CN108572329B - Current sampling device and fault judgment method of parallel feeder power supply system - Google Patents
Current sampling device and fault judgment method of parallel feeder power supply system Download PDFInfo
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- CN108572329B CN108572329B CN201810312880.4A CN201810312880A CN108572329B CN 108572329 B CN108572329 B CN 108572329B CN 201810312880 A CN201810312880 A CN 201810312880A CN 108572329 B CN108572329 B CN 108572329B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/40—Testing power supplies
- G01R31/42—AC power supplies
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
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Abstract
The invention provides a current sampling device and a fault judgment method of a parallel feeder power supply system, wherein the device consists of six current transformers; the current transformers are correspondingly arranged on six feeder lines output by the aviation alternating-current generator one by one, two groups of windings are wound in an iron core of each current transformer by using enameled wires, one winding is used for sampling current for open-circuit protection of the parallel feeder line, and the other winding is used for sampling current for differential protection; the winding for open circuit protection of the parallel feeder is connected with a signal acquisition device of the aviation power supply system; the two windings for differential protection in the same phase have the same number of turns and are defined as the same end of the same name of each feeder line; the starting end of one winding is connected with one end of the first sampling resistor, the tail end of the winding is connected with the starting end of the other winding, the two windings are connected between the first sampling resistor and the second sampling resistor which are connected in series, and the tail end of the other winding is connected with the other end of the second sampling resistor. According to the invention, through the design of the current sampling device, the total number of the current transformers is reduced.
Description
Technical Field
The invention relates to the technical field of aviation power supplies, in particular to a current sampling device and a fault judgment method for a parallel feeder power supply system, which are used for sampling the current of an alternating current power supply system in a double-feeder parallel transmission mode in a large airplane.
Background
1. Electric energy transmission mode of aviation alternating current power supply system
In an aircraft and a low-power supply system, the power consumption requirement of the aircraft can be met only by transmitting electric energy in a single feeder transmission mode, see a schematic diagram of a) on the left side of fig. 1. Along with the continuous increase of the electricity consumption of the airplane, the output power of an airplane power supply system is continuously increased, and the output current of a generator is inevitably increased under the condition that a power supply system is not changed, so that the sectional area of an output feeder line of the generator is required to be correspondingly increased, and the feeder line is thicker and thicker. If the electric energy is still transmitted by adopting a single feeder line transmission mode, the aspects of manufacturing, installing, laying, connecting and the like of the feeder lines face a lot of difficulties and problems, in order to solve the problems, the current reference is made to the power supply design of a large aircraft in the world, a concept of transmitting the electric energy of a power supply system by adopting a double feeder line parallel connection mode is provided, see the schematic diagram b) on the right side of the figure 1, but the specific implementation and the implementation problems still exist, and as foreign manufacturers lock the implementation technology, the current can not be known from the published documents.
2. "differential protection" current sampling
In an aircraft power supply system, a 'differential protection' item is mainly a protection item which is arranged for the short circuit of an output feeder of an aircraft generator, for example, the short circuit caused by the short circuit of the feeder and an aircraft frame or a skin due to the insulation damage of the feeder.
The differential protection needs to collect current signals in an output feeder line of the generator, generally adopts a method of installing a current transformer on the output feeder line of the generator to sample current, compares the sampled current signals with current sampling signals inside the generator, determines that a differential fault exists if a difference value exceeds a specified value, and implements protection. The power supply system of the single feeder transmission system generally adopts the current sampling method shown in fig. 2. Accordingly, the current sampling method shown in fig. 3 may be adopted in the doubly-fed parallel transmission power supply system. However, when the applicant designs and uses the current transformer according to the method shown in fig. 3, the applicant finds that the coil of the current transformer needs to have a larger inner diameter as two feeders pass through the coil, so that the volume of the whole current transformer is correspondingly increased, and the overall design requirement of a large-sized airplane cannot be met.
3. Parallel feeder open circuit protection current sampling
In addition, the applicant also finds that, in the process of designing the doubly-fed parallel transmission mode, for a doubly-fed parallel transmission mode power supply system, when a fault that one feeder line in parallel feeder lines is open-circuited occurs, current in the remaining feeder lines is doubled, and faults such as large current overheating and even fire of the feeder lines easily occur, so that a 'parallel feeder line open-circuit protection' item needs to be added to the doubly-fed parallel transmission mode power supply system, and the item is not needed in the traditional single feeder line transmission mode power supply system.
In order to reduce the influence of faults on the whole power supply system, a parallel feeder open circuit protection item is set, and the parallel feeder open circuit protection item is a unique protection item of a double-feed line parallel transmission mode power supply system.
The mode of the parallel feeder open circuit protection is as follows: a current transformer is installed on each generator output feeder to perform current sampling, a current signal in each feeder is collected, the sampled signals of two feeders in the same phase are compared, if the difference value exceeds a specified value, it is determined that an open circuit fault of the parallel feeder exists, and protection needs to be implemented, see fig. 4.
Disclosure of Invention
Technical problem to be solved
Obviously, if according to the above preliminary design, in a high-power (high-capacity) aircraft ac power supply system of a large aircraft, a doubly-fed line parallel transmission mode is adopted to transmit the electric energy of the generator, and a "differential protection" function and a "parallel feeder open circuit protection" function are to be realized, at least 9 current transformer coils need to be installed on the output feeder of the generator to sample the current, as shown in fig. 5, which results in an excessively large total volume and a correspondingly excessively large weight of the current sampling device, and is difficult to meet the overall design requirements of the large aircraft.
Technical scheme
The overall idea of the invention is to eliminate the "differential protection" current sampling device (the "differential protection" current transformer) and to incorporate its function into the "parallel feeder open circuit protection" current sampling device, as a result of which the number of current transformer coils is reduced from 9 to 6 (the largest 3 are eliminated). Therefore, the invention provides a current sampling device and a fault judgment method of a parallel feeder power supply system.
The current sampling device of the parallel feeder power supply system is characterized in that: consists of six current transformers; the six current transformers are correspondingly arranged on six feeders output by the aviation alternating-current generator one by one, wherein each phase of the aviation alternating-current generator adopts two parallel feeders with the same specification and length to output, the single-phase output current of the generator is I, and the current in each feeder is I/2;
two groups of windings are wound in an iron core of each current transformer by using enameled wires, and the two windings are uniformly distributed on the iron core for one circle; one winding is used for current sampling of parallel feeder open circuit protection, and the other winding is used for current sampling of differential protection;
the winding for open circuit protection of the parallel feeder is connected with a signal acquisition device of the aviation power supply system;
the two windings for differential protection in the same phase have the same number of turns and are defined as the same end of the same name of each feeder line; the wiring mode of two windings for differential protection in the same phase is as follows: the starting end of one winding is connected with one end of a first sampling resistor, the tail end of the winding is connected with the starting end of the other winding, the two windings are connected between the first sampling resistor and a second sampling resistor which are connected in series, and the tail end of the other winding is connected with the other end of the second sampling resistor; the resistance values of the first sampling resistor and the second sampling resistor are the same; and voltage signals of the first sampling resistor and the second sampling resistor are connected with a signal acquisition device of the aviation power supply system.
The method for judging the fault of the parallel feeder power supply system by using the device is characterized by comprising the following steps of:
the method comprises the following steps that a signal acquisition device of an aviation power supply system respectively acquires output signals of windings used for parallel feeder open circuit protection in each current transformer, the output signals of the windings used for parallel feeder open circuit protection in two current transformers in the same phase are compared, if the difference value exceeds a specified value, the parallel feeder open circuit fault is determined to exist, and protection needs to be implemented;
the signal acquisition device of the aviation power supply system acquires the voltage sum U2 of two series sampling resistors connected with windings for differential protection in two current transformers in the same phase, and calculates to obtain a current I according to a formula U2-RI/N2, wherein N2 is the number of turns of the windings for differential protection in the current transformers, and R is the resistance value of the sampling resistors; and comparing the calculated current value with an in-phase current signal in the aircraft generator, determining that a differential fault exists if the difference value exceeds a specified value, and implementing protection.
Advantageous effects
The invention firstly realizes the transmission of the electric energy of the generator by adopting a double-feed line parallel transmission mode in a high-power (high-capacity) airplane alternating current power supply system of a large airplane, and realizes the functions of differential protection and parallel feed line open circuit protection; and more importantly, by designing the current sampling device, the total number of the current transformers is reduced, the weight is correspondingly reduced, and the total design requirement of the large airplane is met.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1: an electric energy transmission mode of an aviation alternating current power supply system; (a) single feeder transmission mode, (b) double feeder parallel transmission mode.
FIG. 2: a schematic diagram of current sampling of 'differential protection' in a single feeder transmission mode;
FIG. 3: a schematic diagram of current sampling of differential protection in a dual-feeder parallel transmission mode;
FIG. 4: the current sampling mode of 'parallel feeder open circuit protection';
FIG. 5: a schematic diagram of a current sampling coil installation mode;
FIG. 6: the N2 windings on two parallel feeders of the same phase are connected schematically;
FIG. 7: comparing scheme connection relation graphs;
FIG. 8: the invention relates to a connection relation graph.
Detailed Description
The following detailed description of embodiments of the invention is intended to be illustrative, and not to be construed as limiting the invention.
As shown in fig. 6, the current sampling device of the parallel feeder power supply system in the present embodiment is composed of six current transformers; the six current transformers are correspondingly arranged on six feeders output by the aviation alternating-current generator one by one, wherein each phase of the aviation alternating-current generator adopts two parallel feeders with the same specification and length to output, the single-phase output current of the generator is I, and the current in each feeder is I/2.
Two groups of windings are wound in an iron core of each current transformer by using enameled wires, and the two windings are uniformly distributed on the iron core for one circle so as to reduce leakage inductance; one winding is used for current sampling of parallel feeder open circuit protection, the number of turns is N1, the other winding is used for current sampling of differential protection, and the number of turns is N2.
The winding with the number of turns of N1 and used for open-circuit protection of the parallel feeder is connected with a signal acquisition device of an aviation power supply system, and whether the open-circuit fault of the parallel feeder exists is judged by comparing current sampling signals of two in-phase parallel feeders.
The number of turns of two windings for differential protection in the same phase is the same, and is both N2, and when the installation ensures that the two windings for differential protection in the same phase and the same-name end of each feeder are defined the same. The wiring mode of two windings for differential protection in the same phase is as follows: the start end of one winding is connected with one end of a first sampling R21 resistor, the tail end of the winding is connected with the start end of the other winding, the two windings are connected between the first sampling resistor R21 and the second sampling resistor R22 which are connected in series in common, and the tail end of the other winding is connected with the other end of the second sampling resistor R22; the resistance values of the first sampling resistor and the second sampling resistor are the same; voltage signals of the first sampling resistor and the second sampling resistor are connected with a signal acquisition device of the aviation power supply system; the corresponding current is obtained through calculation by collecting the sum of voltages at two ends of the first sampling resistor R21 and the second sampling resistor R22, and the calculated current is compared with an in-phase current signal in the aircraft generator to judge whether a differential fault exists.
If the current in the N2 winding is relatively large (hundreds of milliamps or more), the sampling resistor can be mounted near the coil, which can reduce one lead (the wire connected to "terminal 2" in fig. 6); if the current in the N2 winding is relatively small (tens of milliamps or less), a sampling resistor should be placed in the generator controller.
The method for judging the fault of the parallel feeder power supply system by using the device mainly realizes differential protection and parallel feeder open circuit protection:
and if the difference value exceeds a specified value, the parallel feeder line open circuit fault is determined to exist, and protection needs to be implemented.
The signal acquisition device of the aviation power supply system acquires the voltage sum U2 of two series sampling resistors connected with windings for differential protection in two current transformers in the same phase, and calculates to obtain a current I according to a formula U2-RI/N2, wherein N2 is the number of turns of the windings for differential protection in the current transformers, and R is the resistance value of the sampling resistors; and comparing the calculated current value with an in-phase current signal in the aircraft generator, determining that a differential fault exists if the difference value exceeds a specified value, and implementing protection.
The following demonstrates, in conjunction with the comparison scheme shown in fig. 7 and the present embodiment scheme shown in fig. 8, that the present invention can achieve differential protection:
definitions and description:
1) the specifications and the lengths of the feeder 1 and the feeder 2 of the two parallel feeders are completely the same;
2) the generator single-phase output current (the current in each feeder line is I/2);
3) n2, N21, N22 are winding turns for differential protection, and N2 ═ N21 ═ N22;
4) r, R21 and R22 are sampling resistors, and R21 is R22;
5) u2 is the voltage across the sampling resistor.
And (3) calculating:
for the comparative scheme:
because I2 is I/N2
So that U2-R × I2-RI/N2
For the scheme in this example:
because I21 is I/2N21, I22 is I/2N22
So that U21 ═ R21 × I21 ═ R21I/2N21
U22＝R22×I22＝R22I/2N22
Because R21 ═ R22 ═ R, N21 ═ N22 ═ N2
Then, U21-R21I/2N 21-RI/2N 2
U22＝R22I/2N22＝RI/2N2
And U2 is U21+ U22 is RI/2N2+ RI/2N2
Available U2 ═ RI/N2
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.
Claims (2)
1. The utility model provides a current sampling device of parallelly connected feeder electrical power generating system which characterized in that: consists of six current transformers; the six current transformers are correspondingly arranged on six feeders output by the aviation alternating-current generator one by one, wherein each phase of the aviation alternating-current generator adopts two parallel feeders with the same specification and length to output, the single-phase output current of the generator is I, and the current in each feeder is I/2;
two groups of windings are wound on an iron core of each current transformer by using enameled wires, and the two windings are uniformly distributed on the periphery of the iron core; one winding is used for current sampling of parallel feeder open circuit protection, and the other winding is used for current sampling of differential protection;
the winding for open circuit protection of the parallel feeder is connected with a signal acquisition device of the aviation power supply system;
the number of turns of the two windings for differential protection in the same phase is the same, and the definitions of the two windings for differential protection in the same phase and the homonymous ends of the respective feeder lines are the same; the wiring mode of two windings for differential protection in the same phase is as follows: the starting end of one winding is connected with one end of a first sampling resistor, the tail end of the winding is connected with the starting end of the other winding, the two windings are connected between the first sampling resistor and a second sampling resistor which are connected in series, and the tail end of the other winding is connected with the other end of the second sampling resistor; the resistance values of the first sampling resistor and the second sampling resistor are the same; and voltage signals of the first sampling resistor and the second sampling resistor are connected with a signal acquisition device of the aviation power supply system.
2. The method for judging the fault of the parallel feeder power supply system by using the device of claim 1 is characterized in that:
the method comprises the following steps that a signal acquisition device of an aviation power supply system respectively acquires output signals of windings used for parallel feeder open circuit protection in each current transformer, the output signals of the windings used for parallel feeder open circuit protection in two current transformers in the same phase are compared, and if the difference value exceeds an open circuit fault detection specified value, the parallel feeder open circuit fault is determined to exist, and protection needs to be implemented;
the signal acquisition device of the aviation power supply system acquires the voltage sum U2 of two series sampling resistors connected with windings for differential protection in two current transformers in the same phase, and calculates to obtain a current I according to a formula U2-RI/N2, wherein N2 is the number of turns of the windings for differential protection in the current transformers, and R is the resistance value of the sampling resistors; and comparing the calculated current value with the in-phase current signal in the aviation alternating-current generator, determining that a differential fault exists if the difference value exceeds a differential fault detection set value, and implementing protection.
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| CN201810312880.4A CN108572329B (en) | 2018-04-09 | 2018-04-09 | Current sampling device and fault judgment method of parallel feeder power supply system |
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| CN201810312880.4A CN108572329B (en) | 2018-04-09 | 2018-04-09 | Current sampling device and fault judgment method of parallel feeder power supply system |
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| CN108572329B true CN108572329B (en) | 2020-03-24 |
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| US11268989B2 (en) * | 2018-11-02 | 2022-03-08 | Hamilton Sundstrand Corporation | Dual feeder systems having current transformers |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101796421A (en) * | 2007-07-19 | 2010-08-04 | 空中客车运营简易股份公司 | Improved current sensor |
| CN104049127A (en) * | 2013-03-15 | 2014-09-17 | 霍尼韦尔国际公司 | Parallel harness current imbalance and failure detection |
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| US20060044710A1 (en) * | 2004-08-24 | 2006-03-02 | Beneditz Bruce D | Ground fault detector for generator feeder |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101796421A (en) * | 2007-07-19 | 2010-08-04 | 空中客车运营简易股份公司 | Improved current sensor |
| CN104049127A (en) * | 2013-03-15 | 2014-09-17 | 霍尼韦尔国际公司 | Parallel harness current imbalance and failure detection |
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