Power supply circuit and power supply method for backup emergency diesel generator sets in pressurized water reactor nuclear power plants

Abstract

This invention discloses a power supply circuit for a backup emergency diesel generator set in a pressurized water reactor nuclear power plant, including a backup transfer bus. The backup transfer bus is connected to an outlet switch, a common bus feeder switch, and a multi-reactor bus feeder switch. The outlet switch is connected to a backup emergency diesel generator. The common bus feeder switch and the multi-reactor bus feeder switch are connected in parallel to a second circuit breaker. The common bus feeder switch is connected to the common bus via a power supply switch. The common bus is connected to a distribution transfer bus via a first switch group. Each reactor bus feeder switch is connected to an auxiliary power supply, and each auxiliary power supply is connected to the distribution transfer bus. This invention also discloses a diesel generator set power supply method that ensures that in the event of a failure of any emergency diesel generator, a switching operation can be performed to place the backup emergency diesel generator in a normal hot standby state, performing the emergency power supply function of the reactor emergency bus, without causing the unit status to be downgraded.

Description

Technical Field

[0001] This invention belongs to the field of power supply circuit technology, and relates to a power supply circuit for a backup emergency diesel generator set in a pressurized water reactor nuclear power plant. This invention also relates to a method for powering a diesel generator set. Background Technology

[0002] The emergency power system of a pressurized water reactor nuclear power plant includes emergency diesel generator sets and a power distribution system. The emergency diesel generators (referred to as emergency generators) serve as an emergency power source. In the event of a loss of both the main external power source and auxiliary external power sources, the nuclear power plant's emergency diesel generator sets are capable of meeting the power requirements of emergency plant equipment, ensuring a safe reactor shutdown, and preventing damage to critical equipment due to the loss of normal external power.

[0003] The emergency busbar is normally equipped with two incoming line switches. One line comes from the low-voltage side of the high-voltage plant service transformer, which serves as the normal working power supply for the emergency busbar. The other line comes from the emergency diesel generator, which provides emergency power to the emergency busbar when the normal power supply is lost.

[0004] Therefore, to ensure the safe and stable operation of nuclear power plants, the operating technical specifications for nuclear power plants impose high requirements on the availability of emergency diesel generators. Risks such as damage to critical and sensitive equipment and components during the diesel generator's lifespan, natural disasters or equipment failures leading to unavailable external power sources, and maintenance periods for auxiliary transformers may occur. To ensure the safety of the plant's power supply, the unit may have to be moved to a hot shutdown state. Furthermore, the downtime caused by the emergency diesel generator returning to the plant for maintenance or malfunction is lengthy (the repair and replacement of critical components is estimated to take approximately 300 days), which will affect the unit's power generation economics. Summary of the Invention

[0005] The purpose of this invention is to provide a backup emergency diesel generator power supply circuit for pressurized water reactor nuclear power plants, which solves the problem of long downtime caused by emergency diesel generators returning to the factory for maintenance or failure in the existing technology.

[0006] A second objective of this invention is to provide a method for supplying power to a diesel generator set.

[0007] The first technical solution adopted in this invention is a backup emergency diesel generator power supply circuit for a pressurized water reactor nuclear power plant, including a backup transfer bus. The backup transfer bus is connected to an outlet switch, a common bus feeder switch, and a multi-reactor bus feeder switch. The outlet switch is connected to a backup emergency diesel generator. The common bus feeder switch and the multi-reactor bus feeder switch are connected in parallel to a second circuit breaker. The common bus feeder switch is connected to the common bus via a power supply switch. The common bus is connected to a distribution transfer bus via a first switch group. Each reactor bus feeder switch is connected to an auxiliary power distribution power supply. Each auxiliary power distribution power supply is connected to the distribution transfer bus.

[0008] The first technical solution of this invention is also characterized by: The power distribution transfer bus is connected to the power distribution bus in sequence through the power distribution transfer bus feeder switch, the step-down transformer, and the power distribution bus feeder switch. Auxiliary power distribution equipment is installed on the power distribution bus.

[0009] The public busbar is connected to the first normal incoming switch.

[0010] The first switch group includes a first busbar feeder switch and a first busbar incoming switch connected to each other. The first busbar feeder switch is connected to the common busbar, and the first busbar incoming switch is connected to the power distribution transfer busbar.

[0011] The auxiliary power supply includes the reactor emergency bus, which is connected to the power distribution transfer bus via the second switch group. The reactor emergency bus is connected to the reactor bus feeder switch via the standby incoming switch. The reactor emergency bus is connected to an emergency diesel generator via the emergency incoming switch. The standby incoming switch and the emergency incoming switch on the same auxiliary power supply are connected in parallel to the third circuit breaker.

[0012] The reactor emergency bus is connected to a second normal incoming switch.

[0013] The second switch group includes a second bus feeder switch and a second bus incoming switch connected together. The second bus feeder switch is connected to the reactor emergency bus, and the second bus incoming switch is connected to the power distribution transfer bus. All second bus incoming switches of the second switch group are connected in parallel with the first bus incoming switch on the first circuit breaker.

[0014] The second technical solution adopted in this invention is a diesel generator set power supply method, specifically as follows: when an emergency diesel generator fails, a standby emergency diesel generator takes over its operation, the first circuit breaker is pushed to its corresponding second bus incoming switch, the second circuit breaker is pushed to its corresponding reactor bus feeder switch, and the corresponding third circuit breaker is pushed to the standby incoming switch, the output switch is placed in the working closed position, the second bus feeder switch corresponding to the emergency diesel generator is placed in the working closed position, and the distribution transfer bus feeder switch and the distribution bus feeder switch are placed in the working closed position.

[0015] The second technical solution of the present invention is further characterized by: When the standby emergency diesel generator is in cold standby mode, all the second normal incoming line switches are opened, and the remaining switches are placed in the isolation open position. The standby transfer bus, distribution transfer bus, and distribution bus are all de-energized, and the reactor emergency bus is powered by the normal power source.

[0016] When the standby emergency diesel generator is undergoing periodic testing in cold standby mode, the first busbar feeder switch, the first busbar incoming switch, the distribution transfer busbar feeder switch, and the distribution busbar feeder switch will be switched off.

[0017] The beneficial effects of this invention are: This invention adds a safety-grade backup emergency diesel generator as the power supply circuit for the plant's emergency diesel generators. When a normal emergency diesel generator fails and becomes unavailable, it has the capability to completely replace it in performing all related functions. It ensures that in the event of a failure of any emergency diesel generator, a switching operation can place the added backup emergency diesel generator into a normal hot standby state, performing the emergency power supply function of the reactor emergency bus, without causing a unit downtime, thus ensuring the stability, safety, and economy of unit operation. The switching operation allows the backup emergency diesel generator to replace the emergency diesel generator, eliminating the need for emergency diesel generator maintenance on the critical path and saving maintenance time. By configuring multiple auxiliary power supplies, it achieves flexible and diverse auxiliary power supply, ensuring reliable auxiliary power supply when the backup emergency diesel generator is performing its function. The connection between the distribution transfer bus and the common bus enables the periodic testing of the backup emergency diesel generator. It allows for the commissioning and periodic load testing of the added backup emergency diesel generator, and verifies its availability through grid-connected load testing. Attached Figure Description

[0018] Figure 1 This is the power supply circuit diagram of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] For the backup emergency diesel generator power supply circuit of a pressurized water reactor nuclear power plant, see [link / reference]. Figure 1This includes a backup transfer busbar, which is connected to an outlet switch, a common busbar feeder switch, and a multi-reactor busbar feeder switch. The outlet switch is connected to a backup emergency diesel generator. The common busbar feeder switch and the multi-reactor busbar feeder switch are connected in parallel to the second circuit breaker, enabling flexible switching of auxiliary power distribution for the backup emergency diesel generator. This ensures that the backup emergency diesel generator can supply power to only one section of the busbar, while also meeting the independence requirements of the emergency power system. The common busbar feeder switch is connected to the common busbar via a power supply switch. The common busbar is connected to the distribution transfer busbar via the first switch group. Each reactor busbar feeder switch is connected to an auxiliary power distribution source, and each auxiliary power distribution source is connected to the distribution... The power transfer busbars are connected, and the distribution transfer busbars are connected to the distribution busbars in sequence through the distribution transfer busbar feeder switch, step-down transformer, and distribution busbar feeder switch. Auxiliary equipment power distribution is installed on the distribution busbars, and the common busbar is connected to the first normal incoming switch. The common busbar feeder switch enables the standby emergency diesel generator to connect with the plant's common busbar to meet the requirements of the standby emergency diesel generator's periodic testing, commissioning, and grid connection testing. Through the design of sharing a second circuit breaker, only one step-down transformer is needed (the voltage level of the auxiliary equipment power distribution is 380V, while the output voltage level of the standby emergency diesel generator is 6kV) to meet the power demand of the auxiliary equipment power distribution, reducing the number of step-down transformers and the number of circuit breakers used.

[0021] The first switch group includes a first busbar feeder switch and a first busbar incoming switch connected to each other. The first busbar feeder switch is connected to the common busbar, and the first busbar incoming switch is connected to the power distribution transfer busbar.

[0022] The auxiliary power supply includes the reactor emergency bus, which is connected to the power distribution transfer bus via the second switch group. The reactor emergency bus is connected to the reactor bus feeder switch via the standby incoming switch. An emergency diesel generator is connected to the reactor emergency bus via the emergency incoming switch. The standby incoming switch and the emergency incoming switch on the same auxiliary power supply are connected in parallel to the third circuit breaker. The reactor emergency bus is connected to the second normal incoming switch.

[0023] The second switch group includes a second bus feeder switch and a second bus incoming switch connected together. The second bus feeder switch is connected to the reactor emergency bus, and the second bus incoming switch is connected to the power distribution transfer bus. The second bus incoming switches of all the second switch groups are connected in parallel with the first bus incoming switch on the first circuit breaker to ensure the independence of each section of the reactor emergency bus.

[0024] The diesel generator set power supply method is as follows: When an emergency diesel generator fails, a switching operation is performed to allow a backup emergency diesel generator to take over its operation. The first circuit breaker is switched to its corresponding second bus incoming switch, the second circuit breaker is switched to its corresponding reactor bus feeder switch, and the corresponding third circuit breaker is switched to the backup incoming switch. The output switch is placed in the working closed position, the second bus feeder switch corresponding to the emergency diesel generator is placed in the working closed position, and the distribution transfer bus feeder switch and the distribution bus feeder switch are placed in the working closed position. The auxiliary equipment of the backup emergency diesel generator is powered by the corresponding reactor emergency bus, and other switches remain in their original states.

[0025] When the standby emergency diesel generator is in cold standby mode, all second normal incoming line switches are opened, and all other switches are placed in the isolation open position. The standby transfer bus, distribution transfer bus, and distribution bus are not energized. The reactor emergency bus is powered by the normal power supply. When the standby emergency diesel generator is in cold standby mode and periodic tests are carried out, the first bus feeder switch, the first bus incoming line switch, the distribution transfer bus feeder switch, and the distribution bus feeder switch are turned off.

[0026] Given that the maintenance cycle of emergency diesel generators is long and occupies the critical path of the overhaul during pressurized water reactor nuclear power plant overhauls, the wiring design of this invention enables the standby emergency diesel generator to replace the emergency diesel generator through switching operations. This allows the overhaul of the emergency diesel generator to be scheduled during routine operations without occupying the critical path of the overhaul, saving overhaul time. According to the power generation economy of pressurized water reactor nuclear power, a single unit can increase power generation revenue by approximately RMB 3.84 billion over its entire lifespan.

[0027] Example 1: The power supply circuit for the backup emergency diesel generator set of the pressurized water reactor nuclear power plant includes a backup transfer bus. The backup transfer bus is connected to an outlet switch, a common bus feeder switch, and a multi-reactor bus feeder switch. The outlet switch is connected to a backup emergency diesel generator. The common bus feeder switch and the multi-reactor bus feeder switch are connected in parallel to the second circuit breaker. The common bus feeder switch is connected to the common bus through a power supply switch. The common bus is connected to the distribution transfer bus through the first switch group. Each reactor bus feeder switch is connected to an auxiliary equipment power supply. Each auxiliary equipment power supply is connected to the distribution transfer bus.

[0028] The power distribution transfer bus is connected to the power distribution bus in sequence through the power distribution transfer bus feeder switch, the step-down transformer, and the power distribution bus feeder switch. Auxiliary power distribution equipment is installed on the power distribution bus.

[0029] The public busbar is connected to the first normal incoming switch.

[0030] The first switch group includes a first busbar feeder switch and a first busbar incoming switch connected to each other. The first busbar feeder switch is connected to the common busbar, and the first busbar incoming switch is connected to the power distribution transfer busbar.

[0031] Example 2: The power supply circuit for the backup emergency diesel generator set of the pressurized water reactor nuclear power plant includes a backup transfer bus. The backup transfer bus is connected to an outlet switch, a common bus feeder switch, and a multi-reactor bus feeder switch. The outlet switch is connected to a backup emergency diesel generator. The common bus feeder switch and the multi-reactor bus feeder switch are connected in parallel to the second circuit breaker. The common bus feeder switch is connected to the common bus through a power supply switch. The common bus is connected to the distribution transfer bus through the first switch group. Each reactor bus feeder switch is connected to an auxiliary equipment power supply. Each auxiliary equipment power supply is connected to the distribution transfer bus.

[0032] The power distribution transfer bus is connected to the power distribution bus in sequence through the power distribution transfer bus feeder switch, the step-down transformer, and the power distribution bus feeder switch. Auxiliary power distribution equipment is installed on the power distribution bus.

[0033] The public busbar is connected to the first normal incoming switch.

[0034] The first switch group includes a first busbar feeder switch and a first busbar incoming switch connected to each other. The first busbar feeder switch is connected to the common busbar, and the first busbar incoming switch is connected to the power distribution transfer busbar.

[0035] The auxiliary power supply includes the reactor emergency bus, which is connected to the power distribution transfer bus via the second switch group. The reactor emergency bus is connected to the reactor bus feeder switch via the standby incoming switch. The reactor emergency bus is connected to an emergency diesel generator via the emergency incoming switch. The standby incoming switch and the emergency incoming switch on the same auxiliary power supply are connected in parallel to the third circuit breaker.

[0036] Example 3: The power supply circuit for the backup emergency diesel generator set of the pressurized water reactor nuclear power plant includes a backup transfer bus. The backup transfer bus is connected to an outlet switch, a common bus feeder switch, and a multi-reactor bus feeder switch. The outlet switch is connected to a backup emergency diesel generator. The common bus feeder switch and the multi-reactor bus feeder switch are connected in parallel to the second circuit breaker. The common bus feeder switch is connected to the common bus through a power supply switch. The common bus is connected to the distribution transfer bus through the first switch group. Each reactor bus feeder switch is connected to an auxiliary equipment power supply. Each auxiliary equipment power supply is connected to the distribution transfer bus.

[0037] The power distribution transfer bus is connected to the power distribution bus in sequence through the power distribution transfer bus feeder switch, the step-down transformer, and the power distribution bus feeder switch. Auxiliary power distribution equipment is installed on the power distribution bus.

[0038] The public busbar is connected to the first normal incoming switch.

[0039] The auxiliary power supply includes the reactor emergency bus, which is connected to the power distribution transfer bus via the second switch group. The reactor emergency bus is connected to the reactor bus feeder switch via the standby incoming switch. The reactor emergency bus is connected to an emergency diesel generator via the emergency incoming switch. The standby incoming switch and the emergency incoming switch on the same auxiliary power supply are connected in parallel to the third circuit breaker.

[0040] The reactor emergency bus is connected to a second normal incoming switch.

[0041] Example 4: The power supply circuit for the backup emergency diesel generator set of the pressurized water reactor nuclear power plant includes a backup transfer bus. The backup transfer bus is connected to an outlet switch, a common bus feeder switch, and a multi-reactor bus feeder switch. The outlet switch is connected to a backup emergency diesel generator. The common bus feeder switch and the multi-reactor bus feeder switch are connected in parallel to the second circuit breaker. The common bus feeder switch is connected to the common bus through a power supply switch. The common bus is connected to the distribution transfer bus through the first switch group. Each reactor bus feeder switch is connected to an auxiliary equipment power supply. Each auxiliary equipment power supply is connected to the distribution transfer bus.

[0042] The power distribution transfer bus is connected to the power distribution bus in sequence through the power distribution transfer bus feeder switch, the step-down transformer, and the power distribution bus feeder switch. Auxiliary power distribution equipment is installed on the power distribution bus.

[0043] The auxiliary power supply includes the reactor emergency bus, which is connected to the power distribution transfer bus via the second switch group. The reactor emergency bus is connected to the reactor bus feeder switch via the standby incoming switch. The reactor emergency bus is connected to an emergency diesel generator via the emergency incoming switch. The standby incoming switch and the emergency incoming switch on the same auxiliary power supply are connected in parallel to the third circuit breaker.

[0044] The reactor emergency bus is connected to a second normal incoming switch.

[0045] The second switch group includes a second bus feeder switch and a second bus incoming switch connected together. The second bus feeder switch is connected to the reactor emergency bus, and the second bus incoming switch is connected to the power distribution transfer bus. All second bus incoming switches of the second switch group are connected in parallel with the first bus incoming switch on the first circuit breaker.

[0046] Example 5: The power supply circuit for the backup emergency diesel generator set of the pressurized water reactor nuclear power plant includes a backup transfer bus. The backup transfer bus is connected to an outlet switch, a common bus feeder switch, and a multi-reactor bus feeder switch. The outlet switch is connected to a backup emergency diesel generator. The common bus feeder switch and the multi-reactor bus feeder switch are connected in parallel to the second circuit breaker. The common bus feeder switch is connected to the common bus through a power supply switch. The common bus is connected to the distribution transfer bus through the first switch group. Each reactor bus feeder switch is connected to an auxiliary equipment power supply. Each auxiliary equipment power supply is connected to the distribution transfer bus.

[0047] The power distribution transfer bus is connected to the power distribution bus in sequence through the power distribution transfer bus feeder switch, the step-down transformer, and the power distribution bus feeder switch. Auxiliary power distribution equipment is installed on the power distribution bus.

[0048] The auxiliary power supply includes the reactor emergency bus, which is connected to the power distribution transfer bus via the second switch group. The reactor emergency bus is connected to the reactor bus feeder switch via the standby incoming switch. The reactor emergency bus is connected to an emergency diesel generator via the emergency incoming switch. The standby incoming switch and the emergency incoming switch on the same auxiliary power supply are connected in parallel to the third circuit breaker.

[0049] The reactor emergency bus is connected to a second normal incoming switch.

[0050] Example 6: The diesel generator set power supply method is as follows: When an emergency diesel generator fails, the standby emergency diesel generator takes over its operation. The first circuit breaker is switched to its corresponding second bus incoming switch, the second circuit breaker is switched to its corresponding reactor bus feeder switch, and the corresponding third circuit breaker is switched to the standby incoming switch. The outgoing switch is placed in the working closed position, the second bus feeder switch corresponding to the emergency diesel generator is placed in the working closed position, and the distribution transfer bus feeder switch and the distribution bus feeder switch are placed in the working closed position.

[0051] When the standby emergency diesel generator is in cold standby mode, all second normal incoming line switches are opened, and all other switches are placed in the isolation open position. The standby transfer bus, distribution transfer bus, and distribution bus are all de-energized, and the reactor emergency bus is powered by the normal power source. When the standby emergency diesel generator is in cold standby mode and periodic tests are carried out, the first bus feeder switch, the first bus incoming line switch, the distribution transfer bus feeder switch, and the distribution bus feeder switch are turned off.

Claims

1. A backup emergency diesel generator power supply circuit for a pressurized water reactor nuclear power plant, characterized in that, It includes a backup transfer bus, which is connected to an outlet switch, a common bus feeder switch, and a multi-reactor bus feeder switch. The outlet switch is connected to a backup emergency diesel generator. The common bus feeder switch and the multi-reactor bus feeder switch are connected in parallel to the second circuit breaker. The common bus feeder switch is connected to the common bus via a power supply switch. The common bus is connected to the distribution transfer bus via the first switch group. Each reactor bus feeder switch is connected to an auxiliary equipment power supply. Each auxiliary equipment power supply is connected to the distribution transfer bus.

2. The power supply circuit for the backup emergency diesel generator set in a pressurized water reactor nuclear power plant according to claim 1, characterized in that, The power distribution transfer bus is connected to the power distribution bus in sequence through the power distribution transfer bus feeder switch, the step-down transformer, and the power distribution bus feeder switch. Auxiliary power distribution equipment is installed on the power distribution bus.

3. The power supply circuit for the backup emergency diesel generator set in a pressurized water reactor nuclear power plant according to claim 2, characterized in that, The common busbar is connected to a first normal incoming switch.

4. The power supply circuit for the backup emergency diesel generator set in a pressurized water reactor nuclear power plant according to claim 3, characterized in that, The first switch group includes a first busbar feeder switch and a first busbar incoming switch connected to each other. The first busbar feeder switch is connected to the common busbar, and the first busbar incoming switch is connected to the power distribution transfer busbar.

5. The power supply circuit for the backup emergency diesel generator set of a pressurized water reactor nuclear power plant according to any one of claims 1-4, characterized in that, The auxiliary power supply includes a reactor emergency bus, which is connected to the power distribution transfer bus via a second switch group. The reactor emergency bus is connected to the reactor bus feeder switch via a standby incoming switch. An emergency diesel generator is connected to the reactor emergency bus via an emergency incoming switch. The standby incoming switch and the emergency incoming switch on the same auxiliary power supply are connected in parallel to the third circuit breaker.

6. The power supply circuit for the backup emergency diesel generator set in a pressurized water reactor nuclear power plant according to claim 5, characterized in that, The reactor emergency bus is connected to a second normal incoming switch.

7. The power supply circuit for the backup emergency diesel generator set in a pressurized water reactor nuclear power plant according to claim 6, characterized in that, The second switch group includes a second bus feeder switch and a second bus incoming switch connected to each other. The second bus feeder switch is connected to the reactor emergency bus, and the second bus incoming switch is connected to the power distribution transfer bus. The second bus incoming switches of all the second switch groups are connected in parallel with the first bus incoming switch on the first circuit breaker.

8. A diesel generator set power supply method, characterized in that, The power supply circuit for the backup emergency diesel generator set of the pressurized water reactor nuclear power plant as described in claim 7 is specifically as follows: when a certain emergency diesel generator fails, the backup emergency diesel generator takes over its operation, the first circuit breaker is pushed into its corresponding second bus incoming switch, the second circuit breaker is pushed into its corresponding reactor bus feeder switch, and at the same time, the corresponding third circuit breaker is pushed into the backup incoming switch, the output switch is placed in the working closed position, the second bus feeder switch corresponding to the emergency diesel generator is placed in the working closed position, and the distribution transfer bus feeder switch and the distribution bus feeder switch are placed in the working closed position.

9. The diesel generator set power supply method according to claim 8, characterized in that, When the standby emergency diesel generator is in cold standby mode, all the second normal incoming line switches are opened, and the remaining switches are placed in the isolation open position. The standby transfer bus, distribution transfer bus, and distribution bus are all de-energized, and the reactor emergency bus is powered by the normal power source.

10. The diesel generator set power supply method according to claim 9, characterized in that, When the standby emergency diesel generator is undergoing periodic testing in cold standby mode, the first busbar feeder switch, the first busbar incoming switch, the distribution transfer busbar feeder switch, and the distribution busbar feeder switch will be switched off.

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