CN108667038B - Starting method of high-voltage SVG (static var generator) and ice melting device with low impact current - Google Patents
Starting method of high-voltage SVG (static var generator) and ice melting device with low impact current Download PDFInfo
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- CN108667038B CN108667038B CN201810389380.0A CN201810389380A CN108667038B CN 108667038 B CN108667038 B CN 108667038B CN 201810389380 A CN201810389380 A CN 201810389380A CN 108667038 B CN108667038 B CN 108667038B
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- 238000002844 melting Methods 0.000 title claims abstract description 34
- 230000008018 melting Effects 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims abstract description 32
- 230000003068 static effect Effects 0.000 title description 2
- 239000003990 capacitor Substances 0.000 claims description 20
- 238000005070 sampling Methods 0.000 claims description 4
- 230000005540 biological transmission Effects 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
- H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G7/00—Overhead installations of electric lines or cables
- H02G7/16—Devices for removing snow or ice from lines or cables
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/20—Arrangements for adjusting, eliminating or compensating reactive power in networks in long overhead lines
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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- 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
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/10—Flexible AC transmission systems [FACTS]
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- Engineering & Computer Science (AREA)
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Abstract
The invention relates to a starting method of a high-voltage SVG and ice melting device with low impact current. It is characterized by comprising three stages: 1) an uncontrolled rectification charging stage, 2) an active constant power charging stage with a starting resistor, and 3) a bypass soft starting resistor and then an active charging stage. The invention fully utilizes the starting resistance current-limiting function of the soft-start switch cabinet without changing the original hardware equipment, reduces the starting current impact of the high-voltage SVG and ice melting device, reduces the starting time and improves the stability of the power grid.
Description
Technical Field
The invention relates to the field of circuit devices of alternating current transmission and distribution networks, in particular to a starting method of a low-impact current high-voltage SVG (scalable vector graphics) and ice melting device.
Background
The SVG and ice melting device can compensate the reactive loss of the line under the normal operation state, and can perform timely reactive regulation under the condition of system fault while improving the line voltage, thereby improving the stability of a power transmission system. And the voltage of the user terminal is maintained, and the voltage stability of the equipment is enhanced. The reactive power of the dynamic compensation system improves the power factor, reduces the line loss, saves energy and reduces consumption. Suppressing voltage fluctuations and flicker.
The SVG and ice melting device can be directly connected with a power grid on an 6/10/35kV bus at present, and can be widely applied to various application places such as transformer substations, wind power plants, solar power plants and mines.
The conventional universal starting method for high-voltage SVG and ice melting comprises two stages: 1) and 2) entering an active charging stage after bypassing the soft start resistor.
1. An uncontrolled rectification charging stage: closing an incoming line breaker switch, charging direct current capacitors of all power module units of the high-voltage SVG and ice melting device after current is limited by a starting resistor of a starting cabinet, locking driving signals of all IGBTs in the process, enabling all full-bridge power modules to be diode full-bridge rectifying circuits, enabling direct current loads of the circuits to be direct current capacitors, and enabling each phase to be formed by cascading N full-bridge rectifying circuits; because the capacitance values of the direct current side capacitors of each full-bridge rectification circuit are equal, the direct current voltage of each full-bridge rectification circuit is also basically equal, and the theoretical upper limit value is as follows:
the peak value of line voltage/(2N), N is the number of cascaded power modules of each phase, and the uncontrolled rectifying process is finished when the voltage reaches or approaches the value (or the process time exceeds 10-20 seconds).
2. And (3) entering an active charging stage after bypassing the soft start resistor:
and switching on the soft start switch, bypassing the starting resistor, modulating, triggering and starting all the IGBTs, and charging the direct current capacitors of all the power module units until the voltage of the direct current capacitors of the power units reaches a set value.
The above method mainly has the following defects: in the starting process, the maximum voltage value (1.414 multiplied by the power grid line voltage/(2N)) which can be charged by each module in the uncontrolled rectification charging stage is reached, at this time, the maximum voltage which can be output by the power module unit group is 0.866 times of the power grid voltage, and the power grid voltage has a difference of { (1-0.866) multiplied by the power grid voltage }, which cannot be avoided, and a larger impact current is generated on a power grid system at the moment of pulse starting, so that adverse effects are caused on the power grid and equipment on the power grid. For example, in a 10kV system, the resistance value of the reactor is 4mH, and at the moment when the soft-start switch is turned on, due to the existence of the voltage difference, the instantaneous impact current can reach 1000A, which may cause the switch protection action.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a technical scheme of a starting method of a low-impact-current high-voltage SVG and ice melting device.
The starting method of the high-voltage SVG and ice melting device with low impact current is characterized by comprising three stages: 1) an uncontrolled rectification charging stage, 2) an active constant power charging stage with a starting resistor, and 3) a bypass soft starting resistor and then an active charging stage.
The starting method of the high-voltage SVG and ice melting device with low impact current is characterized in that: after the high-voltage SVG and ice melting device is electrified and passes through an uncontrolled rectification charging stage, the output of a modulation power module unit group is in the same phase with the power grid voltage and the amplitude is lower than the reference voltage of the power grid voltage, active constant power charging is carried out on the direct current capacitor of the power module unit of the high-voltage SVG and ice melting device, when the voltage value of the direct current capacitor of the power module unit is increased to be more than [1.414 multiplied by the power grid line voltage/1.732 ]/the number of power unit modules connected in series, the output of the modulation power module unit group and the reference voltage of the power grid voltage in the same phase and the amplitude are adjusted to enable the differential pressure to be 0, at the moment, a soft start switch is switched on, a bypass start resistor is switched on, the voltage of the power module unit is gradually.
The starting method of the low-impact-current high-voltage SVG and ice melting device is characterized in that the charging time of the uncontrolled rectification charging stage is 40-60S, and the voltage of the direct current capacitor of the power module unit group is charged to be more than 380V.
The starting method of the high-voltage SVG and ice melting device with low impact current is characterized in that: after charging in the uncontrolled rectification charging stage, under the condition that the starting resistor is not bypassed, modulating output reference voltage, wherein the modulated output reference voltage is set as: and the voltage phase of the power grid voltage sampling PLL is the same as the voltage of the power grid voltage sampling PLL, the amplitude is 4-6kV lower than the output voltage value of the power grid voltage, the voltage value is kept constant, pulses are sent to all IGBTs, the voltage difference between the output of the power module unit group and the power grid voltage is kept constant, and active constant-power charging is carried out.
The starting method of the low-impact-current high-voltage SVG and ice melting device is characterized in that the charging time of the active constant-power charging stage with the starting resistor is 60-90S, and the resistance value of the starting resistor is 500k omega.
The starting method of the high-voltage SVG and ice melting device with low impact current is characterized in that: and (4) switching on the soft start switch, and switching from the start parameter to the normal operation control parameter within 1 ms.
The starting method of the high-voltage SVG and ice melting device with low impact current is characterized in that the rated working voltage of the power module unit is 700-900V.
Under the condition of not changing original hardware equipment, the current limiting function of the starting resistor of the soft starting switch cabinet is fully utilized, the starting current impact of the high-voltage SVG and ice melting device is reduced, the starting time is shortened, and the overcurrent protection action of the device caused by the large current impact at the starting moment is avoided; meanwhile, the impact on a power grid system is avoided, and the voltage fluctuation at the moment of starting is reduced, so that the work abnormity such as protection tripping of other online equipment of the power grid caused by the starting of the high-voltage SVG and ice melting device is effectively reduced, and the stability of the system is improved. For example, in a 10kV system, the resistance value of the reactor is 4mH, and at the moment when the soft start switch is switched on, because the differential pressure is close to 0, the instantaneous impact current can be controlled below 20A, so that the device cannot be impacted.
Drawings
FIG. 1 is a schematic diagram of a start-up procedure according to the present invention;
fig. 2 is a control flow chart of the active constant power charging phase.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The starting method aims to stably increase the capacitance voltage of the power module unit of the high-voltage SVG and ice melting device to a rated value and ensure that the problems of overvoltage, overcurrent and the like do not occur in the process.
The high-voltage SVG and ice melting device is a conventional device and comprises a soft start switch cabinet, a power module unit group, an electric reactor and a control unit.
The soft start switch cabinet is mainly formed by connecting a soft start switch and a start resistor in parallel; it should be noted that the power of the starting resistor of the present invention should meet the requirement of active constant power charging, which is one of the innovative points of the present invention.
A power module unit group: the power module is composed of N power module units which are connected in series and divided into ABC three phases; the power module unit comprises an IGBT, a power module control panel and a direct current capacitor, and when the power module unit works normally, the power module unit group is connected with a power grid through a soft start switch cabinet after being filtered by a reactor.
And the control unit is used for adjusting the output of the reactive power and the active power of the high-voltage SVG and ice melting device by controlling the difference value between the output voltage of the power module unit group and the amplitude and phase of the power grid voltage.
If the amplitude of the grid voltage is higher than the output voltage, the device sends out inductive reactive power.
If the amplitude of the output voltage of the device is higher than the voltage of the power grid, the device sends out capacitive reactive power.
If the amplitude of the output voltage of the device is equal to the voltage of the power grid, the device does not emit capacitive reactive power or absorb inductive reactive power, namely the reactive power of the power grid side is zero at the moment, and the device is in an ideal working state of a load.
Therefore, the reactive power required by the power grid can be absorbed or generated rapidly in real time by adjusting the amplitude of the output voltage of the device, so that the purpose of rapidly and dynamically adjusting the reactive power is achieved.
The whole starting process consists of 3 stages: 1) an uncontrolled rectification charging stage, 2) an active constant power charging stage with a starting resistor, and 3) a bypass soft starting resistor and then an active charging stage.
1. An uncontrolled rectification charging stage:
in the process, all the driving signals of the IGBTs/MOSFETs are locked, all the full-bridge power modules are diode full-bridge rectifying circuits, the direct-current load of the circuit is a direct-current capacitor, and each phase is formed by cascading 14 full-bridge rectifying circuits. The main contactor (main switch) grid is closed to charge the full-bridge rectifying circuits through the starting resistor, and the function of the starting resistor is to limit charging current. Because the capacitance values of the direct current side capacitors of each full-bridge rectification circuit are equal, the direct current voltage of each full-bridge rectification circuit is also basically equal, and the theoretical upper limit value is as follows:
line voltage peak/(2N), N is the number of cascaded power modules per phase.
Due to the existence of the second stage (namely the active constant-power charging stage with the starting resistor), when the voltage reaches more than 95 percent of the value, the uncontrolled rectifying process is finished, and the uncontrolled rectifying charging time is shortened compared with the traditional method.
2. And (3) an active constant power charging stage with a starting resistor:
in the case where the starting resistor is not bypassed, the active control rectification process is started as follows:
1) the reference voltage of the modulation output is set as:
a) the same phase as the voltage of the power grid;
b) the output voltage remains constant;
2) pulsing all IGBTs.
Thus, the charging current is kept constant, and active constant-power charging is achieved. In this manner:
modulation ratio of PWM
And M represents a modulation ratio,
is the initial average value of the dc voltage of the power module unit,
the direct current voltage of the power module unit is measured in real time and is averaged, and the average value is reduced along with the rise of the direct current voltage, so that the output voltage of the module is kept constant:
due to the fact that
The charging current remains constant (grid voltage) unchanged.
The total output voltage of the power module cell group is set to a modulation output target voltage Vo (lower than the grid voltage), and the modulation output (PWM output) of the power module cell group is started. Because the total output voltage Vo of the power module unit group is less than the voltage of a power grid, a fixed voltage difference exists on the charging resistor, the current is kept constant, and the power grid actively charges the direct current capacitor of the power module unit of the high-voltage SVG and ice melting device at constant power.
The high-voltage SVG and ice melting device continuously checks the voltage of the power module unit and gradually increases the direct-current voltage target of the power module unit, so that the voltage of the power module unit continuously rises until the voltage value of the direct-current capacitor of the power module unit rises to the active constant-power charging target voltage value UsdS2 of the power module.
And modulating the output voltage to be lower than the power grid voltage, actively charging the direct current capacitor of the power module unit of the high-voltage SVG and ice melting device at constant power, modulating and outputting voltage with the same phase and amplitude as the power grid voltage after the voltage value of the direct current capacitor of the power module unit is increased to [1.414 multiplied by the power grid line voltage/1.732 ]/the number of modules of the power unit connected in series and the theoretical maximum alternating current output voltage of the device is larger than or equal to the current alternating current voltage at the power grid side, and finishing the constant power charging stage.
Wherein, the maximum value of the total output voltage of the power module unit group is as follows: the module mean voltage x number of series unit modules N must be greater than or equal to the voltage peak of the grid 1.414 x grid line phase voltage, (where grid line phase voltage = grid line voltage/1.732), i.e. the individual module mean voltage is greater than or equal to (1.414 x grid line voltage/1.732/number of series unit modules).
3. And (3) entering an active charging stage after bypassing the soft start resistor:
and switching on the soft start switch, bypassing the starting resistor, modulating and triggering all the IGBTs, and charging the direct current capacitors of all the power module units until the voltage of the direct current capacitors of the power module units reaches a set value.
Claims (6)
1. A starting method of a low-impact current high-voltage SVG and ice melting device is characterized by comprising three stages: 1) an uncontrolled rectification charging stage, 2) an active constant power charging stage with a starting resistor, and 3) a bypass soft starting resistor and then an active charging stage;
after the high-voltage SVG and ice melting device is electrified and passes through an uncontrolled rectification charging stage, the output of a modulation power module unit group is in the same phase with the power grid voltage and the amplitude is lower than the reference voltage of the power grid voltage, active constant power charging is carried out on the direct current capacitor of the power module unit of the high-voltage SVG and ice melting device, when the voltage value of the direct current capacitor of the power module unit is increased to be more than [1.414 multiplied by the power grid line voltage/1.732 ]/the number of power unit modules connected in series, the reference voltage with the same phase and the same amplitude as the power grid voltage is modulated to ensure that the differential pressure is 0, at the moment, a soft start switch is closed, a bypass start resistor is used for gradually adjusting the voltage of the power module unit until the rated working voltage is reached, and the starting;
the power module unit group is formed by connecting N power module units in series.
2. The method for starting the low-impact-current high-voltage SVG and ice-melting device according to claim 1, wherein the charging time of said uncontrolled rectifying charging phase is 40-60S, and the voltage of the DC capacitor of the power module unit group is charged to above 380V.
3. The method of starting a low-rush-current, high-voltage SVG cum ice melting device as claimed in claim 1 wherein: after charging in the uncontrolled rectification charging stage, under the condition that the starting resistor is not bypassed, modulating output reference voltage, wherein the modulated output reference voltage is set as: and the voltage phase of the power grid voltage sampling PLL is the same as the voltage of the power grid voltage sampling PLL, the amplitude is 4-6kV lower than the output voltage value of the power grid voltage, the voltage value is kept constant, pulses are sent to all IGBTs, the voltage difference between the output of the power module unit group and the power grid voltage is kept constant, and active constant-power charging is carried out.
4. The method for starting the low-inrush-current high-voltage SVG de-icing device according to claim 1, wherein the charging time of the active constant-power charging stage with the starting resistor is 60-90S, and the resistance of the starting resistor is 500 kOmega.
5. The method of starting a low-rush-current, high-voltage SVG cum ice melting device as claimed in claim 1 wherein: and (4) switching on the soft start switch, and switching from the start parameter to the normal operation control parameter within 1 ms.
6. The method for starting the low-impact-current high-voltage SVG and ice-melting device according to claim 1, wherein said power module unit has a rated operating voltage of 700-.
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| CN201810389380.0A CN108667038B (en) | 2018-04-27 | 2018-04-27 | Starting method of high-voltage SVG (static var generator) and ice melting device with low impact current |
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| CN109412567A (en) * | 2018-12-28 | 2019-03-01 | 上海南芯半导体科技有限公司 | A kind of guard method of device for power switching failure process |
| CN110456198B (en) * | 2019-08-14 | 2021-09-28 | 国网湖南省电力有限公司 | Soft power-on method in chain type SVG two-in-one-string test mode |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103855717A (en) * | 2014-03-27 | 2014-06-11 | 安徽工业大学 | Pulse-free soft starting method of low-voltage SVG (static var generator) |
| CN104158197A (en) * | 2014-08-22 | 2014-11-19 | 成都迈硕电气有限公司 | SVG-based line voltage compensation method |
| CN104218585A (en) * | 2014-09-17 | 2014-12-17 | 国家电网公司 | Active power filter with power unit and control method thereof |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103855717A (en) * | 2014-03-27 | 2014-06-11 | 安徽工业大学 | Pulse-free soft starting method of low-voltage SVG (static var generator) |
| CN104158197A (en) * | 2014-08-22 | 2014-11-19 | 成都迈硕电气有限公司 | SVG-based line voltage compensation method |
| CN104218585A (en) * | 2014-09-17 | 2014-12-17 | 国家电网公司 | Active power filter with power unit and control method thereof |
Non-Patent Citations (1)
| Title |
|---|
| 一种单相MMC预充电控制策略;何震等;《电源学报》;20170131;第15卷(第1期);第50-51页 * |
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