Composite wireless excitation system and method for pumped storage generator

Abstract

The invention discloses a composite wireless excitation system and method for a pumped storage generator, and relates to the technical field of pumped storage power generation, the composite wireless excitation system comprises a motor assembly and a wireless excitation assembly, the motor assembly comprises a rotor core, a rotor winding, a stator core, a stator winding, a stator shell, a rotor shaft and a bearing; the wireless excitation assembly comprises a fixed excitation assembly, a rotary excitation assembly, a fixed communication assembly and a rotary communication assembly. The fixed excitation assembly comprises a fixed magnetic core and a fixed wireless excitation winding; the rotary excitation assembly comprises a rotary magnetic core and a rotary wireless excitation winding; the fixed magnetic core and the rotary magnetic core are both of a pot-type structure. The fixed communication assembly is a fixed signal winding; the rotary communication assembly is a rotary signal winding. The method comprises a transmission process and a dynamic process. The invention has the advantages of easy manufacture, small volume and high power density.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pumped storage power generation, in particular to a composite wireless excitation system and method for a pumped storage generator. BACKGROUND

[0002] Wireless power transmission technology is a new type of power transmission method realized through electromagnetic effect or energy exchange; the rotary loose coupling transformer, as the key part of this technology, is widely used in the power supply of rotating equipment. Compared with the traditional wired power transmission method, the contact slip ring is omitted, which can effectively prevent safety accidents caused by slip ring aging and electric sparks, and is more safe and reliable.

[0003] The existing rotary loose coupling transformer is mainly of the magnetic pot type, made of ferrite, with simple structure and small size, but low power density; The patent number 202120511722.9 has a new design of the magnetic core structure, and the stator and rotor are coaxial and located in the same plane, which realizes miniaturization, but is only suitable for medium frequency and low speed environment, and the actual power density is not improved; The patent number 202010844240.5 also designs a coaxial nested rotary transformer, which adopts interleaved winding to reduce leakage inductance, and the rotor part has no core, thereby reducing iron loss, although the power density and transmission efficiency are improved to some extent, but the actual structure is complex and the manufacturing process is difficult, and in the actual application process, it is found that it is easy to occur axial deviation, causing safety hazards.

[0004] Moreover, there is a dynamic gap between the rotating and stationary parts of the pumped storage unit, and the energy and signal transmission structure of the traditional wireless excitation technology cannot adapt to this special environment, and it is difficult to realize stable and efficient energy and signal transmission under such a dynamic structure gap, thereby leading to its ineffective application in the pumped storage unit.

[0005] Therefore, it is particularly important to research a wireless power supply loose coupling transformer that can be effectively applied to the pumped storage power station unit. SUMMARY

[0006] The present application has the advantages of easy manufacturing, small size and high power density.

[0007] The technical scheme of the present application is as follows: A composite wireless excitation system for a pumped storage generator, comprising a motor assembly and a wireless excitation assembly, the motor assembly comprising a rotor core, a rotor winding, a stator core, a stator winding, a stator shell, a rotor shaft and a bearing; The wireless excitation assembly comprises a fixed excitation assembly, a rotating excitation assembly, a fixed communication assembly and a rotating communication assembly; The fixed excitation assembly comprises a fixed magnetic core and a fixed wireless excitation winding, and the external circuit part of the fixed wireless excitation winding comprises a DC source and a fixed DC-HAC circuit; The rotating excitation assembly comprises a rotating magnetic core and a rotating wireless excitation winding; the fixed magnetic core and the rotating magnetic core are both in a pot type structure, and the external circuit of the rotating wireless excitation winding is a rotating DC-HAC circuit; The fixed communication assembly is a fixed signal winding, and the external circuit of the fixed signal winding comprises a fixed signal generation / accepting circuit and a total controller; The rotating communication assembly is a rotating signal winding, and the external circuit of the rotating signal winding comprises a rotating signal generation / accepting circuit and a rotor controller.

[0008] In the foregoing pumped storage generator composite wireless excitation system, the rotor shaft is arranged in the middle of the stator shell; the stator core is arranged in the stator shell and in contact with the stator shell; the rotor core is arranged on the rotor shaft and inside the stator core; the rotor core is provided with a rotor winding outside; the stator core is provided with a stator winding inside; the stator shell is provided with bearings at both ends, and the rotor shaft is arranged in the bearings.

[0009] In the foregoing pumped storage generator composite wireless excitation system, the fixed magnetic core is connected with the stator shell; The rotating magnetic core is connected with the rotor shaft; The rotor shaft directly passes through the middle hollow position of the fixed magnetic core and the rotating magnetic core to drive the rotating magnetic core to rotate; The fixed wireless excitation winding and the fixed signal winding are arranged in the fixed magnetic core correspondingly; The rotating wireless excitation winding and the rotating signal winding are arranged in the rotating magnetic core correspondingly and distributed on both sides of the rotor shaft.

[0010] In the foregoing pumped storage generator composite wireless excitation system, a radial air gap with a distance of 2-3 mm is arranged between the fixed magnetic core and the stator shell; An air gap with a distance of 2-3 mm is arranged between the fixed magnetic core and the rotating magnetic core.

[0011] In the foregoing pumped storage generator composite wireless excitation system, the fixed wireless excitation winding is connected with the DC source through the fixed DC-HAC circuit to form the primary side of the wireless excitation channel and provide excitation power for the secondary side through voltage conversion; The rotating wireless excitation winding is connected with the rotor winding through the rotating DC-HAC circuit to form the secondary side of the wireless excitation channel and inject the power transmitted by the wireless excitation channel into the rotor winding to complete excitation.

[0012] In the foregoing pumped storage generator composite wireless excitation system, the fixed signal winding is connected to the total controller through a fixed signal generation / accepting circuit to generate or demodulate a modulated wave carrying a signal; The rotating signal winding is connected to the rotor controller through a rotating signal generation / accepting circuit to generate or demodulate a modulated wave carrying a signal in cooperation with the fixed communication assembly, so as to realize monitoring and control of the rotating wireless excitation winding state.

[0013] In the foregoing pumped storage generator composite wireless excitation system, the number of turns of the fixed wireless excitation winding and the rotating wireless excitation winding is greater than that of the fixed signal winding and the rotating signal winding, so as to reduce the crosstalk suffered by the wireless excitation channel.

[0014] In the foregoing pumped storage generator composite wireless excitation system, the rotor core and the stator core are made of ultra-thin silicon steel sheets and / or nanocrystalline materials; and the stator winding, the rotor winding, the fixed wireless excitation winding, the fixed signal winding, the rotating wireless excitation winding and the rotating signal winding are made of Litz wires and copper wires.

[0015] A pumped storage generator composite wireless excitation method, the transmission process is as follows: The total controller controls the start of the direct current source, outputs a direct current voltage to the fixed DC-HAC circuit, and inputs the direct current into the fixed wireless excitation winding after the direct current is inverted into high-frequency alternating current; The fixed wireless excitation winding generates a high-frequency magnetic field, which is coupled to the rotating wireless excitation winding through the air gap between the fixed magnetic core and the rotating magnetic core, and a high-frequency alternating current is induced on the rotating side; The alternating current output by the rotating wireless excitation winding is rectified and filtered by the rotating DC-HAC circuit, converted into direct current, and then adjusted to the excitation voltage required by the rotor winding by the Buck voltage stabilizing circuit, and injected into the rotor winding; The rotor controller collects the excitation current of the rotor winding in real time, sends the current feedback signal to the fixed side through the rotating signal winding, and the total controller adjusts the duty cycle of the fixed DC-HAC circuit according to the feedback to make it stable within the target value range.

[0016] In the foregoing pumped storage generator composite wireless excitation method, the dynamic process is as follows: When the rotor shaft radial runout is caused by the change of the operating speed of the pumped storage unit, so that the air gap between the fixed magnetic core and the rotating magnetic core fluctuates, the rotating side induced voltage decreases; The rotor controller detects the decrease of the rotating DC-HAC circuit input voltage through the voltage sensor, and immediately sends an air gap fluctuation signal to the total controller; After the total controller receives the signal, the output voltage of the fixed DC-HAC circuit is raised to compensate for the coupling loss caused by the increase of air gap, so as to ensure the stability of the output voltage of the rotating side and the fluctuation of the excitation current within a certain range.

[0017] Compared with the prior art, the application has the following beneficial effects: 1、The motor assembly is composed of a rotor core, a rotor winding, a stator core, a stator winding, a stator shell, a rotor shaft and a bearing, cooperates with a wireless excitation assembly matched with the motor assembly, and is designed by simple structure, so that the motor assembly is relatively easy to process and the difficulty of manufacturing process is reduced. 2、Compared with ferrite, amorphous alloy and other magnetic materials, the silicon steel sheet has increased saturation magnetic density, and in the application, the silicon steel sheet magnetic core is optimized and integrated with the circuit and the supporting structure in structure; the structural design of the silicon steel sheet considers the spatial adaptability with the circuit elements, so that the miniaturization integration of electromagnetism and the circuit system is realized; the supporting structure stably installs the silicon steel sheet magnetic core, so that the stability and reliability of the magnetic circuit during the operation of the rotating equipment are ensured, the entire equipment is miniaturized, and the wireless power supply system of the rotating equipment can be better applied. 3、The application is different from the traditional wireless excitation technology in the equipment layout structure, and adopts a distributed structure design; different functional modules of the wireless excitation system are distributed and installed at appropriate positions in the motor according to the structural characteristics of the pumped storage power station, and are connected through special communication and energy transmission lines, so that the structural layout of the power station is adapted, and the reliability and flexibility of the system are improved. 4、The application combines the loose coupling transformer and the excitation assembly and the communication assembly in the loose coupling transformer, so that stable and efficient energy transmission can be achieved even in the special environment of the pumped storage unit, and the wireless excitation transmission demand of the pumped storage power station is met. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a magnetic circuit structure schematic diagram of the application; Figure 2 is a circuit structure schematic diagram of the application.

[0019] The drawing comprises the following components: 1, a stator shell; 2, a rotor shaft; 3, a stator core; 4, a rotor core; 5, a stator winding; 6, a rotor winding; 7, a bearing; 8, a direct current source; 11, a fixed magnetic core; 12, a fixed wireless excitation winding; 13, a fixed signal winding; 14, a fixed DC-HAC circuit; 15, a fixed signal generation / accepting circuit; 16, a total controller; 21, a rotating magnetic core; 22, a rotating wireless excitation winding; 23, a rotating signal winding; 24, a rotating DC-HAC circuit; 25, a rotating signal generation / accepting circuit; and 27, a rotor controller. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0021] Example 1. A pumped-storage generator combined with wireless excitation system, such as... Figure 1 As shown, it includes a motor assembly and a wireless excitation assembly; The motor assembly includes a rotor core 4, a rotor winding 6, a stator core 3, a stator winding 5, a stator housing 1, a rotor shaft 2, and a bearing 7. The wireless excitation assembly includes a fixed excitation assembly, a rotary excitation assembly, a fixed communication assembly, and a rotary communication assembly; The fixed excitation assembly includes a fixed magnetic core 11 and a fixed wireless excitation winding 12. The external circuit portion of the fixed wireless excitation winding 12 includes a DC source 8 and a fixed DC-HAC circuit 14. The rotating excitation assembly includes a rotating magnetic core 21 and a rotating wireless excitation winding 22; both the fixed magnetic core 11 and the rotating magnetic core 21 are canister-type structures, and the external circuit of the rotating wireless excitation winding 22 is a rotating DC-HAC circuit 24. The fixed communication component is a fixed signal winding 13, and the external circuit of the fixed signal winding 13 includes a fixed signal generation / receiving circuit 15 and a main controller 16. The rotating communication component is a rotating signal winding 23, and the external circuit of the rotating signal winding 23 includes a rotating signal generation / receiving circuit 25 and a rotor controller 27.

[0022] The fixed excitation assembly is fixed by an external bracket. The fixed excitation assembly is coaxially mounted on the outer periphery of the rotating excitation assembly, and there is a radial air gap with a fixed distance between them. There is no physical contact between the fixed excitation assembly and the rotating excitation assembly, and a fixed radial air gap is maintained. Electromagnetic coupling is carried out through this radial air gap.

[0023] The rotor shaft 2 passes through the middle of the stator housing 1; the stator core 3 is located inside the stator housing 1 and in contact with the stator housing 1; the rotor core 4 is sleeved on the rotor shaft 2 and located inside the stator core 3; the rotor core 4 is provided with a rotor winding 6 on its outside; the stator core 3 is provided with a stator winding 5 inside; the stator housing 1 is provided with bearings 7 at both ends, and the rotor shaft 2 passes through the bearings 7.

[0024] The fixed magnetic core 11 is connected to the stator housing 1, and a radial air gap of 2-3 mm is provided between the fixed magnetic core 11 and the stator housing 1. The rotating magnetic core 21 is connected to the rotor shaft 2; An air gap of 2-3 mm is provided between the fixed magnetic core 11 and the rotating magnetic core 21; The rotor shaft 2 passes directly through the hollow space between the fixed magnetic core 11 and the rotating magnetic core 21, driving the rotating magnetic core 21 to rotate; The fixed wireless excitation winding 12 and the fixed signal winding 13 are wound in the fixed magnetic core 11; The rotating wireless excitation winding 22 and the rotating signal winding 23 are wound in the rotating magnetic core 21 and distributed on both sides of the rotor shaft 2.

[0025] The rotor core 4 and stator core 3 are made of ultra-thin silicon steel sheets stacked together; the stator winding 5, rotor winding 6, fixed wireless excitation winding 12, fixed signal winding 13, rotating wireless excitation winding 22 and rotating signal winding 23 are made of Litz wire.

[0026] like Figure 2 As shown, the circuit structure of the pumped storage generator composite wireless excitation system includes a fixed-side circuit and a rotating-side circuit; wherein the fixed magnetic core 11 and the rotating magnetic core 21 are represented in simplified form as a common air gap; The fixed-side circuit consists of a fixed wireless excitation winding 12, a fixed DC-HAC circuit 14, a DC source 8, a fixed signal winding 13, a fixed signal generation / receiving circuit 15, and a main controller 16. The fixed wireless excitation winding 12 is connected to the DC source 8 through the fixed DC-HAC circuit 14, forming the primary side of the wireless excitation channel, and provides excitation power to the secondary side through voltage transformation. The fixed signal winding 13 is connected to the main controller 16 through the fixed signal generation / receiving circuit 15 to generate or demodulate the modulated wave carrying the signal.

[0027] The rotating side circuit consists of a rotating wireless excitation winding 22, a rotating DC-HAC circuit 24, a rotor winding 6, a rotating signal winding 23, a rotating signal generation / receiving circuit 25, and a rotor controller 27. The rotating wireless excitation winding 22 is connected to the rotor winding 6 through the rotating DC-HAC circuit 24, forming the secondary side of the wireless excitation channel, and injecting the power transmitted by the wireless excitation channel into the rotor winding 6 to complete the excitation. The rotating signal winding 23 is connected to the rotor controller 27 through the rotating signal generation / receiving circuit 25, and is matched with the fixed communication component to generate or demodulate the modulated wave carrying the signal, thereby realizing the monitoring and control of the state of the rotating wireless excitation winding 22.

[0028] The number of turns of the fixed wireless excitation winding 12 and the rotating wireless excitation winding 22 is greater than the number of turns of the fixed signal winding 13 and the rotating signal winding 23, thereby reducing crosstalk to the wireless excitation channel.

[0029] A combined wireless excitation method for pumped storage generators, characterized by the following specific transmission process: The total controller 16 controls the starting of the direct current source 8, and outputs a direct current voltage to the fixed DC-HAC circuit 14, so as to convert the direct current into high-frequency alternating current and then input the high-frequency alternating current into the fixed wireless excitation winding 12; The fixed wireless excitation winding 12 generates a high-frequency magnetic field, which is coupled to the rotating wireless excitation winding 22 through the air gap between the fixed magnetic core 11 and the rotating magnetic core 21, and induces high-frequency alternating current on the rotating side; The alternating current output by the rotating wireless excitation winding 22 is rectified (by a diode full-bridge rectifier), filtered (by an electrolytic capacitor), converted into direct current, and then adjusted to the required excitation voltage of the rotor winding 6 by a Buck voltage stabilizing circuit, and finally injected into the rotor winding 6; The rotor controller 27 collects the excitation current of the rotor winding 6 in real time, sends a current feedback signal to the fixed side through the rotating signal winding 23, and the total controller 16 adjusts the duty cycle of the fixed DC-HAC circuit 14 according to the feedback, so as to stabilize in the target value range.

[0030] The dynamic process is as follows: When the radial runout of the rotor shaft 2 caused by the change of the operating speed of the pumped storage unit causes the fluctuation of the air gap between the fixed magnetic core 11 and the rotating magnetic core 21, the induced voltage on the rotating side decreases; The rotor controller 27 detects the decrease of the input voltage of the rotating DC-HAC circuit 24 through a voltage sensor, and immediately sends an air gap fluctuation signal to the total controller 16; After receiving the signal, the total controller 16 increases the output voltage of the fixed DC-HAC circuit 14, compensates for the coupling loss caused by the increase of the air gap, and ensures the stability of the output voltage on the rotating side and the fluctuation of the excitation current within a certain range.

[0031] Embodiment 2: A composite wireless excitation system of a pumped storage generator, which is suitable for pumped storage units.

[0032] The stator core 3 and the rotor core 4 are made of nanocrystalline alloy (saturation magnetic density 1.5T), which is suitable for low-temperature environments of-30℃; the fixed magnetic core 11 and the rotating magnetic core 21 have a lamination thickness of 0.15mm; The circuit, the IGBT of the fixed DC-HAC circuit 14 adopts a low-temperature type (-40℃-150℃), and the filter capacitor of the rotating DC-HAC circuit 24 adopts a low-temperature electrolytic capacitor (-55℃~105℃); The winding parameters, the fixed wireless excitation winding 12 has 200 turns and a wire cross-sectional area of 3mm 2 ; the rotating wireless excitation winding 22 has 200 turns; Running effect, excitation power 40kW, low temperature-30℃ start, transmission efficiency 88-90%; air gap 2mm, speed 1500r / min, excitation current stable at 150A±5A; continuous running for 500h in low temperature environment, no circuit element failure, system reliability 99.8%; Example 3. A pumped storage generator composite wireless excitation system, high power density optimization.

[0033] Winding, fixed wireless excitation winding 12 and rotating wireless excitation winding 22 use multi-strand litz wire (100 strands, 0.2mm), reduce skin effect, improve high frequency transmission efficiency; Fixed magnetic core 11 and rotating magnetic core 21 use 35W ultra-thin silicon steel sheet (lower iron loss), center column diameter increased to 80mm, improve magnetic flux; Circuit, fixed DC-HAC circuit 14 switch frequency increased to 50kHz, reduce magnetic core volume; Running effect, system volume reduced, power density improved, transmission efficiency 95-96%; air gap 2.5mm, speed 2500r / min, excitation current fluctuation ≤3%, meet high power density unit demand.

Claims

1. A composite wireless excitation system of a pumped storage generator, comprising a motor assembly and a wireless excitation assembly, characterized in that: the motor assembly comprises a rotor core (4), a rotor winding (6), a stator core (3), a stator winding (5), a stator shell (1), a rotor shaft (2) and a bearing (7); the wireless excitation assembly comprises a fixed excitation assembly, a rotating excitation assembly, a fixed communication assembly and a rotating communication assembly; the fixed excitation assembly comprises a fixed magnetic core (11) and a fixed wireless excitation winding (12), and the external circuit of the fixed wireless excitation winding (12) comprises a DC source (8) and a fixed DC-HAC circuit (14); the rotating excitation assembly comprises a rotating magnetic core (21) and a rotating wireless excitation winding (22); the fixed magnetic core (11) and the rotating magnetic core (21) are both in a pot type structure, and the external circuit of the rotating wireless excitation winding (22) is a rotating DC-HAC circuit (24); the fixed communication assembly is a fixed signal winding (13), and the external circuit of the fixed signal winding (13) comprises a fixed signal generation / acceptance circuit (15) and a total controller (16); the rotating communication assembly is a rotating signal winding (23), and the external circuit of the rotating signal winding (23) comprises a rotating signal generation / acceptance circuit (25) and a rotor controller (27).

2. A composite off-line excitation system for a pumped storage generator according to claim 1, characterized in that: The rotor shaft (2) is arranged in the middle of the stator shell (1); the stator core (3) is arranged in the stator shell (1) and in contact with the stator shell (1); the rotor core (4) is arranged on the rotor shaft (2) and inside the stator core (3); the rotor core (4) is externally provided with the rotor winding (6); the stator core (3) is internally provided with the stator winding (5); the stator shell (1) is provided with bearings (7) at both ends, and the rotor shaft (2) is arranged in the bearings (7).

3. A composite off-line excitation system for a pumped storage generator according to claim 1, characterized in that: The fixed magnetic core (11) is connected with the stator shell (1); The rotating magnetic core (21) is connected with the rotor shaft (2); The rotor shaft (2) directly passes through the middle hollow position of the fixed magnetic core (11) and the rotating magnetic core (21) to drive the rotating magnetic core (21) to rotate; The fixed wireless excitation winding (12) and the fixed signal winding (13) are correspondingly arranged in the fixed magnetic core (11); The rotating wireless excitation winding (22) and the rotating signal winding (23) are correspondingly arranged in the rotating magnetic core (21) and distributed on both sides of the rotor shaft (2).

4. A composite off-line excitation system for a pumped storage generator according to claim 3, characterized in that: A radial air gap with a distance of 2-3 mm is arranged between the fixed magnetic core (11) and the stator shell (1); An air gap with a distance of 2-3 mm is arranged between the fixed magnetic core (11) and the rotating magnetic core (21).

5. A composite off-line excitation system for a pumped storage generator according to claim 1, characterized in that: The fixed wireless excitation winding (12) is connected with the DC source (8) through the fixed DC-HAC circuit (14) to form a primary side of a wireless excitation channel and provide excitation power for a secondary side through voltage conversion; The rotating wireless excitation winding (22) is connected with the rotor winding (6) through the rotating DC-HAC circuit (24) to form a secondary side of the wireless excitation channel and inject power transmitted by the wireless excitation channel into the rotor winding (6) to complete excitation.

6. A composite off-line excitation system for a pumped storage generator according to claim 5, characterized in that: The fixed signal winding (13) is connected with the general controller (16) through the fixed signal generating / accepting circuit (15) to generate or demodulate the modulated wave carrying the signal; The rotating signal winding (23) is connected with the rotor controller (27) through the rotating signal generating / accepting circuit (25) to generate or demodulate the modulated wave carrying the signal, so as to realize the monitoring and control of the rotating wireless excitation winding (22).

7. A composite off-line excitation system for a pumped storage generator according to claim 1, characterized in that: The number of turns of the fixed wireless excitation winding (12) and the rotating wireless excitation winding (22) is greater than that of the fixed signal winding (13) and the rotating signal winding (23), so as to reduce the crosstalk suffered by the wireless excitation channel.

8. A composite off-line excitation system for a pumped storage generator according to claim 1, characterized in that: The rotor core (4) and the stator core (3) adopt ultra-thin silicon steel sheets and / or nanocrystalline materials; the stator winding (5), the rotor winding (6), the fixed wireless excitation winding (12), the fixed signal winding (13), the rotating wireless excitation winding (22) and the rotating signal winding (23) adopt Litz wires and / or copper wires.

9. The pumped storage generator composite wireless excitation system pumped storage generator composite wireless excitation method according to any one of claims 1-8, characterized in that, The transmission process is as follows: The general controller (16) controls the direct current source (8) to start, outputs a direct current voltage to the fixed DC-HAC circuit (14), and inputs the direct current into the fixed wireless excitation winding (12) after the direct current is inverted into high-frequency alternating current; The fixed wireless excitation winding (12) generates a high-frequency magnetic field, which is coupled to the rotating wireless excitation winding (22) through the air gap between the fixed magnetic core (11) and the rotating magnetic core (21), and induces a high-frequency alternating current on the rotating side; The alternating current output by the rotating wireless excitation winding (22) is rectified and filtered by the rotating DC-HAC circuit (24), converted into direct current, and then adjusted to the excitation voltage required by the rotor winding (6) through the Buck voltage stabilizing circuit, and injected into the rotor winding (6); The rotor controller (27) collects the excitation current of the rotor winding (6) in real time, sends the current feedback signal to the fixed side through the rotating signal winding (23), and the general controller (16) adjusts the duty cycle of the fixed DC-HAC circuit (14) according to the feedback to make it stable within the target value range.

10. A composite wireless excitation method of a pumped storage generator according to claim 9, characterized in that, The dynamic process is as follows: When the radial runout of the rotor shaft (2) caused by the change of the operating speed of the pumped storage unit causes the air gap fluctuation between the fixed magnetic core (11) and the rotating magnetic core (21), the rotating side induction voltage decreases; The rotor controller (27) detects the decrease of the input voltage of the rotating DC-HAC circuit (24) through the voltage sensor, and immediately sends the air gap fluctuation signal to the general controller (16); After receiving the signal, the general controller (16) increases the output voltage of the fixed DC-HAC circuit (14) to compensate for the coupling loss caused by the increase of the air gap, so as to ensure the stability of the output voltage on the rotating side and the fluctuation of the excitation current within a certain range.

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