CN114321030A - Hydraulic power generation system and control method thereof - Google Patents
Hydraulic power generation system and control method thereof Download PDFInfo
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- CN114321030A CN114321030A CN202111356232.7A CN202111356232A CN114321030A CN 114321030 A CN114321030 A CN 114321030A CN 202111356232 A CN202111356232 A CN 202111356232A CN 114321030 A CN114321030 A CN 114321030A
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- 238000010248 power generation Methods 0.000 title claims abstract description 90
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- 238000004146 energy storage Methods 0.000 claims abstract description 159
- 230000001360 synchronised effect Effects 0.000 claims abstract description 47
- 230000001276 controlling effect Effects 0.000 claims description 38
- 230000005611 electricity Effects 0.000 claims description 9
- 239000007788 liquid Substances 0.000 claims description 5
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- 239000003921 oil Substances 0.000 description 79
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Abstract
The application provides a hydraulic power generation system and a control method thereof. The hydraulic pump is used for converting electric energy into hydraulic energy and outputting high-pressure oil, the high-pressure oil of the hydraulic pump can be input into the hydraulic motor at stable pressure and flow, the hydraulic motor is used for converting the hydraulic energy of the high-pressure oil into mechanical energy to be output, the output rotating speed of the hydraulic motor is kept constant, the hydraulic energy storage device is connected with the hydraulic pump, the energy storage device is driven to do work through the high-pressure oil to store energy, the energy stored in the hydraulic energy storage device can be input into the hydraulic motor at stable pressure and flow through the driving oil to release energy, the hydraulic motor is connected with the synchronous generator to be used for driving the synchronous generator to generate constant-frequency electric energy, the synchronous generator is connected into a power grid, the problem that the total rotational inertia caused by the use of a power electronic device in the current power grid is continuously reduced is solved, and the capacity of the power grid for efficiently receiving new energy is improved.
Description
Technical Field
The invention relates to the technical field of energy storage, in particular to a hydraulic power generation system and a control method thereof.
Background
With the development of a new round of energy revolution mainly based on clean energy, the proportion of new energy in the power grid in China is higher and higher. However, in the new energy technology, a power electronic device is mostly connected to a power grid, and the power electronic device has no rotational inertia, and cannot actively provide necessary voltage and frequency support for the power grid, nor provide necessary damping action. Especially as the penetration of distributed energy sources connected to the grid via power electronics is higher and higher, the total moment of inertia of the grid is decreasing and thus the risk of large frequency deviations of the grid when heavy loads or sudden changes of the power supply occur is increasing. The access of high-proportion power electronic devices can cause the power grid to be in a low inertia level for a long time, and unbalanced power impact of the system is increased, so that greater and greater pressure is brought to safe and stable operation of the power system. In order to improve and relieve the operating pressure of a power grid and the consumption pressure of new energy, an energy storage system with a certain capability of supporting dynamic adjustment of the power grid is urgently needed to improve the capability of the power grid for efficiently receiving the new energy.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. To this end, an embodiment of the present invention proposes a hydraulic power generation system. The embodiment of the invention also provides a control method of the hydraulic power generation system.
The hydraulic power generation system of the embodiment of the invention comprises: the hydraulic pump is used for converting electric energy into hydraulic energy and outputting high-pressure oil; the hydraulic motor is used for converting hydraulic energy of the high-pressure oil liquid into mechanical energy to be output, and the output rotating speed of the hydraulic motor is kept constant; a hydraulic energy storage device, which includes an energy storage device, connected to the hydraulic pump so as to drive the energy storage device to do work by high-pressure oil output from the hydraulic pump to store energy, the high-pressure oil stored in the hydraulic energy storage device being able to be input to the hydraulic motor at a stable pressure to release energy; the hydraulic motor is connected with the synchronous generator and used for driving the synchronous generator to generate constant-frequency electric energy, and the synchronous generator is connected to a power grid.
The hydraulic power generation system provided by the embodiment of the invention comprises the hydraulic energy storage device with two functions of energy storage and energy release, the hydraulic pump and the hydraulic energy storage device are matched with each other, so that the pressure of high-pressure oil input into the hydraulic motor is stable, the output rotating speed of the hydraulic motor is kept constant, and the hydraulic motor with the constant output rotating speed can drive the synchronous generator to generate constant-frequency electric energy to meet the requirement of power transmission to a power grid. Therefore, the hydraulic power generation system provided by the embodiment of the invention is connected with the power grid, decoupling, rectification, frequency modulation and voltage stabilization of the power electronic device are not needed, the problem that the total rotational inertia is continuously reduced due to the use of the power electronic device in the current power grid is solved, the rotational inertia in the power grid can be improved, necessary voltage and frequency support is provided for the power grid, the risk of large frequency deviation of the power grid is reduced, the power system can safely and stably operate, and the capability of the power grid for efficiently receiving new energy is improved.
In some embodiments, the hydraulic power generation system includes a first hydraulic valve group and a second hydraulic valve group, the first hydraulic valve group is disposed between the hydraulic pump and the hydraulic motor for regulating the pressure of high-pressure oil entering the hydraulic motor, and the second hydraulic valve group is disposed between the hydraulic pump and the hydraulic energy storage device for controlling the input or output of the high-pressure oil to or from the hydraulic energy storage device so as to control the energy storage or release of the hydraulic energy storage device.
In some embodiments, the first hydraulic valve set is located downstream of the second hydraulic valve set, the first hydraulic valve set further being used to regulate the pressure of the high-pressure oil input to the hydraulic motor from the hydraulic energy storage device.
In some embodiments, an oil outlet of the hydraulic motor communicates with an oil inlet of the hydraulic pump so that oil output from the hydraulic motor is input into the hydraulic pump.
In some embodiments, the hydraulic power generation system further includes a third hydraulic valve group, the third hydraulic valve group is disposed between an oil outlet of the hydraulic pump and an oil inlet of the hydraulic pump, and when the pressure of the hydraulic power generation system is too high, the third hydraulic valve group is opened to realize the circulation of oil between the oil outlet of the hydraulic pump and the oil inlet of the hydraulic pump.
In some embodiments, the hydraulic pump draws power from a power grid or from a renewable energy farm, the hydraulic power generation system has a power release state and a power storage state,
in the energy storage state, a part of high-pressure oil output from the hydraulic pump is input into the hydraulic energy storage device for energy storage, another part of high-pressure oil output from the hydraulic pump is input into the hydraulic motor, and the synchronous generator is in no-load or standby state;
in the energy releasing state, high-pressure oil in the hydraulic energy storage device is output, the high-pressure oil is input into the hydraulic motor, the synchronous generator generates electricity,
and in the energy storage state and the energy release state, the output rotating speed of the hydraulic motor is constant.
In some embodiments, the hydraulic power generation system is provided with a standby state in which the synchronous generator idles and the hydraulic pump stands by.
In another aspect, an embodiment of the present invention provides a method for controlling a hydraulic power generation system, where the hydraulic power generation system is the hydraulic power generation system according to any one of the embodiments described above, and the method includes:
detecting the current frequency f of the grid and/or the oil pressure p in the hydraulic power generation system,
controlling the hydraulic energy storage device to release or store energy according to f and/or p;
when the hydraulic energy storage device stores energy, high-pressure oil output from the hydraulic pump is controlled to enter the hydraulic energy storage device, when the hydraulic energy storage device releases energy, the high-pressure oil in the hydraulic energy storage device is controlled to be input into the hydraulic motor, and the synchronous generator inputs constant-frequency electric energy to a power grid.
In some embodiments, the control method further comprises:
setting a preset frequency threshold f' of the power grid, judging the magnitude of f, and controlling the hydraulic energy storage device to store or release energy according to the magnitude of f;
if f is larger than f', controlling the hydraulic pump to take power from a power grid, and storing energy by the hydraulic energy storage device;
if f is less than f', controlling the hydraulic energy storage device to release energy, and generating power by the synchronous generator;
and if f is equal to f ', controlling the hydraulic energy storage device to release or store energy so as to keep p equal to a preset pressure value p'.
In some embodiments, the control method further comprises:
setting a preset pressure value p' of oil in the hydraulic power generation system, and controlling the hydraulic energy storage device to store or release energy according to p;
if p is less than p', controlling the hydraulic energy storage device to release energy;
if p is more than p', controlling the hydraulic energy storage device to store energy;
and if p is equal to p ', controlling the hydraulic energy storage device to release or store energy so that p is equal to p'.
Drawings
Fig. 1 is a schematic diagram of a hydraulic power generation system in an embodiment of the present invention.
Reference numerals:
1. a hydraulic power generation system; 11. a hydraulic pump; 12. a hydraulic motor; 13. a hydraulic energy storage device; 14. a synchronous generator; 15. a grid-connected device; 161. a first hydraulic valve block; 162. a second hydraulic valve block; 163. a third hydraulic valve bank; 171. a first pipeline; 172. a second pipeline; 173. a third pipeline; 174. a fourth pipeline.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
A hydraulic power generation system 1 provided by an embodiment of the present invention is described below with reference to fig. 1, and the hydraulic power generation system 1 includes a hydraulic pump 11, a hydraulic motor 12, a hydraulic energy storage device 13, and a synchronous generator 14.
The hydraulic pump 11 is configured to convert electric energy into hydraulic energy and output high-pressure oil, that is, hydraulic energy converted from electric energy is included in the high-pressure oil output by the hydraulic pump 11. An oil outlet of the hydraulic pump 11 is communicated with an oil inlet of the hydraulic motor 12, high-pressure oil output from the hydraulic pump 11 can be input into the hydraulic motor 12 at a stable pressure, the hydraulic motor 12 is used for converting hydraulic energy in the high-pressure oil from the hydraulic pump 11 into mechanical energy to be output, or the hydraulic motor 12 is used for converting the hydraulic energy into rotational inertia, and the output rotation speed of the hydraulic motor 12 can be kept constant under the driving of the high-pressure oil with a constant pressure.
The hydraulic energy storage means 13 comprises energy storage means. The hydraulic accumulator 13 is connected with each of the hydraulic pump 11 and the hydraulic motor 12. The hydraulic energy storage device 13 has two functional states of energy storage and energy release, and during energy storage, high-pressure oil output from the hydraulic pump 11 is input into the hydraulic energy storage device 13 to drive the energy storage device to do work so as to store energy, so that hydraulic energy in the redundant high-pressure oil can be converted and stored in the hydraulic energy storage device 13. During energy release, the energy stored in the hydraulic energy storage device 13 can be input into the hydraulic motor 12 by driving the high-pressure oil, or in other words, during the energy release, the hydraulic energy stored in the hydraulic energy storage device 13 is input into the hydraulic motor 12, the hydraulic motor 12 converts the hydraulic energy into mechanical energy and outputs the mechanical energy, and the pressure of the part of the high-pressure oil input into the hydraulic motor 12 from the hydraulic energy storage device 13 is stable.
That is, when the hydraulic energy output from the hydraulic pump 11 has a margin, the surplus hydraulic energy can be converted and stored in the hydraulic energy storage device 13, and when the hydraulic pump 11 stops operating or the hydraulic energy generated by the hydraulic pump 11 is insufficient to meet the system discharge demand, the hydraulic energy stored in the hydraulic energy storage device 13 can be supplemented to the system for power generation.
Because the pressure of the high-pressure oil liquid input into the hydraulic motor 12 is kept stable, the output rotating speed of the hydraulic motor 12 is constant, the output end of the hydraulic motor 12 is in transmission connection with the input end of the synchronous generator 14, the hydraulic motor 12 drives the synchronous generator 14 to generate constant-frequency electric energy, and the synchronous generator 14 is connected to the power grid through the grid-connected device 15.
The hydraulic power generation system 1 provided by the embodiment of the invention comprises a hydraulic energy storage device 13 with two functions of energy storage and energy release, wherein a hydraulic pump 11 and the hydraulic energy storage device 13 are matched with each other, so that the pressure of high-pressure oil input into a hydraulic motor 12 is stable, the output rotating speed of the hydraulic motor 12 is kept constant, the hydraulic motor 12 with the constant output rotating speed can drive a synchronous generator 14 to generate constant-frequency electric energy, and the requirement of power transmission to a power grid is met. . Therefore, the hydraulic power generation system 1 provided by the embodiment of the invention is connected with the power grid, decoupling, rectification, frequency modulation and voltage stabilization of a power electronic device are not needed, the problem that the total rotational inertia is continuously reduced due to the use of the power electronic device in the current power grid is solved, the rotational inertia in the power grid can be improved, necessary voltage and frequency support is provided for the power grid, the risk of large frequency deviation of the power grid is reduced, the power system can safely and stably operate, and the capability of the power grid for efficiently receiving new energy is improved.
One embodiment of the present invention will be described below by taking a schematic view of a hydraulic power generation system 1 shown in fig. 1 as an example.
As shown in fig. 1, the hydraulic power generation system 1 includes a hydraulic pump 11, a hydraulic motor 12, a hydraulic energy storage device 13, and a synchronous generator 14. The hydraulic pump 11 may take electricity from the grid or from a renewable energy farm. The synchronous generator 14 is connected to the grid via a grid connection 15.
The hydraulic power generation system 1 includes a first hydraulic valve group 161 and a second hydraulic valve group 162, and the first hydraulic valve group 161 is provided between the hydraulic pump 11 and the hydraulic motor 12 for regulating the pressure of the high-pressure oil entering the hydraulic motor 12. The second hydraulic valve group 162 is provided between the hydraulic pump 11 and the hydraulic energy storage device 13, and is used for controlling whether high-pressure oil is input into the hydraulic energy storage device 13 from the hydraulic pump 11 or output from the hydraulic energy storage device 13 and input into the hydraulic motor 12 so as to control the hydraulic energy storage device 13 to store or release energy.
When the hydraulic energy storage device 13 stores energy, the second hydraulic valve set 162 communicates the hydraulic pump 11 and the hydraulic energy storage device 13, and high-pressure oil output from the hydraulic pump 11 is input into the hydraulic energy storage device 13 through the second hydraulic valve set 162. When the hydraulic energy storage device 13 releases energy, the second hydraulic valve set 162 communicates the hydraulic energy storage device 13 and the hydraulic motor 12, and high-pressure oil in the hydraulic energy storage device 13 is input into the hydraulic motor 12 through the second hydraulic valve set 162.
In the present embodiment, as shown in fig. 1, the first hydraulic valve group 161 is located downstream of the second hydraulic valve group 162, that is, the first hydraulic valve group 161 is also used for regulating the pressure of the high-pressure oil input from the hydraulic energy storage device 13 to the hydraulic motor 12. In other embodiments, another hydraulic valve set may be disposed downstream of the second hydraulic valve set 162 to regulate the pressure of the high-pressure oil supplied from the hydraulic energy storage device 13 to the hydraulic motor 12, and the first hydraulic valve set 161 is only used for regulating the pressure of the high-pressure oil supplied from the hydraulic pump 11 to the hydraulic motor 12. The present disclosure is not to be limited.
Specifically, as shown in fig. 1, the oil outlet of the hydraulic pump 11 communicates with the oil inlet of the hydraulic motor 12 through a first pipeline 171, and a first hydraulic valve block 161 is provided on the first pipeline 171. The oil outlet of the hydraulic pump 11 is communicated with the oil inlet of the hydraulic energy storage device 13 through a second pipeline 172, and the second hydraulic valve group 162 is arranged on the second pipeline 172. The hydraulic power generation system 1 further includes a third pipeline 173, one end of the third pipeline 173 is connected to the second hydraulic valve set 162, and the other end is communicated with an inlet of the first hydraulic valve set 161. Optionally, the second hydraulic valve set 162 is a three-way valve.
When the hydraulic energy output from the hydraulic pump 11 has a margin, the hydraulic energy storage device 13 stores energy, the second hydraulic valve set 162 is opened and communicates the hydraulic energy storage device 13 and the hydraulic pump 11, a part of the high-pressure oil output from the hydraulic pump 11 is input to the hydraulic motor 12 through the first pipeline 171, and the pressure entering the hydraulic motor 12 is stabilized by adjusting the first hydraulic valve set 161, and another part of the high-pressure oil output from the hydraulic pump 11 is input to the hydraulic energy storage device 13 through the second pipeline 172 for storage.
When the hydraulic pump 11 stops operating, or the hydraulic energy generated by the hydraulic pump 11 is not enough to meet the system discharge requirement, the hydraulic energy storage device 13 releases energy, the second hydraulic valve set 162 is opened and is communicated with the hydraulic energy storage device 13 and the hydraulic motor 12, the high-pressure oil output by the hydraulic pump 11 is input into the hydraulic motor 12 through the first pipeline 171, the high-pressure oil output by the hydraulic energy storage device 13 flows into the third pipeline 173 through the second hydraulic valve set 162, and then is input into the hydraulic motor 12 through the first hydraulic valve set 161, and the pressure entering the hydraulic motor 12 is constant by adjusting the first hydraulic valve set 161.
Further, as shown in fig. 1, an oil outlet of the hydraulic motor 12 communicates with an oil inlet of the hydraulic pump 11, so that the oil output from the hydraulic motor 12 is input into the hydraulic pump 11 to form an oil closed circuit.
Further, the hydraulic power generation system 1 further includes a third hydraulic valve set 163, and the third hydraulic valve set 163 is disposed between the oil outlet of the hydraulic pump 11 and the oil inlet of the hydraulic pump 11. Specifically, as shown in fig. 1, the hydraulic power generation system 1 further includes a fourth pipeline 174, the fourth pipeline 174 is disposed outside the hydraulic pump 11, one end of the fourth pipeline 174 is communicated with an oil outlet of the hydraulic pump 11, and the other end is communicated with an oil inlet of the hydraulic pump 11. When the pressure of the hydraulic power generation system 1 is too high, the third hydraulic valve set 163 is opened so as to realize the circulation of oil between the oil outlet of the hydraulic pump 11 and the oil inlet of the hydraulic pump 11, and the damage caused by the too high pressure in the system is prevented.
The hydraulic power generation system 1 in the present embodiment has an energy release state and an energy storage state.
In the energy storage state, a part of the high-pressure oil output from the hydraulic pump 11 is input to the hydraulic energy storage device 13 for energy storage, another part of the high-pressure oil output from the hydraulic pump 11 is input to the hydraulic motor 12, the synchronous generator 14 is idle or standby, and the electric energy input to the hydraulic pump 11 is stored in the hydraulic energy storage device 13 in the form of hydraulic energy.
In the energy release state, the high-pressure oil in the hydraulic energy storage device 13 is output, the high-pressure oil is input into the hydraulic motor 12, the synchronous generator 14 generates electricity, and the hydraulic energy stored in the hydraulic energy storage device 13 is converted into electric energy to be output.
It will also be appreciated that in the present embodiment, in the stored energy state, there is only energy input and no energy output, i.e. the hydraulic pump 11 is running, the generator is idling and no power is transmitted to the outside. In the energy release state, only energy is output and no energy is input, i.e. the hydraulic pump 11 is not operated, and the generator transmits electricity to the outside.
It should be noted that the energy storage state and the energy release state of the hydraulic power generation system 1 have other situations, for example, in some embodiments, in the energy storage state, for the hydraulic power generation system 1, there may be an energy input, and there may also be an energy input, where the input energy is greater than the output energy, and it is also understood that a part of the hydraulic energy generated by the operation of the hydraulic pump 11 is used to drive the generator to generate electricity outwards, and another part of the hydraulic energy is stored in the hydraulic energy storage device 13. In the energy release state, the hydraulic power generation system 1 may have energy input or energy input, but the output energy is greater than the input energy, or it may be understood that the hydraulic pump 11 is operated, but the generated hydraulic energy is not enough to drive the synchronous generator 14 to generate constant-frequency electric energy, and at this time, the hydraulic energy storage device 13 is required to perform supplementary compensation.
It will be appreciated that the output speed of the hydraulic motor 12 remains constant in both the charging and discharging states. Alternatively, the output rotation speed of the hydraulic motor 12 (the input rotation speed of the synchronous generator 14) is constantly at 3000 rpm. The output frequency of the synchronous generator 14 is stabilized at 50 Hz.
It should be noted that the national grid frequency reference line is 50Hz, and the output rotation speed of the hydraulic motor 12 can be constant at 3000 rpm. The foreign power grid frequency reference line is 60Hz, the output rotating speed of the hydraulic motor 12 can be constant at 3600rpm, namely, the pressure and the flow of the high-pressure oil liquid input into the hydraulic motor 12 can be adjusted according to the frequency reference of the power grid, and further the rated rotating speed of the hydraulic motor 12 is adjusted.
In some embodiments, the hydraulic power generation system 1 is provided with a standby state in which the synchronous generator 14 idles and the hydraulic pump 11 stands by. The hydraulic pump 11 is not powered and does not perform power conversion. In a standby state, the hydraulic power generation system 1 is in an energy holding stage, that is, there is no energy input or no energy output, the hydraulic energy storage device 13 stores or releases energy, the pressure and flow of hydraulic oil in a control system pipeline can meet the power consumption of the system, the constant-speed operation of the synchronous generator 14 is maintained, but the synchronous generator 14 does not generate power, that is, the synchronous generator 14 does not idle.
In some embodiments, the hydraulic power generation system 1 can be connected to the power grid, can perform inertia response or frequency modulation on the power grid, and can determine whether to enable the hydraulic power generation system 1 to enter an energy storage state, an energy release state or a standby state by determining the frequency state of the power grid.
When the frequency of the power grid rises (for example, more than 50Hz), the hydraulic power generation system 1 enters an energy storage state, draws overflowed electric energy from the power grid, converts the electric energy into hydraulic energy, and stores the hydraulic energy in the hydraulic energy storage device 13, so that the frequency of the power grid is reduced. When the frequency of the power grid drops (for example, less than 50Hz), the hydraulic energy in the hydraulic energy storage device 13 is converted into electric energy to be input into the power grid, so that the frequency of the power grid is increased. When the frequency in the grid is equal to a preset value (for example, the grid frequency is equal to 50Hz), the hydraulic power generation system 1 is put into a standby state.
The invention also provides a control method of the hydraulic power generation system 1, and the hydraulic power generation system 1 is the hydraulic power generation system 1 according to any one of the embodiments of the invention.
The control method of the hydraulic power generation system 1 includes the steps of:
detecting the current frequency f of the electricity network and/or the oil pressure p in the hydraulic power generation system 1,
controlling the hydraulic energy storage device 13 to release or store energy according to f and/or p;
when the hydraulic energy storage device 13 stores energy, high-pressure oil output from the hydraulic pump 11 is controlled to enter the hydraulic energy storage device 13, when the hydraulic energy storage device 13 releases energy, the high-pressure oil in the hydraulic energy storage device 13 is controlled to be input into the hydraulic motor 12, and the synchronous generator 14 inputs constant-frequency electric energy to a power grid.
That is, the control method of the hydraulic power generation system 1 according to the embodiment of the present invention includes determining that the hydraulic energy storage device 13 releases or stores energy according to at least one of the oil pressure p in the hydraulic power generation system 1 and the current frequency of the grid.
If the energy storage is needed, the hydraulic pump 11 is controlled to absorb electric energy from the power grid, the hydraulic pump 11 converts the electric energy into hydraulic energy, and at least one part of the hydraulic energy is stored in the hydraulic energy storage device 13 for buffering. In the process, the synchronous generator 14 may be in an idle or standby state, that is, hydraulic energy is fully input into the hydraulic energy storage device 13, and the synchronous generator 14 may also generate electricity, that is, a part of the hydraulic energy is used to be converted into electric energy, and another part of the hydraulic energy is stored in the hydraulic energy storage device 13.
If the energy release is needed, the high-pressure oil in the hydraulic energy storage device 13 is controlled to be input into the hydraulic motor 12, and the synchronous generator 14 inputs constant-frequency electric energy into the power grid. In the process, the hydraulic pump 11 can be operated or standby, when the hydraulic pump 11 is operated, the hydraulic energy generated by the hydraulic pump 11 is not enough to drive the synchronous generator 14, the hydraulic energy storage device 13 releases energy to compensate, and when the hydraulic pump 11 is standby, the hydraulic energy input to the hydraulic motor 12 is all from the hydraulic energy storage device 13.
According to the control method of the hydraulic power generation system 1 provided by the embodiment of the invention, the hydraulic energy generated by the hydraulic pump 11 is buffered or compensated by controlling the hydraulic energy storage device 13 to store and release kinetic energy, so that the hydraulic power generation system 1 can participate in power grid regulation, the overflowed energy is stored in the hydraulic energy storage device 13 according to the overflow proportion or is extracted from the hydraulic energy storage device 13 according to the missing proportion to supplement the power grid, and the frequency fluctuation of the power grid is reduced.
In some embodiments, the control method of the hydraulic power generation system 1 further includes the steps of:
setting a preset frequency threshold f' of the power grid, judging the magnitude of f, and controlling the hydraulic energy storage device 13 to store or release energy according to the magnitude of f;
if f is larger than f', the hydraulic pump 11 is controlled to take power from the power grid, and the hydraulic energy storage device 13 stores energy;
if f is less than f', controlling the hydraulic energy storage device 13 to release energy, and generating power by the synchronous generator 14;
if f is equal to f ', the hydraulic energy storage device 13 is controlled to release or store energy so as to keep p equal to the preset pressure value p'.
In order to cope with the frequency fluctuations of the grid, a preset frequency threshold f 'of the grid, i.e. the ideal frequency of the grid, is set, optionally f' is 50 Hz. When the frequency of the grid rises and exceeds f ', the hydraulic pump 11 absorbs electric energy from the grid, the hydraulic energy storage device 13 stores energy, and the frequency of the grid is gradually reduced to the ideal value f', and the synchronous generator 14 can be in an idle or standby state. When the frequency of the power grid drops below f ', the hydraulic pump 11 can be in a standby state, the hydraulic energy storage device 13 releases energy, and the synchronous generator 14 is driven to generate electricity, so that the frequency of the power grid gradually rises to the ideal value f'.
When the frequency of the power grid is equal to the preset frequency threshold value f ', the hydraulic energy storage device 13 is controlled to release or store the kinetic energy, that is, the hydraulic pressure in the hydraulic power generation system 1 is lowered or raised by releasing or storing the kinetic energy to maintain the preset pressure value p', so that the hydraulic power generation system 1 can cope with the next frequency fluctuation of the power grid in the best state.
In some embodiments, the control method of the hydraulic power generation system 1 further includes the steps of:
setting a preset pressure value p' of oil in the hydraulic power generation system 1, and controlling the hydraulic energy storage device 13 to store or release energy according to p;
if p is less than p', controlling the hydraulic energy storage device 13 to release energy;
if p is more than p', controlling the hydraulic energy storage device 13 to store energy;
if p ═ p ', the hydraulic energy storage device 13 is controlled to release or store energy so that p ═ p'.
That is to say, when the oil pressure in the hydraulic power generation system 1 does not reach the preset pressure value p ', the hydraulic energy storage device 13 is controlled to release energy, so that the oil pressure in the hydraulic power generation system 1 rises, and when the oil pressure in the hydraulic power generation system 1 is greater than the preset pressure value p', the hydraulic energy storage device 13 is controlled to store energy, so that the oil pressure in the hydraulic power generation system 1 falls. p-p' enables the hydraulic power generation system 1 to cope with the frequency fluctuations of the grid in a better state.
In some embodiments, the control method of the hydraulic power generation system 1 includes:
setting a preset frequency interval and a preset frequency threshold f 'of a power grid, wherein the minimum frequency threshold of the preset frequency interval is f1, the maximum frequency threshold is f2, f1 is greater than f' < f2, judging whether f is in the preset frequency interval, and if so, enabling the hydraulic power generation system 1 to enter an inertia response stage;
in the inertia response stage, judging the magnitude of f, and controlling the hydraulic energy storage device 13 to store or release energy according to the magnitude of f;
if f is more than or equal to f1 and is less than f', controlling the hydraulic energy storage device 13 to release energy;
if f' is more than f and less than or equal to f2, controlling the hydraulic energy storage device 13 to store energy;
if f is equal to f ', the hydraulic energy storage device 13 is controlled to release or store energy so as to keep p equal to the preset pressure value p'.
If f exceeds a preset frequency interval, the hydraulic power generation system 1 enters a frequency modulation stage;
entering a frequency modulation stage, judging the magnitude of f, and controlling the hydraulic energy storage device 13 to store or release energy according to the magnitude of f;
if f is more than f2, controlling the hydraulic energy storage device 13 to release energy;
if f is less than f1, controlling the hydraulic energy storage device 13 to store energy;
optionally, f1 is (50-0.033) Hz, and f2 is (50+0.033) Hz, i.e. the preset frequency interval is (50 ± 0.033) Hz.
The hydraulic power generation system 1 has an inertia response stage and a frequency modulation stage, and when the frequency of the power grid is greater than or equal to (50-0.033) Hz and less than or equal to (50+0.033) Hz, the hydraulic power generation system 1 enters the inertia response stage. When the frequency of the power grid is less than (50-0.033) Hz or greater than (50+0.033) Hz, the hydraulic power generation system 1 enters a frequency modulation phase.
After the hydraulic power generation system 1 enters an inertia response stage, judging the current frequency f of the power grid, if (50-0.033) Hz is less than or equal to f and less than 50Hz, controlling the hydraulic energy storage device 13 to release energy, if 50Hz is less than or equal to f and less than or equal to (50+0.033) Hz, controlling the hydraulic energy storage device 13 to store energy, and if f is 50Hz, controlling the hydraulic energy storage device 13 to store energy or release energy so that p is kept equal to a preset pressure value p', so that the hydraulic power generation system 1 can cope with the frequency fluctuation of the power grid at the next time in the best state.
After the hydraulic power generation system 1 enters a frequency modulation stage, the current frequency f of the power grid is judged, if f is greater than (50+0.033) Hz, the hydraulic energy storage system is controlled to store energy, and if f is less than (50-0.033) Hz, the hydraulic energy storage system is controlled to release energy.
According to the control method of the hydraulic power generation system 1 provided by the embodiment of the invention, the hydraulic energy storage system stores or releases energy, so that the pressure of the high-pressure oil liquid input into the hydraulic motor 12 is stable, the output rotating speed of the hydraulic motor 12 is kept constant, and the hydraulic motor 12 with the constant output rotating speed can drive the synchronous generator 14 to generate constant-frequency electric energy, so that the requirement of power transmission to a power grid is met. The hydraulic energy generated by the hydraulic pump 11 can be buffered and compensated by the arrangement of the hydraulic energy storage device 13, and the input pressure of the hydraulic motor 12 cannot be influenced by the change of the hydraulic energy generated by the hydraulic pump 11, so that the input of the constant-frequency electric energy into the power grid by the synchronous generator 14 cannot be influenced.
By adopting the control method of the hydraulic power generation system 1 provided by the embodiment of the invention, decoupling, rectification, frequency modulation and voltage stabilization of the power electronic device are not needed, the problem that the total rotational inertia is continuously reduced due to the use of the power electronic device in the conventional power grid is solved, the rotational inertia in the power grid can be improved, necessary voltage and frequency support is provided for the power grid, the risk of large frequency deviation of the power grid is reduced, the power system can safely and stably operate, and the capability of the power grid for efficiently receiving new energy is improved.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
In the present disclosure, the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" and the like mean that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A hydraulic power generation system, comprising:
the hydraulic pump is used for converting electric energy into hydraulic energy and outputting high-pressure oil;
the hydraulic motor is used for converting hydraulic energy of the high-pressure oil liquid into mechanical energy to be output, and the output rotating speed of the hydraulic motor is kept constant;
a hydraulic energy storage device, which includes an energy storage device, connected to the hydraulic pump so as to drive the energy storage device to work by high-pressure oil output from the hydraulic pump to store energy, wherein the high-pressure oil stored in the hydraulic energy storage device can be input to the hydraulic motor at a stable pressure and flow rate to release energy;
the hydraulic motor is connected with the synchronous generator and used for driving the synchronous generator to generate constant-frequency electric energy, and the synchronous generator is connected to a power grid.
2. The hydraulic power generation system of claim 1, comprising a first hydraulic valve set and a second hydraulic valve set, wherein the first hydraulic valve set is disposed between the hydraulic pump and the hydraulic motor for regulating the pressure of the high-pressure oil entering the hydraulic motor, and the second hydraulic valve set is disposed between the hydraulic pump and the hydraulic energy storage device for controlling the input or output of the high-pressure oil to or from the hydraulic energy storage device so as to control the energy storage or release of the hydraulic energy storage device.
3. The hydraulic power generation system of claim 2, wherein the first hydraulic valve block is located downstream of the second hydraulic valve block, the first hydraulic valve block further configured to regulate the pressure of the high-pressure oil input to the hydraulic motor from the hydraulic energy storage device.
4. The hydraulic power generation system of claim 1, wherein an oil outlet of the hydraulic motor communicates with an oil inlet of the hydraulic pump such that oil output from the hydraulic motor is returned to the hydraulic pump.
5. The hydraulic power generation system of claim 1, further comprising a third hydraulic valve set disposed between an oil outlet of the hydraulic pump and an oil inlet of the hydraulic pump, wherein when the hydraulic power generation system is under excessive pressure, the third hydraulic valve set opens to allow oil to flow between the oil outlet of the hydraulic pump and the oil inlet of the hydraulic pump.
6. The hydraulic power generation system of claim 1, wherein the hydraulic pump draws power from a power grid or from a renewable energy farm, the hydraulic power generation system having a de-energized state and an energized state,
in the energy storage state, a part of high-pressure oil output from the hydraulic pump is input into the hydraulic energy storage device for energy storage, another part of high-pressure oil output from the hydraulic pump is input into the hydraulic motor, and the synchronous generator is in no-load or standby state;
in the energy releasing state, high-pressure oil in the hydraulic energy storage device is output, the high-pressure oil is input into the hydraulic motor, the synchronous generator generates electricity,
and in the energy storage state and the energy release state, the output rotating speed of the hydraulic motor is constant.
7. The hydraulic power generation system according to claim 6, characterized in that the hydraulic power generation system is provided with a standby state in which the synchronous generator idles and the hydraulic pump stands by.
8. A control method of a hydraulic power generation system, characterized in that the hydraulic power generation system is the hydraulic power generation system according to any one of claims 1 to 7, comprising the steps of:
detecting the current frequency f of the grid and/or the oil pressure p in the hydraulic power generation system,
controlling the hydraulic energy storage device to release or store energy according to f and/or p;
when the hydraulic energy storage device stores energy, high-pressure oil output from the hydraulic pump is controlled to enter the hydraulic energy storage device, when the hydraulic energy storage device releases energy, the high-pressure oil in the hydraulic energy storage device is controlled to be input into the hydraulic motor, and the synchronous generator inputs constant-frequency electric energy to a power grid.
9. The control method of the hydraulic power generation system according to claim 8, characterized by further comprising:
setting a preset frequency threshold f' of the power grid, judging the magnitude of f, and controlling the hydraulic energy storage device to store or release energy according to the magnitude of f;
if f is larger than f', controlling the hydraulic pump to take power from a power grid, and storing energy by the hydraulic energy storage device;
if f is less than f', controlling the hydraulic energy storage device to release energy, and generating power by the synchronous generator;
and if f is equal to f ', controlling the hydraulic energy storage device to release or store energy so as to keep p equal to a preset pressure value p'.
10. The control method of the hydraulic power generation system according to claim 9, characterized by further comprising:
setting a preset pressure value p' of oil in the hydraulic power generation system, and controlling the hydraulic energy storage device to store or release energy according to p;
if p is less than p', controlling the hydraulic energy storage device to release energy;
if p is more than p', controlling the hydraulic energy storage device to store energy;
and if p is equal to p ', controlling the hydraulic energy storage device to release or store energy so that p is equal to p'.
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