A method for implementing security load staged start

Abstract

This invention discloses a method for implementing graded startup of safety loads, comprising: 1) collecting information on the safety loads of the generator set and setting graded startup delays for the safety loads; 2) determining the power failure logic of the safety busbar, and if the determination result is that the busbar is de-energized, proceeding to step 3); 3) if the power failure time of the safety busbar is greater than T1, stopping all safety loads, and then proceeding to step 4); 4) determining the successful startup logic of the diesel generator set, and if the determination result is yes, proceeding to step 5); 5) determining the voltage recovery logic of the safety busbar, and if the determination result is yes, proceeding to step 6); 6) determining whether the power failure time of the safety busbar is greater than or equal to T2, and if the power failure time of the safety busbar is less than T2, the safety loads of the generator set are started in stages according to the set graded startup delays; if the power failure time of the safety busbar is greater than or equal to T2, the safety loads of the generator set are not started. This method can ensure the safe shutdown of the generator set.

Description

Technical Field

[0001] This invention belongs to the field of power plant safety power supply technology, and relates to a method for implementing graded start-up of safety loads. Background Technology

[0002] When a power plant experiences a complete power outage or a loss of auxiliary power to its generating units, the emergency power supply switches to the diesel generator set's emergency power supply. The emergency power supply serves emergency loads, ensuring the safe shutdown of the boilers and turbines in the event of a plant-wide power outage or loss of auxiliary power to the generating units. Emergency loads must be able to restart quickly after the emergency power supply is restored.

[0003] Defects and shortcomings of existing technology:

[0004] In practical applications, due to the different configurations and protections of various safety load switchgear, as well as the coordination between the self-starting program of the switch configuration and the logic of DCS (Distributed Control System) / TCS (Turbine Control System), various faults often occur, leading to self-starting failures. These include diesel generator starting failures, safety loads not starting in the designed sequence or not starting at all, and diesel generator sets failing to start due to sudden excessive load. These issues pose significant hidden dangers to power plants and cannot guarantee the safe shutdown of the boiler and turbine. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for implementing graded start-up under safety load, which can ensure safe shutdown of the boiler and turbine.

[0006] To achieve the above objectives, the method for implementing graded start-up of security loads according to the present invention includes the following steps:

[0007] 1) Collect information on the unit's security load and set graded start-up delays for the unit's security load;

[0008] 2) Determine the power failure logic of the safety bus. If the determination result is that the bus is de-energized, proceed to step 3).

[0009] 3) When the power outage time of the safety section busbar is greater than T1, stop all safety loads and then proceed to step 4);

[0010] 4) Determine if the diesel generator set has started successfully. If the result is yes, proceed to step 5).

[0011] 5) Determine if the voltage of the busbar in the safety section has returned to normal. If the determination result is yes, proceed to step 6).

[0012] 6) Determine whether the power outage time of the safety bus is greater than or equal to T2. If the power outage time of the safety bus is less than T2, the unit's safety load will be started in stages according to the staged start-up delay set in step 1). If the power outage time of the safety bus is greater than or equal to T2, the unit's safety load will not be started.

[0013] The specific operation of step 1) is as follows:

[0014] 101) Obtain the configuration information of the unit's safety section load;

[0015] 102) When dealing with an accident, the security load is classified according to the importance of the safe shutdown of the unit, and then the start-up delay of the security load is set according to the classification results.

[0016] In step 2), the result of the busbar power failure logic in the security distribution section is busbar power failure when the following conditions are met;

[0017] 201) The measured value of the bus voltage in the security distribution section is less than Um, where Um is less than the bus undervoltage start switching criterion of the automatic switching device for security power supply;

[0018] 202) The incoming circuit breakers of the working power supply line 1 and working power supply line 2 of the security distribution section are in operation;

[0019] 203) The incoming circuit breaker of the diesel generator set in the security distribution section is in operation.

[0020] In step 3), if the power outage time of the safety busbar exceeds T1, all safety loads are stopped. The specific process is as follows:

[0021] 301) When the power supply to the safety section busbar is lost, the power outage time of the safety section busbar begins to be counted;

[0022] 302) When the power outage time of the safety section busbar is greater than T1, all safety loads shall be stopped, where T1 is greater than the main and backup power supply switching time and less than the diesel generator self-starting time.

[0023] In step 4), the logic result for successful diesel generator start-up is as follows:

[0024] 401) The output voltage of the diesel generator is greater than Uh;

[0025] 402) The diesel generator set outlet circuit breaker is closed.

[0026] In step 5), the logic result for restoring the normal voltage of the safety section busbar is as follows:

[0027] 501) The logic result of the diesel generator set starting successfully is yes;

[0028] 502) The bus voltage of the security distribution section is greater than the preset voltage value;

[0029] 503) The incoming circuit breakers of the working power supply line 1 and working power supply line 2 of the security distribution section are in operation;

[0030] 504) The incoming circuit breaker of the diesel generator set in the security distribution section is closed.

[0031] The preset voltage value is 0.9Un.

[0032] In step 6), T2 is greater than the time required for the diesel generator set to start three times.

[0033] The present invention has the following beneficial effects:

[0034] In specific operation, the method for implementing graded start-up of safety loads described in this invention sets a graded start-up delay for the safety loads. This allows the safety loads to start in stages after the safety power supply is switched to the generator set, thus avoiding the significant hidden dangers to the power plant caused by diesel generator start-up failures, safety loads not starting in the designed sequence or not starting at all, or diesel generator sets suddenly being overloaded and failing to start. This ensures the safe shutdown of the boiler and turbine. Attached Figure Description

[0035] Figure 1 This is a flowchart of the present invention;

[0036] Figure 2 This is a structural diagram of the security power supply in this invention. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, 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 merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0038] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0039] refer to Figure 1 and Figure 2 The method for implementing graded start-up of security loads according to the present invention includes the following steps:

[0040] 1) Collect information on the unit's security load and set graded start-up delays for the unit's security load;

[0041] The specific operation of step 1) is as follows:

[0042] 101) Obtain the configuration information of the unit's safety section load;

[0043] 102) When dealing with an accident, the security loads are classified according to their importance to the safe shutdown of the unit. Then, based on the classification results, the security loads are set with graded start-up delays. The automatic start-up of the security loads is controlled by the DCS / TCS control system, and the automatic start-up function is not set at the security load switch.

[0044] 2) Determine the power failure logic of the safety bus. If the power failure is determined to be a bus, proceed to step 3).

[0045] The power failure logic of the security distribution section busbar in step 2) is as follows:

[0046] 201) If the measured value of the bus voltage in the security distribution section is less than Um, in order to ensure the reliability of the operation, Um shall be less than the bus undervoltage start switching criterion of the automatic switching device for security power supply.

[0047] 202) The incoming circuit breakers of the working power supply line 1 and working power supply line 2 of the security distribution section are in operation;

[0048] 203) The incoming circuit breaker of the diesel generator set in the security distribution section is in the open position;

[0049] The power failure logic of the security distribution section busbar is implemented by the DCS / TCS control system.

[0050] 3) When the power outage time of the safety section busbar is greater than T1, stop all safety loads and then proceed to step 4);

[0051] In step 3), if the power outage time of the safety busbar exceeds T1, all safety loads are stopped. The specific process is as follows:

[0052] 301) When the power supply to the safety section busbar is lost, the power outage time of the safety section busbar begins to be counted;

[0053] 302) T1 is greater than the main and backup power switching time, while T1 is less than the diesel generator self-starting time;

[0054] The judgment process in step 3) is implemented by the DCS / TCS control system; at the same time, the DCS / TCS control system issues a stop safety load command.

[0055] 4) Determine if the diesel generator set has started successfully. If the result is yes, proceed to step 5).

[0056] The logic for the successful start-up of the diesel generator set in step 4) is as follows:

[0057] 401) The output voltage of the diesel generator is greater than Uh;

[0058] 402) The diesel generator set outlet circuit breaker is closed;

[0059] The successful start-up logic of the diesel generator set is implemented by the DCS / TCS control system.

[0060] 5) Determine if the voltage of the busbar in the safety section has returned to normal. If the determination result is yes, proceed to step 6).

[0061] The logic for restoring the bus voltage of the safety section to normal in step 5) is as follows:

[0062] 501) The logic result of the diesel generator set starting successfully is yes;

[0063] 502) The bus voltage of the security distribution section is greater than 0.9Uh;

[0064] 503) The incoming circuit breakers of the working power supply line 1 and working power supply line 2 of the security distribution section are in operation;

[0065] 504) The incoming circuit breaker of the diesel generator set in the security distribution section is closed;

[0066] The logic for restoring the bus voltage of the protection section to normal is implemented by the DCS / TCS control system.

[0067] 6) Determine whether the power outage time of the safety busbar is greater than or equal to T2. If the power outage time of the safety busbar is less than T2, the unit's safety load will be started in stages according to the staged start-up delay set in step 1). If the power outage time of the safety busbar is greater than or equal to T2, the unit's safety load will not be started.

[0068] In step 6), T2 is greater than the time required for the diesel generator set to start three times.

[0069] It should be noted that this invention sets graded start-up delays for each safety load in the DCS / TCS control system. During restart, each safety load starts in stages according to the set graded start-up delays. This avoids the problems of diesel generator start-up failure, safety loads not starting in the designed order or not starting at all, and concentrated start-up of safety loads causing sudden loading and start-up failure of the diesel generator set, which pose great hidden dangers to the power plant.

[0070] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for implementing graded start-up of security loads, characterized in that, Includes the following steps: 1) Collect information on the unit's security load and set graded start-up delays for the unit's security load; 2) Determine the power failure logic of the safety bus. If the determination result is that the bus is de-energized, proceed to step 3). 3) When the power outage time of the safety busbar exceeds T1, stop all safety loads and proceed to step 4). 4) Determine if the diesel generator set has started successfully. If the result is yes, proceed to step 5). 5) Determine if the voltage of the busbar in the safety section has returned to normal. If the determination result is yes, proceed to step 6). 6) Determine whether the power outage time of the safety bus is greater than or equal to T2. If the power outage time of the safety bus is less than T2, the unit's safety load will be started in stages according to the staged start-up delay set in step 1). If the power outage time of the safety bus is greater than or equal to T2, the unit's safety load will not be started. The specific operation of step 1) is as follows: 101) Obtain the configuration information of the unit's safety section load; 102) When dealing with an accident, the security load is classified according to the importance of the safe shutdown of the unit, and then the graded start-up delay is set according to the classification results. In step 2), the result of the busbar power failure logic in the security distribution section is busbar power failure when the following conditions are met; 201) The measured value of the bus voltage in the security distribution section is less than Um, where Um is less than the bus undervoltage start switching criterion of the automatic switching device for security power supply; 202) The incoming circuit breakers of the working power supply line 1 and working power supply line 2 of the security distribution section are in operation; 203) The incoming circuit breaker of the diesel generator set in the security distribution section is in the open position; In step 3), if the power outage time of the safety busbar exceeds T1, all safety loads are stopped. The specific process is as follows: 301) When the power supply to the safety section busbar is lost, the power outage time of the safety section busbar begins to be counted; 302) When the power outage time of the safety section busbar is greater than T1, all safety loads shall be stopped, where T1 is greater than the main and backup power supply switching time and less than the diesel generator self-starting time. In step 4), the logic result for successful diesel generator start-up is as follows: 401) The output voltage of the diesel generator is greater than Uh; 402) The diesel generator set outlet circuit breaker is closed; In step 5), the logic result for restoring the normal voltage of the safety section busbar is as follows: 501) The logic result of the diesel generator set starting successfully is yes; 502) The bus voltage of the security distribution section is greater than the preset voltage value; 503) The incoming circuit breakers of the working power supply line 1 and working power supply line 2 of the security distribution section are in operation; 504) The incoming circuit breaker of the diesel generator set in the security distribution section is closed.

2. The method for implementing graded start-up of security loads according to claim 1, characterized in that, The preset voltage value is 0.9Uh.

3. The method for implementing graded start-up of security loads according to claim 1, characterized in that, In step 6), T2 is greater than the start-up time of the diesel generator set for the third time.

Images