JP3927907B2 - Rotary dynamic system power distributor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates generally to power switching systems, and more particularly to a reliable sub-cycle power switching / distribution system capable of supporting loads that are greatly affected by power interruption.
[0002]
[Description of Background Art]
Buildings with large computer centers require large amounts of power. In the case of a backbone computer that needs to have a power source that needs to continuously supply constant power, it is more difficult to efficiently supply appropriate power to the building.
[0003]
Conventionally, power has been supplied to a main computer from a power circuit of an uninterruptible power supply (UPS). The UPS circuit monitors the power supply to the computer (that is, the circuit load), and switches to a standby power source such as a battery and supplies the power to the circuit load in the event of a power failure. From the perspective of the computer, the power can be kept running without any loss of power.
[0004]
Very important data center computer equipment is powered by two UPS systems and two UPS power distribution systems. Although such a system is redundant, it supplies power to the data processing device from the backup UPS system and the power transmission path, while maintaining the system, or against failure or malfunction in one power transmission path. It becomes possible to deal with it.
[0005]
This system architecture is referred to as a “system plus system” design. In electrical terms, as close to the critical load as possible, by equipping a switching device, typically a static changeover switch (STS), the main power source for the critical load, ie, the regular power source and the standby power source That is, it becomes possible to select an alternative power source. Typically, this switch is located in a power divider (PDU) that supplies power to the computer device. A typical PDU includes at least one step-down transformer and a distribution panel. The transformer converts the UPS's 480 volt power output to the 208/120 volt required by the computer equipment. If a static switch is installed in front of the transformer, only one transformer is required, but if a static switch is installed after the transformer, two transformers are required. .
[0006]
As described above, in the conventional important power distribution circuit, power is switched between the main power supply and the standby power supply using the power switching circuit. At the center of such a conventional power switching circuit is a static changeover switch (STS). The STS automatically switches the system power supply from the main power supply to the standby power supply when the main power supply fails. In general, STS circuits are designed using silicon controlled rectifier (SCR) power switching elements. In other words, the semiconductor element is used for quickly switching the power supply destination from the main power source to the standby power source.
In general, STS-based circuits are highly reliable in that they continue to supply power to critical applications in the event of a main power failure, but they are still vulnerable because the STS circuit itself can fail. It is.
[0007]
A typical STS mean time between failures (MTBF) is 400,000 hours. Although it may seem like a long time, the more STS equipped on a site, the lower the overall reliability of that site proportionally. For example, at a site equipped with 20 STSs, the overall system MTBF is about 20,000 hours (slightly shorter than 2.5 years). MTBF in a large-scale data center equipped with 50 or more is less than one year. For modern data centers that are designed to run 24 hours a day throughout the year, this failure rate is very severe.
[0008]
Accordingly, there is a need in the art to provide a highly reliable switching circuit that switches power supply from a main power source and a backup power source to a target load.
[0009]
[Means for Solving the Problems]
The system and method harmonize with the principles of the present invention that address the previously raised needs by providing an improved power distributor that powers critical equipment that requires uninterruptible power. .
[0010]
According to one aspect of the present invention, a power distributor comprising a plurality of elements is provided. The element monitors the synchronous motor generator, the first and second mechanical switches, the regular input power supply and the alternative input power supply, and opens the first mechanical switch when a malfunction is detected in the regular power supply. And a transfer logic circuit configured to reverse the switching state of the first and second mechanical switches to close the second mechanical switch.
[0011]
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention along with the description, objects, advantages, and principles of the invention. The same or similar parts in the drawings are denoted by the same reference numerals.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In the following detailed description, reference is made to the accompanying drawings, which illustrate embodiments of the invention. Other embodiments are possible and modifications may be made to the embodiments without departing from the spirit and scope of the present invention. Accordingly, the following detailed description does not limit the invention. Rather, the scope of the present invention is defined by the appended claims.
[0013]
As described herein, power is delivered to a target load such as an important computer system by a power divider (PDU). The PDU has a main power source and a standby power source, and can be switched to the standby power source when a problem occurs in the normal power source. Power is sent to the target load so that the target load can operate continuously as if there was no interruption of power. In PDUs, rotary technology can be used in the form of a synchronous motor generator set that includes a flywheel to provide a “transition” of power switching.
[0014]
FIG. 1 is a single line wiring diagram showing components of a power divider (PDU) according to the present invention.
[0015]
During normal operation, the PDU 100 receives power input from two individual power sources, which are named as a normal power source “A” 101 and an alternative power source “B” 102. This input power is sent from one of the two 400 amp circuit breakers 105,106. Generally, the power from the power supplies 101, 102 is 480 volts.
[0016]
Contactors 111 and 112 are standard three-pole mechanical switches that are operated by electrical signals under the control of transfer logic 110. The line sides of the contactors 111 and 112 are connected to the power source, and the load side is connected to the motor generator 115. When the service power supply 101 fails, the transfer logic 110 controls the contactors 111 and 112 to switch to the alternative power supply 102.
[0017]
The transfer logic 110 performs control based on input information from the detection device. In particular, the current transformer (CT) 140 and the instrument transformer (PT) 141 are located at the output of the generator 121 ahead of the contactors 111 and 112, and (a) the common input power supply 101 and the alternative input power supply 102 (B) to find out abnormalities such as insufficient voltage and overcurrent occurring at the tip of the input power supplies 101 and 102 and the output section of the generator 121. Synchronous motor generator 115 is indicated by peripheral components 116-122 within the dotted line in FIG.
[0018]
Components 116-122 include contactors 116, 117, start / execute logic 118, pony start motor 119, synchronous motor 120, generator 121 and flywheel 122.
[0019]
The motor generator 115 performs two functions of the PDU 100. That is, (1) 480 volt input power is transformed into 208/120 volt power normally required by the load device, and (2) transiting when switching from the normal power source 101 to the alternative power source 102 (or vice versa) It is easy to do.
[0020]
Occasionally, the synchronous motor generator 115 may need to be taken offline for repair or maintenance. In that situation, the circuit breakers 127, 128 are activated and the bypass control circuit 126 is used to pass power from either the motor generator 115 or the transformer 125 and the power path from the active power source is stepped down. Determined by transformer 125. Similar to transformer 125, synchronous motor generator 115 converts input power to 208/120 volt power used at the output. However, at the time of a power failure, the transformer 125 cannot continue the stable power supply.
[0021]
Finally, the electric power from the motor generator 115 or the transformer 125 passes through the circuit breaker 130 and is sent to the circuit distribution panel to which the load device is connected. The circuit distribution panel may be, for example, a 225 ampere, 3 pole 4 wire 42 circuit distribution panel.
[0022]
(Normal operation)
Next, normal operation of the PDU 100 will be described. In normal operation, power is supplied to the contactor switch 111 from the service power source 101 through the circuit breaker 105. When the contactor switch 111 is closed, power can be sent to the synchronous motor generator 115. Conversely, when the contactor 112 is opened, the power supply from the alternative power source 102 to the motor generator 115 is cut off. At this time, when the bypass transformer 125 is not used, the circuit breakers 107 and 108 are preferably set to open.
[0023]
In the synchronous motor generator 115, the contactor 116 is opened, the contactor 117 is closed, input power is supplied to the motor 120, and the generator 121 rotates. When connected as shown in FIG. 1, the motor 120 and generator 121 transform 480 volt input power to 208/120 volt output power, which is applied to circuit breaker 128 and circuit breaker group 130. And is supplied to the output circuit distribution panel and the target load. Since the motor 120 and the generator 121 are mechanically connected, there is a complete electrical separation between the power input to the motor and the power output from the generator to the backbone computer equipment load.
[0024]
Further, the motor 120 supplies power to the flywheel 122. The flywheel 122 supplies backup power to the generator for a short period when the input power of the generator 121 is interrupted. Flywheels are well known in the art. Generally, a flywheel stores energy as mechanical kinetic energy by rotation of the flywheel. When power to the generator 121 is interrupted, the generator 121 converts the kinetic energy of the rotating flywheel into electrical energy until a stable power supply is obtained online.
[0025]
(Operation during power transmission)
The transfer logic circuit 110 monitors whether there is a problem with the input power supply by using the current transformer 140 and the instrument transformer 141. When a failure such as power interruption or sudden decrease is detected, the transfer logic 110 opens the contactor switch 111 and simultaneously closes the contactor switch 112 to start switching to the alternative power supply 102. .
[0026]
The three-pole mechanical contactor is characterized in that since it takes time to close the contactor, an electric circuit is formed, and the contactor is opened by the circuit to interrupt the electric circuit. Therefore, when the electrical signal for opening the contactor 111 and closing the contactor 112 is output from the transfer logic 110, the contactor 111 opens before the contactor 112, so that the power supplies 101 and 102 are electrically connected. Is reliably separated.
[0027]
The contactors 111 and 112 are available as 400 ampere tripolar contactors. This contactor can be purchased from several companies such as General Electric. Contactor “pickup” (PU) time (ie, elapsed time to close) is 110 to 115 milliseconds, and “dropout” (DO) time (ie, elapsed time to open) is 70 to 80 milliseconds. Seconds. PU is obtained by applying voltage to the working coil and measuring from the end of operation of the contactor armature, DO is measuring from turning off the voltage of the working coil to the end of operation of the contactor armature Obtained by. When the transfer logic circuit 110 turns off the voltage of one contactor coil and simultaneously applies a voltage to the coil of the other contactor, the power supply is turned off because at least 30 milliseconds elapse between the contactor opening and closing. Securely separated.
[0028]
The transfer logic 110 is configured not to be sensitive to undervoltage or overcurrent conditions downstream of the system, but to be sensitive only to an undervoltage downstream of the contactor switches 111, 112, ie, a single phase condition.
[0029]
The interruption of power caused by a delay prior to switching the alternative power source 102 to the motor generator 115 may cause the synchronous motor 120 to lose synchronization with the input power. The pony motor 119 is used for resynchronization with the motor 120. The start / execute logic 118 closes the contactor 116 when the motor 120 loses synchronization and power is supplied to the pony motor 119 and then the motor 120 detects resynchronization with the input power. At this time, the start / execute logic 118 opens the contactor 116 and supplies power to the pony motor 119.
[0030]
While the alternate power source is supplied online and the motor 120 is resynchronizing, the flywheel 122 supplies energy to the generator 121 and the generator 121 supplies the available power for the target load. You can continue. From the viewpoint of the target load, power is not interrupted even for a moment.
[0031]
During the transmission process described above, the frequency of the generator 121, which typically generates 60 Hertz power, can decay to about 59.5 Hertz. This decay lasts for approximately 6 Hertz (1/10 second) until the alternate power is supplied online and the motor 120 is resynchronized. The frequency returns to normal within an additional 15 seconds and never falls below the minimum input requirements of the load (eg, computer device).
[0032]
Unlike power distributors based on static transfer switches that completely cease power during operation for 4-8 milliseconds, PDU 100 does not interrupt power. At the time of a power failure, the generator 121 continues to generate electric power by increasing or decreasing the voltage of only about 1 volt.
[0033]
(Operation during maintenance)
The motor generator 115 may be manually removed from the electrical circuit of FIG. 1 for maintenance and inspection. In particular, when circuit breakers 105, 106, 128 are opened, motor generator 115 is electrically isolated from the system. Prior to isolating the motor generator 115, the supply of power is routed to the transformer 125 via the circuit breaker 107 or 108. The transformer 125 may be a delta-wy step-down transformer that transforms 480 volt input power to 208/120 volt output power. The bypass control circuit 126 controls switching from the motor generator 115 to the transformer 125.
[0034]
In a delta star transformer, a phase shift (eg, a 30 degree phase shift) is inserted between the input voltage and the output voltage. When the transformer 125 is a delta star type transformer, it is necessary to insert a phase shift into the output of the motor generator 115 to match the output of the transformer.
[0035]
(Physical implementation)
FIG. 2 is a diagram illustrating a physical layout of the PDU 100. As shown, the proposed PDU unit is 82 inches high and 210 inches long. The PDU depth may be 38 inches. These dimensions are just an example, and one skilled in the art can appreciate that other equivalent PDUs can be constructed with other dimensions. Normally, the PDU 100 is installed in a building near the target load.
[0036]
Synchronous motor generators such as synchronous motor generator 115 are well known in the art. One such motor generator manufacturer is Kato Manufacturing, Mankato, Minnesota. If a phase shift is needed to match the phase shift inserted by the transformer 125, the Kato motor generator may be modified with non-standard windings to insert the phase shift.
[0037]
Above, we explained a power distribution module that does not worry about power outages. In a PDU, an internal backup energy source such as a flywheel is used to easily and reliably switch from a main power source to a standby power source in the event of a power failure. Furthermore, the PDU can realize a high-reliability operation without depending on the semiconductor static changeover switch, and can be configured by off-the-shelf parts that can be easily purchased.
[0038]
Although returning to the use of mechanical switching devices instead of static switching devices may seem like a regression, the reliability of mechanical devices is higher than the reliability of their electronic equivalents. During the operation of the mechanical switch, only a “transfer” of power is required. This is supplied from a synchronous motor generator inserted in the power circuit between the switching device and the critical load equipment. As the voltage is stepped down, the motor operates at 480 volts when the generator generates 208/120 volts of power. This replaces the standard PDU transformer.
[0039]
While the preferred embodiments of the invention have been illustrated and described, they are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Corrections and changes can be made in harmony with the above teachings, or corrections and changes can be made based on embodiments of the present invention. For example, while converting 480 volt power to 120 volt power has been described, those skilled in the art will understand that a given level can be easily changed based on the power requirements of a particular site. Can do. It is also clear that the number of power supplies is not limited to two. More than two power sources can be used within the scope of the present invention. The scope of the invention is defined by the claims and their equivalents.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing components of a power distributor according to the present invention.
FIG. 2 is a diagram illustrating a physical layout of a power distributor.

Claims (9)

A synchronous motor generator having a power input wiring for receiving power and a power output wiring for sending power, storing energy received from the power input wiring and causing a wiring failure of the received input power The synchronous motor generator, which sends the stored energy to the power output wiring;
A first mechanical switch connected to a utility power source and the power input wiring of the synchronous motor generator;
An alternative power source and a second mechanical switch connected to the power input wiring of the synchronous motor generator;
The first and second mechanical types are configured to monitor the normal power source and the alternative power source and open the first mechanical switch and close the second mechanical switch when a failure of the normal power source is detected. Configured to reverse the switching state of the switch ,
A power distribution panel connected to the output wiring of the synchronous motor generator;
One input part of a step-down transformer is connected to the normal power supply and the alternative power supply via a circuit breaker, and further includes the step-down transformer to which the power distribution panel is connected to the output part.
A power distributor including a transfer logic circuit. Further comprising a power divider of claim 1 bypass control circuit configured to perform a route pickled supply power to one of said step-down transformer and the synchronous motor generator. The power distributor according to claim 1, wherein the electric power received by the synchronous motor generator is 480 volts, and the synchronous motor generator transforms the received electric power to 120 volts through an output wiring of the synchronous motor generator. The power distributor of claim 1, wherein the energy stored by the synchronous motor generator is stored as kinetic energy by a flywheel. The transfer logic circuit simultaneously sends signals to the first and second mechanical switches when the switching states of the first and second mechanical switches are reversed. The power distributor of claim 1, wherein the primary power switch and the alternative power supply are reliably separated by opening the first mechanical switch before the switch is closed. A first power source;
A second power source;
A first three-pole mechanical switch connected to the first power source on the line side;
A second three-pole mechanical switch to which the second power supply is connected on the line side;
A synchronous motor generator system including a motor, a generator, and a flywheel, wherein an input portion of the synchronous motor generator is connected to a load side of the first and second mechanical switches, and the first and second The synchronous motor generator system that receives electric power from the first and second power sources via two mechanical switches and outputs a transformed version of the received electric power;
Configured to monitor the first power supply and connected to a transformer / current transformer located in front of the first and second mechanical switches and at the output of the motor generator A transfer logic comprising the transfer logic that simultaneously outputs a command for reversing the switching states of the first and second mechanical switches when the transfer logic detects a failure of the first power supply. ,
By simultaneously outputting the command, the power received by the synchronous motor generator is temporarily interrupted, and the generator of the synchronous motor generator generates power from the energy stored in the flywheel. it allows to compensate for the temporary interruption of the power, continue to output the electric power supplied from said synchronous motor generator as an available power,
further,
A power distribution panel connected to the output of the synchronous motor generator;
Including one step-down transformer connected to the first and second power sources via a circuit breaker, and one output portion connected to the power distribution panel;
Power distributor. The power distributor of claim 6 , further comprising a bypass control circuit configured to route power supply from the utility power source A or the alternative power source B to the step-down transformer and the synchronous motor generator. . The power distributor of claim 6 , wherein the power received by the synchronous motor generator is 480 volts, and the synchronous motor generator transforms the received power to an output power of 120 volts. When the switching states of the first and second mechanical switches are reversed, the first mechanical switch opens before the second mechanical switch closes, so the first power source and the second mechanical switch The power divider of claim 6 , wherein the power sources of the are reliably separated.

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