JP2010273405A - Uninterruptible power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the operation property of an uninterruptible power supply system equipped with a plurality of uninterruptible power units that operate, in parallel or two sets of uninterruptible power systems, consisting of uninterruptible power sources of independent operation and is equipped with a plurality of cross boards that perform power supply, from either of the two sets of uninterruptible power systems to a corresponding load. <P>SOLUTION: In the embodied uninterruptible power supply system, each of high-speed cross boards is constituted of two sets of thyristor switches, two CTs, and two sets of change-over control circuits to lessen the disturbance of a voltage across a load concerned, as compared with conventional types, by controlling a lapping period when power is supplied simultaneously from both uninterruptible power supply systems via the change-over control circuit not only at maintenance but also at normal switching of power supply path to the load by auxiliary CTs 71, 72 and 75, shunt resistors 73 and 74, arithmetic elements 76 and 78, resistors 77, 79 and PT80, a power arithmetic circuit 81, and a switch-off determining circuit 82, which constitute each of the two sets of change-over control circuits. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention comprises two uninterruptible power supply systems consisting of a plurality of uninterruptible power supplies operated in parallel or a single-machine uninterruptible power supply, and either one of the two uninterruptible power supply systems is connected to a corresponding load. The present invention relates to an uninterruptible power supply system including a plurality of switching boards for supplying power.

  FIG. 8 is a circuit configuration diagram showing a conventional example of this type of uninterruptible power supply system including the configuration of Patent Document 1 below.

  In this figure, 10 is a 1-system power system composed of a commercial power system and private power generation facilities, and 11 to 14 are uninterruptible power supplies (hereinafter referred to as UPS 11 to UPS 14) that form a 1-system uninterruptible power supply. This 1-system power system and 1-system UPS form a 1-system uninterruptible power supply system. Similarly, 20 is a two-system power system composed of a commercial power system and private power generation facilities, and 21 to 24 are uninterruptible power sources forming a two-system uninterruptible power supply (hereinafter referred to as UPS 21 to UPS 24, and these are generic names). The 2 system UPS and the 2 system UPS form a 2 system uninterruptible power system. Reference numeral 31 denotes a system control circuit that controls the operation system of the entire uninterruptible power supply system.

  In this 1-system uninterruptible power supply system, each of the UPSs 11 to 14 includes a bypass circuit that performs direct power feeding from the 1-system power system 10 and also has a function of operating in parallel with each other. Similarly, in the 2 system uninterruptible power supply system, each of the UPS 21 to UPS 24 is provided with a bypass circuit that performs direct power feeding from the 2 system power system 20 and also has a function of operating in parallel with each other.

  The high-speed switching panel 40 is formed of thyristor switches 41 and 42 as high-speed switches and a switching command circuit 43, and supplies power to the load A (100) by a command from the system control circuit 31 to the switching command circuit 43. It has a function to perform from the 1 system uninterruptible power system or the 2 system uninterruptible power system. Similarly, the high-speed switching board 50 is formed of thyristor switches 51 and 52 as high-speed switches and a switching command circuit 53, and supplies power to the load B (200) by a command from the system control circuit 31 to the switching command circuit 53. It has a function to perform from the 1 system uninterruptible power system or the 2 system uninterruptible power system.

  In either of the high-speed switching boards 40 and 50, for example, the power supply switching of the load corresponding to the system 2 uninterruptible power system from the system 1 uninterruptible power system can be performed at high speed using the illustrated thyristor switch. In preparation, the output voltages of the uninterruptible power supply systems are phase-synchronized with each other.

  Moreover, for the above-mentioned, each component in the uninterruptible power supply system shown in FIG. 8 is formed using a well-known technique.

JP 2007-306643 A

  In this type of uninterruptible power supply system, for example, in order to perform maintenance of each uninterruptible power supply without stopping power supply to each load, for example, one system It is required to switch the power supply of the load corresponding to the uninterruptible power system 2 from the uninterruptible power system.

  However, in the conventional uninterruptible power supply system shown in FIG. 8, in either of the high-speed switching panels 40 and 50, for example, the power supply switching of the load corresponding to the 2-system uninterruptible power system from the 1-system uninterruptible power system is performed. When the 1-system switch and the 2-system switch shown in FIG. 9A as the thyristor switch shown in FIG. 8 are used, a slight overlap period is provided between both switches as shown in FIG. 9A. As shown in FIG. 9A, a large disturbance may occur in the output voltage of the uninterruptible power supply system, which is the voltage across the load at this time.

  That is, this voltage disturbance causes the load sharing power to change abruptly as shown in FIG. 10, so that the output current from the uninterruptible power supply system 2 rapidly increases as shown in FIG. This is due to the voltage drop caused by the wiring impedance of the uninterruptible power system.

  An object of the present invention is to provide a system that can further reduce disturbance of the output voltage of the uninterruptible power supply system even when the power supply path to the load is switched as shown in FIG. 9B.

This first invention comprises two uninterruptible power supply systems comprising a plurality of uninterruptible power supplies operated in parallel or a single-machine uninterruptible power supply, and corresponds to either one of the two uninterruptible power supply systems. In the uninterruptible power supply system comprising a plurality of switching panels for supplying power to the load, the output voltages of the uninterruptible power supply systems being phase-synchronized with each other,
When switching the power supply path of the load corresponding to the other uninterruptible power system from each uninterruptible power system by the respective switching boards, first, the power is supplied to the corresponding load simultaneously from both power supply paths. A lap period control function for controlling the period of simultaneous power feeding based on the load power from time, the change in the shared power of the one uninterruptible power system, and the cross current component between the two uninterruptible power systems It is characterized by having.

Moreover, 2nd invention is the uninterruptible power supply system of said 1st invention,
The wrap period control function detects current output means for detecting an output current of each uninterruptible power supply system during simultaneous power feeding, current derivation means for deriving a load current at this time, and detects an output voltage to the load Voltage detecting means, a power calculation circuit for calculating load active power, cross current active power and cross current reactive power based on the output current, load current and load voltage, load active power, cross current active power and cross current reactive power And a switch-off determination circuit for ending the simultaneous power supply period.

  According to the present invention, since the uninterruptible power supply system is provided with the wrap period control function, the load voltage can be changed not only during maintenance, but also when switching the power supply path to the load during normal operation. An uninterruptible power supply system with less disturbance can be provided.

Circuit configuration diagram of an uninterruptible power supply system showing an embodiment of the present invention Partial detailed circuit configuration diagram of FIG. Partial detailed circuit configuration diagram of FIG. Part detailed flowchart of FIG. Characteristic diagram for explaining the operation of FIG. Characteristic diagram for explaining the operation of FIG. Characteristic diagram for explaining the operation of FIG. Circuit diagram of uninterruptible power supply system showing conventional example Waveform diagram explaining the operation of FIG. Characteristic diagram for explaining the operation of FIG.

  FIG. 1 is a circuit configuration diagram of an uninterruptible power supply system showing an embodiment of the present invention. Components having the same functions as those of the conventional configuration shown in FIG. 8 are denoted by the same reference numerals.

  That is, in FIG. 1, in the 1-system UPS and the 2-system UPS, the UPS 11 to UPS 14 and the UPS 21 to UPS 24 are all of the same specifications and capacity, and the output voltages of the 1-system UPS and the 2-system UPS are mutually different. The phase is synchronized. Reference numeral 32 denotes a system control circuit that controls the operation system of the entire uninterruptible power supply system.

  Further, the high-speed switching board 44 is formed by thyristor switches 41 and 42, CTs (current transformers) 45 and 46, and switching control circuits 47 and 48, and the system control circuit 32 to the switching control circuit 47 and the switching control circuit 48. In response to the command, a high-speed switch function for supplying power to the load A (100) from the 1-system uninterruptible power system or the 2-system uninterruptible power system is provided. Similarly, the high-speed switching board 54 is formed of thyristor switches 51 and 52, CT 55 and 56, and switching control circuits 57 and 58. In response to a command from the system control circuit 32 to the switching control circuit 57 and the switching control circuit 58, It has a high-speed switch function for supplying power to the load B (200) from the 1-system uninterruptible power system or the 2-system uninterruptible power system. In this figure, thyristor switches 41, 42, 51, and 52 are shown as an example of a high-speed switch. However, a hybrid in which a circuit breaker is connected in parallel with the thyristor may be used, or an IGBT may be used.

  FIG. 2 is a detailed circuit configuration diagram relating to the high-speed switching board 44 in the uninterruptible power supply system shown in FIG.

  Each of the switching control circuits 47 and 48 includes auxiliary CTs 71 and 72, shunt resistors 73 and 74, auxiliary CT75, arithmetic elements 76 and 78, resistors 77 and 79, PT (transformer) 80, a power arithmetic circuit 81, And a switch-off determination circuit 82.

  Here, since the secondary side of the auxiliary CT 72 in the switching control circuit 47 and the secondary side of the auxiliary CT 72 in the switching control circuit 48 are connected to each other by a connecting line, an added value of the current flowing in CT45 and CT46, That is, a load current flowing through the load A is obtained. Accordingly, the circuit configuration including the shunt resistors 73 and 74, the auxiliary CT 75, the arithmetic element 76, and the resistor 77 corresponds to the load current at the output of the arithmetic element 76. A voltage value can be obtained. Further, a current value flowing through CT45 or CT46, that is, a voltage value corresponding to the output current of the 1-system UPS or the 2-system UPS can be obtained as the output of the arithmetic element 78.

  FIG. 3 is a detailed circuit configuration diagram of the power calculation circuit 81 in the switching control circuits 47 and 48 shown in FIG.

  The power calculation circuit 81 includes a load power calculator 81a for calculating the load active power from the output voltage of the uninterruptible power supply system, which is the voltage across the load A obtained by the PT 80 shown in FIG. , A multiplication calculator 81b for deriving a half value of the load current, a subtraction calculator 81c for obtaining a difference between the half value of the load current and the output current, that is, a cross current under this condition, A cross current power calculator 81d for calculating a cross current active power and a cross current reactive power from the cross current and the output voltage is provided.

  As described above, the difference between the half value of the load current and the output current is defined as the cross current in the uninterruptible power supply system. When the load sharing power of the uninterruptible power supply system becomes substantially equal, that is, when the output current at the switching destination increases to become half the load current and the cross current becomes zero, This is because an uninterruptible power supply system with less disturbance of the load voltage can be provided by completing the switching operation.

  The circuit configuration shown in FIG. 2 shows one phase of the uninterruptible power supply system. Therefore, when the uninterruptible power supply system has a three-phase output, the components 71 to 80 in the switching control circuits 47 and 48 are shown. The power calculation circuit 81 performs three-phase power calculation and includes load active power (three-phase power value), cross-current active power (three-phase power value), and cross-current reactive power (three-phase power value). Should be output. Further, the high-speed switching board 54 has the same circuit configuration as that of FIG.

  In the following, regarding either the high-speed switching board 44 or the high-speed switching board 44, for example, the operation when switching the power supply of the load corresponding to the other uninterruptible power supply system from one uninterruptible power supply system will be described. The operation will be described with reference to the flowchart of FIG.

  FIG. 5 shows an example of switching the power supply of the load A from the state in which the load A is supplied from the system 1 uninterruptible power system to the system 2 uninterruptible power system in the uninterruptible power system shown in FIG. FIG. 6 is a characteristic diagram for explaining the operation of FIG. 2 and shows a switching state when the wiring impedance of the 1-system uninterruptible power supply system and the wiring impedance of the 2-system uninterruptible power supply system are substantially equal.

  As commands from the system control circuit 32 to the switching control circuit 47 and the switching control circuit 48, first, the switching control circuit 48 receives the switch-on command and turns on the thyristor switch 42, and the switching control circuit 47 issues a switch-off command. Received (FIG. 4, step S1, branch Y), the burden power value of the 1-system uninterruptible power supply system at this time is obtained from the output value from the power calculation circuit 81 of the switching control circuit 47 (step S2).

  The burden power value is obtained by subtracting the cross current active power output from the power calculation circuit 81 from ½ of the load active power output from the power calculation circuit 81.

  Next, in step S3, the change of the burden power value obtained in step S2 with the previous value is monitored, and as shown in FIG. 5, the burden power of the 1-system uninterruptible power supply system is in a decreasing state. (Branch Y), the process proceeds to step S4.

  In step S4, the burden power value obtained in step S2 is a predetermined determination value, for example, a value obtained by adding 10% of the load active power to ½ of the load active power output from the power calculation circuit 81, That is, when the value is equal to or less than the determination value set to about 0.6 times the load active power (branch Y), the process proceeds to step S7, the thyristor switch 41 is turned off, and a timer described later is reset in step S8. As a result, when the load sharing power of both uninterruptible power supply systems becomes substantially equal, as shown in FIG. 5, the disturbance of the load voltage can be further reduced by completing this switching operation.

  In step S4, when the burden electric power value obtained in step S2 has not decreased to the determination value (branch N), the process proceeds to steps S5 and S6 described later.

  FIG. 6 shows an example of switching the power supply of the load A from the state where the load A is supplied from the system 1 uninterruptible power system to the system 2 uninterruptible power system in the uninterruptible power system shown in FIG. FIG. 6 is a characteristic diagram for explaining the operation of FIG. 2 and shows a switching state when the wiring impedance of the 2-system uninterruptible power supply system is larger than the wiring impedance of the 2-system uninterruptible power supply system.

  As commands from the system control circuit 32 to the switching control circuit 47 and the switching control circuit 48, first, the switching control circuit 48 receives the switch-on command and turns on the thyristor switch 42, and the switching control circuit 47 issues a switch-off command. Received (step S1, branch Y), the burden power value of the 1-system uninterruptible power supply system at this time is obtained from the output value from the power calculation circuit 81 of the switching control circuit 47 (step S2).

  Next, in step S3, the change of the burden power value obtained in step S2 with the previous value is monitored, and as shown in FIG. 6, the burden power of the 1-system uninterruptible power supply system is in a decreasing state. (Branch Y), the process proceeds to step S4.

  In step S4, when the burden electric power value obtained in step S2 has not decreased to the determination value (branch N), the process in step S7 is not performed as a process result in steps S5 and S6 described later ( S5, branch N, S6, branch N), the process returns to step S2.

  In step S3 in a state in which the route from step S2 to step S7 is repeated, as shown in FIG. 6, the change in the shared power value is caused by the difference in the wiring impedance between the two uninterruptible power systems. When there is no more (branch N), it moves to step S9.

  In this step S9, this switching operation is started, and when this step S9 is entered for the first time (branch N), the process proceeds to step S10 and a timer for measuring the stable time (about 40 milliseconds) shown in FIG. 6 is set. If the timer has already started the measurement operation (branch Y), the process proceeds to step S11.

  In step S11, when the timer has reached the stable time (branch Y), the process proceeds to step S7, the thyristor switch 41 is turned off, and the timer is reset in step S8, as shown in FIG. This switching operation is completed, and the disturbance of the load voltage at this time can be further reduced.

  If the timer has not reached the stable time in step S11 (branch N), the process in step S7 is not performed as a result of processing in steps S5 and S6 described later (S5, branch N, S6, branch). N) Return to step S2.

  FIG. 7 shows an example of switching the power supply of the load A from the state where the load A is supplied from the system 1 uninterruptible power system to the system 2 uninterruptible power system in the uninterruptible power system shown in FIG. FIG. 6 is a characteristic diagram for explaining the operation of FIG. 2, and shows a switching state when electric power is injected from the 1-system uninterruptible power supply system to the 2-system uninterruptible power supply system at the time of switching.

  As commands from the system control circuit 32 to the switching control circuit 47 and the switching control circuit 48, first, the switching control circuit 48 receives the switch-on command and turns on the thyristor switch 42, and the switching control circuit 47 issues a switch-off command. Received (step S1, branch Y), the burden power value of the 1-system uninterruptible power supply system at this time is obtained from the output value from the power calculation circuit 81 of the switching control circuit 47 (step S2).

  Next, in step S3, the change of the burden power value obtained in step S2 with the previous value is monitored, and as shown in FIG. 7, the burden power of the 1-system uninterruptible power supply system is in an increasing state. (Branch Y), the process proceeds to step S4.

  This increased state is a state in which a phase difference and a voltage difference power are generated between the output voltage of the 1-system uninterruptible power system and the output voltage of the 2-system uninterruptible power system due to some factor. This is due to the fact that active power is being injected from the system into the 2-system uninterruptible power supply system.

  In step S4, since the burden power value obtained in step S2 has increased (branch N), the process moves to step S5, and when this burden power value exceeds the determination value as shown in FIG. At this time, the cross current active power value from the power calculation circuit 81 exceeds the load active power value from the power calculation circuit 81, or the cross current active power value is negative, and the absolute value thereof is the load active power value. When the value corresponds to 10% (branch Y), the process proceeds to step S7, the thyristor switch 41 is turned off, and the timer is reset in step S8.

  As a result, it is possible to avoid an abnormal situation such as an increase in the intermediate DC voltage inside each UPS due to a long lap period between the 1-system uninterruptible power system and the 2-system uninterruptible power system.

  Although the switching state is not illustrated, in step S6 after passing through the path of steps S2 to S5 or the paths of steps S2, S3, S9 to S11, and S5, the cross-flow reactive power value from the power calculation circuit 81 at this time Is over a predetermined reference value, for example, a value corresponding to 10% of the load active power value at this time (branch Y), the process proceeds to step S7, the thyristor switch 41 is turned off, and in step S8 the above-mentioned Reset the timer.

  This processing is in a state where a phase difference and voltage difference power are generated between the output voltage of the 1-system uninterruptible power system and the output voltage of the 2-system uninterruptible power system for some reason, and the 1-system uninterruptible power system In order to avoid an abnormal situation that occurs when reactive power is exchanged between the system 2 and the uninterruptible power supply system 2 and this state becomes longer.

  According to the uninterruptible power supply system of the present invention, since the CT 45, 46, 55, and 56 and the switching control circuits 47, 48, 57, and 58 are provided, the power supply path to the load at the normal time as well as during maintenance is provided. When switching between, the uninterruptible power supply system with less disturbance of the load voltage can be provided as compared with the prior art.

  DESCRIPTION OF SYMBOLS 10 ... 1 system power system, 11-14 ... Uninterruptible power supply, 20 ... 2 system power system, 21-24 ... Uninterruptible power supply, 31, 32 ... System control circuit, 40, 44, 50, 54 ... High speed switching board, 41, 42, 51, 52 ... thyristor switch, 43, 53 ... switching command circuit, 45, 46, 55, 56 ... CT, 47, 48, 57, 58 ... switching control circuit, 71, 72 ... auxiliary CT, 73, 74 ... Shunt resistance, 75 ... Auxiliary CT, 76, 78 ... Arithmetic element, 77, 79 ... Resistance, 80 ... PT, 81 ... Power calculator, 82 ... Switch-off determination circuit.

Claims (2)

Two sets of uninterruptible power systems consisting of multiple uninterruptible power supplies operated in parallel or single-unit uninterruptible power supplies, and switching to supply power to the corresponding load from either one of these two uninterruptible power systems In the uninterruptible power supply system comprising a plurality of panels, the output voltages of the uninterruptible power supply systems being phase-synchronized with each other,
When switching the power supply path of the load corresponding to the other uninterruptible power supply system from one uninterruptible power supply system by the respective switching boards,
First, power is supplied simultaneously to the corresponding load from both power supply paths, the load power from this time, the change in the shared power of the one uninterruptible power system, and the cross current component between the two uninterruptible power systems Based on the above, an uninterruptible power supply system comprising a lap period control function for controlling the period of simultaneous power feeding. In the uninterruptible power supply system according to claim 1,
The lap period control function is:
Current detecting means for detecting the output current of each uninterruptible power supply system during simultaneous power feeding, current deriving means for deriving a load current at this time, voltage detecting means for detecting an output voltage to the load, and A power calculation circuit that calculates load active power, cross current active power, and cross current reactive power based on output current, load current, and load voltage, and the simultaneous power supply based on the load active power, cross current active power, and cross current reactive power An uninterruptible power supply system formed from a switch-off determination circuit for ending a period.

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