Primary frequency modulation control system and method for pumped storage unit based on water head self-adaption

Abstract

The invention provides a primary frequency modulation control system and a primary frequency modulation control method for a pumped storage unit based on water head self-adaption, which are used for solving the problem that primary frequency modulation control parameters of the pumped storage unit in the prior art cannot be self-adaptively adjusted according to the water head change and can monitor the water head change in real time and automatically adjust the primary frequency modulation control parameters. The primary frequency modulation performance of the pumped storage unit under different water head conditions is improved, and the adjustment performance and adaptability of the unit are improved. The primary frequency modulation control system comprises a water head monitoring and processing module, a primary frequency modulation parameter setting module, a PID (Proportion Integration Differentiation) controller parameter correction module and a primary frequency modulation control module.

Description

Technical Field

[0001] The invention relates to the technical field of primary frequency regulation control of a pumped storage unit, and in particular to a primary frequency regulation control system of a pumped storage unit based on water head adaptation. Background Art

[0002] The stability and reliability of the power system are important foundations for ensuring the safe and stable operation of the power grid. As an important component of the power system, the quality of the primary frequency regulation function of the pumped storage unit directly determines the response speed and regulation ability of the system when facing frequency fluctuations. The traditional primary frequency regulation control method based on fixed parameters is unable to make dynamic adjustments according to the actual operating conditions of the unit (especially the change in water head), resulting in limited regulation effect and unable to meet the high requirements of modern power systems for stability and reliability.

[0003] During the operation of the pumped storage unit, the water head changes frequently and in a wide range, which has a significant impact on the torque characteristics and flow characteristics of the unit. This impact is further transmitted to the active power output of the generator set, resulting in the performance of the primary frequency regulation being affected, especially the change in the regulation depth, which directly affects the integral value of the primary frequency contribution. Therefore, the change in water head has become an important factor that must be considered in the process of primary frequency regulation parameter setting.

[0004] With the continuous development of power systems and the increasing requirements for power quality, modern power systems have put forward higher requirements for the regulation performance of pumped storage units. The units are required to be able to quickly and accurately perform frequency regulation under various complex operating conditions to maintain the stability of the system frequency. This requires not only a higher level of automation and intelligence, but also a stronger adaptive ability to dynamically adjust according to real-time operating conditions.

[0005] The primary frequency regulation control method based on fixed parameters cannot achieve efficient operation because it cannot adapt to changes under different water head conditions. The limitation of this method is that it lacks flexibility and adaptability and cannot be dynamically adjusted according to the actual operating conditions of the unit. Therefore, it is urgent to develop a primary frequency regulation control method that can be adaptively adjusted according to water head changes to improve the primary frequency regulation performance of pumped storage units under different water head conditions.

[0006] In summary, the development of a pumped-storage unit primary frequency regulation control system based on head adaptation can realize real-time monitoring and precise control of the unit's operating status, thereby automatically adjusting the primary frequency regulation control parameters according to head changes and improving the unit's regulation performance and adaptability. It is an inevitable choice to adapt to the stability and reliability requirements of the power system, solve the complexity of the operating characteristics of pumped-storage units, meet new needs for the development of the power system, overcome the limitations of existing technologies, and promote technological progress and innovation. Summary of the invention

[0007] The present invention aims to address the technical defects of the prior art and provide a primary frequency regulation control system and method for a pumped-storage unit based on head adaptation, so as to solve the problem in the prior art that the primary frequency regulation control parameters of the pumped-storage unit cannot be adaptively adjusted according to the change of water head. The method can monitor the change of water head in real time and automatically adjust the primary frequency regulation control parameters to improve the primary frequency regulation performance of the pumped-storage unit under different water head conditions and improve the regulation performance and adaptability of the unit.

[0008] The present invention provides the following technical solution: a primary frequency regulation control system of a pumped storage unit based on water head adaptation, comprising a water head monitoring and processing module, a primary frequency regulation parameter setting module, a PID controller parameter correction module and a primary frequency regulation control module;

[0009] The water head monitoring and processing module monitors the water head parameters of the pumped storage unit in real time through sensors and transmits the data to the controller, which processes and analyzes the received water head data and calculates the real-time water head;

[0010] The primary frequency modulation parameter setting module is used to set the parameters of the test water head, proportional gain, integral gain, differential gain, frequency dead zone, modulation difference coefficient and frequency modulation limit when conducting a primary frequency modulation test;

[0011] The PID controller parameter correction module, when the unit is in primary frequency modulation action, compares the test water head in the primary frequency modulation parameter setting module with the real-time water head, calculates the PID controller parameter correction coefficient according to the real-time water head, and corrects the PID controller parameters;

[0012] The primary frequency regulation control module applies the calculated PID controller parameter correction coefficient to the primary frequency regulation control system of the pumped storage unit, automatically adjusts the primary frequency regulation control parameters according to different water heads, and improves the primary frequency regulation performance of the pumped storage unit under different water head conditions.

[0013] Preferably, the sensor is a water level measuring sensor for measuring the water level height of the upper reservoir and the lower reservoir, and a plurality of water level measuring sensors are provided, respectively provided at the upper reservoir and the lower reservoir;

[0014] The calculation formula of the water head parameter of the pumped storage unit is:

[0015] H=H s -H x (1)

[0016] Where H is the water head of the pumped storage unit, H s is the water level of the reservoir above the pumped storage unit, H x It is the water level height of the reservoir below the pumped storage unit.

[0017] Preferably, the output expression of the PID controller is:

[0018]

[0019] Where Y is the guide vane opening; Δx is the relative deviation between the controlled variable and the set value; K P is the proportional gain coefficient; K I is the integral gain coefficient; K D is the differential gain coefficient.

[0020] Preferably, the differential gain coefficient K D =0, the PID controller parameter correction module compares the test water head in the primary frequency modulation parameter setting module with the real-time water head of the unit operation, calculates the proportional gain correction coefficient and the integral gain correction coefficient in the PID controller according to the real-time water head, and corrects the control parameters of the PID controller; the calculation formulas of the proportional gain correction coefficient and the integral gain correction coefficient are as follows:

[0021]

[0022] Where K pm Is the proportional gain correction coefficient when the PID controller is operated, K Im Is the integral gain correction coefficient when the PID controller is operated, K p is the proportional gain of the PID controller set during a frequency modulation test, K I is the integral gain of the PID controller set during a frequency modulation test, H sy is the unit water head during a frequency modulation test, H is the real-time water head during the unit operation, and H max is the maximum operating head of the unit, H min is the minimum operating water head of the unit, and α is the correction parameter.

[0023] Preferably, the primary frequency modulation control module calculates the difference between the frequency setting value and the actual frequency, that is, the frequency difference signal Δf1, according to the subtraction block SUB3:

[0024] Δf1=f sp -f pv (5)

[0025] Where Δf1 is the frequency difference signal, f sp is the power setting value, f pv is the actual power feedback value;

[0026] The primary frequency modulation parameter setting module sets a frequency dead zone, and the frequency dead zone is not greater than 0.05 Hz;

[0027] The primary frequency modulation parameter setting module sets a modulation difference coefficient, and the modulation difference coefficient is not greater than 3%.

[0028] Preferably, the frequency dead zone is set to 0.05 Hz, and the frequency dead zone processing module formula is:

[0029]

[0030] Among them, Δf is the frequency difference signal after the frequency modulation dead zone.

[0031] Preferably, the frequency difference signal after the frequency modulation dead zone is subjected to the power closed loop error adjustment formula f(Δf) to calculate the power variation ΔP1, and the power closed loop error adjustment formula is:

[0032]

[0033] Among them, ΔP1 is the power change of the primary frequency modulation, Δf is the frequency difference signal after the frequency modulation dead zone, and e p It is the adjustment rate, and the adjustment rate is 3% to 4%.

[0034] Preferably, the relative value ΔP of the power deviation between the actual power of the unit and the power setting value is:

[0035] ΔP=P sp +ΔP1-P pv (8)

[0036] Among them, P sp is the power setting value, ΔP1 is the primary frequency modulation power change, P pv is the actual power of the unit.

[0037] Preferably, the correction parameter α=1.

[0038] The primary frequency regulation control method of a pumped storage unit based on water head adaptation performs the following steps:

[0039] Step 1, by installing water level measurement sensors in the upper reservoir and the lower reservoir, measuring the water head parameters in real time, processing the water head parameters, and operating the water head by the computer group to determine the water head status;

[0040] Step 2, set the main parameters of the primary frequency modulation test and adjust the PID control parameters; set the test water head, proportional gain, integral gain, differential gain, frequency dead zone, adjustment coefficient and frequency modulation limit in the primary frequency modulation control module;

[0041] Step 3, establishing a mathematical relationship between the real-time water head and the unit's primary frequency modulation PID controller parameters, and determining the relationship between the real-time water head and the guide vane opening and power control parameters;

[0042] Step 4, calculating the PID controller parameter correction coefficient according to the real-time water head, and correcting the PID controller parameters;

[0043] Step 5: The unit control system implements a frequency modulation control under the current water head according to the received PID controller parameter value.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The primary frequency regulation control system of pumped storage units based on water head adaptation is an advanced control technology, which aims to improve the primary frequency regulation performance of pumped storage units under different water head conditions. It is mainly composed of four modules: water head monitoring and processing module, primary frequency regulation parameter setting module, PID controller parameter correction module and primary frequency regulation control module. These four modules work together to realize the function of automatically adjusting the primary frequency regulation control parameters according to the real-time water head changes, thereby improving the regulation performance and adaptability of pumped storage units under different water head conditions.

[0046] Water head monitoring and processing module: This module monitors the water head parameters of the pumped storage unit in real time through high-precision sensors to ensure the accuracy and real-time nature of the data. The data collected by the sensor is transmitted to the controller, which processes and analyzes the received data. It can process and analyze the data collected by the sensor in real time and finally calculate the real-time water head value. The system can monitor the water head changes of the pumped storage unit in real time and automatically adjust the primary frequency modulation control parameters according to the real-time water head to improve the regulation performance and adaptability of the unit. At the same time, the system can automatically adapt to water head changes, reduce manual intervention and operation and maintenance costs, and reduce economic losses caused by fault downtime by improving the regulation performance and stability of the unit.

[0047] Primary frequency modulation parameter setting module: When conducting a primary frequency modulation test, this module is responsible for setting key parameters such as test water head, proportional gain, integral gain, differential gain, frequency dead zone, modulation coefficient and frequency modulation limit. The setting of these parameters is crucial for subsequent PID controller parameter correction and primary frequency modulation control;

[0048] PID controller parameter correction module: When the unit performs primary frequency modulation, this module compares the test water head set in the primary frequency modulation parameter setting module with the real-time water head; based on the change of real-time water head, the PID controller parameter correction coefficient is calculated, and the PID controller parameters are dynamically corrected. This adaptive adjustment mechanism enables the control system to better respond to water head changes and improve the accuracy and response speed of frequency modulation;

[0049] Primary frequency regulation control module: This module applies the calculated PID controller parameter correction coefficient to the primary frequency regulation control system of the pumped storage unit; it automatically adjusts the primary frequency regulation control parameters according to the different water heads, so that the pumped storage unit can maintain the best frequency regulation performance under different water head conditions. This adaptive adjustment capability significantly improves the regulation performance and adaptability of the unit;

[0050] In summary, the pumped storage unit primary frequency regulation control system based on water head adaptation effectively solves the problem in the prior art that the pumped storage unit primary frequency regulation control parameters cannot be adaptively adjusted according to water head changes by real-time monitoring of water head changes and automatically adjusting control parameters. The application of this system not only improves the primary frequency regulation performance of the pumped storage unit, but also enhances the stability and reliability of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a system composition structure diagram of the present invention;

[0052] Figure 2 This is a structural diagram of a frequency modulation parameter setting module of the present invention;

[0053] Figure 3 This is a primary frequency modulation logic design diagram of the pumped storage unit with adaptive water head control according to the present invention;

[0054] Figure 4 Schematic diagram of the control flow of the present invention. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. All other embodiments obtained by ordinary technicians in the field without making creative work based on the embodiments of the present invention shall fall within the scope of protection of the present invention.

[0056] like Figures 1 to 4 As shown, it shows a specific embodiment of the present invention: Figures 1 to 4 As shown, the primary frequency regulation control system of the pumped storage unit based on water head adaptation disclosed in the present invention includes a water head monitoring and processing module, a primary frequency regulation parameter setting module, a PID controller parameter correction module and a primary frequency regulation control module;

[0057] The water head monitoring and processing module monitors the water head parameters of the pumped storage unit in real time through sensors and transmits the data to the controller, which processes and analyzes the received water head data and calculates the real-time water head;

[0058] The primary frequency modulation parameter setting module is used to set the parameters of the test water head, proportional gain, integral gain, differential gain, frequency dead zone, modulation difference coefficient and frequency modulation limit when conducting a primary frequency modulation test;

[0059] The PID controller parameter correction module, when the unit is in primary frequency modulation action, compares the test water head in the primary frequency modulation parameter setting module with the real-time water head, calculates the PID controller parameter correction coefficient according to the real-time water head, and corrects the PID controller parameters;

[0060] The primary frequency regulation control module applies the calculated PID controller parameter correction coefficient to the primary frequency regulation control system of the pumped storage unit, automatically adjusts the primary frequency regulation control parameters according to different water heads, and improves the primary frequency regulation performance of the pumped storage unit under different water head conditions.

[0061] The above-mentioned primary frequency regulation parameter setting module adjusts the PID parameters of the speed regulator of the pumped storage unit through a primary frequency regulation test. Figure 2 , set the frequency modulation dead zone, differential coefficient, frequency modulation limit and the adjusted PID parameters, and record the test water head when adjusting the speed regulator PID parameters.

[0062] Preferably, the sensor is a water level measuring sensor for measuring the water level height of the upper reservoir and the lower reservoir, and a plurality of water level measuring sensors are provided, which are respectively provided at the upper reservoir and the lower reservoir;

[0063] The calculation formula of the water head parameter of the pumped storage unit is:

[0064] H=H s -H x (1)

[0065] Where H is the water head of the pumped storage unit, H s is the water level of the reservoir above the pumped storage unit, H x It is the water level height of the reservoir below the pumped storage unit.

[0066] Reference Figure 1 , which is a system composition structure diagram of the present invention, a primary frequency regulation control system and method of a pumped storage unit based on head adaptive control, mainly includes a head monitoring and processing module, a primary frequency regulation parameter setting module, a PID controller parameter correction module and a primary frequency regulation control module.

[0067] The hydraulic head of a pumped storage unit refers to the difference between the water levels of the upper and lower reservoirs. By measuring the water levels of the upper and lower reservoirs, the hydraulic head of the pumped storage unit can be calculated.

[0068] H=H s -H x

[0069] Among them, H is the water head of the pumped storage unit, H s is the water level of the upper reservoir of the pumped storage unit, Hx It is the water level height of the lower reservoir of the pumped storage unit. The water level heights of the upper and lower reservoirs can be measured by water level measuring sensors. In practical applications, in order to improve the measurement accuracy, it is usually necessary to average the water levels of multiple measuring points. Therefore, multiple water level measuring sensors are set to improve the measurement accuracy.

[0070] Preferably, the output expression of the PID controller is:

[0071]

[0072] Where Y is the guide vane opening; Δx is the relative deviation between the controlled variable and the set value; K P is the proportional gain coefficient; K I is the integral gain coefficient; K D is the differential gain coefficient.

[0073] In actual operation, the water head of the pumped storage unit changes frequently and in a wide range. According to the power formula, when other factors remain unchanged, the change in water head will directly affect the power output of the unit. The power formula is as follows:

[0074] P=ρgHQη

[0075] Where: ρ is the density of water, g is the acceleration of gravity, H is the water head, Q is the flow rate, and η is the unit efficiency

[0076] If the turbine runs at low head, it means that the potential energy of water is reduced, and the ability to convert into mechanical energy is reduced, which leads to a decrease in the power output of the unit. When the grid frequency exceeds the primary frequency regulation dead zone, the proportional gain and integral gain values ​​should be appropriately increased to enhance the proportional and integral effects, speed up the regulation speed and the speed of eliminating static errors, and enhance the primary frequency regulation performance.

[0077] Preferably, the differential gain coefficient K D =0, the PID controller parameter correction module compares the test water head in the primary frequency modulation parameter setting module with the real-time water head of the unit operation, calculates the proportional gain correction coefficient and the integral gain correction coefficient in the PID controller according to the real-time water head, and corrects the control parameters of the PID controller; the calculation formulas of the proportional gain correction coefficient and the integral gain correction coefficient are as follows:

[0078]

[0079] Where K pm Is the proportional gain correction coefficient when the PID controller is operated, K Im Is the integral gain correction coefficient when the PID controller is operated, K p is the proportional gain of the PID controller set during a frequency modulation test, KI is the integral gain of the PID controller set during a frequency modulation test, H sy is the unit water head during a frequency modulation test, H is the real-time water head during the unit operation, and H max is the maximum operating head of the unit, H min is the minimum operating water head of the unit, and α is the correction parameter.

[0080] In the present invention, the PID controller parameters are composed of proportional and integral effects, that is, the differential gain is set to 0. The PID controller parameter correction module compares the test water head in the primary frequency modulation parameter setting module with the real-time water head of the unit operation, calculates the proportional gain and integral gain correction coefficients in the PID controller according to the real-time water head, and corrects the PID controller control parameters, such as Figure 3 As shown in the dashed box, when Δf>0, that is, the frequency difference exceeds the primary frequency modulation dead zone, the primary frequency modulation is activated, and the PID controller parameter correction coefficient is calculated as shown in formula (3) and formula (4), where K pm is the proportional gain of the PID controller; K Im is the integral gain of the PID controller operation; K p is the proportional gain of the PID controller set during a frequency modulation test; K I is the integral gain of the PID controller set during a frequency modulation test; H sy is the unit water head during a frequency modulation test; H is the real-time water head during the unit operation; H max is the maximum operating water head of the unit; H min is the minimum operating water head of the unit; α is the correction parameter, which is generally set to 1; K is generally set in the PID controller parameters of the hydropower unit speed regulator D is 0, that is, there are only proportional and integral control in the PID controller.

[0081] Preferably, the primary frequency modulation control module calculates the difference between the frequency setting value and the actual frequency, that is, the frequency difference signal Δf1, according to the subtraction block SUB3:

[0082] Δf1=f sp -f pv (5)

[0083] Where Δf1 is the frequency difference signal, f sp is the power setting value, f pv is the actual power feedback value;

[0084] The primary frequency modulation parameter setting module sets a frequency dead zone, and the frequency dead zone is not greater than 0.05 Hz;

[0085] The primary frequency modulation parameter setting module sets a modulation difference coefficient, and the modulation difference coefficient is not greater than 3%.

[0086] The above primary frequency modulation control module, refer to Figure 3 , the difference between the frequency setting value and the actual frequency is calculated according to the subtraction block SUB3, that is, the frequency difference signal Δf 1；

[0087] The dead zone of primary frequency regulation of hydropower should be set to no more than 0.05Hz. In the power regulation mode, the differential coefficient should be no more than 3%. Under the condition of non-rated power operation, the frequency regulation load change amplitude of hydropower units participating in primary frequency regulation should not be limited. By adding a frequency step signal to the speed regulator, the primary frequency regulation action of the unit is simulated, and the PID controller parameters are adjusted so that its primary frequency regulation performance meets the requirements of the "Technical Regulations and Test Guidelines for Primary Frequency Regulation of Grid-connected Power Sources". For example, the frequency regulation dead zone of a pumped storage power station is set to 0.049Hz, the differential coefficient is set to 2.6% in the power regulation mode, the frequency regulation limit is set to 100%, the PID controller parameter proportional gain is set to 11, the integral gain is set to 9, and the differential gain is set to 0. A 0.15Hz step signal is added to the speed regulator. In 5s, the unit load reaches 76% of the primary frequency regulation target load, and in 15s, it reaches 90% of the primary frequency regulation target load. Its primary frequency regulation performance meets the requirements of the guidelines.

[0088] Preferably, the frequency dead zone is set to 0.05 Hz, and the frequency dead zone processing module formula is:

[0089]

[0090] Among them, Δf is the frequency difference signal after the frequency modulation dead zone.

[0091] In order to avoid frequent operation of the power station when the grid frequency fluctuates slightly and to improve the stability of the system, a frequency dead zone will be set for primary frequency regulation. The frequency dead zone is required to be no greater than 0.05Hz. When the grid frequency is within the frequency dead zone, the unit does not participate in the primary frequency regulation action. The frequency difference signal Δf1 is processed by the frequency dead zone module to obtain the frequency difference signal Δf after the frequency dead zone.

[0092] Preferably, the frequency difference signal after the frequency modulation dead zone is subjected to the power closed loop error adjustment formula f(Δf) to calculate the power variation ΔP1, and the power closed loop error adjustment formula is:

[0093]

[0094] Among them, ΔP1 is the power change of the primary frequency modulation, Δf is the frequency difference signal after the frequency modulation dead zone, and e p is the adjustment rate, and the adjustment rate is 3% to 4%.

[0095] Preferably, the relative value ΔP of the power deviation between the actual power of the unit and the power setting value is:

[0096] ΔP=P sp +ΔP1-P pv (8)

[0097] Among them, P sp is the power setting value, ΔP1 is the primary frequency modulation power change, P pv is the actual power of the unit.

[0098] Preferably, the correction parameter α=1.

[0099] Except for the vibration area and cavitation area, the pumped storage unit does not have a primary frequency modulation limit, and the frequency modulation limit is generally 100%.

[0100] In order to make the pumped storage unit adjust the output power in time according to the change of system frequency to maintain the stability of the grid frequency. When the system frequency deviates from the rated value, the primary frequency regulation system will calculate the power action amount according to the frequency deviation and add this action amount to the power setting value, thereby changing the output power of the hydropower unit to respond to the change of system frequency. The relative value of the power deviation ΔP between the actual power of the unit and the power setting value is:

[0101] ΔP=P sp +ΔP1-P pv

[0102] Among them, P sp is the power setting value, ΔP1 is the primary frequency modulation power change, P pv is the actual power of the unit.

[0103] In practical applications, the expression of PID controller is:

[0104] Y=K Pm ΔP+K Im ∫ΔPdt

[0105] Proportional Gain

[0106] Integral gain

[0107] Where ΔP is the relative deviation between the actual power and the given power, K pm is the proportional gain of the PID controller; K Im is the integral gain of the PID controller operation; K p is the proportional gain of the PID controller set during a frequency modulation test; K I is the integral gain of the PID controller set during a frequency modulation test; H sy is the unit water head during a frequency modulation test; H is the real-time water head during the unit operation; H max is the maximum operating water head of the unit; Hmin is the minimum operating water head of the unit; α is the correction parameter, which is generally taken as 1.

[0108] In practical applications, the test head H sy The unit primary frequency regulation setting parameter is K p , K I , the test head can select the rated head. In actual operation, the operating head conditions of pumped storage units are constantly changing. The maximum head and minimum head of a pumped storage power station are nearly 100 meters apart. The head conditions during operation not only change frequently but also have a large range of changes. Since the operating head of the unit will affect the torque characteristics and flow characteristics of the turbine, it will affect the active power output of the generator set during the primary frequency regulation process, and thus affect the performance of the primary frequency regulation, especially for pumped storage power stations with frequent changes in working head and large head height. The fixed parameter PID controller parameters are not suitable for the primary frequency regulation process under all head conditions of the pumped storage unit.

[0109] When the grid frequency exceeds the dead zone of the unit's primary frequency regulation, the unit's primary frequency regulation will be actuated, and the unit's actual integrated power and the percentage of the unit's primary frequency regulation theoretical integrated power in the corresponding time will be used as the primary frequency regulation pass rate for the unit.

[0110] The calculation formula of the theoretical integral power of the unit primary frequency regulation is:

[0111]

[0112] Among them, Q LJ is the theoretical integral power of the unit's primary frequency regulation; n is the duration of the frequency difference exceeding the dead zone. If it exceeds 60s, it is calculated as 60s; P r is the rated power; Δf(t) is the frequency deviation; f r is the rated frequency; e p It is the turbine regulation coefficient in power mode.

[0113] The calculation formula for the actual integrated power of the unit's primary frequency regulation is:

[0114]

[0115] Among them, Q SJ is the actual integrated power of the unit's primary frequency regulation; n is the duration of the frequency difference exceeding the dead zone. If it exceeds 60s, it will be calculated as 60s; P is the actual power at time t; P0 is the actual power at the moment before the primary frequency regulation action.

[0116]

[0117] Among them, Q Hi It is the pass rate of the unit's primary frequency regulation.

[0118] The pass rate of a single frequency modulation should be no less than 80%. If it is lower than 80%, it means that the single frequency modulation action is unqualified. If it is greater than 120%, it means that the single frequency modulation is over-regulated.

[0119] Different water heads have a significant impact on the primary frequency regulation pass rate of pumped storage units. When the water head is high, the water flow potential energy is large, and the turbine converts water energy into mechanical energy quickly, so that the unit responds quickly to changes in system frequency, and the power adjustment speed is fast and large. If the system frequency drops, the high-head unit can quickly increase the water flow and output power, but it may cause primary frequency regulation over-regulation due to the fast power adjustment speed and large amplitude. When the water head is low, the water flow potential energy is small, the turbine conversion capacity is weak, the unit response speed is slow, and the power adjustment amplitude is small. Although the impact on system stability is relatively small, it may cause primary frequency regulation to fail due to weak power adjustment ability and inability to respond to large changes in system frequency in time.

[0120] The present invention uses the proportional gain K pm and integral gain K Im The calculation formula is to fix the parameter K p , K I K changes according to the change of the unit's operating head. pm and K Im , thereby improving the adaptive proportional gain K of the pumped storage unit under different water heads according to the water head changes pm and integral gain K Im , thus changing the primary frequency modulation quality. When the correction parameter α is 1:

[0121] When the actual water head H is equal to the test water head H sy , that is, H=H sy , when the frequency modulation is performed once, the controller parameters of the PID controller are the control parameters set during the frequency modulation test;

[0122]

[0123] When the actual water head H is less than the test water head H sy , that is, H<H sy , then the proportional gain and integral gain values ​​should be appropriately increased to enhance the proportional and integral effects, enhance the primary frequency modulation performance, and prevent the primary frequency modulation action from being unqualified. During the primary frequency modulation action, the PID controller parameters are:

[0124]

[0125] When the actual water head H is greater than the test water head H sy , that is, H>H sy, then the proportional gain and integral gain values ​​should be appropriately reduced to weaken the proportional and integral effects, weaken the primary frequency modulation performance, and prevent the primary frequency modulation from over-regulating. When the primary frequency modulation is in action, the PID controller parameters are:

[0126]

[0127] From the above, it can be seen that when the actual water head H is equal to the test water head H sy When the frequency modulation is performed once, the PID controller parameters are the control parameters set during the frequency modulation test; when the actual water head H is less than the test water head H sy When the water flow potential energy decreases, the turbine conversion capacity weakens, the unit response speed is slow, the power adjustment range is small, and the power adjustment capacity is weak. It is necessary to appropriately enhance the proportional and integral effects to prevent the primary frequency regulation action from being unqualified; when the actual water head H is greater than the test water head H sy , the potential energy of water flow becomes larger, and the turbine converts water energy into mechanical energy quickly, so that the unit responds to system frequency changes quickly, and the power adjustment speed is fast and the amplitude is large. However, the fast power adjustment speed and large amplitude may cause the primary frequency regulation to be over-regulated. It is necessary to appropriately weaken the proportional and integral effects to prevent the primary frequency regulation from being over-regulated.

[0128] During the actual operation of the pumped-storage unit, the water head conditions change frequently and in a wide range. The primary frequency regulation setting parameters should be set according to the actual situation. Different schemes should be adopted under different water heads. The PID controller parameter correction calculation formula can be determined according to the actual project. Different correction formulas can be used for the proportional gain and the integral gain. This is of great significance for improving the primary frequency regulation quality of the pumped-storage unit and maintaining the frequency stability of the power system.

[0129] Reference Figure 4 , the primary frequency regulation control method of the pumped storage unit based on water head adaptation performs the following steps:

[0130] Step 1, by installing water level measurement sensors in the upper reservoir and the lower reservoir, measuring the water head parameters in real time, processing the water head parameters, and operating the water head by the computer group to determine the water head status;

[0131] Step 2, set the main parameters of the primary frequency modulation test and adjust the PID control parameters; set the test water head, proportional gain, integral gain, differential gain, frequency dead zone, adjustment coefficient and frequency modulation limit in the primary frequency modulation control module;

[0132] Step 3, establishing a mathematical relationship between the real-time water head and the unit's primary frequency modulation PID controller parameters, and determining the relationship between the real-time water head and the guide vane opening and power control parameters;

[0133] Step 4, calculating the PID controller parameter correction coefficient according to the real-time water head, and correcting the PID controller parameters;

[0134] Step 5: The unit control system implements a frequency modulation control under the current water head according to the received PID controller parameter value.

[0135] The method measures the water head state of the pumped storage unit in real time, sets the test water head and the adjusted PID controller parameters during the primary frequency modulation test, establishes the mathematical relationship between the real-time water head and the PID controller parameters of the unit primary frequency modulation, calculates the PID controller parameter correction coefficient according to the real-time water head, corrects the PID controller parameters, and realizes the next frequency modulation control of the current water head. The present invention can automatically adjust the PID controller control parameters according to the water head change, improve the next frequency modulation performance of different water heads, and is of great significance to ensuring the safe and stable operation of the unit and the frequency stability of the power system.

[0136] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the field without departing from the purpose of the present invention. These changes involve related technologies well known to those skilled in the art, which all fall within the scope of protection of the patent of the present invention.

[0137] Many other changes and modifications may be made without departing from the concept and scope of the present invention.It should be understood that the present invention is not limited to the specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. A pumped storage unit primary frequency regulation control system based on water head adaptation, characterized in that: It includes water head monitoring and processing module, primary frequency modulation parameter setting module, PID controller parameter correction module and primary frequency modulation control module; The water head monitoring and processing module monitors the water head parameters of the pumped storage unit in real time through sensors and transmits the data to the controller, which processes and analyzes the received water head data and calculates the real-time water head; The primary frequency modulation parameter setting module is used to set the parameters of the test water head, proportional gain, integral gain, differential gain, frequency dead zone, modulation difference coefficient and frequency modulation limit when conducting a primary frequency modulation test; The PID controller parameter correction module, when the unit is in primary frequency modulation action, compares the test water head in the primary frequency modulation parameter setting module with the real-time water head, calculates the PID controller parameter correction coefficient according to the real-time water head, and corrects the PID controller parameters; The primary frequency regulation control module applies the calculated PID controller parameter correction coefficient to the primary frequency regulation control system of the pumped storage unit, automatically adjusts the primary frequency regulation control parameters according to different water heads, and improves the primary frequency regulation performance of the pumped storage unit under different water head conditions.

2. The primary frequency regulation control system of a pumped storage unit based on water head adaptation according to claim 1 is characterized in that: The sensor adopts a water level measuring sensor, which is used to measure the water level height of the upper reservoir and the lower reservoir. A plurality of water level measuring sensors are provided, which are respectively provided at the upper reservoir and the lower reservoir; The calculation formula of the water head parameter of the pumped storage unit is: H=H s -H x (1), Where H is the water head of the pumped storage unit, H s is the water level of the reservoir above the pumped storage unit, H x It is the water level height of the reservoir below the pumped storage unit.

3. The primary frequency regulation control system of a pumped storage unit based on water head adaptation according to claim 2 is characterized in that: The output expression of the PID controller is: Where Y is the guide vane opening; Δx is the relative deviation between the controlled variable and the set value; K P is the proportional gain coefficient; K I is the integral gain coefficient; K D is the differential gain coefficient.

4. The primary frequency regulation control system of a pumped storage unit based on water head adaptation according to claim 3 is characterized in that: The differential gain coefficient K D =0, the PID controller parameter correction module compares the test water head in the primary frequency modulation parameter setting module with the real-time water head of the unit operation, calculates the proportional gain correction coefficient and the integral gain correction coefficient in the PID controller according to the real-time water head, and corrects the control parameters of the PID controller; the calculation formulas of the proportional gain correction coefficient and the integral gain correction coefficient are as follows: Where K pm Is the proportional gain correction coefficient when the PID controller is operated, K Im Is the integral gain correction coefficient when the PID controller is operated, K p is the proportional gain of the PID controller set during a frequency modulation test, K I is the integral gain of the PID controller set during a frequency modulation test, H sy is the unit water head during a frequency modulation test, H is the real-time water head during the unit operation, and H max is the maximum operating head of the unit, H min is the minimum operating water head of the unit, and α is the correction parameter.

5. The primary frequency regulation control system of a pumped storage unit based on water head adaptation according to any one of claims 1 to 4, characterized in that: The primary frequency modulation control module calculates the difference between the frequency setting value and the actual frequency according to the subtraction block SUB3, that is, the frequency difference signal Δf1: Δf1=f sp -f pv (5), Where Δf1 is the frequency difference signal, f sp is the power setting value, f pv is the actual power feedback value; The primary frequency modulation parameter setting module sets a frequency dead zone, and the frequency dead zone is not greater than 0.05 Hz; The primary frequency modulation parameter setting module sets a modulation difference coefficient, and the modulation difference coefficient is not greater than 3%.

6. The primary frequency regulation control system of a pumped storage unit based on water head adaptation according to claim 5 is characterized in that: The frequency dead zone is set to 0.05 Hz, and the frequency dead zone processing module formula is: Among them, Δf is the frequency difference signal after the frequency modulation dead zone.

7. The primary frequency regulation control system of a pumped storage unit based on water head adaptation according to claim 6 is characterized in that: The frequency difference signal after the frequency modulation dead zone is calculated by the power closed loop error formula f(Δf) to obtain the power change ΔP1. The error formula under the power closed loop is: Among them, ΔP1 is the power change of the primary frequency modulation, Δf is the frequency difference signal after the frequency modulation dead zone, and e p is the adjustment rate, and the adjustment rate is 3% to 4%.

8. The primary frequency regulation control system of a pumped storage unit based on water head adaptation according to claim 7 is characterized in that: The relative value of the power deviation ΔP between the actual power of the unit and the power setting value is: ΔP=P sp +ΔP1-P pv (8), Among them, P sp is the power setting value, ΔP1 is the primary frequency modulation power change, P pv is the actual power of the unit.

9. The primary frequency regulation control system of a pumped storage unit based on water head adaptation according to claim 4 is characterized in that: The correction parameter α=1.

10. A method for primary frequency regulation control of a pumped storage unit based on water head adaptation, characterized in that: The primary frequency regulation control system of a pumped storage unit based on water head adaptation according to any one of claims 1 to 9 is adopted to perform the following steps: Step 1, by installing water level measurement sensors in the upper reservoir and the lower reservoir, measuring the water head parameters in real time, processing the water head parameters, and operating the water head by the computer group to determine the water head status; Step 2, set the main parameters of the primary frequency modulation test and adjust the PID control parameters; set the test water head, proportional gain, integral gain, differential gain, frequency dead zone, adjustment coefficient and frequency modulation limit in the primary frequency modulation control module; Step 3, establishing a mathematical relationship between the real-time water head and the unit's primary frequency modulation PID controller parameters, and determining the relationship between the real-time water head and the guide vane opening and power control parameters; Step 4, calculating the PID controller parameter correction coefficient according to the real-time water head, and correcting the PID controller parameters; Step 5: The unit control system implements a frequency modulation control under the current water head according to the received PID controller parameter value.

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