The present invention relates to a direct current high speed circuit breaker used in railway dc substation facilities and dc power transmission and distribution facilities.
A direct current circuit breaker is difficult to achieve interruption or cutting-off performance because there is no zero point in the current to be cut off unlike an alternating current circuit breaker.
An air type circuit breaker is arranged to interrupt an arc stretched in an arc chute. Therefore, the air circuit breaker might become unable to confine the current and cause ground fault.
A vacuum type circuit breaker is arranged, as shown in a dc high speed vacuum circuit breaker (HSVCB) disclosed in Non-patent Documents 1 and 2, for example, to produce a zero current point forcibly by injecting current in a direction opposite to a main circuit current in a vacuum valve, and thereby interrupt the current.
Non-Patent Document 1: “Current state of dc feeding circuit and problems in the future”, Noriaki Munakata, Railway & Electric Technology, 2010 APRIL Vol. 21, No. 4, p. 62˜p. 66.
Non-Patent Document 2: “Performance Verification of Direct Current High Speed Circuit Breaker electric railway substation direct current high speed vacuum circuit breaker” Shinichi Hase and five others, Railway Cybernetics Symposium Bulletin (2000.11.12), Paper No. 640, p. 471˜p. 475.
Although the vacuum type circuit breaker can confine current, the construction is very complicated for generating current zero points forcibly, the maintenance and inspection are troublesome, and the complicated structure increases the possibility of failure.
It is an object of the present invention to provide a direct current interruption apparatus which can eliminate the need for a circuit for generating current zero points forcibly, and which is simple in the construction and lower in the cost.
According to a first aspect of the present invention as recited in claim 1, one end or first end of a main contact or main contact unit of a dc high speed vacuum circuit breaker for each phase is connected with a positive output end for one phase of a rectifier including a bridge of semiconductor devices for converting ac power to dc power, and the other ends or second ends of the main contacts or main contact units are connected together.
In the above-mentioned construction, a pulse-shaped current flows through an arm of each phase in the rectifier and the current is commutated sequentially among the arms of the phases, so that the current becomes equal to zero after the commutation. The dc high speed vacuum circuit breaker interrupts the current reduced to zero by the commutation. Therefore, the interruption is easier.
Thus, there is no need for a circuit for producing a current zero point forcibly, the construction of the dc interruption apparatus is simplified, the maintenance and inspection are easier and the const is reduced.
According to a second aspect as recited in claim 2, the dc high speed vacuum circuit breaker is disposed or installed in a dc distribution board or switch board in the construction of the first aspect as recited in claim 1.
According to a third aspect as recited in claim 3, a busbar, bus or bus line is provided for each phase, and the bus lines of the respective phases are disposed in the dc distribution board and connected, respectively, with the positive output ends of the respective phases of the rectifier in the construction of the second aspect as recited in claim 2.
In the above-mentioned construction, the bus line is provided for each phase before the junction (common connection) where the positive output ends of the respective phases of the rectifier are connected together. Accordingly, it is possible to connect two or more sets of the dc distribution boards and the dc high speed vacuum circuit breakers in parallel with the bus lines for the respective phases. Therefore, the construction is adequate for the facilities for transmitting and distributing electricity to a plurality of dc loads connected in parallel with respect to the rectifier.
According to a fourth aspect as recited in claim 4, the rectifier comprises a six-phase rectifier for full-wave rectification of all the phases of a three-phase ac power source in the construction according to the first to third aspects as recited in claims 1 to 3.
According to a fifth aspect as recited in claim 5, the rectifier comprises a twelve-phase rectifier including a first rectifier and a second rectifier, ac sides of the first and second rectifiers being connected, respectively, with two mutually-insulated secondary windings of a multi-winding transformer, and positive output ends of the first and second rectifiers are connected so that the positive output end of the first rectifier for one phase is connected with the output end of the second rectifier for the same phase, in the construction according to one of the first to third aspects as recited in claims 1 to 3.
According to a sixth aspect as recited in claim 6, the rectifier comprises a twelve-phase rectifier including a first rectifier and a second rectifier, ac sides of the first and second rectifiers being connected, respectively, with two mutually-insulated secondary windings of a multi-winding transformer, and positive output ends of the first and second rectifiers are connected so that the positive output end of the first rectifier for one phase or a given phase is connected with the positive output end of the second rectifier for a different phase different from the given phase.
In the above-mentioned construction, the main contact of one phase of the dc high speed vacuum circuit breaker receives alternately the flow of current of a given phase of the first rectifier and the flow of current of another phase different from the given phase of the second rectifier. Therefore, the peak value or crest value in the waveform of the current flowing through each main contact of the dc high speed vacuum circuit breaker is lower, and the zero points are produced more frequently (twice as compared to the construction according to the fifth aspect as recited in claim 5) so that the period is shorter. Consequently, the dc interruption apparatus can perform the interruption quickly.
According to a seventh aspect as recited in claim 7, a backflow preventing diode is provided for each of the phases, and the second ends of the main contacts of the dc high speed vacuum circuit breaker are connected together through anode-cathode structures of backflow preventing diodes.
In the above-mentioned construction, it is possible to prevent the voltage and current from flowing around from one circuit to another circuit connected with the bus lines, and thereby keep the voltage and current of each phase independent from those of the other phases.
According to an eighth aspect as recited in claim 8, a negative electrode end of the rectifier is connected through an anode-cathode structure of a flywheel diode to a common connection point to which the second ends of the main contacts of the dc high speed vacuum circuit breaker are connected, in the construction according to one of the first to seventh aspect as recited in claims 1 to 7.
In the above-mentioned construction, at the time of interruption of the dc high speed vacuum circuit breaker, the current due to a residual energy of a reactance contained in the dc load flows through the flywheel diode, and does not pass through the dc high speed vacuum circuit breaker. Therefore, it is possible to prevent the time until the zero point from being elongated.
(1) According to the first to eighth aspects of the present invention as recited in claims 1˜8, the circuit for forcibly producing zero current points is not required, the construction of the dc interruption apparatus is simplified, the operation for maintenance and inspection is easier and the cost is reduced.
(2) According to the third aspect as recited in claim 3, it is possible to connect two or more sets of the dc distribution boards and the dc high speed vacuum circuit breakers in parallel with the bus lines each provided for one phase. Therefore, the construction is readily used for the facilities for transmitting and distributing electricity to a plurality of dc loads connected in parallel with respect to the rectifier.
(3) According to the sixth aspect as recited in claim 6, the peak value value in the waveform of the current flowing through the dc high speed vacuum circuit breaker is lower, and the period for producing zero points is shorter (twice as compared to the construction according to the fifth aspect as recited in claim 5), and the interruption apparatus can perform the interruption quickly.
(4) According to the seventh aspect as recited in claim 7, it is possible to prevent the voltage and current from flowing around from one circuit to another circuit connected with the bus lines, and thereby keep the voltage and current of each phase independent from those of the other phases.
(5) According to the eighth aspect as recited in claim 8, at the time of interruption by the dc high speed vacuum circuit breaker, the current due to a residual energy of a reactance contained in the dc load flows through the flywheel diode, and does not pass through the dc high speed vacuum circuit breaker. Therefore, it is possible to prevent the time until the zero point from being elongated.
Although an embodiment or embodiments of the present invention is explained hereinafter with reference to the drawings, the present invention is not limited to examples of the embodiment(s). A dc substation of an earlier technology is arranged to connect a plus side of the dc output of a rectifier with a dc switch board or dc distribution board and to transmit electricity to contact line(s) or trolley wire(s) for railway, through a single pole dc circuit breaker. In the examples of the embodiment(s), by contrast, the arms for the respective phases of a rectifier are connected to a dc distribution or switch board individually without connecting together, and the currents of the phases are merged together into a dc output on the output side of a three pole dc circuit breaker.
A substation according to the embodiment is constructed as shown in
Although the positive side output line 40 is formed in the distribution board 100 in
Moreover, it is optional to form a connection point by connecting the second ends of main contacts 30a, 30b and 30c together, instead of forming the positive side output line 40.
A pulse-shaped current passing through a zero point flows in an arm of each phase of the rectifier 20, and the pulse-shaped current commutates sequentially among the arms. In the configuration of
In this way, the dc high speed vacuum circuit breaker 30 is arranged to cut off the current having a zero point generated by commutation. Therefore, the dc high speed vacuum circuit breaker 30 does not require a circuit for producing a current zero point forcibly as in the dc high speed vacuum circuit breaker of the earlier technology, and hence makes it possible to simplify the construction of the dc interruption apparatus, to facilitate the maintenance and inspection and to reduce the cost.
Following is explanation on practical examples in which the dc interruption apparatus according to the present invention is applied to railway dc substation facilities.
In
In
The output power of six-phase rectifier 20A is supplied to the electric car or railway vehicle 220 through the bus lines 110a, 110b and 110c in the dc distribution boards 100a and 100b, the main contacts 30a, 30b and 30c of dc high speed vacuum circuit breakers 30A and 30B, the positive side output lines 40a and 40b and the electric car lines 200a and 200b.
In this way, the bus lines 110a, 110b and 110c are provided so that one bus line is provided for each phase. Accordingly, it is possible to connect a plurality of the dc distribution boards (100a, 100b) and a plurality of the dc high speed vacuum circuit breakers (30A, 30B) in parallel, and to supply the electric power to a plurality of the loads (the electric car(s) 220 running along the electric car lines 200a, 200b) connected in parallel with respect to the six-phase rectifier 20A.
In
The phase currents Ia, Ib and Ic flowing through primary windings of the rectifier transformer 11A are shown in
As shown in
The dc high speed vacuum circuit breaker 30B can be operated in the same manner.
In a second practical example, the present invention is applied to a 12-phase rectifier (12 pulse rectifier) 20B as shown in
In
The output power of 12-phase rectifier 20B is supplied to the electric car or cars 220 through the bus lines 110a, 110b and 110c in the dc distribution boards 100a and 100b, the main contacts 30a, 30b and 30c of dc high speed vacuum circuit breakers 30A and 30B, the positive side output lines 40a and 40b and the electric car lines 200a and 200b.
In this way, the bus lines 110a, 110b and 110c are provided so that one bus line is provided for each phase. Accordingly, it is possible to connect a plurality of the dc distribution boards or distribution boards (100a, 100b) and a plurality of the dc high speed vacuum circuit breakers (30A, 30B) in parallel, and to supply the electric power to a plurality of the loads (the electric car(s) 220 running along the electric car lines 200a, 200b) connected in parallel with respect to the 12-phase rectifier 20B.
In
The phase currents Ia, Ib and Ic flowing through primary windings of the rectifier transformer 11B are shown in
As shown in
The dc high speed vacuum circuit breaker 30B can be operated in the same manner.
In the second practical example, the positive output ends of the same phase of the rectifiers 21A and 21B are connected together. Therefore, the current of rectifier 21A and the current of rectifier 21B are added for the same phase at the same timing. Accordingly, as shown in
The interruption timings of contacts 30a, 30b and 30c of the dc high speed vacuum circuit breaker 30A shown in
(1) First, at a time instant 0.410(s), for example, the electrodes of the main contacts 30a, 30b and 30c of the dc high speed vacuum circuit breaker 30A are opened. In this case, the current is already equal to zero at one of the three poles. In this example, the current Idc (the current flowing through the main contact 30c) is equal to zero as shown in
After the time instant 0.410(s), irregular 8 pulse currents continue flowing through the main contacts 30a and 30b of the remaining two poles.
(2) At a time instant 0.411(s), the interruption of current Ida is completed by the main contact 30a of the pole where the current becomes equal to zero first among the remaining two poles. After the time instant 0.411(s), the irregular 8 pulse current continues flowing through the main contact 30b of the remaining one pole.
(3) At a time instant 0.418(s), the main contact 30b of the last pole completes the interruption of current Idb at the current zero point of Idb.
In this way, the current interruption is completed at all the main contacts of the dc high speed vacuum circuit breaker 30A.
The dc high speed vacuum circuit breaker 30B is operated in the same manner.
In a third practical example, the present invention is applied to a 12-phase rectifier (12 pulse rectifier) 20C as shown in
In
The output power of 12-phase rectifier 20C is supplied to the electric car or cars 220 through the bus lines 110a, 110b and 110c in the dc distribution boards 100a and 100b, the main contacts 30a, 30b and 30c of dc high speed vacuum circuit breakers 30A and 30B, the positive side output lines 40a and 40b and the electric car lines 200a and 200b.
In this way, the bus lines 110a, 110b and 110c are provided so that one bus line is provided for each phase. Accordingly, it is possible to connect a plurality of the dc distribution boards or distribution boards (100a, 100b) and a plurality of the dc high speed vacuum circuit breakers (30A, 30B) in parallel, and to supply the electric power to a plurality of the loads (the electric car(s) 220 running along the electric car lines 200a, 200b) connected in parallel with respect to the 12-phase rectifier 20C.
In
The phase currents Ia, Ib and Ic flowing through primary windings of the rectifier transformer 11B are shown in
As shown in
In the third practical example, the positive output end of the rectifier 22A for each phase is connected with the positive output end of the rectifier 22B for another phase. Therefore, the currents from rectifiers 22A and 22B flow alternately at different timings. Accordingly, as shown in
Consequently, current zero points are generated more frequently at shorter periods (twice faster) and hence the apparatus can interrupt the current faster.
If, in the case in which a plurality of circuits are connected with the bus lines 110a, 110b and 110c in the configurations of
Accordingly, in the fourth practical example, back flow preventing diode or diodes are interposed between the output terminal of the circuit breaker and the current junction point (the positive side output line 40a, 40b).
Moreover, when the reactance contained in the load side dc circuit is greater than a predetermined value, the energy stored in the reactance dulls the interruption of the current at the time of interruption of great current such as short circuiting current, and thereby increases the time until the current zero point is reached.
To prevent this problem, in the fourth practical example, the current due to the residual energy in the reactance is separated from the current passing through the circuit breaker by a flywheel diode connected between the negative end of the rectifier and the positive side output line 40a, 40b.
A 12-phase rectifier 20D includes a rectifier 23A including an ac side connected with the star winding section on the secondary side of rectifier transformer 11C and a rectifier 23B including an ac side connected with the delta winding section on the secondary side of rectifier transformer 11C. The positive output ends (the cathode terminals of the diodes of the upper arms) of the rectifiers 23A and 23B for two different phases are connected together.
The bus lines 110a, 110b and 110c in the dc distribution board 100a are connected with the positive side output line 40a, respectively, through the main contacts 30a, 30b and 30c of the dc high speed vacuum circuit breaker 30A and the anode-cathode structures of back flow preventing diodes 50a, 50b and 50c.
The bus lines 110a, 110b and 110c in the dc distribution board 100b are connected with the positive side output line 40b, respectively, through the main contacts 30a, 30b and 30c of the dc high speed vacuum circuit breaker 30B and the anode-cathode structures of back flow preventing diodes 50a, 50b and 50c.
The back flow preventing diodes 50a, 50b and 50c may be provided in the distribution boards 100a, 100b or may be disposed outside the distribution boards 100a, 100b.
The negative ends of rectifiers 23A and 23B are connected to the positive side output line 40a through the anode-cathode structure of a flywheel diode 60A, and connected, through the anode-cathode structure of a flywheel diode 60B, to the positive side output line 40b. In
In this construction, the back flow preventing diodes 50a, 50b and 50c prevent the flow of currents from the positive side output lines 40a and 40b to the bus lines 110a, 110b and 110c of the respective phases. Therefore, the apparatus can prevent the voltage and current from flowing around from one circuit to another and maintain the independence of the voltage and current for each phase.
Furthermore, at the time of interruption of the dc high speed vacuum circuit breakers 30A, 30B, a current due to residual energy of the reactance L flows through the flywheel diode 60A or 60B without passing through the dc high speed vacuum circuit breakers 30A, 30B. Therefore, this configuration can prevent prolongation of the time until the current zero point.
The addition of backflow preventing diode or diodes 50a, 50b and 50c and the flywheel diode or diodes 60A, 60B is applicable to the dc substations shown in
The present invention is applicable not only to the six-phase rectifier and the twelve-phase rectifier, but also to other multiphase rectifiers. In this case, too, the same operations and effects can be achieved.
Number | Date | Country | Kind |
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2014-252506 | Dec 2014 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2015/083568 | 11/30/2015 | WO | 00 |