A CN111224589B CN 111224589 B CN111224589 B CN 111224589B CN 202010100851 A CN202010100851 A CN 202010100851A CN 111224589 B CN111224589 B CN 111224589B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
- H02P9/007—Control circuits for doubly fed generators
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
- H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
- H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
- H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M5/4585—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
- H02P9/006—Means for protecting the generator by using control
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
- H02M1/123—Suppression of common mode voltage or current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P2101/00—Special adaptation of control arrangements for generators
- H02P2101/15—Special adaptation of control arrangements for generators for wind-driven turbines
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/70—Wind energy
- Y02E10/76—Power conversion electric or electronic aspects
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
The invention belongs to the field of electric appliance circuits, and particularly relates to a common-mode voltage control method for a converter of a double-fed motor.A generating circuit of common-mode voltage is added on a circuit of a double-fed generator and the converter, and the generating circuit adopts a bridge arm and is connected on a direct-current bus; the control signal of the common-mode voltage injection bridge arm is that the sum of SPWM signals at the power grid side is divided by 3, and the sum of SVPWM signals at the motor side is divided by 3:
that is: v. of com_zero2 (t)＝‑v zero1 (t)‑v zero2 (t), ideally: v. of zero1 (t)+v com_zero2 (t)+v zero2 (t) =0. Compared with the traditional common-mode voltage generating circuit, the invention has the advantages of small power and low cost, and can inhibit low-frequency common-mode signals vzero1 and vzero2, thereby being beneficial to the insulation of a motor winding and preventing the leakage of a rotor bearing and a slip ring.
Description
Technical Field
The invention belongs to the field of electric appliance circuits, and particularly relates to a common-mode voltage control method of a double-fed motor converter system.
Background
A double-fed generator and a converter system are the most widely applied solution of a wind generating set. Because the converter of the double-fed system is connected to the rotor side, the power of the converter is only 1/3 to 1/4 of the power of the motor, and the converter is low in cost, low in loss and high in efficiency. However, the generator rotor windings are connected to the converter via slip rings, and the rotor slip rings and the rotor bearings often fail. The main cause of insulation damage is sudden rotor voltage dv/dt, which includes differential and common mode voltages. The differential mode voltage is usually adjusted by means of filters and IGBT switching speeds.
In the common mode voltage solution, some direct current side bus line is adopted to add capacitance to the ground to suppress the peak, and the method adopts a bypass common mode current; some methods increase the impedance of the transmission path of the common-mode signal by increasing the common-mode reactance. The doubly-fed motor generally uses a motor rotor to increase a grounding slip ring, so that a rotor bearing is protected. The invention cancels the low-frequency common-mode voltage between the rotor and the ground by adding the common-mode voltage generating circuit, thereby greatly reducing and reducing the amplitude of the common-mode voltage source.
And common mode voltage is reduced, and damage such as electric corrosion and the like caused by common mode leakage current can be greatly reduced. And the faults of a slip ring and a bearing connected with the rotor of the doubly-fed motor are reduced.
The similar circuit is on UPS (uninterrupted power supply), but different from the software control algorithm of the scheme, the parameter characteristics of the hardware circuit are different, and the application load is different. The added bridge arm of the UPS is used for providing a common neutral line for a load and a power supply and simultaneously improving the utilization rate of the voltage at the direct current side, the UPS is a constant-frequency and constant-voltage power supply in an application occasion, and the input frequency and the output frequency are the same. The bridge arm circuit added in the scheme is applied to a variable-frequency and variable-voltage power supply, and has different input and output frequencies and different voltages. The scheme provides the common-mode voltage for offsetting the common-mode voltage applied to the motor, and the circuit current value is small.
The IGBT driving signal is generally a pulse signal modulated by a sine wave and a triangular carrier, and the three-phase SPWM modulated signal (with a frequency w 1) is as follows:
v a ＝V m cosω 1 t
v b ＝V m cos(ωt 1 -120)
v c ＝V m cos(ωt 1 +120)
in order to increase the utilization of the dc-side bus voltage, a common-mode voltage component V is often added zero1 V is commonly used zero1 The generation method is as the formula:
thereby generating an SVPWM modulated signal.
v az ＝V m cosω 1 t+V zero1
v bz ＝V m cos(ω 1 t-120)+V zero1
v cz ＝V m cos(ω 1 t+120)+V zero1
And comparing the SVPWM modulation signal with a triangular carrier to generate a driving pulse signal.
The frequency and the voltage of the motor side are different from those of the power grid side, the three phases R, S and T of the motor side correspond to IGBT bridge arm driving signals which are pulse signals modulated by sinusoidal signals, namely SPWM modulation signals, the frequency is w2, and the following steps are performed:
v R (t)＝V n cosω 2 t
v S (t)＝V n cos(ω 2 t-120)
v T (t)＝V n cos(ω 2 t+120)
to improve the output maximum voltage capability, a common-mode harmonic voltage component V is often added zero2 V is commonly used zero2 The generation method is as the formula:
thereby generating an SVPWM modulated signal.
v Rz (t)＝V n cosω 2 t+v zero2 (t)
v Sz (t)＝V n cos(ω 2 t-120)+v zero2 (t)
v Tz (t)＝V n cos(ω 2 t+120)+v zero2 (t)
And comparing the SVPWM modulation signal with the triangular carrier to generate a driving pulse signal.
Because of V zero1 And V zero2 The presence of these two common mode voltage signals causes the motor winding rotor to present this common mode voltage to ground, resulting in a rotor bearing voltage and a ground current to the slip ring.
Disclosure of Invention
In order to solve the defects and shortcomings in the prior art, the invention provides a generating circuit for increasing a common-mode voltage, which adopts a bridge arm to be connected on a direct-current bus, wherein the bridge arm is only used for generatingCommon mode voltage, no load current, low power, and low frequency common mode signal suppression zero1 And V zero2 Therefore, the insulation of the motor winding is facilitated, the voltage of a rotor bearing of the double-fed motor is reduced, and the grounding current of the slip ring is reduced.
The technical scheme of the invention is as follows: a common-mode voltage control method of a doubly-fed motor converter system is characterized in that a generating circuit of common-mode voltage is added on a doubly-fed generator and a converter circuit, and the generating circuit adopts a bridge arm and is connected to a direct-current bus; the control signal of the common-mode voltage injection bridge arm is that the sum of SPWM signals at the power grid side is divided by 3, and the sum of SPWM signals at the motor side is divided by 3:
that is: v. of com_zero (t)＝v zero1 (t)+v zero2 (t)，
Ideally: v. of com_zero1 (t)-v zero1 (t)-v zero2 (t)＝0；
The SVPWM signals of the power grid side are as follows:
the motor side SVPWM signals are as follows:
preferably, the common-mode voltage injection bridge arm is a bridge arm with a structure similar to a 7-bridge arm, and the bridge arm is only used for generating the common-mode voltage and has no load current.
Preferably, the common mode voltage generating circuit adopts an IGBT device with rated current far smaller than that of a main loop, and the cost is low.
Preferably, the common mode voltage generating circuit adopts IGBT devices with higher frequency.
Preferably, in order to eliminate the PWM higher harmonics of the IGBT device, a filter capacitor and an attenuation resistor may also be added to the rotor side.
Preferably, the method for controlling the common-mode voltage of the converter of the doubly-fed motor comprises the following specific steps:
(1) Calculating an SVPWM common-mode voltage signal at the side of a power grid;
(2) Calculating an SVPWM common-mode voltage signal at the motor side;
(3) Adding the two to obtain the required common mode injection voltage signal
(4) The obtained signal is used as a modulation wave and a triangular carrier to generate a driving signal for the common-mode voltage injection circuit.
The invention adds a common mode voltage generating circuit on the double-fed generator and converter circuit, the generating circuit adopts a bridge arm and is connected on a direct current bus; the bridge arm is only used for generating common-mode voltage, has no load current, has small power and can inhibit low-frequency common-mode signals V zero1 And V zero2 Thereby being beneficial to the insulation of the motor winding and reducing the voltage of the rotor bearing and the slip ring grounding current.
Drawings
FIG. 1 is an electrical schematic diagram of a circuit for generating a common mode voltage added to a doubly-fed generator and converter circuit according to the present invention;
FIG. 2 is an electrical schematic diagram of a common mode voltage generating circuit and a rotor filter circuit added to a doubly-fed generator and converter circuit according to the present invention;
FIG. 3 is a diagram of the common mode voltage conduction path of the present invention;
FIG. 4 is a schematic flow chart of the present invention;
FIG. 5 is an electrical schematic diagram of a prior art doubly-fed generator and converter;
fig. 6 is a diagram of common mode voltage conduction paths in the related art.
Detailed Description
The present invention will be described in further detail with reference to the attached drawings, but the present invention is not limited thereto.
As shown in fig. 1-4, 1. A method for controlling a common-mode voltage of a converter of a doubly-fed motor, which adds a generating circuit of the common-mode voltage to a circuit of a doubly-fed generator and the converter, wherein the generating circuit adopts a bridge arm and is connected to a direct current bus; the control signal of the common-mode voltage injection bridge arm is the power grid sideThe sum of the motor side SPWM signals is divided by 3, the sum of the motor side SPWM signals is divided by 3:
that is: v. of com_zero2 (t)＝v zero1 (t)+v zero2 (t)，
Ideally: v. of zero1 (t)+v com_zero2 (t)+v zero2 (t)＝0；
The SPWM signals of the power grid side are as follows:
the motor side SPWM signal is as follows: />
The common-mode voltage injection bridge arm is a bridge arm with a structure similar to a 7-bridge arm, and the bridge arm is only used for generating common-mode voltage and has no load current.
The common mode voltage generating circuit adopts an IGBT device with rated current far smaller than that of the main loop, and the cost is lower.
The common mode voltage generating circuit adopts IGBT devices with higher frequency.
In order to eliminate PWM higher harmonic waves of the IGBT device, a filter capacitor and an attenuation resistor can be added on the rotor side.
A method for controlling the common-mode voltage of a doubly-fed motor converter comprises the following specific steps:
(1) Calculating an SVPWM common-mode voltage signal at the side of a power grid;
(2) Calculating an SVPWM common-mode voltage signal at the motor side;
(3) After addition, the required common mode injection voltage signal is obtained
(4) The modulation wave and the triangular carrier wave generate a driving signal for the common mode voltage injection circuit.
The invention adds a common mode voltage generating circuit on the double-fed generator and converter circuit, the generating circuit adopts a bridge arm and is connected on a direct current bus; the bridge arm is only used for generating common-mode voltage, has no load current and small power, and can inhibit low-frequency common-mode signals vzero1 and vzero2, so that the insulation of a motor winding is facilitated, the electric leakage of a rotor bearing and a slip ring is prevented, and compared with a traditional common-mode voltage generating circuit, the low-frequency common-mode voltage generating circuit has the advantages of lower power consumption and lower cost.
Claims (6)
1. A common-mode voltage control method of a doubly-fed motor converter system is characterized by comprising the following steps: a generating circuit of common mode voltage is added on a circuit of the double-fed generator and the converter, the generating circuit adopts a bridge arm, is connected on a direct current bus, and outputs and is connected with a system ground wire; the control signal of the common-mode voltage injection bridge arm is obtained by dividing the sum of SVPWM signals at the power grid side by 3, adding the sum of the SVPWM signals at the motor side by 3:
namely: v. of com_zero (t)＝v zero1 (t)+v zero2 (t)，
Ideally: v. of com_zero (t)-v zero1 (t)-v zero2 (t)＝0；
The SVPWM signals of the power grid side are as follows:
the motor side SVPWM signals are as follows:
2. the common-mode voltage control method of the doubly-fed machine converter system according to claim 1, wherein: the common-mode voltage injection bridge arm is a bridge arm with a structure similar to a 7-bridge arm, the bridge arm is only used to generate common mode voltage and no load current.
3. The common-mode voltage control method of the doubly-fed machine converter system according to claim 1, wherein: the common mode voltage generating circuit adopts an IGBT device with rated current far smaller than that of the main loop, and the cost is low.
4. The common-mode voltage control method of the doubly-fed machine converter system according to claim 1, wherein: the common mode voltage generating circuit adopts a power electronic switching device IGBT or MOSFET with higher frequency.
5. The common-mode voltage control method of the doubly-fed machine converter system according to claim 3 or 4, wherein: in order to eliminate the PWM higher harmonic wave of the IGBT device, a filter capacitor and an attenuation resistor can be added.
6. The common-mode voltage control method of the doubly-fed machine converter system according to claim 1, wherein: the method comprises the following specific steps:
(1) Calculating an SVPWM common-mode voltage signal at the side of a power grid;
(2) Calculating an SVPWM common-mode voltage signal at the motor side;
(3) After addition, the required common mode injection voltage signal is obtained
(4) The obtained signal is used as a modulation wave and a triangular carrier to generate a driving signal for the common-mode voltage injection circuit.
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| CN107968435A (en) * | 2017-12-15 | 2018-04-27 | 远景能源（江苏）有限公司 | Wind-power electricity generation double-wind-ing gene rator system common-mode voltage suppressing method |
| CN108092303A (en) * | 2017-12-05 | 2018-05-29 | 东南大学 | A kind of fault tolerant control method and system of wind generator system back-to-back converter |
| CN110112946A (en) * | 2018-01-31 | 2019-08-09 | 北京金风科创风电设备有限公司 | Method and device for controlling voltage at AC output end of machine side inverter of converter |
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2020
- 2020-02-19 CN CN202010100851.9A patent/CN111224589B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106537748A (en) * | 2014-06-04 | 2017-03-22 | Abb瑞士股份有限公司 | Electrical converter with high machine side common mode voltage |
| CN104917406A (en) * | 2015-05-27 | 2015-09-16 | 浙江大学 | Common-mode-injection-based nearest level modulation method for MMC |
| CN107039991A (en) * | 2017-04-24 | 2017-08-11 | 北京交通大学 | A kind of light storage off-network independent power supply device and method based on MMC topologys |
| CN107579653A (en) * | 2017-09-28 | 2018-01-12 | 上海交通大学 | A kind of wind electric converter bridge arm is multiplexed reconfigurable control method and system |
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