JP2008220136A - Protection relay system of distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protection relay system of a distribution system capable of surely and easily achieving protection coordination in the event of a power failure/power restoration and of having flexibility in a throwing order and selective interruption for loads. <P>SOLUTION: The mode switch setting function of a digital relay A enables selective interruption setting and throwing order setting by digital relays B to switch to a host computer C. The load current holding function of the digital relay A holds the load current immediately before power failure occurrence obtained from respective digital relays B, enabling to select loads thrown in a sequential order after starting an emergency generator due to the power failure occurrence. The load current value diagnosis function of each digital relay B identifies that rush current and load current are stabilized, thereby protecting a false protective operation when power is restored. When there is a load with an abnormal current value, the selective interruption/throwing order setting exception function of each digital relay B causes the digital relay A to except the load from the selective interruption setting and the throwing order setting. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a protective relay system for a distribution system in which a circuit breaker selected by a power failure detection is automatically opened in a distribution system (high / low voltage system) and automatically turned on by power recovery.

  An example of the configuration of the power distribution system and the protective relay system is shown in FIG. The distribution system is supplied with high voltage from the high voltage power source to the high voltage bus 2 via the circuit breaker 1, and the high voltage bus 2 can select a load separated from the high voltage bus 2 A by the interconnection switch 3. From the high voltage buses 2 and 2A, power is distributed to the loads 12 to 15 through the circuit breakers 4 to 7 and the transformers 8 to 11 at a low pressure. Further, the high-voltage bus 2 </ b> A can be supplied with power from the emergency generator 17 via the circuit breaker 16.

This protective relay system for the distribution system takes in the voltage and current of the high-voltage power supply with a transformer (VT) and current transformer (CT), and then breaks the circuit breaker 1 when a power failure or reverse power flow occurs on the high-voltage power supply side from these voltages and currents. Is provided to provide a digital relay 18 that is protected from being disconnected from the high-voltage power source. In addition, the protective relay system is provided with digital relays 19 to 22 for each load system, opens the circuit breakers 4 to 7 connected to the load in the event of a power failure, overcurrent, etc., and disconnects the load from the high-voltage bus. Protect the load from power outages. These digital relays 19 to 22 perform a protection operation in cooperation with the digital relay 18 through a LAN connection, and further enable information transmission from the digital relay 18 to an upper computer such as a distribution management room (for example, refer to Patent Document 1). .
JP 2000-333362 A

  The conventional protection relay system has the following problems.

  (1) When a power failure occurs on the high-voltage side, the load is temporarily disconnected by the digital relays 18, 19-22, but when the primary circuit breakers 4-7, etc., remain on, the power is restored. Inrush current to the transformers 8 to 11 and load starting current may occur, and the upper digital relay 18 may detect overcurrent and open the circuit breaker 1.

  (2) In order to prevent the erroneous shutoff operation due to the inrush current and load starting current, the set value should be set appropriately. In view of this, the settling value of the overcurrent relay must be reviewed. Further, in the future, if opportunities for using high-voltage load inverters increase, for example, it will be necessary to readjust the set value in consideration of the inrush current of the input transformer 11.

  (3) As a countermeasure against the inrush current and the start-up current, even if the transformer primary side circuit breaker is opened after a power failure, an overcurrent will occur due to the inrush current when the transformer is turned on all at once. Although it is necessary to set, it is necessary to redesign the input sequence circuit every time the load status is changed, such as addition or reduction of load equipment.

  (4) When a power failure occurs, the generator 17 is activated to supply power to the load. However, if the generated power of the generator cannot bear all the loads, the selective selection to select and input the load (selection) However, the power consumption of each load often fluctuates greatly, and power cannot be supplied using the generator capacity to the maximum.

  An object of the present invention is to ensure protection coordination in the event of a power outage / recovery and change of distribution equipment, etc., and to protect the power distribution system with flexibility in the order of loading and selection interruption. It is to provide an electric system.

  In order to solve the above-described problems, the present invention has the following configuration.

(1) A protective relay system for a distribution system that distributes power from a high-voltage power source to a high-voltage bus, steps down the voltage from the high-voltage bus with a transformer, and distributes power to multiple loads at a low pressure.
A digital relay A that disconnects the high-voltage bus from the high-voltage power supply by opening the circuit breaker between the high-voltage power supply and the high-voltage bus in the event of a power failure on the high-voltage power supply side from the voltage and current of the high-voltage power supply,
A plurality of digital relays B connected to the digital relay A so as to be able to transmit information and provided for each load system, and disconnecting the load from the high-voltage bus by opening the circuit breaker connected to the load in the event of a power failure or overcurrent And
When the digital relay A detects the occurrence of a power failure in the high-voltage power supply, it transmits the power failure occurrence to each digital relay B, and the load current data immediately before the occurrence of the power failure received from each digital relay by the load current holding means. Keep it,
Each digital relay B that has received the occurrence of a power failure from the digital relay A opens the circuit breaker connected to the transformer to be protected after identifying the occurrence of the power failure,
When the digital relay A confirms that the high-voltage power supply has been restored, it sends a turn-on command for the circuit breaker of the load system to each of the digital relays B according to the turn-on order set in advance by the turn-on order setting means.
Each digital relay B that has received a closing command from the digital relay A performs the opening of the circuit breaker opened when a power failure occurs,
The digital relay B confirms that the load current flowing through the load system has been stabilized by the load current diagnostic means after the circuit breaker is turned on, and transmits information on the completion of the insertion to the digital relay A,
When the digital relay A receives the closing completion from the digital relay B, it repeats this ordering to send the ordering instruction to the digital relay B of the load that will be the next ordering to complete the power recovery process. It is characterized by doing.

  (2) When the occurrence of a power failure is detected, the digital relay A is configured to set a selective break for each breaker in advance by a selective break setting unit, and to transmit a breaker break command to the digital relay according to this setting. Features.

  (3) Each of the digital relays B is set so as to exclude the selective interruption of the circuit breaker by the selective interruption exclusion means, and the interruption command by the digital relay A is excluded according to this setting.

  (4) In a configuration in which the distribution system includes an emergency generator, when the power failure of the high-voltage power source continues and power is supplied to the load only from the emergency generator, the digital relay A calculates the load current value immediately before the power failure. Referring to FIG. 2, a charging command is transmitted to each of the digital relays B so that loads are sequentially loaded up to an amount of power corresponding to the power generation capacity of the emergency generator.

  (5) Means equivalent to the selective cut-off setting means and the input order setting means provided in the digital relay are provided in the host computer, and the digital relay A is provided by the digital relay A side or the host computer side by the mode switching setting means. It is characterized in that the selection block and the order of switching are switched.

  As described above, according to the present invention, it is possible to reliably and easily obtain protection coordination at the time of power failure / recovery and change of distribution facilities, etc., and to provide flexibility in the order of loading and selective interruption. it can. Specifically, the following effects are obtained.

  (1) Since the load is cut off when a power failure occurs, it is possible to prevent malfunction of the upper relay A due to inrush current and start-up current when power is restored. In addition, it is not necessary to adjust the settling value when adding transformers or changing loads.

  (2) After power is restored, it is confirmed that the current detection is stable, and the order is input, so that the host system can perform a stable protection operation.

  (3) The selection interruption setting at the time of a power failure and the turn-on order setting at the time of power recovery can be freely changed by the setting by the digital relay A and the host computer, and the load turn-on order and selection interruption can be made flexible. it can.

  (4) Since each digital relay B can be set so as to exclude the selection interruption and the turn-on order, it is possible to set the selection cut-off and the turn-on order for each load system, so that the load turn-on order and the selection interruption are highly flexible. be able to.

  (5) Since a load having a capacity corresponding to the generator capacity is input, the maximum load power can be supplied without causing the emergency generator to be loaded with a load exceeding the rated capacity.

  FIG. 1 is a configuration diagram of a protective relay system of a distribution system showing an embodiment of the present invention. The distribution system configuration is the same as that shown in FIG. As in Fig. 3, the protective relay system has a digital relay A installed on the high-voltage system side, and a digital relay B installed on the low-voltage side connected to each load. To do. Further, the digital relay A enables communication with the upper computer C.

  Also, digital relays A and B are functions that general digital relays have, for example, a detection signal input for overcurrent, undervoltage, overvoltage, etc., protection calculation function for tripping the circuit breaker, and automatic turning on function at power recovery It has a set value setting function, a relay test function, a maintenance function, a display function for executing these functions, a communication transmission function, and a setting operation touch panel. The host computer C also has a remote monitoring control function for each part necessary for managing the power distribution system, a control console for executing these functions, a display function, and a communication transmission function.

  In this embodiment, at least the functions shown in FIG. 1 are added to the digital relays A and B and the upper computer C. These functional configurations will be described in detail below.

(1) Function of digital relay A ・ The mode switching setting function enables the selection cut-off and setting order of the digital relay B in the hand mode by switching the “hand-far” switching SW, and in the remote mode. Selection blocking by the host computer C and setting of the input order are made possible.

  ・ Selection cutoff setting function and input order setting function make it possible to select load cutoff and input order on the touch panel screen.

  -The load current holding function has an area for storing the load current received from each digital relay B, and holds it as load current data immediately before the occurrence of a power failure. This data is used to select the load to be put in order after the emergency generator is started due to a power outage.

(2) Function of digital relay B ・ The load current value diagnosis function recognizes that the inrush current and the load current are stable, and prevents erroneous protection operation at the time of power recovery.

  The setting interruption function of the selection interruption / on order is a setting function for excluding from the setting of the selection interruption / on order by the digital relay A when the load current value is abnormal, and this setting data is transmitted to the digital relay A Then, it excludes from those settings.

(3) Functions of host computer C-The selective cut-off / turn-on order setting function enables the selective cut-off setting and the turn-on order setting of each load when the mode switching setting of the digital relay A is "distant mode".

  Hereinafter, the protection operation at the time of power failure and power recovery according to the present embodiment will be described.

  (S1) The occurrence of a power failure in the high-voltage power supply is detected by the digital relay A. At this time, the digital relay A transmits the occurrence of a power failure of the high-voltage power supply to each of the digital relays B, and holds the load current data immediately before the occurrence of the power failure received from each of the digital relays by the load current holding function.

  (S2) Each digital relay B that has received a power outage from the digital relay A opens the circuit breaker connected to the protection target transformer after identifying the power outage due to undervoltage, etc., that is, trips to the primary circuit breaker of the transformer Output a command and release it.

  At this time, the digital relay A transmits a cut-off command only to the digital relay B of the load when the selective cut-off for each breaker of the load system is set in advance by the selective cut-off setting function of itself or the host computer. To do. Further, when the digital relay B side is set to exclude the selective interruption by the selective interruption exclusion function, the interruption instruction by the digital relay A is excluded.

  (S3) After the high-voltage power supply is restored or the emergency generator starts up, the digital relay A confirms that there is a lead-in voltage or a high-voltage bus voltage, and opens according to the input sequence set by the digital relay A or the host computer C. A closing command for the circuit breaker is transmitted to each digital relay B.

  (S4) Each digital relay B that has received a closing command from the digital relay A switches on the circuit breaker that is opened when a power failure occurs, that is, the transformer primary circuit breaker.

  (S5) After the circuit breaker is turned on, the digital relay B monitors the load current flowing through the transformer by its load current value diagnosis function, confirms that it is stable, and sends the information on the completion of the connection to the digital relay A To do.

  As shown in FIG. 2, the stability check of the load current is determined as a stabilized time when only the load current is obtained after the inrush current flowing through the transformer or the load is added to the load current.

  (S6) When the digital relay A receives the closing completion from the digital relay B that has transmitted the closing command, the digital relay A transmits a closing command to the digital relay B of the load in the next charging order. This ordering is repeated through the processes S4 to S5, and the power recovery process is completed.

  However, if the power outage of the high-voltage power supply continues and the load is supplied only from the emergency generator, the digital relay A refers to the load current value immediately before the power outage and reaches the amount of power that matches the power generation capacity of the emergency generator. A sending command is sent to each digital relay B so that the loads are put in order.

  The power distribution system to which the present embodiment can be applied is not limited to the configuration of FIG. 3, and can be applied to a power distribution system having a high voltage system and a low voltage system to obtain equivalent operational effects.

The block diagram of the protection relay system of the power distribution system which shows embodiment of this invention. The figure which shows the example of a load current waveform and stability confirmation. The block diagram of the protection relay system of the conventional power distribution system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High voltage system circuit breaker 2,2A High voltage bus 4-7 Breaker according to load system 8-11 Transformer 12-15 Load 16 Emergency generator circuit breaker 17 Emergency generator 18, A Digital relay (high voltage system for)
19-22, B Digital relay (for low voltage system)
C Host computer

Claims (5)

It is a protective relay system for a distribution system that distributes power from a high-voltage power source to a high-voltage bus, and steps down the voltage from this high-voltage bus with a transformer to distribute power to multiple loads at low pressure.
A digital relay A that disconnects the high-voltage bus from the high-voltage power supply by opening the circuit breaker between the high-voltage power supply and the high-voltage bus at the time of a power failure on the high-voltage power supply side from the voltage and current of the high-voltage power supply,
A plurality of digital relays B that are connected to the digital relay A so as to be able to transmit information and are provided for each load system, and disconnect the load from the high-voltage bus by opening the circuit breaker connected to the load in the event of a power failure or overcurrent. And
When the digital relay A detects the occurrence of a power failure in the high-voltage power supply, the digital relay A transmits the power failure occurrence to the digital relays B, and the load current data immediately before the power failure received from the digital relays by the load current holding means. Keep it,
Each digital relay B that receives the occurrence of a power failure from the digital relay A, after identifying the occurrence of a power failure, opens a circuit breaker connected to a transformer to be protected,
When the digital relay A confirms the restoration of the high-voltage power supply, it transmits a closing command for the circuit breaker of the load system to each of the digital relays B in accordance with the closing order preset by the closing order setting means.
Each digital relay B that has received a closing command from the digital relay A performs the closing of the circuit breaker opened when a power failure occurs,
The digital relay B confirms that the load current flowing through the load system is stable by the load current diagnostic means after the circuit breaker is turned on, and sends information on the completion of the insertion to the digital relay A,
When the digital relay A receives the completion of insertion from the digital relay B, the digital relay A repeats the order insertion of sending the ordering instruction to the digital relay B of the load in the next order of ordering, and the power recovery process is completed. A protective relay system for the power distribution system.   The digital relay A is characterized in that, when the occurrence of a power failure is detected, a selective interruption for each circuit breaker is set in advance by a selective interruption setting means, and a breaker interruption command is transmitted to the digital relay according to this setting. The protective relay system for the distribution system according to claim 1.   Each of the digital relays B is set so as to exclude the selective interruption of the circuit breaker by the selective interruption exclusion means, and the interruption command by the digital relay A is excluded according to this setting. A protective relay system for the described distribution system.   In a configuration in which the distribution system includes an emergency generator, when the power failure of the high-voltage power source continues and power is supplied to the load only from the emergency generator, the digital relay A refers to the load current value immediately before the power failure, The charging command is transmitted to each of the digital relays B so as to sequentially load up to the amount of power corresponding to the power generation capacity of the emergency generator. A protective relay system for the described distribution system.   Means equivalent to the selective cut-off setting means and the input order setting means provided in the digital relay are provided in the host computer, and the digital relay A is selectively cut off by the digital relay A side or the host computer side by the mode switching setting means. 5. The protective relay system for a distribution system according to any one of claims 1 to 4, wherein the charging order is switched.

Images