CN110265990B - Multi-well coupling common direct current bus voltage balance control and fault detection method for oil pumping unit - Google Patents
Multi-well coupling common direct current bus voltage balance control and fault detection method for oil pumping unit Download PDFInfo
- Publication number
- CN110265990B CN110265990B CN201810197917.3A CN201810197917A CN110265990B CN 110265990 B CN110265990 B CN 110265990B CN 201810197917 A CN201810197917 A CN 201810197917A CN 110265990 B CN110265990 B CN 110265990B
- Authority
- CN
- China
- Prior art keywords
- voltage
- fault
- direct current
- bus
- pumping unit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000005086 pumping Methods 0.000 title claims abstract description 47
- 238000001514 detection method Methods 0.000 title claims abstract description 24
- 230000008878 coupling Effects 0.000 title claims abstract description 13
- 238000010168 coupling process Methods 0.000 title claims abstract description 13
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 13
- 238000000034 method Methods 0.000 claims abstract description 14
- 230000005540 biological transmission Effects 0.000 claims description 15
- 230000004069 differentiation Effects 0.000 claims description 5
- 125000004122 cyclic group Chemical group 0.000 claims description 3
- 238000007405 data analysis Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 3
- 238000010248 power generation Methods 0.000 claims description 3
- 239000003129 oil well Substances 0.000 abstract description 5
- 230000001105 regulatory effect Effects 0.000 abstract description 2
- 230000006641 stabilisation Effects 0.000 abstract description 2
- 238000011105 stabilization Methods 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
-
- 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
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Eletrric Generators (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention provides a voltage balance control and fault detection method for a multi-well coupling common direct current bus of an oil pumping unit, which is a method capable of realizing voltage stabilization of the multi-well common direct current bus of the oil pumping unit, detecting the position of a fault line and cutting the fault line. The system suitable for the invention is composed of a three-phase alternating current power supply, a transformer, a rectifying device, a direct current bus, a circuit breaker, a variable frequency terminal, a voltage and current detection module, a controller, an oil pumping well and the like, and adopts a double-end power supply mode to increase the power supply stability of the system. The output frequency of the variable frequency terminal is regulated by detecting the voltage of the direct current bus, so that the speed of the pumping unit for drawing electric energy is controlled, and the voltage of the bus is maintained within a reasonable range; the faults inside and outside the area are judged through the power direction element, then the ratio of the voltage amplitude value to the current differential is calculated, the specific position of the fault is determined, the corresponding circuit breaker is operated, the fault line is cut off, and the normal operation of the pumping well on other normal lines is protected. The invention is suitable for a double-end power supply multi-oil well group control system.
Description
Technical Field
The invention belongs to the field of multi-well coupling common direct current bus group control of pumping units, and particularly relates to a multi-well coupling common direct current bus voltage balance control and fault detection method of a pumping unit.
Technical Field
In order to reduce the electric energy loss of a power supply circuit and improve the utilization rate of the circuit electric energy, and simultaneously prevent the phenomenon of power theft of residents nearby an oil field, the current oil field mostly adopts a direct current bus power supply mode. The electric energy transmitted by the distribution network is reduced by a transformer and then is changed into direct current by a rectifying device, the electric energy forms a direct current loop along a positive bus and a negative bus, the multi-port pumping unit is connected in parallel on the direct current loop, and the direct current loop is inverted by an inversion device to drive a motor of the pumping unit to work. However, at the present stage, most direct current transmission lines are in single-ended power supply, and when a certain section of the line fails, the whole line needs to be disconnected, so that the normal operation of the pumping well on the other normal line sections is seriously influenced.
Because the stroke and the stroke frequency of the multi-port oil pumping unit are different in the working process, the electric energy fluctuation of the electric network can be caused when the electric energy is drawn from the electric network. In order to ensure that the electric energy of the power grid operates in a reasonable fluctuation interval, the working state of each oil well needs to be adjusted in real time so as to enable the oil wells to operate in a peak-shifting mode. The stroke frequency and the energy consumption of the up-and-down stroke also change along with the change of the load during the operation of the pumping unit. In order to avoid voltage drop on a power grid during multi-well synchronous operation, a mode of manually and irregularly adjusting parameters is generally adopted. However, due to irregular change of the working state of the oil pumping unit, manual parameter adjustment is often in a hysteresis state.
Disclosure of Invention
The invention aims to solve the defects of the prior art, and provides a multi-well coupling common direct current bus voltage balance control and fault detection method for an oil pumping unit, which maintains the stability of the direct current bus line voltage, effectively cuts off fault lines and reduces the number of motor-pumped wells which are stopped due to line faults.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the group control system of the pumping wells consists of a three-phase alternating current power supply, a transformer, a rectifying device, a direct current bus, a circuit breaker, a variable frequency terminal, a voltage and current detection module, a controller, pumping wells and the like, and a plurality of pumping well variable frequency terminals are hung on the direct current bus to carry out group control, so that the cyclic sharing of the reverse power generation energy of a plurality of pumping wells on the group control system is realized, the harmonic pollution of network measurement is reduced, and the power factor of system work is improved.
The direct current bus is composed of positive and negative buses, a double-end power supply mode is adopted, the direct current buses are protected in sections according to the length of the line, protection devices such as circuit breakers are arranged on two sides of each section of power transmission line, and the capability of stable operation of the system is improved.
The DC bus voltage balance control can realize the stability of DC bus voltage and maintain the range of voltage fluctuation in a reasonable range, and the realization steps are as follows:
step 1: the detection device detects the voltage of the direct current bus and the stroke frequency of each motor-pumped well motor in real time, and sends detection signals back to the controller through the information transmission module in real time for logic judgment and data analysis;
step 2: judging whether the bus voltage is in a normal range, and if the bus voltage exceeds the normal range, sending a control signal to control all motor-pumped well variable frequency terminals;
step 3: when the bus voltage is below a reasonable range, an instruction is sent to the variable frequency terminal through the information transmission module, so that the output frequency is reduced, and the speed of the pumping unit for drawing electric energy is suspended; when the bus voltage is above a reasonable range, an instruction is sent to the variable frequency terminal through the information transmission module, so that the output frequency is improved, and the speed of the pumping unit for drawing electric energy is increased; and when the bus voltage is stable, the current monitoring state is maintained.
The direct current bus fault detection method of the pumping well group control system can effectively judge whether the direct current bus has a monopolar fault or a bipolar fault, and the voltages between the positive electrode and the negative electrode are equal in magnitude and opposite in direction during steady-state operation; when a single pole fails, one pole voltage is zero, and the other pole voltage value is twice that of the steady state; in bipolar failure, the voltage across the electrodes is nearly zero.
The power direction element is used for judging whether the fault is an intra-area fault or an external-area fault, the direction of the bus line is set to be a positive direction, and the circuit breaker reliably operates when various faults occur in the positive direction and reliably does not operate when faults occur in the reverse direction.
The mathematical expression of the ratio method of the voltage amplitude and the current differentiation is as follows:
wherein u is p 、u n Respectively positive and negative bus voltages, i p Is the positive current, L s 、L m The self inductance and the mutual inductance of the lines in unit length are respectively;
the equation of motion is:
wherein k is set ＝(L s -L m ) l,1 represents the total length of the line.
When an interelectrode metallic fault occurs, the ratio of the voltage amplitude value to the current differential of the fault interelectrode in a short time is mainly related to the fault distance, and the line position and the fault distance of the fault can be determined by comparing the ratio with the setting value, so that the fault line is effectively cut off.
According to the multi-well coupling common direct current bus voltage balance control and fault detection method for the pumping unit, when the direct current bus voltage fluctuation is out of the allowable range, the output frequency is changed by controlling the variable frequency terminals of all pumping units, and the speed of the pumping unit for drawing electric energy is regulated, so that the bus voltage is stable; the direct current bus adopts a double-end power supply mode, so that the stability of power supply is improved; judging the position of the fault by a ratio method of voltage amplitude and current differentiation, and operating protective elements such as a breaker and the like to cut off the fault line so as to maintain the normal operation of other oil wells.
Drawings
FIG. 1 is a schematic diagram of a group control of an oil well powered by two ends of a DC bus, and is a drawing for explaining the abstract;
FIG. 2 is a flow chart of DC bus voltage equalization control;
FIG. 3 is a schematic diagram showing an interelectrode fault occurring in a certain section of a DC line, wherein 3-1 is a positive DC bus, 3-2 is a negative DC bus, 3-3 is a filter capacitor, points A and B are short circuit points, and a dotted line is the direction of a short circuit current;
fig. 4 is a flow chart of dc bus fault detection and removal.
Detailed Description
In order to more specifically explain the present invention, the following describes the technical scheme of the present invention in detail with reference to the drawings and the specific embodiments.
As shown in figure 1, the group control system of the pumping unit well adopts a double-end power supply mode, and consists of a three-phase alternating current power supply 1-1, a transformer 1-2, a rectifying device 1-3, a direct current bus 1-4, a circuit breaker 1-5, a variable frequency terminal 1-6, a voltage and current detection module, a controller 1-7, the pumping unit well 1-8 and the like, wherein the variable frequency terminal of the pumping unit well is hung on the direct current bus for group control, so that the cyclic sharing of the reverse power generation energy of the pumping unit wells on the group control system is realized, the network measurement harmonic pollution is reduced, and the power factor of the system work is improved.
The direct current bus consists of positive and negative phases, the direct current bus is protected in sections according to the length of the line, and protection devices such as circuit breakers are arranged on two sides of each section of power transmission line, so that the stable operation capacity of the system is improved.
As shown in the flowchart of fig. 2, the voltage balancing control of the dc bus can realize the stabilization of the dc bus voltage, and maintain the voltage fluctuation range within a reasonable range, and the implementation steps are as follows:
step 1: the detection device detects the voltage of the direct current bus and the stroke frequency of each motor-pumped well motor in real time, and sends detection signals back to the controller through the information transmission module in real time for logic judgment and data analysis;
step 2: judging whether the bus voltage is in a normal range, and if the bus voltage exceeds the normal range, sending a control signal to control all motor-pumped well variable frequency terminals;
step 3: when the bus voltage is below a reasonable range, an instruction is sent to the variable frequency terminal through the information transmission module, so that the output frequency is reduced, and the speed of the pumping unit for drawing electric energy is suspended; when the bus voltage is above a reasonable range, an instruction is sent to the variable frequency terminal through the information transmission module, so that the output frequency is improved, and the speed of the pumping unit for drawing electric energy is increased; and when the bus voltage is stable, the current monitoring state is maintained.
As shown in fig. 3, the equation can be obtained taking into account the coupling relationship between the positive and negative lines:
wherein: u (u) p 、u n Respectively positive and negative voltages, i p 、i n Respectively positive and negative electrode currents, R s 、R m 、L s 、L m The self resistance, the mutual resistance, the self inductance and the mutual inductance of the unit length of the line are respectively represented, and x is the fault distance of the line.
When the fault occurs in the area, fault current directly flows to the protection installation position of the power transmission line from the fault point, so that the current of the positive bus and the negative bus is equal in magnitude and opposite in direction, namely:
i p ＝-i n (2)
substitution of formula (2) into formula (1) yields:
the conversion of formula (3) can be achieved:
under the bipolar fault condition of the direct current bus, the interelectrode capacitance discharges rapidly, the direct current voltage decreases rapidly during the fault, and the direct current increases rapidly. So that the current differential value di p Far greater than the current amplitude i p Equation (4) can be simplified as:
the formula (5) is a mathematical expression of a ratio method of voltage amplitude and current differentiation, and is used as a protection criterion.
The equation of motion is:
wherein the setting value k set ＝(L s -L m ) l,1 represents the total length of the line.
To protect the full length of the line, protection is refused from long-distance ground faults. Under the condition of being provided with a boundary element, canOptimizing the setting method in the formula (6), and multiplying the product of the total length of the line and the distributed inductance by a coefficient K slightly larger than 1 rel So as to increase the sensitivity of protection and expand the protection range.
The whole length of the line is set as follows:
L set ＝K rel L s l(7)
with the increase of the fault distance, the rising rate of the current in the fault loop is obviously reduced, the ratio of the current amplitude of the fault pole to the current differential can not be ignored, so that the formula (5) is not established any more, the ratio of the voltage value adopted by the protection criterion to the current differential is larger than the product of the assumed fault distance and the distributed inductance, and with the increase of the fault distance, the deviation from the theoretical value is larger, so that the method is suitable for the medium-short distance transmission line.
As shown in the flow chart of fig. 4, the method for detecting the fault of the direct current bus of the group control system of the pumping unit well can effectively judge whether the direct current bus has a monopolar fault or a bipolar fault, and the voltages between the positive electrode and the negative electrode are equal in magnitude and opposite in direction during steady-state operation; when a single pole fails, one pole voltage is zero, and the other pole voltage value is twice that of the steady state; in bipolar failure, the voltage across the electrodes is nearly zero.
The power direction element is used for judging whether the fault is an intra-area fault or an external-area fault, the direction of the bus line is set to be a positive direction, and the circuit breaker reliably operates when various faults occur in the positive direction and reliably does not operate when faults occur in the reverse direction.
When the interelectrode metallic fault occurs, the ratio of the voltage amplitude value and the current differential of the fault interelectrode is mainly related to the fault distance in a short time, and the line position and the fault distance of the fault can be determined by comparing the fault with the setting value, so that the fault line is effectively cut off, and the stable operation of motor-pumped wells carried by other normal lines is ensured.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (5)
1. A pumping unit multi-well coupling common direct current bus voltage balance control and fault detection method is based on a double-end direct current power supply pumping unit multi-well group control system, and the balance of bus voltage is realized by adopting a mode of detecting bus voltage in real time and adjusting the output frequency of a variable frequency terminal; judging faults inside and outside a zone through a power direction element, determining the specific position of the fault through a method for calculating the ratio of voltage amplitude and current differentiation, and operating a corresponding breaker to protect the normal operation of an oil pumping well on other normal lines;
the DC bus voltage balance control can realize the stability of DC bus voltage and maintain the range of voltage fluctuation in a reasonable range, and the realization steps are as follows:
step 1: the detection device detects the voltage of the direct current bus and the stroke frequency of each motor-pumped well motor in real time, and sends detection signals back to the controller through the information transmission module in real time for logic judgment and data analysis;
step 2: judging whether the bus voltage is in a normal range, and if the bus voltage exceeds the normal range, sending a control signal to control all motor-pumped well variable frequency terminals;
step 3: when the bus voltage is below a reasonable range, an instruction is sent to the variable frequency terminal through the information transmission module, so that the output frequency is reduced, and the speed of the pumping unit for drawing electric energy is suspended; when the bus voltage is above a reasonable range, an instruction is sent to the variable frequency terminal through the information transmission module, so that the output frequency is improved, and the speed of the pumping unit for drawing electric energy is increased; when the bus voltage tends to be stable, the current monitoring state is maintained;
the mathematical expression of the ratio method of the voltage amplitude and the current differentiation is as follows:
wherein up and un are respectively positive and negative bus voltages, ip is positive current, ls and Lm are respectively self inductance and mutual inductance of the circuit in unit length;
the equation of motion is:
wherein kset= (Ls-Lm) l, l represents the total length of the line;
when an interelectrode metallic fault occurs, the ratio of the voltage amplitude value and the current differential of the fault interelectrode in a short time is mainly related to the fault distance, and the line position and the fault distance of the fault can be determined by comparing the fault with the setting value, so that a fault line is effectively cut off, and the stable operation of motor-pumped wells carried by other normal lines is ensured.
2. The method for balanced control and fault detection of the voltage of the multi-well coupling common direct current bus of the pumping unit according to claim 1 is characterized in that: the multi-well group control system of the pumping unit consists of a three-phase alternating current power supply, a transformer, a rectifying device, a direct current bus, a circuit breaker, a variable frequency terminal, a voltage and current detection module, a controller, a pumping unit well and the like, and the variable frequency terminals of the pumping unit wells are hung on the direct current bus to carry out group control, so that the cyclic sharing of the reverse power generation energy of the pumping unit wells on the group control system is realized, the harmonic pollution of network measurement is reduced, and the power factor of the system work is improved.
3. The method for balanced control and fault detection of the voltage of the multi-well coupling common direct current bus of the pumping unit according to claim 1 is characterized in that: the direct current bus is composed of positive and negative buses, a double-end power supply mode is adopted, the direct current buses are protected in sections according to the length of the line, protection devices such as circuit breakers are arranged on two sides of each section of power transmission line, and the capability of stable operation of the system is improved.
4. The method for balanced control and fault detection of the voltage of the multi-well coupling common direct current bus of the pumping unit according to claim 1 is characterized in that: the direct current bus fault detection method of the multi-well group control system of the oil pumping unit can effectively judge whether the direct current bus has a single-pole fault or a double-pole fault, and the voltages between the positive electrode and the negative electrode are equal in magnitude and opposite in direction during steady-state operation; when a single pole fails, one pole voltage is zero, and the other pole voltage value is twice that of the steady state; in bipolar failure, the voltage across the electrodes is nearly zero.
5. The method for balanced control and fault detection of the voltage of the multi-well coupling common direct current bus of the pumping unit according to claim 1 is characterized in that: the power direction element is used for judging whether the fault is an intra-area fault or an external-area fault, the direction of the bus line is set to be a positive direction, and the circuit breaker reliably operates when various faults occur in the positive direction and reliably does not operate when faults occur in the reverse direction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810197917.3A CN110265990B (en) | 2018-03-12 | 2018-03-12 | Multi-well coupling common direct current bus voltage balance control and fault detection method for oil pumping unit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810197917.3A CN110265990B (en) | 2018-03-12 | 2018-03-12 | Multi-well coupling common direct current bus voltage balance control and fault detection method for oil pumping unit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110265990A CN110265990A (en) | 2019-09-20 |
| CN110265990B true CN110265990B (en) | 2023-11-14 |
Family
ID=67911420
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810197917.3A Active CN110265990B (en) | 2018-03-12 | 2018-03-12 | Multi-well coupling common direct current bus voltage balance control and fault detection method for oil pumping unit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110265990B (en) |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103004048A (en) * | 2010-06-14 | 2013-03-27 | Abb研究有限公司 | Fault protection of HVDC transmission lines |
| CN103500261A (en) * | 2013-10-22 | 2014-01-08 | 国家电网公司 | Method for fault simulation of direct current transmission system |
| CN104820159A (en) * | 2015-04-30 | 2015-08-05 | 国家电网公司 | Direct-current bipolar short-circuit fault identification method of flexible direct-current power transmission system |
| CN104852669A (en) * | 2015-04-30 | 2015-08-19 | 西安鹏瑞石油科技有限公司 | Variable-frequency mutual feedback control system for group control of oil wells |
| CN105098738A (en) * | 2015-09-08 | 2015-11-25 | 山东大学 | Pilot protection method of high-voltage direct current transmission line based on S transformation |
| CN106058828A (en) * | 2016-07-18 | 2016-10-26 | 天津大学 | Multi-terminal flexible DC power grid line direction pilot protection method |
| CN106707081A (en) * | 2016-11-25 | 2017-05-24 | 许继集团有限公司 | Flexible DC power distribution network monopolar grounding fault identification and fault protection method |
| CN107359603A (en) * | 2017-09-06 | 2017-11-17 | 华中科技大学 | Hvdc transmission line multistage distance protection method and system based on one-terminal data |
| WO2017202165A1 (en) * | 2016-05-26 | 2017-11-30 | 珠海格力电器股份有限公司 | Method of identifying fault in dc microgrid power line, device, and dc microgrid system |
| CN107478950A (en) * | 2017-07-28 | 2017-12-15 | 许继集团有限公司 | A kind of discrimination method of the bipolar short trouble of DC line |
-
2018
- 2018-03-12 CN CN201810197917.3A patent/CN110265990B/en active Active
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103004048A (en) * | 2010-06-14 | 2013-03-27 | Abb研究有限公司 | Fault protection of HVDC transmission lines |
| CN103500261A (en) * | 2013-10-22 | 2014-01-08 | 国家电网公司 | Method for fault simulation of direct current transmission system |
| CN104820159A (en) * | 2015-04-30 | 2015-08-05 | 国家电网公司 | Direct-current bipolar short-circuit fault identification method of flexible direct-current power transmission system |
| CN104852669A (en) * | 2015-04-30 | 2015-08-19 | 西安鹏瑞石油科技有限公司 | Variable-frequency mutual feedback control system for group control of oil wells |
| CN105098738A (en) * | 2015-09-08 | 2015-11-25 | 山东大学 | Pilot protection method of high-voltage direct current transmission line based on S transformation |
| WO2017202165A1 (en) * | 2016-05-26 | 2017-11-30 | 珠海格力电器股份有限公司 | Method of identifying fault in dc microgrid power line, device, and dc microgrid system |
| CN107437794A (en) * | 2016-05-26 | 2017-12-05 | 珠海格力电器股份有限公司 | The recognition methods of direct-current grid bus-bar fault, device and DC micro power grid system |
| CN106058828A (en) * | 2016-07-18 | 2016-10-26 | 天津大学 | Multi-terminal flexible DC power grid line direction pilot protection method |
| CN106707081A (en) * | 2016-11-25 | 2017-05-24 | 许继集团有限公司 | Flexible DC power distribution network monopolar grounding fault identification and fault protection method |
| CN107478950A (en) * | 2017-07-28 | 2017-12-15 | 许继集团有限公司 | A kind of discrimination method of the bipolar short trouble of DC line |
| CN107359603A (en) * | 2017-09-06 | 2017-11-17 | 华中科技大学 | Hvdc transmission line multistage distance protection method and system based on one-terminal data |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110265990A (en) | 2019-09-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN201274399Y (en) | DC great current deicing apparatus with static state reactive compensation function | |
| CN102820646B (en) | Device and method for controlling fault ride-through of power grid of flexible direct-current transmission system | |
| CN108987073A (en) | Voltage transformer harmonic elimination apparatus and application method | |
| CN102427233B (en) | Power saving device with harmonic suppression and voltage stabilization functions | |
| CN1937349A (en) | Comprehensive dynamic compensating device for distribution network | |
| CN111431161B (en) | Neutral point voltage suppression and voltage arc extinction method and system based on active inversion split-phase injection | |
| CN203104085U (en) | High-voltage direct-current power supply system | |
| CN110031726A (en) | A kind of flexible direct current circuitry fault detection method and device | |
| CN204304441U (en) | A kind of reactive power dynamic compensation system | |
| CN105915068A (en) | De-dusting power supply control method, apparatus and system | |
| CN110265990B (en) | Multi-well coupling common direct current bus voltage balance control and fault detection method for oil pumping unit | |
| CN110365037B (en) | Power coordination control method and device for LCC-VSC direct current transmission system | |
| CN203278225U (en) | A capacitor-adjusting automatic arc-extinguishing compensation apparatus | |
| CN207504774U (en) | Variable frequency drive and system | |
| CN101859157A (en) | Current compensation type alternating-current voltage stabilizer | |
| CN107453360A (en) | A kind of power supply quality optimizes device and method | |
| CN105552927A (en) | Parallel compensation system and method for preventing commutation failure of DC power transmission system | |
| CN206135759U (en) | Oil recovery well group intelligent control economizer | |
| CN115693790A (en) | Phase prejudgment-based uninterrupted power supply operation system and method | |
| CN203720692U (en) | Compensation circuit for 380 V high-capacity stabilized voltage supply | |
| CN114566978A (en) | SVG deep well-based non-coal mine electrified railway power supply system and use method thereof | |
| CN112542844A (en) | District electric energy quality optimizing apparatus based on regional wireless communication | |
| CN203456874U (en) | Serial-connection type voltage compensation antagonistic apparatus | |
| CN202930939U (en) | Intelligent type three phase electricity-saving appliance | |
| CN105375490A (en) | Energy-saving power transmission voltage compensation method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |