Pole-changing and full-power speed-changing combined pumped storage unit wiring structure and control method

Abstract

The invention discloses a pole-changing and full-power variable-speed combined pumped storage unit wiring structure and a control method, and relates to the technical field of variable-speed pumped storage unit design and operation control. According to the technical scheme, a full-power variable-speed main loop and a converter bypass are installed between a generator motor and a transformer, full-power variable-speed operation is achieved when the generator motor is in grid connection through the full-power variable-speed main loop, and constant-speed operation is achieved when a generator is in grid connection through the converter bypass. The problems of variable-speed operation of the unit and constant-speed operation when a converter bypass is considered are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of design and operation control of variable speed pumped storage units, and in particular to a connection structure and control method of a pumped storage unit combining pole changing and full power speed changing. Background Art

[0002] Variable speed pumped storage is a cutting-edge technology in the field of pumped storage. There are two mainstream variable speed unit technology routes, one is AC excitation variable speed pumped storage, and the other is full power variable speed pumped storage. The AC excitation variable speed pumped storage unit uses an asynchronous motor, the stator is directly connected to the grid, and the rotor is connected to the grid through the converter. When the converter is out of operation, the unit will also stop operating, and the converter bypass operation cannot be achieved. The stator of the full power variable speed pumped storage unit is directly connected to the grid through the full power converter. When the converter is out of operation, the unit stator can be connected to the grid for synchronous operation, which expands the unit's operating flexibility and reliability. However, medium and large capacity full power pumped storage units are often designed to operate below or above the power frequency due to factors such as converter influence, motor operation reliability and manufacturing cost. This results in the unit being unable to directly connect to the grid under converter bypass conditions.

[0003] Therefore, it is urgent to optimize the design and operation control of full-power pumped storage units and power stations to solve the problem of variable speed operation of the units and constant speed operation when the converter is bypassed. Summary of the invention

[0004] The present invention provides a connection structure and control method for a pumped storage unit combining pole changing and full power speed changing, so as to solve the problem of variable speed operation of the unit and constant speed operation when the converter is bypassed.

[0005] The present invention is achieved through the following technical solutions:

[0006] The first aspect of the present invention provides a connection structure of a pumped storage unit combining pole changing and full power speed changing, comprising a full power speed changing main circuit and a converter bypass; the full power speed changing main circuit and the converter bypass are installed between the generator motor and the transformer;

[0007] The full-power speed-changing main circuit comprises a first conductor, a first isolating switch, a second isolating switch and a converter, wherein the first conductor is used to sequentially connect the first isolating switch, the converter and the second isolating switch along the direction from the generator motor to the transformer; when the first port of the converter is connected to the generator motor through the first isolating switch, and the second port of the converter is connected to the transformer through the second isolating switch, the generator motor is connected to the grid through the full-power converter to achieve full-power speed-changing operation;

[0008] The converter bypass includes a second conductor, which is used to connect the first isolating switch and the second isolating switch; when the first end of the second conductor is connected to the generator motor through the first isolating switch, and the second end of the second conductor is connected to the transformer through the second isolating switch, the generator motor is directly connected to the grid by adjusting the number of pole pairs to achieve constant speed operation.

[0009] Aiming at the flexible operation requirements of large and medium-sized full-power variable-speed pumped storage units, the present invention proposes a wiring structure of a combined pumped storage unit that combines pole changing and full-power variable speed. Through this wiring structure, when the unit is in normal variable speed operation, it is connected to the grid through a full-power converter, and the unit operates at non-power frequency; when the converter is out of operation, the unit is directly connected to the grid through pole changing logarithm adjustment, and the unit operates at power frequency. This enables the unit to operate at full power variable speed and at a constant speed with the converter bypassed.

[0010] Furthermore, the static contact of the first isolating switch is located on the side of the generator motor, and the two moving contacts of the first isolating switch are respectively located on the side of the converter and the first end of the second conductor; the moving contact of the second isolating switch is located on the side of the power grid, and the two moving contacts of the second isolating switch are respectively located on the side of the converter and the second end of the second conductor.

[0011] Furthermore, the full-power speed-changing main circuit also includes a unit output circuit breaker (GCB) and a third isolating switch, and the first conductor sequentially connects the first isolating switch, the converter, the second isolating switch, the unit output circuit breaker and the third isolating switch along the direction from the generator motor to the transformer.

[0012] Furthermore, the converter adopts a modular multi-level matrix converter.

[0013] A second aspect of the present invention provides a pumped storage unit combining pole changing and full power speed changing, comprising: a generator motor, a transformer, a full power speed changing main circuit and a converter bypass, wherein the full power speed changing main circuit and the converter bypass are installed between the generator motor and the transformer;

[0014] The full-power speed-changing main circuit comprises a first conductor, a first isolating switch, a second isolating switch and a converter, wherein the first conductor is used to sequentially connect the first isolating switch, the converter and the second isolating switch along the direction from the generator motor to the transformer; when the first port of the converter is connected to the generator motor through the first isolating switch, and the second port of the converter is connected to the transformer through the second isolating switch, the generator motor is connected to the grid through the full-power converter to achieve full-power speed-changing operation;

[0015] The converter bypass includes a second conductor, which is used to connect the first isolating switch and the second isolating switch; when the first end of the second conductor is connected to the generator motor through the first isolating switch, and the second end of the second conductor is connected to the transformer through the second isolating switch, the generator motor is directly connected to the grid by adjusting the number of pole pairs to achieve constant speed operation.

[0016] Furthermore, the static contact of the first isolating switch is located on the side of the generator motor, and the two moving contacts of the first isolating switch are respectively located on the side of the converter and the first end of the second conductor; the moving contact of the second isolating switch is located on the side of the power grid, and the two moving contacts of the second isolating switch are respectively located on the side of the converter and the second end of the second conductor.

[0017] Furthermore, the full-power speed-changing main circuit also includes a unit output circuit breaker (GCB) and a third isolating switch, and the first conductor sequentially connects the first isolating switch, the converter, the second isolating switch, the unit output circuit breaker and the third isolating switch along the direction from the generator motor to the transformer.

[0018] Furthermore, the rated operating frequency of the generator motor is non-industrial frequency.

[0019] Furthermore, the magnetic pole of the generator motor is designed to be adjustable and is equipped with a pole-changing speed regulation function.

[0020] A third aspect of the present invention provides an operation control method for a pumped storage unit combined with pole changing and full power speed changing according to any one of the second aspects of the present invention, comprising:

[0021] When the power generation and pumping conditions are operating normally, the unit is connected to the grid through a full-power converter, and the converter works in conjunction with the unit's speed control system, excitation system, and cooperative controller to achieve variable speed, variable guide vane opening, and variable power operation.

[0022] When the converter bypass is out of operation in power generation condition, the unit is directly connected to the power grid for power frequency operation by adjusting the pole number, and the speed regulation system is used to set the speed, change the guide vane opening, and operate at variable power;

[0023] When the inverter bypass exits operation in pumping condition, the unit is operated at the industrial frequency by adjusting the pole logarithm. When pumping is started, the existing static variable frequency traction system of the pumped storage power station is used for start-up. After the unit is connected to the grid, the speed and guide vane opening are fixed by the speed control system, and the power is changed for operation.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects: when the unit is connected to the grid through a full-power converter, variable speed operation is achieved under power generation conditions and pumping conditions; when the converter is bypassed and the unit is directly connected to the grid, constant speed operation is achieved under power generation conditions and pumping conditions, thus solving the problem of variable speed operation of large and medium-sized full-power variable speed pumped-storage units and constant speed operation when the converter is bypassed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0026] Figure 1 It is a schematic diagram of electrical switching between variable speed operation and bypass operation of a full-power pumped storage unit in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0028] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to or inherent to other steps or units of the device.

[0029] The terms used in various embodiments of the present invention are only used for the purpose of describing specific embodiments and are not intended to limit various embodiments of the present invention. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as the meaning generally understood by those of ordinary skill in the art to which the various embodiments of the present invention belong. The terms (such as the terms defined in the dictionary generally used) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having an idealized meaning or an overly formal meaning, unless clearly defined in various embodiments of the present invention.

[0030] The embodiments of the present invention provide a connection structure of a pumped storage unit combining pole changing and full-power speed changing, a pumped storage unit combining pole changing and full-power speed changing, and an operation control method thereof, which are suitable for large and medium-sized full-power pumped storage units, and realize variable speed operation of the unit while taking into account constant speed operation when the converter is bypassed.

[0031] Example 1

[0032] This embodiment provides a connection structure of a pumped storage unit that combines pole changing with full-power speed change. Based on this connection structure, the full-power pumped storage unit can achieve variable speed operation and constant speed operation when the converter is bypassed.

[0033] See also Figure 1 The wiring structure diagram of the pumped storage unit combined with pole changing and full power speed changing is shown. The wiring structure includes a full power speed changing main circuit and a converter bypass, and the full power speed changing main circuit and the converter bypass are installed between the generator motor and the transformer.

[0034] The full-power speed-changing main circuit includes a first conductor 1.1, a first isolating switch QS1, a second isolating switch QS2 and a converter. The first conductor 1.1 is used to sequentially connect the first isolating switch QS1, the converter and the second isolating switch QS2 in the direction from the generator motor to the transformer. When the first port A1 of the converter is connected to the generator motor through the first isolating switch QS1, and the second port A2 of the converter is connected to the transformer through the second isolating switch QS2, so that the full-power speed-changing main circuit is turned on, the generator motor is connected to the grid through the full-power converter to achieve full-power speed-changing operation.

[0035] The converter bypass includes a second conductor 2.1, and the two ends of the second conductor are respectively used to connect the first isolating switch QS1 and the second isolating switch QS2. When the first end B1 of the second conductor is connected to the generator motor through the first isolating switch QS1, and the second end B2 of the second conductor is connected to the transformer through the second isolating switch QS2, the generator motor is directly connected to the grid through the pole pair number adjustment to achieve constant speed operation.

[0036] The other end of the transformer is connected to the three-phase power of the grid, and the generator motor, transformer, full-power speed-changing main circuit and converter bypass together constitute a pumped storage unit combining pole-changing and full-power speed-changing. The driving end of the generator motor is connected to the water pump turbine for operation.

[0037] The first conductor 1.1 and the second conductor 2.1 are both three-phase lines. The first isolating switch QS1 and the second isolating switch QS2 have a static contact and two moving contacts, and the two moving contacts are respectively arranged on the first conductor 1.1 and the second conductor 2.1. When the first isolating switch QS1 and the second isolating switch QS2 are closed to the moving contact on the first conductor 1.1, the full-power speed-changing main circuit is connected, and the generator motor is connected to the grid through the full-power converter to achieve full-power speed-changing operation; when the first isolating switch QS1 and the second isolating switch QS2 are closed to the moving contact on the second conductor 2.1, the converter bypass is connected, and the generator motor is directly connected to the grid through the pole pair number adjustment to achieve constant speed operation.

[0038] Furthermore, the static contact of the first isolating switch QS1 is arranged on the side of the generator motor, and the two moving contacts are respectively arranged on the side of the converter and at the first end B1 of the second conductor; the moving contact of the second isolating switch QS2 is arranged on the side of the power grid, and the two moving contacts are respectively located on the side of the converter and at the second end B2 of the second conductor.

[0039] Furthermore, the full-power speed-changing main circuit also includes a unit outlet circuit breaker GCB and a third isolating switch QS3. The first conductor 1.1 sequentially connects the first isolating switch QS1, the converter, the second isolating switch QS2, the unit outlet circuit breaker GCB and the third isolating switch QS3 along the direction from the generator motor to the transformer.

[0040] The third disconnector QS3 includes a static contact and a moving contact, the static contact is arranged on the GCB side of the circuit breaker, and the moving contact is arranged on the transformer side, so that the generator motor, the converter, the circuit breaker and the converter bypass can be disconnected from the power grid as a whole. The static contact of the second disconnector is arranged on the GCB side of the circuit breaker, so that the generator motor, the converter and the converter bypass can be disconnected from the circuit breaker as a whole.

[0041] Furthermore, the rated operating frequency of the generator motor is designed to be non-industrial frequency, that is, not 50Hz. This allows the full-power variable-speed pumped-storage unit to take into account the bypass constant-speed operation function and meet the flexible operation requirements of large and medium-sized full-power variable-speed pumped-storage units. By strengthening the insulation and structure design of the unit, it has the ability to operate at 50Hz, below 50Hz or above 50Hz for a long time.

[0042] Furthermore, the magnetic poles of the unit are designed to be adjustable and equipped with a pole-changing speed regulation function, which can perform pole-changing logarithmic speed regulation.

[0043] Furthermore, the converter adopts a modular multi-level matrix converter (M3C). Figure 1As shown in , the main circuit structure of the M3C converter consists of three sub-converters, each of which has three bridge arms. Each bridge arm consists of N cascaded H-bridge units FB and an AC inductor L. The three neutral points of the three sub-converters are the three phases of the AC system, and each H-bridge unit consists of four IGBTs and a DC capacitor.

[0044] Based on the above wiring structure, the pumped storage unit can operate in both variable speed and fixed speed modes.

[0045] (1) Converter operation mode

[0046] The converter is put into operation under normal operating conditions of the unit. Figure 1 The first isolating switch QS 1 Close the switch in position A1, the second isolating switch QS 2 Close the switch in position A2, the third isolating switch QS 3 The unit's outlet circuit breaker GCB is closed. In this mode, the unit has variable-speed power generation and variable-speed water pumping functions.

[0047] (2) Converter bypass operation mode

[0048] Under the converter bypass condition, the unit is directly connected to the grid for operation. Figure 1 The first isolating switch QS 1 Close the switch in position B1, the second isolating switch QS 2 When the switch is closed in position B2, the unit has the functions of constant speed power generation and constant speed water pumping.

[0049] Example 2

[0050] This embodiment provides a pumped storage unit combining pole changing and full power speed change, including a generator motor, a transformer, and the full power speed change main circuit and converter bypass in Embodiment 1, wherein the full power speed change main circuit and converter bypass are installed between the generator motor and the transformer. The wiring method of the generator motor, the transformer, the full power speed change main circuit and the converter bypass can refer to Embodiment 1 and Figure 1 shown.

[0051] The full-power speed-changing main circuit includes a first conductor 1.1, a first isolating switch QS1, a second isolating switch QS2 and a converter. The first conductor 1.1 is used to sequentially connect the first isolating switch QS1, the converter and the second isolating switch QS2 in the direction from the generator motor to the transformer. When the first port A1 of the converter is connected to the generator motor through the first isolating switch QS1, and the second port A2 of the converter is connected to the transformer through the second isolating switch QS2, so that the full-power speed-changing main circuit is turned on, the generator motor is connected to the grid through the full-power converter to achieve full-power speed-changing operation.

[0052] The converter bypass includes a second conductor 2.1, and the two ends of the second conductor are respectively used to connect the first isolating switch QS1 and the second isolating switch QS2. When the first end B1 of the second conductor is connected to the generator motor through the first isolating switch QS1, and the second end B2 of the second conductor is connected to the transformer through the second isolating switch QS2, the generator motor is directly connected to the grid through the pole pair number adjustment to achieve constant speed operation.

[0053] Furthermore, the static contact of the first isolating switch QS1 is arranged on the side of the generator motor, and the two moving contacts are respectively arranged on the side of the converter and at the first end B1 of the second conductor; the moving contact of the second isolating switch QS2 is arranged on the side of the power grid, and the two moving contacts are respectively located on the side of the converter and at the second end B2 of the second conductor.

[0054] Furthermore, the full-power speed-changing main circuit also includes a unit outlet circuit breaker GCB and a third isolating switch QS3. The first conductor 1.1 sequentially connects the first isolating switch QS1, the converter, the second isolating switch QS2, the unit outlet circuit breaker GCB and the third isolating switch QS3 along the direction from the generator motor to the transformer.

[0055] Furthermore, the rated operating frequency of the generator motor is designed to be non-industrial frequency.

[0056] Furthermore, the magnetic pole of the generator motor is designed to be adjustable and is equipped with a pole-changing speed regulation function, which can perform pole-changing logarithmic speed regulation.

[0057] Furthermore, the converter adopts a modular multi-level matrix converter (M3C).

[0058] Example 3

[0059] This embodiment provides an operation control method for a pumped storage unit, which is applied to the pumped storage unit combined with pole changing and full power speed changing in Embodiment 2. The operation modes of the pumped storage unit include normal operation modes of power generation and pumping conditions, power generation condition converter bypass exit operation mode, and pumping condition converter bypass exit operation mode.

[0060] When the power generation and pumping conditions are operating normally, the unit is connected to the grid through a full-power converter. The converter works in conjunction with the speed control system, excitation system, and cooperative controller of the unit to achieve variable speed, variable guide vane opening, and variable power operation of the unit.

[0061] When the converter bypass is out of operation in power generation condition, the unit is directly connected to the power grid for power frequency operation by adjusting the pole number, and the speed regulation system is used to set the speed, change the guide vane opening, and operate at variable power;

[0062] When the inverter bypass exits operation in pumping condition, the unit is operated at the industrial frequency by adjusting the pole logarithm. When pumping is started, the existing static variable frequency traction system of the pumped storage power station is used for start-up. After the unit is connected to the grid, the speed and guide vane opening are fixed by the speed control system, and the power is changed for operation.

[0063] Furthermore, for units with adjustable magnetic poles and equipped with pole-changing speed regulation function, in the inverter bypass exit operation mode under power generation conditions and the inverter bypass exit operation mode under pumping conditions, the units can be directly connected to the power grid for industrial frequency operation through pole-changing logarithmic speed regulation, and can be operated at a constant speed, variable guide vane opening, and variable power through the speed regulation system.

[0064] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. The connection structure of the pumped storage unit combining pole changing and full power speed changing is characterized by: It includes a full-power speed-changing main circuit and a converter bypass; the full-power speed-changing main circuit and the converter bypass are installed between the generator motor and the transformer; The full-power speed-changing main circuit comprises a first conductor (1.1), a first isolating switch (QS1), a second isolating switch (QS2) and a converter, wherein the first conductor is used to sequentially connect the first isolating switch (QS1), the converter and the second isolating switch (QS1) along the direction from the generator motor to the transformer; when the first port (A1) of the converter is connected to the generator motor through the first isolating switch (QS1), and the second port (A2) of the converter is connected to the transformer through the second isolating switch (QS1), the generator motor is connected to the grid through the full-power converter to achieve full-power speed-changing operation; The converter bypass comprises a second conductor (2.1), the second conductor being used to connect the first isolating switch (QS1) and the second isolating switch (QS2); when the first end (B1) of the second conductor is connected to the generator motor via the first isolating switch (QS1), and the second end (B2) of the second conductor is connected to the transformer via the second isolating switch (QS2), the generator motor is directly connected to the grid by adjusting the number of pole pairs, thereby achieving constant speed operation.

2. The connection structure of the pumped storage unit combining pole changing and full power speed changing according to claim 1 is characterized in that: The static contact of the first isolating switch (QS1) is located at one side of the generator motor, and the two moving contacts of the first isolating switch (QS2) are respectively located at one side of the converter and the first end (B1) of the second conductor; the moving contact of the second isolating switch (QS2) is located at one side of the power grid, and the two moving contacts of the second isolating switch (QS2) are respectively located at one side of the converter and the second end (B2) of the second conductor.

3. The connection structure of the pumped storage unit combining pole changing and full power speed changing according to claim 1 is characterized in that: The full-power speed-changing main circuit also includes a unit output circuit breaker (GCB) and a third isolating switch (QS3), and the first conductor (1.1) sequentially connects the first isolating switch (QS1), the converter, the second isolating switch (QS2), the unit output circuit breaker (GCB) and the third isolating switch (QS3) along the direction from the generator motor to the transformer.

4. The connection structure of the pumped storage unit combining pole changing and full power speed changing according to any one of claims 1 to 3, characterized in that: The converter adopts a modular multi-level matrix converter.

5. A pumped storage unit combining pole changing and full power speed changing, characterized in that: include: A generator motor, a transformer, a full-power speed-changing main circuit and a converter bypass, wherein the full-power speed-changing main circuit and the converter bypass are installed between the generator motor and the transformer; The full-power speed-changing main circuit comprises a first conductor (1.1), a first isolating switch (QS1), a second isolating switch (QS2) and a converter, wherein the first conductor is used to sequentially connect the first isolating switch (QS1), the converter and the second isolating switch (QS2) along the direction from the generator motor to the transformer; when the first port (A1) of the converter is connected to the generator motor through the first isolating switch (QS1), and the second port (A2) of the converter is connected to the transformer through the second isolating switch (QS2), the generator motor is connected to the grid through the full-power converter to achieve full-power speed-changing operation; The converter bypass comprises a second conductor (2.1), the second conductor being used to connect the first isolating switch (QS1) and the second isolating switch (QS2); when the first end (B1) of the second conductor is connected to the generator motor via the first isolating switch (QS1), and the second end (B2) of the second conductor is connected to the transformer via the second isolating switch (QS2), the generator motor is directly connected to the grid by adjusting the number of pole pairs, thereby achieving constant speed operation.

6. The pumped storage unit combining pole changing and full power speed changing according to claim 5, characterized in that: The static contact of the first isolating switch (QS1) is located at one side of the generator motor, and the two moving contacts of the first isolating switch are respectively located at one side of the converter and the first end (B1) of the second conductor; the moving contact of the second isolating switch (QS2) is located at one side of the power grid, and the two moving contacts of the second isolating switch are respectively located at one side of the converter and the second end (B2) of the second conductor.

7. The pumped storage unit combining pole changing and full power speed changing according to claim 5, characterized in that: The full-power speed-changing main circuit also includes a unit output circuit breaker (GCB) and a third isolating switch (QS3), and the first conductor (1.1) sequentially connects the first isolating switch (QS1), the converter, the second isolating switch (QS2), the unit output circuit breaker (GCB) and the third isolating switch (QS3) along the direction from the generator motor to the transformer.

8. The pumped storage unit combining pole changing and full power speed changing according to any one of claims 5 to 7, characterized in that: The rated operating frequency of the generator motor is non-industrial frequency.

9. The pumped storage unit combining pole changing and full power speed changing according to any one of claims 5 to 7, characterized in that: The magnetic pole of the generator motor is designed to be adjustable and is equipped with a pole-changing speed regulation function.

10. The operation control method for the pumped storage unit combined with pole changing and full power speed changing according to any one of claims 5 to 9, characterized in that: include: When the power generation and pumping conditions are operating normally, the unit is connected to the grid through a full-power converter. The converter works in conjunction with the speed control system, excitation system, and cooperative controller of the unit to achieve variable speed, variable guide vane opening, and variable power operation of the unit. When the converter bypass is out of operation in power generation condition, the unit is directly connected to the power grid for power frequency operation by adjusting the pole number, and the speed regulation system is used to set the speed, change the guide vane opening, and operate at variable power; When the inverter bypass exits operation in pumping condition, the unit is operated at the industrial frequency by adjusting the pole logarithm. When pumping is started, the existing static variable frequency traction system of the pumped storage power station is used for start-up. After the unit is connected to the grid, the speed and guide vane opening are fixed by the speed control system, and the power is changed for operation.

Images