A method for preventing new energy access backup automatic switching from failing to start quickly

Abstract

This invention discloses a method to prevent the backup automatic transfer switch from failing to start quickly after new energy source integration. The method includes: acquiring analog signals and switch status information; identifying new energy source islanded operation, including fault identification and bus voltage support identification; when the main power supply fails and the bus voltage has voltage support, it is determined to be new energy source islanded operation; and fast-switching startup, disconnecting the new energy source on the bus and starting the backup automatic transfer switch. The fault identification includes any of the following conditions: main power supply switch closed and power flow reversed, bus frequency below 49.5Hz, or main power supply switch tripped and no current. The voltage support identification requires simultaneously satisfying the control word being activated, the maximum three-phase line voltage being less than 0.88 times the rated value and greater than the no-voltage setting value. This invention effectively solves the problem of backup automatic transfer switch failing to start quickly under no-voltage and no-current conditions after new energy source integration by quickly starting the backup automatic transfer switch through identifying the new energy source islanded operation status.

Description

Technical Field

[0001] This invention relates to the field of power systems and their automation technology, and in particular to a method for preventing the backup automatic transfer switch from failing to start quickly after new energy sources are connected. Background Technology

[0002] Automatic transfer switch (ATS) devices are crucial for ensuring the reliability and continuity of power supply in power systems and are widely used throughout the distribution network. When the main power supply fails, the ATS detects that the main power supply line and busbar are without voltage and current, and then instantly trips the main power supply switch. It then checks whether the backup power supply is in a standby state; if so, it closes the backup line, thereby achieving rapid power restoration.

[0003] With the continuous integration of large-capacity renewable energy sources, a failure in the main power supply can create the illusion of voltage on the busbar. If the protection on the opposite side of the main power supply line trips but the switch on this side does not trip, the renewable energy source will still send current back to the fault point, creating the illusion of current in the main power supply. In this situation, the automatic transfer switch (ATS) will not meet the conditions for starting without voltage or current, and will only start after the anti-islanding protection trips and disconnects the renewable energy source, thus prolonging the ATS's activation time and power recovery time. To ensure rapid startup of the ATS, it is necessary to identify the voltage support of the renewable energy source and to quickly disconnect it.

[0004] Currently, domestic research mainly focuses on disconnecting new energy sources first, and then activating the automatic transfer switch (ATS) after the voltage drops. However, this method prolongs the startup time of the ATS and cannot achieve rapid power restoration. Therefore, this invention proposes a method to prevent the ATS from failing to start quickly after new energy sources are connected. This method enables the ATS to start rapidly after a failure of the main power supply following the connection of new energy sources, thereby restoring power supply as quickly as possible and ensuring the continuity of power supply. Summary of the Invention

[0005] The purpose of this invention is to provide a method to prevent the backup automatic transfer switch from failing to start quickly after new energy sources are connected. This method can reliably identify the isolated operation of new energy sources, thereby quickly disconnecting the new energy sources and starting the backup automatic transfer switch to restore power supply and ensure the continuity of power supply.

[0006] To achieve the above objectives, the present invention is implemented using the following technical solution: This invention provides a method to prevent the backup power supply from failing to start quickly after new energy sources are connected to the grid, comprising the following steps: Step 1: Obtain analog signal and switch status information; Step 2: Identify isolated grid operation of new energy sources. The identification of isolated grid operation of new energy sources includes fault identification and bus voltage support identification. When it is identified that the main power supply has failed and the bus voltage has voltage support, it is determined that there is isolated grid operation of new energy sources. Step 3, quick start-up: when it is determined that there is a new energy isolated grid, disconnect the new energy on the bus and start the backup automatic transfer.

[0007] Optionally, the analog quantities include: Bus I voltage, Bus II voltage, power supply 1 voltage and current, and power supply 2 voltage and current; The switching quantities include: the position of the working line circuit breaker, the position of the standby line circuit breaker, and the position of the sectional circuit breaker.

[0008] Optionally, in the fault identification process, the main power supply is considered to have failed if any of the following conditions are met: Condition 1: The main power supply switch is in the closed position and the power flow direction changes; Condition 2: The bus frequency is below 49.5Hz; Condition 3: The main power supply switch is in the tripped position and there is no current flowing from the main power supply.

[0009] Optionally, in the bus voltage support identification, the bus voltage is considered to have voltage support when the following conditions are met simultaneously: Condition 1: The "Bus Voltage Support Judgment" control word is activated; Condition 2: The maximum value of the three-phase line voltage is less than 0.88 times the rated line voltage. Condition 3: The maximum value of the three-phase line voltage is greater than the preset no-voltage setting value.

[0010] Optionally, the line voltage rating is 100V, and the no-voltage rating is a settable value.

[0011] The power flow direction is obtained through real-time monitoring. During normal operation, the power flow direction is from the line to the bus. When a fault occurs, the power flow direction changes to from the bus to the line.

[0012] The fast-start function includes: Once isolated grid operation of a new energy source is identified, the new energy source is quickly disconnected and the backup automatic transfer switch is activated to quickly restore power supply.

[0013] The advantages of this invention are: by adding the judgment of the isolated grid operation status of new energy, the new energy can be quickly disconnected and the backup automatic transfer device can be started, which effectively solves the problem that the backup automatic transfer device cannot be quickly started under the condition of no pressure and no current after the new energy is connected. Attached Figure Description

[0014] Figure 1 This is the main connection diagram of the automatic backup switching system of the present invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use.

[0016] Example 1: This embodiment describes the implementation process of a method to prevent the backup automatic transfer system from failing to start quickly after new energy source access in an incoming line backup automatic transfer system, such as... Figure 1 As shown ( Figure 1 In the diagram, UL1 and UL2 represent the voltages of power supply 1 and power supply 2, respectively; PT1 and PT2 represent the power supplies (PTs) of bus I and bus II, respectively; and DG1, DG2, DG3, and DG4 represent the new energy sources on each bus section. The analog quantities to be acquired include: voltage and current of 110kV power supply 1 and power supply 2, voltage of bus I, and voltage of bus II; The obtained switch quantities include: switch 111 position, switch 112 position, and switch 131 position.

[0017] Furthermore, the power flow direction of 110kV power sources 1 and 2 is monitored in real time. Under normal operation, the power flow direction of power sources 1 and 2 is from the line to the bus. When a fault occurs at point K1 on the 110kV incoming line and the switch on this side does not trip, the power flow direction of the fault interval changes to from the bus to the line. When the switch on this side trips, the 110kV bus voltage is still greater than zero voltage, but there is no current from the main power supply.

[0018] Taking the fault occurring in main power supply 1 as an example, the fault identification includes: 1) The main power supply switch 111 is closed and the power flow direction of power supply 1 changes; 2) The frequency of bus 1 is below 49.5Hz; 3) The main power supply switch 111 is tripped and there is no current from the main power supply 1.

[0019] If any of the above conditions are met, the main power supply 1 is considered to have failed.

[0020] The identification of the I-type main voltage support includes: "Bus voltage support judgment" control word input I. Bus voltage MAX (Uab, Ubc, Uca) < 0.88Un; I. Bus voltage MAX(Uab, Ubc, Uca) > Uwy; Where MAX(Uab, Ubc, Uca) is the maximum value of the three-phase line voltage, Un is the rated line voltage, which is 100V, and Uwy is the settable voltage-free setting.

[0021] If all the above conditions are met, then the voltage of bus I is considered to be supported by voltage.

[0022] If the fault condition is met and the bus voltage has voltage support, it is considered that Bus I is operating in isolated grid mode with new energy sources. The new energy source DG1 on Bus I is quickly disconnected, and the automatic transfer switch is activated. Switch 111 is tripped and switch 131 is closed to quickly restore power supply.

[0023] Example 2: This embodiment describes the implementation process of a method to prevent the backup automatic transfer system from failing to start quickly after new energy source access in a main transformer backup automatic transfer system, such as... Figure 1 As shown, it includes: Obtain analog quantities, including the voltage of bus I, the voltage of bus II, the high-voltage side voltage of transformer #1 and transformer #2, and the low-voltage side current; Obtain switch status information, including the low-voltage side switches 901 and 902 of transformer #1 and transformer #2, as well as the sectionalizing switch 931.

[0024] Real-time monitoring of power flow direction is performed on switch bay 901 on the low-voltage side of main transformer #1 and switch bay 902 on the low-voltage side of main transformer #2. Under normal operation, the power flow direction on the low-voltage side of the main transformer is from the transformer to the busbar. When a K2 fault occurs in the main transformer, the power flow direction on the low-voltage side changes to from the busbar to the transformer. After the switch on the low-voltage side of the main transformer trips, the 10kV busbar voltage is still greater than zero voltage, but there is no current on the low-voltage side of the main transformer.

[0025] Taking the fault occurring in main power supply 1 as an example, the fault identification includes: 1) The main power supply switch 901 is closed and the power flow direction on the low-voltage side of transformer #1 has changed; 2) The frequency of bus 1 is below 49.5Hz; 3) The main power supply switch 901 tripped and there was no current on the low-voltage side of transformer #1.

[0026] If any of the above conditions are met, it is considered that a fault has occurred on the side of transformer #1.

[0027] The identification of the I-type main voltage support includes: The "Bus Voltage Support Judgment" control word is activated; I. Bus voltage MAX (Uab, Ubc, Uca) < 0.88Un; I. Bus voltage MAX(Uab, Ubc, Uca) > Uwy; Where Uwy is the unpressurized constant value.

[0028] If all the above conditions are met, then the voltage of bus I is considered to be supported by voltage.

[0029] If the fault condition is met and the bus voltage has voltage support, it is considered that the I bus is operating in a new energy isolated grid. The new energy DG3 on the 10kV I bus is quickly disconnected, the automatic transfer switch is activated, the 901 switch is tripped and the 931 switch is closed, and the power supply is quickly restored.

[0030] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preventing the backup automatic transfer switch from failing to start quickly after new energy source access, characterized in that, Includes the following steps: Step 1: Obtain analog signal and switch status information; Step 2: Identify isolated grid operation of new energy sources. The identification of isolated grid operation of new energy sources includes fault identification and bus voltage support identification. When it is identified that the main power supply has failed and the bus voltage has voltage support, it is determined that there is isolated grid operation of new energy sources. Step 3, quick start-up: when it is determined that there is a new energy isolated grid, disconnect the new energy on the bus and start the backup automatic transfer.

2. The method for preventing the backup automatic transfer switch from failing to start quickly after new energy access, as described in claim 1, is characterized in that, The analog quantities include: Bus I voltage, Bus II voltage, Power Supply 1 voltage and current, and Power Supply 2 voltage and current; The switching quantities include: the position of the working line circuit breaker, the position of the standby line circuit breaker, and the position of the sectional circuit breaker.

3. The method for preventing the backup automatic transfer switch from failing to start quickly after new energy access, as described in claim 1, is characterized in that... In the fault identification process, the main power supply is considered to have failed if any of the following conditions are met: Condition 1: The main power supply switch is in the closed position and the power flow direction changes; Condition 2: The bus frequency is below 49.5Hz; Condition 3: The main power supply switch is in the tripped position and there is no current flowing from the main power supply.

4. The method for preventing the backup automatic transfer switch from failing to start quickly after new energy access, as described in claim 1, is characterized in that, In the bus voltage support identification process, the bus voltage is considered to have voltage support when the following conditions are met simultaneously: Condition 1: The "Bus Voltage Support Judgment" control word is activated; Condition 2: The maximum value of the three-phase line voltage is less than 0.88 times the rated line voltage. Condition 3: The maximum value of the three-phase line voltage is greater than the preset no-voltage setting value.

5. A method for preventing the backup automatic transfer switch from failing to start quickly after new energy access, as described in claim 4, characterized in that, The line voltage rating is 100V, and the voltage-free setting is a settable value.

6. The method for preventing the backup automatic transfer switch from failing to start quickly after new energy access, as described in claim 3, is characterized in that... The power flow direction is obtained through real-time monitoring. During normal operation, the power flow direction is from the line to the bus. When a fault occurs, the power flow direction changes to from the bus to the line.

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