Switching method for different source power supply system and control system thereof

Abstract

The present application relates to the technical field of auxiliary power, in particular to a switching method and control system of different-source auxiliary power system. Whether the different-source auxiliary power system adopts partial important load cross configuration is judged, if yes, the running state of each unit in the different-source auxiliary power system is detected; if only one unit is in normal operation and the rest units are in non-grid-connected operation state, it is judged that the parallel switching condition is met; otherwise, it is judged that the parallel switching condition is not met; when the parallel switching condition is met, if normal switching or fault switching is needed, parallel switching is adopted; when the parallel switching condition is not met, if normal switching or fault switching is needed, series switching is adopted. The series switching and parallel switching mode can be adopted for control according to the specific running state of partial different-source auxiliary power system, the switching efficiency is improved, and the reliability of different-source auxiliary power system switching is ensured.

Description

Technical Field

[0001] This invention relates to the field of plant power technology, specifically to a switching method and control system for plant power systems from different sources. Background Technology

[0002] The plant auxiliary power system refers to the system consisting of generating units, low-voltage plant transformers and starting transformers, their power supply network, and plant auxiliary loads. The plant auxiliary power system can be further divided into homogeneous and heterogeneous power systems. Homogeneous power systems consist of a single power system, while heterogeneous power systems use two or more completely different power systems.

[0003] in, Figure 1 This diagram illustrates a common power supply system for plants with different power sources. The system uses a segmented busbar wiring method. During normal operation, 400V busbar I is powered by incoming line I, and 400V busbar II is powered by incoming line II. Specifically, 400V incoming line switches 1DL and 2DL are closed, and the 400V busbar tie switch 3DL is open; the upstream 10KV power switches 4DL and 5DL are closed, and the 10KV busbar tie switch 6DL is open.

[0004] During operation, the plant's power supply system requires normal or fault switching depending on the operating status. Depending on the operating sequence of the circuit breakers, this switching process includes series switching and parallel switching. In series switching, one power source must be disconnected before another can be connected; typically, the auxiliary contacts of the disconnected power source circuit breaker are used to connect the closing circuit of the standby power source circuit breaker. For Figure 1In a power system, when performing a plant auxiliary power switching operation, the bus power switch 1DL (2DL) is usually disconnected first. Only after confirming that 1DL (2DL) has tripped can the bus tie switch 3DL be closed according to the closing conditions. However, according to the power system switching operation specifications, before disconnecting the 1DL (2DL) power switch, the load switch of that bus section must be disconnected as much as possible; the load switch of that bus section can only be put back into operation after the bus tie switch 3DL is closed. During the switching process, the plant auxiliary power bus will lose power, posing a risk of equipment tripping or shutdown. Moreover, the operation steps during the switching process are cumbersome and inefficient. Parallel switching refers to the switching of the working plant auxiliary power supply and the standby power supply in parallel for a short period of time during the plant auxiliary power switching period. It has the advantage of continuous plant auxiliary power supply. However, since parallel switching requires the working plant auxiliary power supply and the standby power supply to operate in parallel for a short period of time, for plant auxiliary power systems from different sources, which come from two completely different power systems, the frequencies, phase differences, and voltage amplitudes on both sides of the switch are different, which does not meet the premise of parallel operation of different power sources. Therefore, while parallel switching has many advantages, it is not applicable to power supply systems from different power sources. That is, existing technologies can only use series switching for normal or fault switching between power supply systems from different power sources. This method has drawbacks such as the risk of power loss on the power supply bus, equipment tripping or shutdown, and cumbersome and inefficient operation procedures during the switching process. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a switching method and control system for different source power systems. This method can control different source power systems by using series switching and parallel switching methods according to their specific operating states. This ensures continuous power supply to the plant while avoiding power loss on the plant power bus, thus improving switching efficiency and ensuring the reliability of switching between different source power systems.

[0006] This invention provides a method for switching between different power supply systems from different power sources, comprising:

[0007] Determine whether the power systems of different power sources adopt cross-configuration of some important loads. If so, detect the operating status of each unit in the power systems of different power sources.

[0008] If only one unit is operating normally at present, while the other units are in a non-grid-connected state, it is determined that the power supply systems of the different power sources currently meet the conditions for parallel switching.

[0009] If at least two generating units are currently operating normally, it is determined that the power supply systems of the different power sources do not currently meet the conditions for parallel switching;

[0010] When the different power supply systems currently meet the conditions for parallel switching, if normal switching or fault switching is required based on the current operating status of the different power supply systems, then the power supply switching is carried out in parallel.

[0011] When the different power supply systems do not currently meet the conditions for parallel switching, if normal switching or fault switching is required based on the current operating status of the different power supply systems, then the power supply switching is performed in series.

[0012] Preferably, when the different source power systems currently meet the conditions for parallel switching, the power system is switched in parallel with the goal of disconnecting the other non-grid-connected units, so that the different source power systems operate in a single power system mode.

[0013] Preferably, when the different source power systems are power supply systems for dual generator units, if any one of the following occurs in the non-grid-connected generator unit: a phase-to-phase short circuit fault in the 400V busbar incoming power switch body, a short circuit fault in the incoming power cable, or a cable meltdown fault, then it is determined that the different source power systems need to switch faults according to the current operating status.

[0014] Preferably, the parallel switching includes:

[0015] Upon receiving the switching operation command, first close the 400V bus tie switch;

[0016] After confirming that the 400V bus tie switch is closed, a command to open the 400V bus section incoming power switch is sent to the target unit.

[0017] When the parallel switching is a fault switching, the target side unit is the faulty side unit; when the parallel switching is a normal switching, the target side unit is the unit that needs to be disconnected.

[0018] Preferably, the serial switching includes:

[0019] Upon receiving the switching operation command, a 400V busbar incoming power switch tripping command is sent to the target unit.

[0020] After confirming that the incoming power switch of the 400V bus section of the faulty unit has been opened, a closing command is sent to the 400V bus tie switch.

[0021] When the series switching is a fault switching, the target side unit is the faulty side unit; when the series switching is a normal switching, the target side unit is the unit that needs to be disconnected.

[0022] Preferably, if one and only one of the 10KV power supply incoming line switches of the upstream line is in the open state and the 10KV bus tie switch is in the closed state, it is determined that only one unit of the different source plant power system is currently operating normally, while the other units are in the off-grid operation state; otherwise, it is determined that at least two units of the different source plant power system are currently operating normally.

[0023] This invention provides a switching control system for different power supply systems from different power sources, comprising:

[0024] The operation status judgment module is used to determine whether the power systems of different power sources adopt partial important load cross-configuration. If so, the operation status of each unit in the power systems of different power sources is detected. If only one unit is operating normally while the other units are in a non-grid-connected operation state, it is determined that the power systems of different power sources currently meet the parallel switching conditions. If at least two units are operating normally, it is determined that the power systems of different power sources currently do not meet the parallel switching conditions.

[0025] The switching control module is used to control the closing or opening of each switch in parallel switching mode when the different source power systems currently meet the parallel switching conditions, and if normal switching or fault switching is required according to the current operating status of the different source power systems, so as to realize the power supply switching; and when the different source power systems currently do not meet the parallel switching conditions, and if normal switching or fault switching is required according to the current operating status of the different source power systems, so as to control the closing or opening of each switch in series switching mode, so as to realize the power supply switching.

[0026] The beneficial effects of this invention are as follows:

[0027] 1. This invention addresses the issue that some new energy enterprises, constrained by power system access and other factors, have two generating units from different source power systems connected to two different substations. Furthermore, since both 10kV and 400V power systems are single-segment configurations, to improve power system reliability, they adopt a partial cross-configuration of important loads compared to typical different-source power systems. For this type of new energy enterprise, during operation, only one generating unit may be running normally, while the others are in a non-grid-connected state. When the power system is in this state, even though it is essentially still a different-source power system, the frequency, phase difference, and voltage amplitude on both sides of the 400V bus tie switch are the same, thus satisfying the parallel switching condition. Compared to the traditional one-size-fits-all series switching control method for different-source power systems, this invention differentiates the operating states of the generating units in different-source power systems with partial cross-configuration of important loads, thereby employing parallel or series switching under different operating states. Parallel switching takes precedence over series switching, thus ensuring continuous power supply to the plant while avoiding power outages on the plant power bus, improving switching efficiency, and guaranteeing the reliability of switching between different source plant power systems.

[0028] 2. This invention addresses the increased electricity costs for enterprises arising from the cross-configuration of different source power systems for some critical loads. When different source power systems meet the conditions for parallel switching, the power system is switched in parallel with the goal of disconnecting the other non-grid-connected generating units, allowing different source power systems to operate in a single power system mode. This avoids energy consumption caused by shut-down units absorbing active power from the system, thus saving electricity costs. Attached Figure Description

[0029] Figure 1 A schematic diagram showing the connection of the existing dual-unit plant auxiliary power systems from different sources;

[0030] Figure 2 This is the control flowchart of the present invention. Detailed Implementation

[0031] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0032] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0033] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0034] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0035] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0036] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. "A plurality" means "two or more."

[0038] This invention retains the series switching operation function commonly used in existing power systems from different sources, while optimizing the switching logic of the entire power system from different sources using automated electrical equipment (DCS control system). Different switching control methods are formulated for different scenarios of the power system from different sources. This achieves multiple switching control methods for power systems from different sources, thereby improving the safety and reliability of the entire power system switching process and ensuring the safe and stable operation of power production.

[0039] Example 1

[0040] like Figure 1 As shown, the existing power grid structure of the dual-unit plant auxiliary power system consists of two bus sections, Bus Section I and Bus Section II, corresponding power supply incoming lines, power supply incoming line switch 1DL (2DL), tie lines, tie switch 3DL, upstream power supply incoming lines, upstream power supply incoming line switch 4DL (5DL), and upstream power supply tie switch 6DL. Figure 2 This invention is aimed at Figure 1 A preferred embodiment of the system provides the following method:

[0041] The method includes:

[0042] Determine whether the power systems of different power sources adopt cross-configuration of some important loads. If so, detect the operating status of each unit in the power systems of different power sources.

[0043] If only one unit is operating normally at present, while the other units are in a non-grid-connected state, it is determined that the power supply systems of the different power sources currently meet the conditions for parallel switching.

[0044] If at least two generating units are currently operating normally, it is determined that the power supply systems of the different power sources do not currently meet the conditions for parallel switching;

[0045] When the different power supply systems currently meet the conditions for parallel switching, if normal switching or fault switching is required based on the current operating status of the different power supply systems, then the power supply switching is carried out in parallel.

[0046] When the different power supply systems do not currently meet the conditions for parallel switching, if normal switching or fault switching is required based on the current operating status of the different power supply systems, then the power supply switching is performed in series.

[0047] This invention, while retaining the original series switching control method, proposes to add a parallel switching control method for different source power systems, enabling parallel switching control of power switches for each bus section of the 400V PC power supply. Based on the existing closing logic of the 400V incoming switch for different source power systems, it adds judgment conditions for the status of the upstream 10KV section power incoming switch 4DL (5DL) and the 10KV section power bus tie switch 6DL, and adds corresponding DCS logic control methods. By implementing multiple switching control methods for different source power systems, it achieves safe and reliable switching functionality.

[0048] In one embodiment, this invention addresses the increased electricity costs for businesses in power systems with overlapping critical loads from different power sources. Extensive statistical and practical analysis revealed the primary cause of this increased cost: even when a generating unit is out of service, it still carries a portion of the power load from the operating unit. Combined with active power losses from the main transformer and 110kV transmission lines, this means that even when a unit is out of service, it continuously draws active power from the system, resulting in increased electricity costs for businesses. To address this issue, this invention, specifically targeting the increased electricity costs in power systems with overlapping critical loads from different power sources, performs a parallel switching of the power supply to different generating units when the parallel switching conditions are met. This aims to disconnect the other non-grid-connected generating units, allowing different power systems to operate in a single power supply mode. This switching is a normal switching, not a fault switching. This switching strategy avoids the energy consumption caused by out-of-service units drawing active power from the system, thus saving electricity costs.

[0049] In one embodiment, when different source power systems are power supply systems for dual generator units, if any one of the following occurs in the non-grid-connected generator unit: a phase-to-phase short circuit fault in the 400V busbar incoming power switch body, a short circuit fault in the incoming power cable, or a cable meltdown fault, it is determined that the different source power systems need to switch faults according to the current operating status.

[0050] In one embodiment, the parallel switching includes:

[0051] Upon receiving the switching operation command, first close the 400V bus tie switch;

[0052] After confirming that the 400V bus tie switch is closed, a command to open the 400V bus section incoming power switch is sent to the target unit.

[0053] When the parallel switching is a fault switching, the target side unit is the faulty side unit; when the parallel switching is a normal switching, the target side unit is the unit that needs to be disconnected.

[0054] In one embodiment, the serial switching includes:

[0055] Upon receiving the switching operation command, a 400V busbar incoming power switch tripping command is sent to the target unit.

[0056] After confirming that the incoming power switch of the 400V bus section of the faulty unit has been opened, a closing command is sent to the 400V bus tie switch.

[0057] When the series switching is a fault switching, the target side unit is the faulty side unit; when the series switching is a normal switching, the target side unit is the unit that needs to be disconnected.

[0058] In one embodiment, if one and only one of the 10KV power supply incoming line switches of the upstream line is in the open state and the 10KV bus tie switch is in the closed state, it is determined that only one unit of the different source plant power system is currently operating normally, while the other units are in the off-grid operation state; otherwise, it is determined that at least two units of the different source plant power system are currently operating normally.

[0059] Example 2

[0060] This invention provides a switching control system for different power supply systems from different power sources, comprising:

[0061] The operation status judgment module is used to determine whether the power systems of different power sources adopt partial important load cross-configuration. If so, the operation status of each unit in the power systems of different power sources is detected. If only one unit is operating normally while the other units are in a non-grid-connected operation state, it is determined that the power systems of different power sources currently meet the parallel switching conditions. If at least two units are operating normally, it is determined that the power systems of different power sources currently do not meet the parallel switching conditions.

[0062] The switching control module is used to control the closing or opening of each switch in parallel switching mode when the different source power systems currently meet the parallel switching conditions, and if normal switching or fault switching is required according to the current operating status of the different source power systems, so as to realize the power supply switching; and when the different source power systems currently do not meet the parallel switching conditions, and if normal switching or fault switching is required according to the current operating status of the different source power systems, so as to control the closing or opening of each switch in series switching mode, so as to realize the power supply switching.

[0063] Example 3

[0064] This embodiment provides a specific production example of a method for switching between different source power supply systems. When applied to power supply system switching control, this method is implemented in the following ways:

[0065] 1. Add parallel switching and closing logic to all incoming line switches 1DL (2DL) and tie switches 3DL of the existing 400V busbar section of the plant power supply at the software control level;

[0066] 2. The status of all incoming line switches 1DL (2DL), tie switch 3DL, and the upstream 10KV section power supply incoming line switch 4DL (5DL) of the 400V bus section of the plant power supply, as well as the 10KV section power supply bus tie switch 6DL, the parallel switching closing logic added in step 1, the status of each switch and the control commands, are all electrically connected to the corresponding logic modules of the DCS control system.

[0067] 3. The DCS control logic periodically scans the closing / opening status of each switch mentioned in step 2, and then automatically scans and judges based on the closing / opening commands of the incoming switch actually operated by the operator.

[0068] 4. Determine whether a 400V plant power supply switch is required. A plant power supply switch is only required when a unit is out of grid (out of service or on standby) or when the incoming switch of a 400V PC section is faulty.

[0069] 5. After determining that a plant power switching operation is required, determine the specific switching method to be adopted based on the status of the upstream 10KV section power incoming switch 4DL, 5DL and the 10KV bus tie switch 6DL.

[0070] The working principle of the plant's power supply system is as follows:

[0071] When the unit generates electricity, the station power current flows through the generator → station power bus switch I(II) → station power bus I(II) → station power transformer I(II) → 400V bus I(II); at the same time, the generated electricity is sent to different substations I(II) after being stepped up by the main transformer via a 10KV power switch, i.e., power supply I(II).

[0072] After the unit is shut down, the plant power is fed back to the plant power system from substation I (II) through the main transformer to provide power for the operation of the auxiliary equipment of the shut-down unit.

[0073] The determination of series / parallel switching conditions mainly includes:

[0074] Parallel switching scenario judgment: Parallel switching is mostly used for switching between two power sources in a system with the same frequency under normal conditions. When the upstream 10KV section power supply incoming switch 4DL or 5DL is open and the upstream power supply tie switch 6DL is closed, the parallel switching condition is met.

[0075] Series switching scenario judgment: Series switching scenarios are mostly used for automatic switching in case of accidents. Figure 1 In the provided system, scenarios capable of parallel switching necessarily also meet the conditions for series switching. However, this application treats other scenarios that do not meet the parallel switching criteria as meeting the series switching criteria.

[0076] Under different plant power switching conditions (i.e. scenarios), if normal switching or fault switching is required based on the current operating status of different source plant power systems, then plant power switching needs to be performed.

[0077] The following are the situations where a failover is required:

[0078] A phase-to-phase short circuit fault occurred in the incoming power switch body of the 1.400V bus section I(II), which caused the incoming switch to be unable to be put into operation for a short time, endangering the safe and stable operation of the unit's auxiliary equipment.

[0079] A short circuit or cable meltdown occurred in the incoming power cable of the 2.400V bus section I(II), causing the incoming switch to be unable to resume operation for a short time, endangering the safe and stable operation of the unit's auxiliary equipment.

[0080] Therefore, when different source power systems supply power to dual generating units, if any one of the following occurs in the non-grid-connected generating unit: a phase-to-phase short circuit fault in the 400V busbar incoming power switch body, a short circuit fault in the incoming power cable, or a cable meltdown fault, it is determined that different source power systems need to switch faults according to their current operating status.

[0081] Regarding the parallel switching process, this embodiment uses the plant power supply I as the fault side for explanation, and the switching steps are as follows:

[0082] S1. The DCS system determines whether the parallel switching conditions of the power switches of each bus section of the 400V PC power supply are met based on the received status of the incoming 10KV power supply switch and the closed / open status of the 10KV power supply bus tie switch. If the conditions are met, the system proceeds to step S2. If the conditions are not met, the system refuses to proceed.

[0083] S2, with the switching target being from 1DL to 3DL;

[0084] S2.1 When the DCS system receives the switching operation command, it first closes the 3DL switch. At this time, the two power supplies, 400V bus 1 and bus 2, are briefly connected in parallel. After confirming that 3DL has been closed, the 1DL opening command is issued according to the opening conditions, and the parallel switching operation is completed.

[0085] S2.2 If 3DL fails to engage, the switching process ends and the 1DL command is no longer executed.

[0086] S3, after the switching is completed, the status of each switch is as follows: 400V incoming line switch 1DL is open and 2DL is closed; 400V bus tie switch 3DL is closed; for the upstream 10KV power supply, only one of 4DL or 5DL is closed and the other is open; 10KV bus tie switch 6DL is closed.

[0087] Regarding the series switching process, this embodiment uses the plant power supply I as the fault side for explanation, and the switching steps are as follows:

[0088] S1. The DCS system determines whether the series switching conditions of the power switches of each bus section of the 400V PC in the plant power supply are met based on the received status of the incoming 10KV power supply switch and the closed / open status of the 10KV power supply bus tie switch. If the conditions are met, the system proceeds to step S2. If the conditions are not met, the system refuses to proceed.

[0089] S2 aims to switch from 1DL to 3DL;

[0090] S2.1 When the DCS system receives the switching operation command, it first trips the 1DL switch; after confirming that the 1DL switch has tripped, it issues a command to close the bus tie switch 3DL according to the closing conditions, and the series switching operation is completed.

[0091] S2.2 If 1DL refuses to switch, the handover process ends and the 3DL command is no longer executed.

[0092] S3, after the switching is completed, the status of each switch is as follows: 400V incoming line switch 1DL is open and 2DL is closed; 400V bus tie switch 3DL is closed; upstream 10KV power supply 4DL and 5DL are closed; 10KV bus tie switch 6DL is open.

[0093] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process may be rearranged without departing from the scope of this disclosure. The appended method claims provide elements of various steps in an exemplary order and are not intended to limit the scope to the specific order or hierarchy described.

[0094] In the detailed description above, various features are combined together in a single embodiment to simplify this disclosure. This approach to disclosure should not be construed as reflecting an intention that embodiments of the claimed subject matter require more features than are explicitly stated in each claim. Rather, as reflected in the appended claims, the invention is presented with fewer features than all of the features of the single disclosed embodiment. Therefore, the appended claims are hereby explicitly incorporated into the detailed description, wherein each claim stands alone as a preferred embodiment of the invention.

[0095] The disclosed embodiments have been described above to enable any person skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the spirit and scope of this disclosure. Therefore, this disclosure is not limited to the embodiments given herein, but is consistent with the broadest scope of the principles and novel features disclosed in this application.

[0096] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0097] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for switching between different power supply systems from different sources, characterized in that, include: Determine whether the power systems of different power sources adopt cross-configuration of some important loads. If so, detect the operating status of each unit in the power systems of different power sources. If only one unit is operating normally at present, while the other units are in a non-grid-connected state, it is determined that the power supply systems of the different power sources currently meet the conditions for parallel switching. If at least two generating units are currently operating normally, it is determined that the power supply systems of the different power sources do not currently meet the conditions for parallel switching; When the different source power systems currently meet the conditions for parallel switching, if normal switching or fault switching is required based on the current operating status of the different source power systems, then parallel switching is adopted for power system switching; wherein, the parallel switching of power system is performed with the goal of disconnecting the other units that are not connected to the grid, so that the different source power systems operate in a single power system mode, and the parallel switching with the goal of disconnecting the other units that are not connected to the grid is a normal switching; When the different power supply systems do not currently meet the conditions for parallel switching, if normal switching or fault switching is required based on the current operating status of the different power supply systems, then the power supply switching is performed in series.

2. The switching method for different power supply systems from different sources according to claim 1, characterized in that: When the plant power system with different sources supplies power to two generating units, if any one of the following occurs in the non-grid-connected generating unit: a phase-to-phase short circuit fault in the 400V busbar incoming power switch body, a short circuit fault in the incoming power cable, or a cable meltdown fault, then it is determined that the plant power system with different sources needs to switch faults according to the current operating status.

3. The switching method for different source power systems according to claim 2, characterized in that, The parallel switching includes: Upon receiving the switching operation command, first close the 400V bus tie switch; After confirming that the 400V bus tie switch is closed, a command to open the 400V bus section incoming power switch is sent to the target unit. When the parallel switching is a fault switching, the target side unit is the faulty side unit; when the parallel switching is a normal switching, the target side unit is the unit that needs to be disconnected.

4. The switching method for different source power systems according to claim 2, characterized in that, The serial switching includes: Upon receiving the switching operation command, a 400V busbar incoming power switch tripping command is sent to the target unit. After confirming that the incoming power switch of the 400V bus section of the target unit has been opened, a closing command is sent to the 400V bus tie switch. When the series switching is a fault switching, the target side unit is the faulty side unit; when the series switching is a normal switching, the target side unit is the unit that needs to be disconnected.

5. The switching method for different power supply systems from different sources according to claim 1, characterized in that: If one and only one of the 10kV power supply incoming line switches of the upstream line is in the open state, and the 10kV bus tie switch is in the closed state, then it is determined that only one unit of the different source plant power system is currently operating normally, while the other units are in the off-grid operation state; otherwise, it is determined that at least two units of the different source plant power system are currently operating normally.

6. A switching control system for different source power systems used in implementing the method as described in any one of claims 1 to 5, characterized in that, include: The operation status judgment module is used to determine whether the power systems of different power sources adopt partial important load cross-configuration. If so, the operation status of each unit in the power systems of different power sources is detected. If only one unit is operating normally while the other units are in a non-grid-connected operation state, it is determined that the power systems of different power sources currently meet the parallel switching conditions. If at least two units are operating normally, it is determined that the power systems of different power sources currently do not meet the parallel switching conditions. The switching control module is used to control the closing or opening of each switch in parallel switching mode when the different source power systems currently meet the parallel switching conditions, and if normal switching or fault switching is required according to the current operating status of the different source power systems, so as to realize the power supply switching; and when the different source power systems currently do not meet the parallel switching conditions, and if normal switching or fault switching is required according to the current operating status of the different source power systems, so as to control the closing or opening of each switch in series switching mode, so as to realize the power supply switching.

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