CN112366654B - AC/DC differential protection method for 12-phase rectifying generator - Google Patents
AC/DC differential protection method for 12-phase rectifying generator Download PDFInfo
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- CN112366654B CN112366654B CN202011202523.6A CN202011202523A CN112366654B CN 112366654 B CN112366654 B CN 112366654B CN 202011202523 A CN202011202523 A CN 202011202523A CN 112366654 B CN112366654 B CN 112366654B
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- 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
- H02H7/06—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 dynamo-electric generators; for synchronous capacitors
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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
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The invention provides an AC/DC differential protection method for a 12-phase rectification generator, which is used for identifying internal faults of the 12-phase rectification generator so as to facilitate fault isolation and reduce unnecessary losses. The invention can solve the problem that the internal faults of the 12-phase rectification generator cannot be identified. By collecting the current of the alternating-current side of the 12-phase winding and the current of the direct-current side of the rectifier bridge and combining the serial-parallel connection relation of the rectifier bridge, whether the current of the alternating-current side and the current of the direct-current side meet the current characteristics of normal operation can be judged, so that whether an internal fault occurs can be judged. When the internal short circuit and the grounding fault of the 12-phase rectifying generator occur, the invention can rapidly judge the fault, provide measures such as fault isolation, power supply recovery and the like for a protection system, and avoid the further expansion of the fault.
Description
Technical Field
The invention relates to an alternating current-direct current differential protection method for a 12-phase rectifying generator, and belongs to the technical field of ship power stations and relay protection.
Background
In land-based power grids, short-circuit faults of rectifier diodes (converter valves) are protected by valve short-circuit faults. The principle is that the current measurement values of the alternating current side and the direct current side of the converter valve are detected, the maximum current value measured by the alternating current side and the maximum value of the current value detected by the direct current side are used for carrying out difference value calculation, and when the current difference value of the maximum current value of the alternating current side and the current difference value of the direct current side exceeds a setting value, fault protection is carried out. Because the land power grid adopts the combined equipment of the transformer and the converter. The short-circuit fault of the internal valve of the converter carries out internal fault protection by comparing the currents of the valve side and the power transmission pole. The fault of the internal winding of the transformer is protected by comparing the primary side and the secondary side.
Currently, in a multi-type ship, a 12-phase rectifying generator is adopted as a main power supply, and the generator capacity is large. According to relevant standard requirements, the generator internal fault protection method should be configured when the generator capacity is greater than 1500 kW. However, since the 12-phase rectifying generator is provided with a rectifying bridge, the internal faults of the 12-phase rectifying generator cannot be distinguished continuously by using an alternator differential protection algorithm. At the same time, the rectifier bridge is used as one of the constituent units of the generator, and the internal fault of the rectifier bridge also belongs to the internal fault of the generator, and must be considered equally with the stator winding.
Disclosure of Invention
The invention aims to solve the technical problems that: the stator winding faults and the rectifier bridge faults of the 12-phase rectification generator cannot be identified.
In order to solve the technical problems, the technical proposal of the invention provides
The invention provides an AC/DC differential protection strategy for a 12-phase rectification generator, which is used for identifying internal faults of the 12-phase rectification generator so as to facilitate fault isolation and reduce unnecessary losses. The invention can solve the problem that the internal faults of the 12-phase rectification generator cannot be identified. By collecting the current of the alternating-current side of the 12-phase winding and the current of the direct-current side of the rectifier bridge and combining the serial-parallel connection relation of the rectifier bridge, whether the current of the alternating-current side and the current of the direct-current side meet the current characteristics of normal operation can be judged, so that whether an internal fault occurs can be judged. When the internal short circuit and the grounding fault of the 12-phase rectifying generator occur, the invention can rapidly judge the fault, provide measures such as fault isolation, power supply recovery and the like for a protection system, and avoid the further expansion of the fault. Under the condition of lacking the algorithm, the system protection can not adopt corresponding fault isolation measures until the generator is difficult to maintain normal machine end voltage only when the internal faults are continuously deteriorated and upgraded. Under the condition, not only is the fault loss increased, but also the power failure risk of the system is increased, and meanwhile, the fault checking work is not facilitated.
Drawings
FIG. 1 is a waveform of a medium voltage DC side voltage obtained by simulation when a diode branch short circuit fault occurs;
FIG. 2 is a schematic diagram of an internal fault of a 12-phase rectifying generator;
fig. 3 is a schematic view of the placement position of the current collecting sensor.
Detailed Description
The invention will be further illustrated with reference to specific examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. Further, it is understood that various changes and modifications may be made by those skilled in the art after reading the teachings of the present invention, and such equivalents are intended to fall within the scope of the claims appended hereto.
The invention provides an alternating current-direct current differential protection method for a 12-phase rectifying generator, which aims at the connection form of a 24-pulse rectifier in the 12-phase rectifying generator, adopts a method combining principle analysis and simulation verification, analyzes the mathematical relationship between the alternating current side current and the direct current side current of the 12-phase rectifying generator, and establishes a mathematical expression between the two. And analyzing the characteristics of the internal faults of the generator in a simulation test mode so as to design fault protection criteria.
The protection range of the internal faults of the 12-phase rectification generator comprises a 12-phase stator winding, a 24-pulse rectifier, related internal connection busbar and the like. The above components are prone to failure types such as stator winding interphase short circuit, broken wire and grounding. Compared with the land network converter structure, the ship 24-pulse rectifier adopts a 2-parallel-2-series connection mode, the differential value of the alternating-current side current and the direct-current side current cannot be obtained in a mode of difference between maximum values, and the differential value is calculated according to the connection mode of a rectifier bridge. Because no converter link exists, the internal faults of the windings and the internal faults of the rectifier are not required to be considered separately, and fault judgment can be performed by directly detecting the current of the neutral point side of the 12-phase winding and the current of the direct current transmission end, converting according to a certain proportion and then comparing the difference value. According to the sensor arrangement position shown in fig. 2, the protection algorithm for the internal fault of the 12-phase rectifying generator is as follows:
ΔI＝max[(Iy1+Iy3),(Iy2+Iy4)]-max[Id+,Id-]
Iy1＝max(Iy1a,Iy1b,Iy1c)
Iy2＝max(Iy2a,Iy2b,Iy2c)
Iy3＝max(Iy3a,Iy3b,Iy3c)
Iy4＝max(Iy4a,Iy4b,Iy4c)
iy1a is the alternating current side current of the a-phase winding in the 12-phase rectification generator Y1 winding, iy1b is the alternating current side current of the b-phase winding in the 12-phase rectification generator Y1 winding, and Iy1c is the alternating current side current of the c-phase winding in the 12-phase rectification generator Y1 winding; iy2a is the ac side current of the a-phase winding in the 12-phase rectified generator Y2 winding, iy2b is the ac side current of the b-phase winding in the 12-phase rectified generator Y2 winding, iy2c is the ac side current of the c-phase winding in the 12-phase rectified generator Y2 winding; iy3a is the ac side current of the a-phase winding of the 12-phase rectified generator Y3, iy3b is the ac side current of the b-phase winding of the 12-phase rectified generator Y3, and Iy3c is the ac side current of the c-phase winding of the 12-phase rectified generator Y3. Δi is the difference between the ac side current and the dc side current, and is used as the basis for fault determination.
The fault protection criteria are:
when the current difference delta I is more than 10-30% In, the internal fault of the 12-phase rectification generator winding can be judged, and In is the rated current of the generator.
Fault protection action time: suggested as ms-scale.
Fault protection action policy: and the internal fault protection is finished through operations such as switching off, de-excitation, shutdown and the like.
Taking a 24-pulse rectifier rectification branch circuit short-circuit fault as an example, a simulation model of a 12-phase rectification generator is built in simulation software, and the short-circuit fault of a specific branch circuit is simulated. A diode short is a fault whose internal or external insulation is damaged or shorted. After the diode is short-circuited, the diode is equivalent to a short-circuited wire, has bidirectional conduction characteristics, and is the most main physical characteristic of the short-circuited fault of the diode. When a diode branch short-circuit fault occurs, a medium-voltage direct-current side voltage waveform is obtained through simulation, and is shown in fig. 1.
As is clear from the dc voltage waveform of fig. 1, a voltage gap occurs in 8 pulse periods during each ac cycle due to the ac side short circuit. The high-voltage bridge 3 is short-circuited in ac two phases when the first voltage is notched, and the forward and reverse phase voltages born by the short-circuited diode and the diode of the half-bridge are increased from the phase voltage to the line voltage. The high-voltage bridge 3 generates an ab two-phase short circuit when the second voltage gap occurs, and the high-voltage bridge 3 generates an ab two-phase short circuit when the third voltage gap occurs. From the above analysis, it is known that the ac-side maximum phase current instantaneous value is a characteristic of the dc-side current instantaneous value. When the voltage of the direct current side is notched, a fault shunt loop is generated in the generator and the rectifier system, so that the maximum current of the alternating current side of the 12-phase generator is 2-phase short-circuit current, and the output direct current is reduced due to sudden drop of the direct current voltage, so that an instantaneous current difference value is generated by the alternating current and the direct current. Thus, the 24-pulse rectifier rectifying leg short-circuit fault can be summarized as:
1) The direct current voltage generates periodic voltage drops;
2) The direct current drops periodically with the voltage;
3) The alternating current side generates periodic 2-phase short-circuit current;
4) The difference between the alternating current side maximum current value and the direct current side current value generates periodic abrupt changes.
Claims (1)
1. A12-phase rectification generator-oriented AC/DC differential protection method is characterized in that a method combining principle analysis and simulation verification is adopted to analyze the mathematical relationship between the alternating current side current and the direct current side current of a 12-phase rectification generator, a mathematical expression between the two is established, and the characteristics of internal faults of the generator are analyzed in a simulation test mode;
for a 24-pulse rectifier adopting a connection form of 2 parallel-2 strings, calculating according to the connection form of a rectifier bridge to obtain a differential value of alternating-current side current and direct-current side current; directly detecting the current of the neutral point side of the 12-phase winding and the current of the direct current transmission end, converting according to a certain proportion, and then comparing the difference value to obtain the differential value for fault judgment;
the protection algorithm of the internal faults of the 12-phase rectification generator is as follows:
ΔI＝max[(Iy1+Iy3),(Iy2+Iy4)]-max[Id+,Id-]
Iy1＝max(Iy1a,Iy1b,Iy1c)
Iy2＝max(Iy2a,Iy2b,Iy2c)
Iy3＝max(Iy3a,Iy3b,Iy3c)
Iy4＝max(Iy4a,Iy4b,Iy4c)
iy1a is the alternating current side current of the a-phase winding in the 12-phase rectification generator Y1 winding, iy1b is the alternating current side current of the b-phase winding in the 12-phase rectification generator Y1 winding, and Iy1c is the alternating current side current of the c-phase winding in the 12-phase rectification generator Y1 winding; iy2a is the ac side current of the a-phase winding in the 12-phase rectified generator Y2 winding, iy2b is the ac side current of the b-phase winding in the 12-phase rectified generator Y2 winding, iy2c is the ac side current of the c-phase winding in the 12-phase rectified generator Y2 winding; iy3a is the ac side current of the a-phase winding in the 12-phase rectified generator Y3 winding, iy3b is the ac side current of the b-phase winding in the 12-phase rectified generator Y3 winding, iy3c is the ac side current of the c-phase winding in the 12-phase rectified generator Y3 winding; Δi is the difference between the ac side current and the dc side current, and is used as the basis for fault determination;
the fault protection criteria are: when the current difference delta I is more than 10-30% In, judging that the internal fault of the 12-phase rectification generator winding occurs, wherein In is the rated current of the generator.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102810856A (en) * | 2012-08-02 | 2012-12-05 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | Phase correction method for arbitrary impulse converter transformer current difference |
| CN103346535A (en) * | 2013-06-20 | 2013-10-09 | 国家电网公司 | Doubling differential protection method for converter transformer |
| CN106684836A (en) * | 2016-11-15 | 2017-05-17 | 南方电网科学研究院有限责任公司 | Valve bank differential protection method performing synthesis judgment based on difference stream waveforms |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102810856A (en) * | 2012-08-02 | 2012-12-05 | 中国南方电网有限责任公司超高压输电公司检修试验中心 | Phase correction method for arbitrary impulse converter transformer current difference |
| CN103346535A (en) * | 2013-06-20 | 2013-10-09 | 国家电网公司 | Doubling differential protection method for converter transformer |
| CN106684836A (en) * | 2016-11-15 | 2017-05-17 | 南方电网科学研究院有限责任公司 | Valve bank differential protection method performing synthesis judgment based on difference stream waveforms |
Non-Patent Citations (1)
| Title |
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| 十二相整流发电机短路计算与仿真分析;申喜等;《舰船电子工程》;20161031;第36卷(第10期);第78-81页 * |
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