Hydraulic full-period frequency regulation new energy generator set and primary frequency regulation method thereof

Abstract

The present invention relates to a hydraulic full-period frequency regulation new energy generator set and a primary frequency regulation method thereof. The generator set includes blades, a one-way quantitative hydraulic pump, a coupling, a proportional throttle valve, a two-way variable hydraulic motor, an excitation synchronous generator, a grid-connected cabinet, a turbine, a water valve, a water storage tank, a water pump, a bladder accumulator, an energy conversion element, a hydraulic oil tank, an overflow valve, a generator, an oil replenishment pump and a one-way valve. According to different wind conditions, it is divided into three areas, namely, a maximum power tracking area, a constant speed area and a constant power area, and when the grid frequency deviates from 50Hz, the stability of the grid frequency is controlled by changing the rotor kinetic energy of the blades and the opening of the proportional throttle valve, the bladder accumulator storage and supply, and the hydraulic storage and supply. The hydraulic storage and supply of the present invention stores more energy and has a longer frequency regulation period. It uses a wind-storage combination method to perform comprehensive frequency regulation control, so that the frequency anti-interference ability of the entire system is enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of frequency regulation of hydraulic new energy generator sets, and in particular relates to a hydraulic full-period frequency regulation new energy generator set and a primary frequency regulation method thereof. Background Art

[0002] Driven by the increasing depletion of fossil fuels and environmental crises, people are exploring new clean energy sources. Compared to coal, oil, and natural gas, wind, current, and wave energy, as clean, renewable energy sources, possess vast reserves and produce electricity without emitting greenhouse gases. Consequently, they are attracting significant attention worldwide, leading to an accelerated energy transition. Hydraulic generator sets, as a new generation of renewable energy power generation equipment, are gaining widespread attention. Their real-time adjustable transmission ratio enables flexible control and mitigates the impact of renewable energy supply fluctuations on power quality. While clean, renewable energy resources are abundant, these resources fluctuate significantly, creating an urgent challenge for ensuring stable power supply from hydraulic generator sets.

[0003] As the installed capacity and penetration of hydraulic new energy generators continue to increase, the requirements for primary frequency regulation of hydraulic new energy generators are also increasing. Traditional grid frequency regulation is primarily achieved through thermal or hydropower units. Hydraulic new energy generators not only lack the ability to regulate frequency themselves, but the intermittent and random nature of their output power also increases the frequency regulation burden on the grid. Existing primary frequency regulation control methods for doubly-fed asynchronous wind turbines include inertia control, droop control, speed overspeed control, pitch control, and step control. These methods solve the frequency regulation problem of wind turbines to a certain extent, but are easily affected by external factors, causing grid frequency fluctuations and frequent operation of wind turbines, which reduces wind energy utilization and wind turbine life.

[0004] The hydraulic energy storage system is the best choice to help hydraulic new energy generators achieve primary frequency regulation. It can provide new energy generator sets with rapid power regulation capabilities. The existing traditional energy storage method mainly uses accumulators to store and release energy for primary frequency regulation of the power grid, but its capacity is small and does not have the function of long-term frequency regulation. When performing frequency regulation work with longer cycles and larger capacities, traditional energy storage methods will have problems.

[0005] To sum up, during the power generation process of hydraulic new energy generator sets, the main problem is the grid frequency fluctuation caused by the uncontrollability of new energy resources and the imbalance between power supply and power consumption. Secondly, traditional accumulator energy storage frequency regulation has problems in facing the requirements of longer cycles and larger capacity frequency regulation. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides a hydraulic full-period frequency regulation new energy generator set and a primary frequency regulation method thereof. According to different wind conditions, a variety of primary frequency regulation methods are proposed, namely, changing the rotor kinetic energy of the blades and the opening of the proportional throttle valve, bladder accumulator energy storage and supply, and hydraulic energy storage and supply, to achieve dynamic balance of the output power of the hydraulic new energy generator set. Hydraulic energy storage and supply can solve the frequency regulation problem of longer period and larger capacity.

[0007] To achieve the above objectives, the present invention discloses the following technical solutions:

[0008] The present invention provides a hydraulic full-period frequency-modulated new energy generator set, which includes blades, a one-way quantitative hydraulic pump, a first coupling, a second coupling, a third coupling, a fourth coupling, a fifth coupling, a proportional throttle valve, a first bidirectional variable hydraulic motor, a second bidirectional variable hydraulic motor, a first excitation synchronous generator, a second excitation synchronous generator, a third excitation synchronous generator, a first grid-connected cabinet, a second grid-connected cabinet, a third grid-connected cabinet, a turbine, a water valve, a water storage tank, a water pump, a bladder accumulator, an energy conversion element, a first hydraulic oil tank, a second hydraulic oil tank, a first overflow valve, a second overflow valve, a generator, an oil replenishment pump and a one-way valve; the paddle is connected to the one-way quantitative hydraulic pump through the first coupling, the oil inlet of the second relief valve is connected to the oil outlet of the one-way quantitative hydraulic pump, the oil outlet of the second relief valve is connected to the oil inlet of the one-way quantitative hydraulic pump, the oil inlet of the proportional throttle valve is connected to the oil outlet of the one-way quantitative hydraulic pump, the oil inlet of the first bidirectional variable hydraulic motor is connected to the oil outlet of the proportional throttle valve, the oil outlet of the first bidirectional variable hydraulic motor is connected to the oil inlet of the one-way quantitative hydraulic pump, the first excitation synchronous generator is connected to the first bidirectional variable hydraulic motor through the second coupling The first excitation synchronous generator is connected to the first grid-connected cabinet and is incorporated into the power grid; the oil inlet of the second bidirectional variable hydraulic motor is connected to the oil outlet of the proportional throttle valve, the second bidirectional variable hydraulic motor is connected to the energy conversion element through the third coupling, the energy conversion element is connected to the bladder accumulator, the energy conversion element is connected to the first hydraulic oil tank, the energy conversion element is connected to the water pump through the fourth coupling, the water pump is connected to the third excitation synchronous generator through the fifth coupling, the third excitation synchronous generator is connected to the third grid-connected cabinet, and The hydraulic pump is connected to the water inlet of the water tank, the oil inlet of the water valve is connected to the water outlet of the water tank, the oil outlet of the water valve is connected to the turbine, the turbine is connected to the second excitation synchronous generator, the second excitation synchronous generator is connected to the second grid-connected cabinet and is connected to the grid; the oil inlet of the one-way valve is connected to the oil outlet of the one-way quantitative hydraulic pump, the oil outlet of the one-way valve is connected to the oil outlet of the oil replenishment pump and the oil inlet of the first overflow valve, the generator drives the oil replenishment pump to rotate, and the oil inlet of the oil replenishment pump and the oil outlet of the first overflow valve are both connected to the second hydraulic oil tank.

[0009] Preferably, the one-way quantitative hydraulic pump, the proportional throttle valve, the first two-way variable hydraulic motor and the second two-way variable hydraulic motor form a hydraulic closed circuit.

[0010] Preferably, the one-way valve, the first overflow valve, the oil replenishment pump and the generator form a hydraulic oil replenishment circuit.

[0011] Another aspect of the present invention provides a primary frequency regulation method for the aforementioned hydraulic full-period frequency regulation new energy generator set, the specific implementation steps of which are as follows:

[0012] S1. When in the maximum power tracking area, the hydraulic new energy generator set performs short-term frequency regulation, and the grid frequency is higher than 50Hz, it is necessary to reduce the blade rotor kinetic energy and reduce the proportional throttle valve opening to achieve short-term frequency regulation; when the grid frequency is lower than 50Hz, it is necessary to increase the blade rotor kinetic energy and increase the proportional throttle valve opening through additional frequency control links to achieve short-term frequency regulation.

[0013] When the grid frequency is closer to 50 Hz, the frequency regulation requirement is met by changing the blade rotor kinetic energy through an additional frequency control link, which is the moment of inertia of the first excitation synchronous generator:

[0014]

[0015] Among them, J w is the total inertia of the blade and load converted to the blade shaft; ω w0 is the speed under maximum power point tracking; ω s is the synchronous speed;

[0016] Δω w =ω w1 -ω w0

[0017] Among them, ω w1 is the minimum operating speed of the blade;

[0018] Δω s =ω s1 -ω s

[0019] Among them, ω s1 The speed of the generator after it meets the frequency regulation requirements;

[0020] By adjusting the output active power, the rotational kinetic energy of the blades is used to support the kinetic energy of the generator rotor to compensate for the power. The active power compensated by the virtual inertia control link of the blades is:

[0021]

[0022] Where ΔP1 represents the power compensated by virtual inertia control; Δf is the system frequency deviation; K df is the virtual inertia coefficient;

[0023] S2. When in the constant speed zone, the hydraulic new energy generator set performs mid-term frequency regulation, and the grid frequency is higher than 50Hz, the second bidirectional variable hydraulic motor and the energy conversion element used as a hydraulic pump store the excess energy in the form of hydraulic energy in the bladder accumulator for mid-term frequency regulation; when the grid frequency is lower than 50Hz, the hydraulic energy stored in the bladder accumulator is released to drive the energy conversion element used as the hydraulic motor to rotate, and drive the third excitation synchronous generator to generate electricity to achieve mid-term frequency regulation.

[0024] When the hydraulic new energy generator set is frequency-regulated in the middle stage, the frequency variation is introduced to implement additional control on the hydraulic energy storage system. The virtual droop control link responds to the system frequency variation. The useful power compensated by the virtual droop control link of the blade is:

[0025] ΔP2=-K pf Δf

[0026] Where ΔP2 represents the power compensated by virtual droop control; K pf is the virtual droop coefficient; Δf is the system frequency deviation;

[0027] S3. When in the constant power zone, the hydraulic new energy generator set performs long-term frequency regulation, and the grid frequency is higher than 50Hz, the excess energy generated by the blades drives the second bidirectional variable hydraulic motor, thereby driving the water pump to transport seawater to the water tank and store it in the form of hydraulic energy for long-term frequency regulation; when the grid frequency is lower than 50Hz, the seawater stored in the water tank flows downward, thereby driving the turbine to rotate and drive the second excitation synchronous generator to generate electricity to achieve long-term frequency regulation.

[0028] Furthermore, when the system is in the maximum power tracking area, the wind speed is at a low wind speed of 6.7-11.7m / s; when the system is in the constant speed area, the wind speed is at a medium wind speed of 11.7-13m / s; when the system is in the constant power area, the wind speed is at a high wind speed greater than 13m / s.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. The present invention can be used in terrains such as offshore mountains or islands in the sea, which contain huge wind energy, ocean current energy and wave energy, and can make full use of these clean and renewable energy sources and land resources.

[0031] 2. A frequency regulation unit is arranged in the hydraulic new energy generator set. Based on the ordinary hydraulic frequency regulation system, the present invention designs four primary frequency regulation methods, and uses a wind-storage combined method to perform comprehensive frequency regulation control to ensure the balance between the power supply on the energy side and the power consumption on the load side, thereby enhancing the anti-interference ability of the entire system frequency.

[0032] 3. Long-term frequency regulation is achieved through turbine power generation and energy supply. Hydropower storage and energy supply can solve the problem of longer-term and larger-capacity frequency regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the hydraulic full-time frequency-modulated new energy generator set of the present invention;

[0034] Figure 2 This is a full-frequency frequency regulation strategy diagram for the hydraulic full-period frequency regulation new energy generator set of the present invention;

[0035] Figure 3 This is a simulation diagram of the system response when the load of the hydraulic full-time frequency-modulated new energy generator set of the present invention suddenly increases by 10.5kW;

[0036] Figure 4 This is a simulation diagram of the system response when the load of the hydraulic full-time frequency-modulated new energy generator set of the present invention suddenly increases by 12kW;

[0037] Figure 5 This is a simulation diagram of the system response when the load of the hydraulic full-time frequency regulation new energy generator set of the present invention suddenly decreases by 6kW.

[0038] Main reference numerals:

[0039] Blade 1, one-way fixed-displacement hydraulic pump 2, first coupling 301, second coupling 302, third coupling 303, fourth coupling 304, fifth coupling 305, proportional throttle valve 4, first bidirectional variable hydraulic motor 501, second bidirectional variable hydraulic motor 502, first excitation synchronous generator 601, second excitation synchronous generator 602, third excitation synchronous generator 603, first grid-connected cabinet 701, second grid-connected cabinet 702, third grid-connected cabinet 703, turbine 8, water valve 9, water tank 10, water pump 11, bladder accumulator 12, energy conversion element 13, first hydraulic oil tank 1401, second hydraulic oil tank 1402, first overflow valve 1501, second overflow valve 1502, generator 16, charge pump 17, one-way valve 18. DETAILED DESCRIPTION

[0040] To fully describe the technical content, objectives and effects of the present invention, the following is a detailed description with reference to the accompanying drawings.

[0041] Hydraulic full-term frequency regulation new energy generator set, such as Figure 1As shown, it includes a blade 1, a one-way fixed-displacement hydraulic pump 2, a first coupling 301, a second coupling 302, a third coupling 303, a fourth coupling 304, a fifth coupling 305, a proportional throttle valve 4, a first bidirectional variable hydraulic motor 501, a second bidirectional variable hydraulic motor 502, a first excitation synchronous generator 601, a second excitation synchronous generator 602, a third excitation synchronous generator 603, a first grid-connected cabinet 701, a second grid-connected cabinet 702, a third grid-connected cabinet 703, a turbine 8, a water valve 9, a water storage tank 10, a water pump 11, a bladder accumulator 12, an energy conversion element 13, a first hydraulic oil tank 1401, a second hydraulic oil tank 1402, a first overflow valve 1501, a second overflow valve 1502, a generator 16, an oil replenishment pump 17 and a one-way valve 18.

[0042] The paddle 1 is connected to the unidirectional fixed-flow hydraulic pump 2 via a first coupling 301. Under the influence of natural wind, currents, and waves at the seaside or at sea, the paddle 1 drives the unidirectional fixed-flow hydraulic pump 2 to rotate. High-pressure oil flows out of the oil outlet of the unidirectional fixed-flow hydraulic pump 2 and into the oil inlet of the proportional throttle valve 4. The proportional throttle valve 4 can continuously and proportionally control the pressure and flow of the hydraulic system, reducing the pressure change shock and achieving control of the actuator, thereby delivering high-pressure oil to the oil inlets of the first bidirectional variable hydraulic motor 501 and the second bidirectional variable hydraulic motor 502. The above hydraulic components form a closed circuit. In the hydraulic system, to prevent the system pressure from exceeding the rated value, a relief valve is required to protect the safe operation of the entire system. When the system pressure exceeds the set value of the relief valve, the relief valve will open and release the excess flow. The oil inlet of the second relief valve 1502 is connected to the oil outlet of the unidirectional fixed-flow hydraulic pump 2, and the oil outlet of the second relief valve 1502 is connected to the oil inlet of the unidirectional fixed-flow hydraulic pump 2.

[0043] In a closed circuit, internal oil leakage is inevitable. In order to ensure that the closed circuit works stably and normally, the closed circuit must be equipped with a corresponding oil replenishment circuit. The oil replenishment circuit here is a typical open hydraulic system. The oil outlet of the one-way quantitative hydraulic pump 2 is connected to the oil inlet of the one-way valve 18. The oil outlet of the one-way valve 18 is connected to the oil inlet of the first relief valve 1501 and the oil outlet of the oil replenishment pump 17. The one-way valve 18 can prevent backflow due to low system pressure. The generator 16 drives the oil replenishment pump 17 to rotate. The oil inlet of the oil replenishment pump 17 and the oil outlet of the first relief valve 1501 are both connected to the second hydraulic oil tank 1402. The first relief valve 1501 serves as a safety valve of the oil replenishment circuit. It opens when the oil replenishment circuit pressure exceeds the system pressure. The above hydraulic components constitute a hydraulic oil replenishment circuit, which can replenish the oil lost due to leakage for the closed circuit.

[0044] The first bidirectional variable hydraulic motor 501 is connected to one end of the first excitation synchronous generator 601 through the second coupling 302, and the other end of the first excitation synchronous generator 601 is connected to the first grid cabinet 701, and finally connected to the grid; the second bidirectional variable hydraulic motor 502 is connected to the energy conversion element 13 through the third coupling 303, and the energy conversion element 13 is connected to the bladder accumulator 12, and the energy conversion element 13 is connected to the first hydraulic oil tank 1401 to realize the conversion of hydraulic energy. The energy conversion element 13 is connected to the first hydraulic oil tank 1401 through the fourth coupling 303. 04 is connected to the water pump 11, the water pump 11 is connected to one end of the third excitation synchronous generator 603 through the fifth coupling 305, the other end of the third excitation synchronous generator 603 is connected to the third grid-connected cabinet 703, and finally is incorporated into the power grid; the water pump 11 is connected to the water tank 10, the water inlet of the water valve 9 is connected to the water tank 10, the water outlet of the water valve 9 is connected to the turbine 8, the turbine 8 is connected to one end of the second excitation synchronous generator 602, the other end of the second excitation synchronous generator 602 is connected to the second grid-connected cabinet 702, and finally is incorporated into the power grid.

[0045] The entire system can achieve both power generation and frequency regulation. The first bidirectional variable hydraulic motor 501 drives the first excitation synchronous generator 601 through the second coupling 302, and is connected to the power grid through the first grid-connected cabinet 701, realizing the power generation process of the hydraulic type new energy generator. Figure 2 As shown, the grid frequency is first analyzed. When the hydraulic new energy generator set is in short-term frequency regulation and the frequency f>50Hz, the frequency regulation is performed by reducing the rotor kinetic energy of blade 1 and increasing the opening of proportional throttle valve 4. When the frequency f<50Hz, the frequency regulation is performed by increasing the rotor kinetic energy of blade 1 and reducing the opening of proportional throttle valve 4. When the hydraulic new energy generator set is in medium-term frequency regulation and the frequency f>50Hz, the frequency regulation is performed by storing the excess energy in the form of hydraulic energy in the bladder accumulator 12. Frequency modulation: When the frequency f is less than 50Hz, frequency modulation is performed by releasing the hydraulic pressure stored in the bladder accumulator 12. When the hydraulic new energy generator set is in long-term frequency modulation and the frequency f is greater than 50Hz, frequency modulation is performed by pumping coastal seawater or seawater around isolated islands to a water tank 10 located on an offshore mountain or island in the sea, where it is stored as hydraulic energy. When the frequency f is less than 50Hz, frequency modulation is performed by releasing the water stored in the water tank 10 located on an offshore mountain or island in the sea, driving the turbine 8 to rotate. The power provided by the energy source is then compared with the power used by the load side until the two powers reach a balance. Otherwise, the frequency modulation value is fed back to the system for frequency modulation.

[0046] For load disturbance, the hydraulic type wind full-period frequency regulation generator set performs frequency regulation control according to the wind-storage joint control strategy mentioned above. The experimental results show that the fixed parameter and variable parameter control make the system frequency response change significantly, and the variable parameter control is better than the fixed parameter control. When the system performs fixed parameter frequency regulation control, its control parameter is fixed to K pf =15 and K df =5.

[0047] The system response simulation diagram when the load of the hydraulic full-time frequency regulation new energy generator set suddenly increases by 10.5kW is as follows: Figure 3 As shown in the figure, after the wind-storage combined frequency regulation control strategy is introduced into the wind turbines, the system frequency response characteristics have changed significantly, among which the maximum frequency deviation value is significantly reduced, the frequency regulation time is significantly shortened, the lowest point of the frequency drop is increased from 49.37Hz to 49.58Hz, the maximum frequency deviation of the system is reduced from 0.63Hz to 0.42Hz, and the frequency regulation time is reduced from 12s without frequency regulation control to 3s.

[0048] The system response simulation diagram when the load of the hydraulic full-time frequency regulation new energy generator set suddenly increases by 12kW is as follows: Figure 4 As shown in the figure, after the introduction of the wind turbine and wind storage combined frequency regulation control strategy, the system frequency changes from a continuous falling state to a recoverable state. Under fixed parameter control, the frequency reaches the lowest point of 49.52 Hz after the wind turbine frequency regulation control at 5.7 s, with a maximum frequency deviation of 0.48 Hz. It returns to a stable state at 49.92 Hz at 9.6 s, and the steady-state frequency deviation is 0.08 Hz.

[0049] The system response simulation diagram of the hydraulic full-term frequency regulation new energy generator set when the load suddenly decreases by 6kW is as follows: Figure 5 As shown in the figure, when fixed parameter frequency modulation control is adopted, the frequency rises to the highest point of 50.23Hz in 5.5s, and the frequency basically returns to stability after 3s of load disturbance. Compared with the control without frequency modulation, the introduction of frequency modulation control has a significant effect on reducing the maximum frequency deviation and frequency adjustment time. The maximum frequency deviation is reduced from 50.35Hz to 50.23Hz, and the frequency adjustment time is reduced from 8s to 3s. In addition, the frequency rise time is also shortened from 5.7s to 5.5s. The frequency modulation control strategy has a significant effect on frequency stability, greatly reducing load fluctuations and improving the stability of system frequency.

[0050] The following further describes a primary frequency regulation method of a hydraulic full-period frequency regulation new energy generator set according to the present invention in conjunction with an embodiment:

[0051] The operating status of a wind turbine can be divided into three areas according to different wind conditions, namely the maximum power tracking area (low wind speed: 6.7-11.7m / s), the constant speed area (medium wind speed: 11.7-13m / s) and the constant power area (high wind speed: >13m / s).

[0052] S1. When in the maximum power tracking area, the optimal speed corresponding to the wind speed is between the starting speed and the rated speed. In order to track the maximum wind energy tracking curve, when the wind speed changes, it is necessary to control the speed of the generator rotor so that it reaches the optimal speed corresponding to the wind speed. At this time, the hydraulic new energy generator set is performing short-term frequency regulation. Because the first excitation synchronous generator 601 is directly connected to the grid, its rotor speed n is coupled with the system frequency f:

[0053] n=60f / p

[0054] Where p is the number of motor pole pairs.

[0055] When the grid frequency is higher than 50Hz, according to the coupling relationship between the rotor speed n and the system frequency f, when the frequency increases, the speed will also increase. Therefore, the entire system needs to reduce the speed for frequency control, so the system takes measures to retract the blade 1 so that the blade 1 is perpendicular to the wind direction. At this time, the resistance of the blade 1 increases, reducing the rotor kinetic energy of the blade 1. At the same time, it is also necessary to reduce the valve opening of the proportional throttle valve 4, and the excess energy transmitted by the blade 1 through the one-way quantitative hydraulic pump 2 is consumed here in the form of heat energy. The high-pressure oil reaching the oil inlet of the first bidirectional variable hydraulic motor 501 is reduced, resulting in a reduction in its speed. The speed of the first excitation generator 601 transmitted through the second coupling 302 is also reduced, and the output power on the energy side is Reduce to achieve short-term frequency regulation; when the grid frequency is lower than 50Hz, according to the coupling relationship between the rotor speed n and the system frequency f, when the frequency decreases, the speed will also decrease. Therefore, the entire system needs to increase the speed to control the frequency, so the system takes feathering measures on the blade 1 to make the blade 1 parallel to the wind direction. At this time, the resistance of the blade 1 is reduced, and the rotor kinetic energy of the blade 1 is increased. At the same time, the valve opening of the proportional throttle valve 4 needs to be increased, and the high-pressure oil transmitted from the one-way quantitative hydraulic pump 2 to the oil inlet of the first two-way variable hydraulic motor 501 increases, resulting in an increase in its speed. The speed transmitted to the first excitation synchronous generator 601 through the second coupling 302 also increases, and the output power on the energy side increases to achieve short-term frequency regulation.

[0056] In the above situation, when the frequency fluctuates, both blade 1 and the first excitation synchronous generator 601 contain rotor kinetic energy. However, since blade 1 is not directly coaxially connected to the first excitation synchronous generator 601, it cannot directly provide inertial support. By releasing the rotor kinetic energy of blade 1 through an additional frequency control link to meet the frequency modulation requirements, it is assumed that the blade will also have the same inertial support for frequency as the first excitation synchronous generator 601. Therefore, the energy provided by the rotor kinetic energy of blade 1 for the inertial response of the system is defined as the virtual inertia of blade 1. The kinetic energy provided by blade 1 during the frequency modulation process is:

[0057]

[0058] Among them, J w is the total inertia of blade 1 and load converted to the blade shaft; ω w0 is the speed under maximum power point tracking; ω w1 is the minimum operating speed of the blade.

[0059] Comparing the hydraulic wind turbine to the traditional synchronous generator set,

[0060]

[0061] Among them, J vir1 is the total inertia of blade 1 and load converted to the blade 1 shaft; ω s is the synchronous speed, ω s1 It is the speed of the synchronous generator set after meeting the frequency regulation requirements.

[0062] The moment of inertia of blade 1 is analogous to the first excitation synchronous generator 601:

[0063]

[0064] Among them, Δω w =ω w1 -ω w0 and Δω s =ω s1 -ω s .

[0065] In addition to the generator releasing its own rotational kinetic energy to respond to frequency fluctuations, the rotor kinetic energy of blade 1 can also be used to further support the generator rotor kinetic energy to compensate for power. This allows blade 1 to provide inertial support when responding to frequency fluctuations, thereby changing the drive power on the generator shaft to balance the grid-side active power and maintain frequency stability. The active power compensated by the virtual inertia control link of blade 1 to respond to frequency fluctuations is:

[0066]

[0067] Where ΔP1 represents the power compensated by virtual inertia control; Δf is the system frequency deviation; Kdf is the virtual inertia coefficient.

[0068] S2. When the speed is in the constant speed zone, the speed corresponding to the optimal wind speed has reached the generator rotor speed limit. The hydraulic new energy generator set performs mid-term frequency regulation. The bladder accumulator 12 in the energy storage system is a hydraulic component that stores and releases energy by rapidly storing and releasing oil. Its energy changes only with its volume. The energy storage system can be compared to the speed regulator in a traditional synchronous generator. By applying additional control elements to the energy storage system, it responds to frequency deviations in real time, changes the power input to the generator, and achieves frequency droop control of the power system.

[0069] When the grid frequency is higher than 50 Hz, the second bidirectional variable hydraulic motor 502 drives the energy conversion element 13 used as a hydraulic pump, and stores the excess energy in the form of hydraulic energy in the bladder accumulator 12 to achieve mid-term frequency regulation; when the grid frequency is lower than 50 Hz, the hydraulic energy stored in the bladder accumulator 12 is released to drive the energy conversion element 13 used as a hydraulic motor to rotate, and then drives the third excitation synchronous generator 603 to generate electricity through the fifth coupling 305 to achieve mid-term frequency regulation.

[0070] By analogy with the generator droop characteristics, it is possible to consider introducing frequency variation to implement additional control on the hydraulic energy storage system, and respond to system frequency changes with the help of the virtual droop control link. The active power compensated by the virtual droop control link of blade 1 is

[0071] ΔP2=-K pf Δf

[0072] Where ΔP2 represents the power compensated by virtual droop control; K pf is the virtual droop coefficient; Δf is the system frequency deviation; when the deviation value of the frequency fluctuation is larger, the more power is compensated by the virtual droop link, thereby reducing the deviation.

[0073] S3. When in the constant power range, the wind energy captured by blades 1 reaches the rated power of the generator, and the hydraulic new energy generator set performs long-term frequency modulation. When the grid frequency is above 50Hz, the excess energy generated by blades 1 drives the unidirectional fixed-flow hydraulic pump 2, which inputs high-pressure oil into the second bidirectional variable hydraulic motor 502, thereby driving the water pump 11 to transport seawater to the water tank 10 for storage as hydraulic energy, thus achieving long-term frequency modulation. When the grid frequency is below 50Hz, the seawater stored in the water tank 10 flows downward, driving the turbine 8, and finally driving the second excitation synchronous generator 602 to generate electricity, thus achieving long-term frequency modulation.

[0074] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A primary frequency modulation method for a hydraulic full-time frequency modulation new energy generator set, characterized in that: The primary frequency modulation method is based on a hydraulic full-period frequency modulation new energy generator set, which includes blades, a one-way quantitative hydraulic pump, a first coupling, a second coupling, a third coupling, a fourth coupling, a fifth coupling, a proportional throttle valve, a first two-way variable hydraulic motor, a second two-way variable hydraulic motor, a first excitation synchronous generator, a second excitation synchronous generator, a third excitation synchronous generator, a first grid-connected cabinet, a second grid-connected cabinet, a third grid-connected cabinet, a turbine, a water valve, a water storage tank, a water pump, a bladder accumulator, an energy conversion element, a first hydraulic oil tank, a second hydraulic oil tank, a first overflow valve, a second overflow valve, a generator, an oil replenishment pump and a one-way valve; The blade is connected to the one-way quantitative hydraulic pump through the first coupling, the oil inlet of the second relief valve is connected to the oil outlet of the one-way quantitative hydraulic pump, the oil outlet of the second relief valve is connected to the oil inlet of the one-way quantitative hydraulic pump, the oil inlet of the proportional throttle valve is connected to the oil outlet of the one-way quantitative hydraulic pump, the oil inlet of the first bidirectional variable hydraulic motor is connected to the oil outlet of the proportional throttle valve, the oil outlet of the first bidirectional variable hydraulic motor is connected to the oil inlet of the one-way quantitative hydraulic pump, the first excitation synchronous generator is connected to the first bidirectional variable hydraulic motor through the second coupling, the first excitation synchronous generator is connected to the first grid-connected cabinet, and is incorporated into the power grid; The oil inlet of the second bidirectional variable hydraulic motor is connected to the oil outlet of the proportional throttle valve, the second bidirectional variable hydraulic motor is connected to the energy conversion element through the third coupling, the energy conversion element is connected to the bladder accumulator, the energy conversion element is connected to the first hydraulic oil tank, the energy conversion element is connected to the water pump through a fourth coupling, the water pump is connected to the third excitation synchronous generator through a fifth coupling, the third excitation synchronous generator is connected to the third grid-connected cabinet and incorporated into the power grid, the water pump is connected to the water inlet of the water storage tank, the water valve oil inlet is connected to the water outlet of the water storage tank, the water valve oil outlet is connected to the turbine, the turbine is connected to the second excitation synchronous generator, the second excitation synchronous generator is connected to the second grid-connected cabinet and incorporated into the power grid; The oil inlet of the one-way valve is connected to the oil outlet of the one-way quantitative hydraulic pump, the oil outlet of the one-way valve is connected to the oil outlet of the replenishing pump and the oil inlet of the first overflow valve, the generator drives the replenishing pump to rotate, and the oil inlet of the replenishing pump and the oil outlet of the first overflow valve are both connected to the second hydraulic oil tank; The primary frequency modulation method comprises the following steps: S1. When in the maximum power tracking area, the hydraulic new energy generator set performs short-term frequency regulation, and the grid frequency is higher than 50Hz, it is necessary to reduce the blade rotor kinetic energy and reduce the proportional throttle valve opening to achieve short-term frequency regulation; when the grid frequency is lower than 50Hz, it is necessary to increase the blade rotor kinetic energy and increase the proportional throttle valve opening through additional frequency control links to achieve short-term frequency regulation; When the grid frequency is closer to 50HZ, the rotor kinetic energy of the blades is changed through an additional frequency control link to meet the frequency regulation requirements. It is the moment of inertia of the first excitation synchronous generator: Among them, J w is the total inertia of the blade and load converted to the blade shaft; ω w0 is the speed under maximum power point tracking; ω s is the synchronous speed; Give w =ω w1 -oh w0 Among them, ω w1 is the minimum operating speed of the blade; Give s =ω s1 -oh s Among them, ω s1 The speed of the generator after it meets the frequency regulation requirements; By adjusting the output active power, the rotational kinetic energy of the blades is used to support the kinetic energy of the generator rotor to compensate for the power. The active power compensated according to the virtual inertia control link of the blades is: Where ΔP1 represents the power compensated by virtual inertia control; Δf is the system frequency deviation; K df is the virtual inertia coefficient; S2. When the hydraulic type new energy generator set is in the constant speed zone and performs mid-term frequency modulation, and the grid frequency is higher than 50Hz, the second bidirectional variable hydraulic motor and the energy conversion element used as a hydraulic pump store the excess energy in the form of hydraulic energy in the bladder accumulator for mid-term frequency modulation; when the grid frequency is lower than 50Hz, the hydraulic energy stored in the bladder accumulator is released to drive the energy conversion element used as a hydraulic motor to rotate, and drive the third excitation synchronous generator to generate electricity to achieve mid-term frequency modulation; When the hydraulic new energy generator set is frequency-adjusted in the middle period, the frequency variation is introduced to implement additional control on the hydraulic energy storage system, and the virtual droop control link is used to respond to the system frequency variation. The useful power compensated by the virtual droop control link of the blade is: ΔP2=-K pf Δf Where ΔP2 represents the power compensated by virtual droop control; K pf is the virtual droop coefficient; Δf is the system frequency deviation; S3. When in the constant power zone, the hydraulic new energy generator set performs long-term frequency modulation, and the grid frequency is higher than 50Hz, the excess energy generated by the blades drives the second bidirectional variable hydraulic motor, thereby driving the water pump to transport seawater to the water tank and store it in the form of hydraulic energy for long-term frequency modulation; when the grid frequency is lower than 50Hz, the seawater stored in the water tank flows downward, thereby driving the turbine to rotate and driving the second excitation synchronous generator to generate electricity to achieve long-term frequency modulation.

2. The primary frequency modulation method of the hydraulic full-period frequency modulation new energy generator set according to claim 1 is characterized in that: The one-way quantitative hydraulic pump, the proportional throttle valve, the first two-way variable hydraulic motor and the second two-way variable hydraulic motor form a hydraulic closed circuit.

3. The primary frequency modulation method of the hydraulic full-period frequency modulation new energy generator set according to claim 1 is characterized in that: The one-way valve, the first relief valve, the oil replenishment pump and the generator form a hydraulic oil replenishment circuit.

4. The primary frequency modulation method of the hydraulic full-period frequency modulation new energy generator set according to claim 1 is characterized in that: When the system is in the maximum power tracking area, the wind speed is at a low wind speed of 6.7-11.7m / s; when the system is in the constant speed area, the wind speed is at a medium wind speed of 11.7-13m / s; when the system is in the constant power area, the wind speed is at a high wind speed greater than 13m / s.

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