Integrated construction method for distributed phase modifier SFC and excitation system

Abstract

The invention discloses an integrated construction method for a distributed phase modifier SFC and an excitation system, and the method comprises the steps: enabling an incoming line switch K1 to be connected with a high-voltage auxiliary power bus during the starting of a phase modifier; the switch K2 is switched off, the isolating switch K3 is switched on, and the field suppression switch K4 is switched on; the phase modifier is normally excited through the excitation power module, and frequency conversion and speed increase are realized through the SFC first power module and the SFC second power module; after the rotating speed of the phase modifier is increased to the rated rotating speed, the disconnecting switch K3 is switched off, and the phase modifier enters a running-down stage; in the running-down stage of the phase modifier, the incoming line switch K1 is switched to a machine end bus, power is supplied to the excitation system through residual voltage of a machine end, the phase modifier is boosted to rated voltage, and grid connection is completed; after grid connection is completed, the switch K2 is closed, and the SFC second power module is converted into an excitation power module. Therefore, the SFC system and the excitation system of the phase modifier are highly fused, the SFC power module is converted into the excitation power module after normal grid connection, and the equipment utilization rate is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motors and electrical appliances, and particularly to an integrated construction method for the SFC and excitation system of a distributed synchronous condenser. Background Art

[0002] With the successive commissioning of new synchronous condensers, synchronous condensers have played an important role in suppressing overvoltages or commutation failures in converter stations, improving cross-regional power transmission capabilities, and supporting the accommodation of newly added renewable energy. At the same time, to solve the voltage support and fault ride-through problems of renewable energy power plants, the first batch of 21 distributed synchronous condensers was put into engineering application at renewable energy power plants in the Hainan area of Qinghai at the end of 2021. As of the end of August 2024, 48 new large-capacity synchronous condensers and 81 new distributed synchronous condensers have been put into operation, and another 110 have signed supply contracts. The new synchronous condensers have become key equipment to support the large-scale development of renewable energy and promote the transformation and upgrading of the energy structure.

[0003] However, the current engineering construction cost of distributed synchronous condensers is too high, and both the integration level of the electrical secondary system and the equipment utilization rate need to be improved. As the starting equipment commonly used for distributed synchronous condensers at present, the SFC occupies a relatively high cost proportion in the electrical secondary system, but it is only used for starting, and the equipment is in an idle state for a long time after grid connection, and the equipment utilization rate is very low. Since both the SFC and the excitation system are composed of high-power thyristors, if they can be shared, it will undoubtedly greatly simplify the electrical secondary system and reduce equipment investment, providing assistance for the popularization and application of distributed synchronous condensers. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides an integrated construction method for the SFC and excitation system of a distributed synchronous condenser, including:

[0005] The generator terminal bus and the high-voltage auxiliary power bus can be respectively connected to the incoming line switch K1;

[0006] The incoming line switch K1 is respectively connected to the input ends of the first SFC power module and the second SFC power module; the output ends of the first SFC power module and the second SFC power module are connected to the synchronous condenser through the disconnecting switch K3;

[0007] The incoming line switch K1 is connected to the input end of the excitation power module; the output end of the excitation power module is connected to the synchronous condenser through the field discharge switch K4;

[0008] The second SFC power module is connected to the excitation power module through the switch K2;

[0009] During the starting period of the synchronous condenser, the incoming line switch K1 is connected to the high-voltage auxiliary power bus; switch K2 is open, disconnecting switch K3 is closed, and exciter switch K4 is closed; the synchronous condenser is normally excited through the excitation power module, and the variable frequency speed increase is achieved through the SFC first power module and the SFC second power module; after the speed of the synchronous condenser rises to the rated speed, disconnecting switch K3 is opened, and the synchronous condenser enters the coasting period;

[0010] During the coasting period of the synchronous condenser, the incoming line switch K1 is switched to the machine terminal bus, and the residual voltage at the machine terminal is used to supply power to the excitation system, so that the synchronous condenser is boosted to the rated voltage and grid connection is completed;

[0011] After grid connection is completed, switch K2 is closed, and the SFC second power module is converted into an excitation power module.

[0012] Furthermore, after the speed of the synchronous condenser rises to the rated speed, disconnecting switch K3 is opened, and the synchronous condenser enters the coasting period, where the rated speed is specifically 105% of the speed.

[0013] Furthermore, it also includes: connecting the SFC first power module to the excitation power module through switch K2, and after grid connection is completed, switch K2 is closed, and the SFC first power module is converted into an excitation power module.

[0014] Furthermore, it also includes: canceling the power supply of the machine terminal bus and the high-voltage auxiliary power bus, adding a grid connection switch on the low-voltage side of the step-up transformer, and during the starting process of the synchronous condenser, the 35kV bus supplies power to the SFC and the excitation system after stepping down through the main transformer.

[0015] Furthermore, it also includes:

[0016] When the synchronous condenser starts, the high-voltage circuit breaker is in the closed state, the grid connection switch is in the open state, and the SFC and the excitation system are supplied with power by stepping down the 35kV bus through the main transformer;

[0017] During the starting period of the synchronous condenser, switch K2 is open, and incoming line switch K1, disconnecting switch K3, and exciter switch K4 are closed;

[0018] During the starting and coasting grid connection process of the synchronous condenser, the power supply is not switched, and after grid connection is completed, K2 is closed, and the SFC second power module is converted into an excitation power module.

[0019] Furthermore, it also includes:

[0020] Canceling the power supply of the machine terminal bus and the high-voltage auxiliary power bus, and supplying power to the SFC and the excitation system by the 35kV bus.

[0021] Furthermore, it also includes:

[0022] When the synchronous condenser starts, the grid connection breaker is in the open state, and the SFC and the excitation system are directly supplied with power by the 35kV bus;

[0023] During the starting period of the synchronous condenser, switch K2 is disconnected, and incoming line switch K1, disconnecting switch K3, and field discharge switch K4 are closed.

[0024] During the starting and coasting process of the synchronous condenser to cut off the network, the power supply is not switched. After grid connection is completed, K2 is closed, and the second power module of the SFC is converted into an excitation power module.

[0025] Furthermore, it also includes:

[0026] The power supply of the generator terminal bus and the high-voltage auxiliary power bus is cancelled, and the 35 kV bus supplies power to the SFC and the excitation system.

[0027] The first power module and the second power module of the SFC adopt 6-pulse rectifier modules.

[0028] An integrated construction method for the SFC and the excitation system of a distributed synchronous condenser provided by the present invention highly integrates the SFC system and the excitation system of the synchronous condenser. After the SFC power module is normally connected to the grid, it is converted into an excitation power module, and the equipment utilization rate is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the main wiring topology 1 of the integrated construction method of the main wiring SFC and the excitation system provided by the embodiment of the present invention;

[0030] Figure 2 It is the schematic diagram of the electrical main wiring of the distributed synchronous condenser involved in the embodiment of the present invention;

[0031] Figure 3 It is the main wiring topology 2 of the integrated construction method of the SFC and the excitation system involved in the embodiment of the present invention;

[0032] Figure 4 It is the main wiring topology 3 of the integrated construction method of the SFC and the excitation system involved in the embodiment of the present invention;

[0033] Figure 5 It is the main wiring of the integrated construction method of the 6-pulse SFC and the excitation system involved in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] Many specific details are set forth in the following description in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar promotions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0035] The present invention aims to make full use of the power components of the SFC, enabling them to become part of the excitation system after completing the starting task, and realizing the integrated design of the starting system and the excitation system.

[0036] The electrical main connection of the distributed synchronous condenser static frequency converter (SFC) and the excitation system is as Figure 2 shown.

[0037] Currently, the main connection of the distributed synchronous condenser follows that of large-capacity synchronous condensers, usually connected to the 35 kV bus of the new energy power station through a step-up transformer. The SFC power supply is taken from the 10 kV plant power of the new energy power station; the excitation system has two power supplies. The starting excitation circuit is taken from the 380 V plant power of the power station, and the main excitation is taken from the machine terminal of the synchronous condenser. During the starting period of the synchronous condenser, the starting excitation provides the excitation current for the synchronous condenser. When the speed of the synchronous condenser reaches 105% of the rated speed, the SFC is powered off, and the synchronous condenser begins to coast down. During the coast-down period, the excitation system switches to the main excitation and quickly rises to the rated voltage, and is synchronized through the synchronization device to complete grid connection.

[0038] It can be Figure 2 seen that there are three groups of transformers in the current SFC and excitation system, with a large number of devices. Moreover, excitation switching is required during the coast-down and grid connection periods, making the control difficult. At the same time, the capacity of the SFC isolation transformer in this system is the largest, and the SFC system is very expensive but is only used during grid connection, resulting in extremely low equipment utilization rate. For this reason, the present invention proposes an integrated construction method for the SFC and the excitation system of the distributed synchronous condenser. Its topological structure is as Figure 1 shown, including:

[0039] The machine terminal bus and the high-voltage plant power bus can be respectively connected to the incoming line switch K1;

[0040] The incoming line switch K1 is respectively connected to the input ends of the first power module of the SFC (corresponding to the SFC power module in Figure 1 ) and the second power module of the SFC (corresponding to the SFC-excitation power module in Figure 1 ); the output ends of the first power module of the SFC and the second power module of the SFC are connected to the synchronous condenser through the disconnecting switch K3;

[0041] The incoming line switch K1 is connected to the input end of the excitation power module; the output end of the excitation power module is connected to the synchronous condenser through the field discharge switch K4;

[0042] The second power module of the SFC is connected to the excitation power module through the switch K2;

[0043] During the starting period of the synchronous condenser, the incoming line switch K1 is connected to the high-voltage auxiliary power bus; switch K2 is open, disconnecting switch K3 is closed, and the field discharge switch K4 is closed; the synchronous condenser is normally excited through the excitation power module, and the variable-frequency speed-up is achieved through the SFC first power module and the SFC second power module; after the speed of the synchronous condenser rises to the rated speed, disconnecting switch K3 is opened, and the synchronous condenser enters the coasting-down stage;

[0044] During the coasting-down stage of the synchronous condenser, the incoming line switch K1 is switched to the machine terminal bus, and the residual voltage at the machine terminal is used to supply power to the excitation system, so that the synchronous condenser is boosted to the rated voltage and the grid connection is completed;

[0045] After the grid connection is completed, switch K2 is closed, and the SFC second power module is converted into an excitation power module, as Figure 1 the SFC-excitation power module marked in the figure.

[0046] After the speed of the synchronous condenser rises to the rated speed, disconnecting switch K3 is opened, and the synchronous condenser enters the coasting-down stage, where the rated speed is specifically 105% of the speed.

[0047] Connect the SFC first power module to the excitation power module through switch K2. After the grid connection is completed, switch K2 is closed, and the SFC first power module is converted into an excitation power module.

[0048] Figure 1 In the shown topological structure, the SFC isolation transformer and the excitation transformer are combined into one, and at the same time, the starting excitation transformer is cancelled. During the starting period of the synchronous condenser, the incoming line K1 switch is connected to the high-voltage auxiliary power bus, and the SFC and the excitation system are powered by the auxiliary power. The high-voltage short-circuit period is in the open state. Switch K2 is open, disconnecting switch K3 is closed, and the field discharge switch K4 is closed. During the starting process, the synchronous condenser is normally excited through the excitation power module, and the variable-frequency speed-up is achieved through two SFC power modules. After the speed of the synchronous condenser rises to 105% of the rated speed, disconnecting switch K3 is opened, and the synchronous condenser enters the coasting-down stage. At this time, the incoming line switch K1 is switched to the machine terminal bus, and the residual voltage at the machine terminal is used to supply power to the excitation system, and the excitation is quickly increased to boost the synchronous condenser to the rated voltage, and the grid connection is completed through the synchronization device. After the grid connection is completed, K2 is closed, and one of the SFC power modules is converted into an excitation power module.

[0049] Figure 1 In the shown topological structure, the synchronous condenser system needs to be additionally connected to the high-voltage auxiliary power and the power supply needs to be switched during the starting period. When the capacity of the auxiliary power is limited or the wiring is inconvenient, the machine terminal bus and the high-voltage auxiliary power bus power supply can be cancelled, and a grid connection switch can be added on the low-voltage side of the step-up transformer. During the starting process of the synchronous condenser, the 35kV bus supplies power to the SFC and the excitation system after being stepped down by the main transformer, as Figure 3 shown. Figure 3In the shown topological structure, when the synchronous condenser starts, the high-voltage circuit breaker is in the closed state, the grid-connection switch is in the open state, and the SFC and the excitation system are powered by the 35 kV bus after stepping down through the main transformer; during the starting of the synchronous condenser, switch K2 is open, and incoming line switch K1, disconnecting switch K3, and field discharge switch K4 are closed.

[0050] During the starting and coasting-to-stop grid-connection process of the synchronous condenser, the power supply is not switched. After grid connection is completed, K2 is closed, and the second power module of the SFC is converted into an excitation power module, that is, Figure 3 the SFC-excitation power module in

[0051] Figure 3 In the shown topological structure, a grid-connection switch is added at the outlet of the synchronous condenser. This grid-connection switch does not need to have the ability to cut off short-circuit current and has a low cost. To further simplify the system, based on Figure 1 the shown topological structure, the Figure 1 supply of the machine terminal bus and the high-voltage auxiliary power bus can also be cancelled, and the SFC and the excitation system are powered by the 35 kV bus after stepping down through the main transformer, or based on Figure 3 the shown topological structure, the grid-connection switch on the low-voltage side of the step-up transformer is cancelled, and the SFC and the excitation system are directly powered by the 35 kV bus, as Figure 4 shown.

[0052] Figure 4 In the shown topological structure, when the synchronous condenser starts, the grid-connection circuit breaker is in the open state, and the SFC and the excitation system are directly powered by the 35 kV bus; the starting and coasting-to-stop grid-connection process is the same as that described in Figure 3 During the starting of the synchronous condenser, switch K2 is open, and incoming line switch K1, disconnecting switch K3, and field discharge switch K4 are closed; during the starting and coasting-to-stop grid-connection process of the synchronous condenser, the power supply is not switched. After grid connection is completed, K2 is closed, and the second power module of the SFC is converted into an excitation power module.

[0053] When the SFC and the excitation system are directly powered by the 35 kV bus, since the capacity of the 35 kV system is much larger than the capacity of the SFC, the harmonics generated by the SFC during the starting of the synchronous condenser have little impact on the 35 kV system. Therefore, based on Figure 1 the shown topological structure, the supply of the machine terminal bus and the high-voltage auxiliary power bus is cancelled, and the 35 kV bus powers the SFC and the excitation system; the first power module and the second power module of the SFC adopt 6-pulse rectifier modules. The wiring topology of the synchronous condenser will be more concise, as Figure 5 shown.

[0054] Specific application embodiments are as follows:

[0055] For distributed synchronous condensers with a capacity of 50 MVA and below, only two power modules are required for the excitation system. Therefore Figure 5The integrated design scheme of the 6-pulse SFC and excitation system shown can fully meet the requirements. Figure 5 The main wiring diagram of the integrated design of the 6-pulse SFC and excitation system shown is the best implementation case. Compared with the traditional method, this case not only significantly reduces equipment such as transformers and starting exciters, but also greatly simplifies the SFC system, significantly compresses the equipment cost, and greatly improves the utilization rate of the SFC power module.

[0056] When the synchronous condenser starts, Figure 5 the shown grid-connected circuit breaker is in the open state. Close the incoming line switch K1 of the SFC-excitation system, and keep the switch K2 in the open state. Close the disconnecting switch K3 and the field discharge switch K4. The SFC power module supplies power to the stator winding of the synchronous condenser, and the excitation power module supplies power to the rotor winding; after driving the synchronous condenser to accelerate to 105% of the rated speed, open the disconnecting switch K3, and the synchronous condenser enters the coasting-down stage; increase the excitation to raise the terminal voltage of the synchronous condenser to the rated voltage, and complete grid connection through the synchronization device; after grid connection is completed, close the switch K2, and the SFC power module is converted into an excitation power module.

[0057] Compared with the prior art, the present invention has the following advantages:

[0058] (1) The SFC system and excitation system of the synchronous condenser proposed by the present invention are highly integrated. After the SFC power module is normally grid-connected, it is converted into an excitation power module, and the equipment utilization rate is greatly improved;

[0059] (2) The present invention significantly reduces the electrical secondary system equipment, the design is more compact and reasonable, the integration degree is greatly improved, and the floor area and equipment cost are significantly reduced.

[0060] (3) The present invention significantly reduces the dependence on the auxiliary power system of the new energy power station, greatly reduces the requirements for supporting equipment, effectively broadens the applicable scenarios of the synchronous condenser, and is very conducive to the engineering promotion and application of the synchronous condenser.

[0061] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0062] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices produce means for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in one block or multiple blocks.

[0063] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in one block or multiple blocks.

[0064] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one flow Figure 1 one flow or multiple flows and / or blocks Figure 1 or means for implementing the functions specified in one block or multiple blocks.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the specific implementation manners of the present invention can still be modified or equivalently replaced, and any modification or equivalent replacement without departing from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims

1. A method for integrating distributed phase condenser SFC and excitation system, characterized in that: include: The machine-end busbar and the high-voltage auxiliary power busbar can be connected to the incoming switch K1 respectively; The incoming switch K1 is connected to the input ends of the SFC first power module and the SFC second power module respectively; the output ends of the SFC first power module and the SFC second power module are connected to the phase regulator through the isolation switch K3; The incoming line switch K1 is connected to the input end of the excitation power module; the output end of the excitation power module is connected to the phase regulator through the demagnetization switch K4; The second power module of SFC is connected to the excitation power module through switch K2; During the phase condenser startup, the incoming switch K1 is connected to the high-voltage auxiliary power busbar; the switch K2 is disconnected, the isolating switch K3 is closed, and the demagnetization switch K4 is closed; the phase condenser is normally excited through the excitation power module, and the frequency conversion speed is increased through the SFC first power module and the SFC second power module; after the phase condenser speed increases to the rated speed, the isolating switch K3 is disconnected, and the phase condenser enters the idling stage; During the phase condenser idling stage, the incoming line switch K1 is switched to the machine-end busbar, and the residual voltage at the machine end is used to power the excitation system, so that the phase condenser voltage is boosted to the rated voltage and the grid connection is completed; After the grid connection is completed, switch K2 is closed to convert the SFC second power module into an excitation power module.

2. The method according to claim 1, characterized in that: After the speed of the phase regulator increases to the rated speed, the isolating switch K3 is disconnected and the phase regulator enters the idling stage, wherein the rated speed is specifically 105% of the speed.

3. The method according to claim 1, characterized in that Also includes: The SFC first power module is connected to the excitation power module through the switch K2. After the grid connection is completed, the switch K2 is closed to convert the SFC first power module into the excitation power module.

4. The method according to claim 1, characterized in that Also includes: The power supply of the machine-end bus and the high-voltage plant power bus is cancelled, and a grid-connected switch is added on the low-voltage side of the step-up transformer. During the starting process of the phase-shifting machine, the 35kV bus is stepped down by the main transformer and then supplies power to the SFC and excitation system.

5. The method according to claim 4, characterized in that Also includes: When the phase regulator is started, the high-voltage circuit breaker is in the closed state, the grid-connected switch is in the open state, and the SFC and excitation system are powered by the 35kV bus after the voltage is stepped down by the main transformer; During the start-up of the phase regulator, the switch K2 is opened, and the incoming switch K1, the isolating switch K3 and the demagnetizing switch K4 are closed; The power supply is not switched during the phase regulator startup and idling shutdown process. After the grid connection is completed, K2 is closed to convert the SFC second power module into an excitation power module.

6. The method according to claim 1, characterized in that Also includes: The power supply from the machine-end bus and high-voltage plant power bus is cancelled, and the 35kV bus supplies power to the SFC and excitation system.

7. The method according to claim 6, characterized in that Also includes: When the phase regulator is started, the grid-connected circuit breaker is in the open state, and the SFC and excitation system are directly powered by the 35kV bus; During the start-up of the phase regulator, the switch K2 is opened, and the incoming switch K1, the isolating switch K3 and the demagnetizing switch K4 are closed; The power supply is not switched during the phase regulator startup and idling shutdown process. After the grid connection is completed, K2 is closed to convert the SFC second power module into an excitation power module.

8. The method according to claim 6, characterized in that Also includes: The generator-side busbar and high-voltage plant power busbar are no longer needed, and the 35kV busbar is used to supply power to the SFC and excitation system. The SFC first power module and the SFC second power module use 6-pulse rectifier modules.

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