Super capacitor energy storage system and control method for improving frequency modulation performance of hydroelectric generating set
By dynamically generating real-time power and operating commands for the supercapacitor energy storage system and hydropower units based on real-time grid frequency deviation, the problem of frequency regulation response delay of hydropower units is solved, and a coordinated frequency regulation effect of rapid response and continuous output is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- POWERCHINA HYDROPOWER DEV GRP CO LTD
- Filing Date
- 2026-03-05
- Publication Date
- 2026-06-12
Smart Images
Figure CN122203282A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of power system frequency regulation control technology, specifically a supercapacitor energy storage system and control method for improving the frequency regulation performance of hydropower units. Background Technology
[0002] Frequency stability is crucial in power systems. Traditionally, hydroelectric generating units, especially axial-flow propeller turbine generators, rely on their speed control systems for frequency regulation. When the grid frequency deviates, the turbine mechanically adjusts the guide vanes and blade opening to change the active power output. However, hydroelectric generating units inherently experience response delays and regulation inertia from detecting frequency changes to mechanically executing power adjustments, making it difficult to quickly track rapid frequency fluctuations. This characteristic renders them insufficient in both speed and accuracy when dealing with the increasing instantaneous power surges in modern power grids.
[0003] To compensate for the insufficient dynamic response of hydropower units, existing technologies propose adding energy storage systems at the hydropower plant side. The conventional approach is to detect frequency deviations and directly assign a fixed power regulation command to both the energy storage system and the hydropower unit, or to set a simple power allocation ratio. While these methods can utilize the rapid response of energy storage for initial support, they fail to fully consider the fundamental differences between hydropower units and energy storage systems in terms of response speed, duration, and regulation characteristics. Simple power superposition or fixed allocation can easily lead to incoordination between the two resources during frequency regulation, potentially resulting in power reversal or mutual cancellation, failing to achieve optimal synergy throughout the entire frequency regulation process. Current technologies lack a control strategy capable of finely coordinating the behavior of both at different time scales throughout the entire frequency regulation event. Summary of the Invention
[0004] This invention aims to solve at least one of the technical problems existing in the prior art; Therefore, this invention proposes a control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units, including: Continuously measure the operating frequency of the power grid and obtain real-time power grid frequency sampling values; The difference between the sampled power grid frequency value and the rated frequency is calculated to obtain the power grid frequency deviation. Determine whether the absolute value of the power grid frequency deviation exceeds a preset dead zone threshold; When the judgment result is yes, the coordinated frequency regulation control process of the hydropower unit and the supercapacitor energy storage system is started. Based on the power grid frequency deviation, the rated capacity of the hydropower unit, and its primary frequency regulation droop coefficient, the total power regulation required under the current operating conditions is calculated. Based on the preset timing stage division rules, the entire frequency modulation response process is divided into different power distribution stages; For different power distribution stages, the instantaneous power command of the supercapacitor energy storage system and the target opening command of the hydro turbine governor are dynamically generated. According to the real-time power command, the supercapacitor energy storage array is controlled to absorb or release corresponding active power from the power plant bus through the bidirectional converter. According to the target opening command, the governor of the hydroelectric turbine is controlled to adjust the opening of the guide vanes and blades, thereby changing the active power output of the hydroelectric generator unit. Monitor the combined output of the hydropower unit and the supercapacitor energy storage system to ensure that it follows the total power adjustment throughout the frequency regulation process.
[0005] Furthermore, based on the grid frequency deviation, the rated capacity of the hydropower unit, and its primary frequency regulation droop coefficient, the total power regulation required under the current operating conditions is calculated, including: Obtain the preset rated frequency value, rated power value of the hydropower unit, and primary frequency regulation droop coefficient value; Divide the power grid frequency deviation by the rated frequency value to obtain a relative frequency deviation ratio. Divide the relative frequency deviation ratio by the primary frequency modulation droop coefficient value to obtain a power regulation coefficient; The total power regulation is calculated by multiplying the power regulation coefficient by the rated power value of the hydropower unit.
[0006] Furthermore, based on the preset timing stage division rules, the entire frequency modulation response process is divided into different power allocation stages, including: From the moment the coordinated frequency modulation control process starts, an end time point for an initial fast response phase is defined, which is composed of the start time plus a fixed short time period. Starting from the end time of the initial rapid response phase, an end time of a continuous output phase is defined, which is composed of the end time of the initial rapid response phase plus a fixed intermediate time period. Starting from the end time of the continuous output phase, a transition phase end time is defined. The end time is composed of the end time of the continuous output phase plus a fixed long period of time, or is triggered by the condition that the hydropower unit output reaches a stable balance. After the transition phase, the system enters the steady-state operation and energy storage recovery phase.
[0007] Furthermore, for different power distribution stages, the system dynamically generates real-time power commands for the supercapacitor energy storage system and target opening commands for the hydropower turbine governor, including: During the initial rapid response phase, the instantaneous power command of the supercapacitor energy storage system is set to be equal to the total power adjustment amount, and a locking command to maintain the current opening degree is sent to the hydro turbine governor. During the continuous output phase, the instantaneous power command of the supercapacitor energy storage system is maintained equal to the total power adjustment amount, and the locking command is continuously sent to the hydro turbine governor. During the transition phase, the instantaneous power command of the supercapacitor energy storage system is smoothly reduced from the total power regulation to zero according to a preset descent function. At the same time, the lock command on the hydro turbine governor is released, and the target opening command is generated based on the current remaining grid frequency deviation. During the steady-state operation and energy storage recovery phase, the instantaneous power command of the supercapacitor energy storage system is set to zero, and a low-power charging command is generated to restore the supercapacitor's state of charge to an intermediate value. The step of smoothly decaying the instantaneous power command of the supercapacitor energy storage system from the total power regulation amount to zero according to a preset decay function includes: Set a linear decay slope from the total power adjustment amount to zero; In each control cycle, the value of the instantaneous power command is subtracted from the product of the linear decay slope and the cycle duration until the value of the instantaneous power command decreases to zero. Alternatively, an inertial time constant can be set, and the instantaneous power command value at each moment can be calculated according to the dynamic response curve of the first-order inertial element.
[0008] Furthermore, during the steady-state operation and energy storage recovery phase, a low-power charging command is generated to restore the supercapacitor's state of charge to an intermediate value, including: Monitor the real-time state of charge of the supercapacitor energy storage array; Calculate the difference between the real-time state of charge value and the target intermediate state of charge value; When the grid frequency stabilizes near the rated frequency, a constant power charging command or a proportional adjustment charging command with limited amplitude is generated based on the difference. The charging command is used as the new instantaneous power command for the supercapacitor energy storage system until the real-time state of charge value recovers to near the target intermediate state of charge value.
[0009] Furthermore, it also includes a logical judgment process to prevent power reversal: Throughout the frequency regulation response process, the actual active power output or absorbed by the supercapacitor energy storage system is calculated in real time by integration to obtain the actual power contribution of the supercapacitor. Based on the sign of the total power regulation and the frequency modulation duration, the theoretical power contribution of the supercapacitor is calculated. The sign of the actual contributed electricity is continuously compared with the sign of the theoretical contributed electricity; When it is detected that the sign of the actual contributed power is about to change in the opposite direction to the sign of the theoretical contributed power, the direction of the instantaneous power command of the supercapacitor energy storage system is immediately reversed.
[0010] Furthermore, the rated power parameters of the supercapacitor energy storage system in the method are determined as follows: Analyze the historical operating data of the power station where the hydropower unit is located, and statistically analyze the maximum total power regulation calculated in each power grid frequency disturbance event; The maximum total power adjustment is taken as the minimum required value for the rated power configuration of the supercapacitor energy storage system.
[0011] Furthermore, the rated energy parameters of the supercapacitor energy storage system in the method are determined as follows: Determine the typical duration of a frequency modulation event; Multiply the total power adjustment by the typical duration to obtain a basic energy requirement value; Considering that supercapacitors need to be able to complete a full frequency modulation event under both charging and discharging conditions, and that their initial state of charge is maintained at 50%, the basic energy requirement value is multiplied by two, and the calculated result is used as the minimum required value for the rated energy configuration of the supercapacitor energy storage system.
[0012] Furthermore, monitoring the combined output of the hydropower unit and the supercapacitor energy storage system, ensuring it follows the total power adjustment throughout the frequency regulation process, includes: Real-time acquisition of actual power output measurements of hydropower units and actual power output measurements of supercapacitor energy storage systems; The actual output measurement value is added to the actual power output measurement value to obtain the real-time combined output value; The difference between the combined output value and the total power adjustment is calculated to obtain the combined output deviation; The combined output deviation is used as a feedback correction quantity and is superimposed on the generation logic of the real-time power command of the supercapacitor energy storage system and the target opening command of the hydropower turbine governor, respectively, to eliminate the deviation.
[0013] Furthermore, the present invention also includes a supercapacitor energy storage system for improving the frequency regulation performance of hydropower units. The system includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the steps of the control method for improving the frequency regulation performance of hydropower units using supercapacitor energy storage as described above.
[0014] Compared with the prior art, the beneficial effects of the present invention are: The frequency regulation response process is divided into multiple stages based on time sequence. This division is based on the differences in dynamic characteristics between hydropower units and supercapacitors. The control strategy is designed according to the core requirements of each stage. In the initial stage, the supercapacitor is prioritized for rapid power compensation, while the mechanical response of the hydropower unit is initiated simultaneously. In subsequent stages, the power support is systematically shifted from energy storage to the hydropower unit, with the unit ultimately undertaking steady-state regulation. This method decouples the action sequences of the two resources in time, allowing the rapid response of the supercapacitor to be fully utilized in the early stages of disturbance, while ensuring continuous output from the hydropower unit, thereby optimizing the efficiency of regulation resource coordination throughout the entire process.
[0015] For each specific stage, two sets of control commands are dynamically and collaboratively generated based on real-time frequency deviation: power commands for the supercapacitor and operating commands for the hydropower unit. These two sets of commands are jointly calculated under the same control logic to ensure coordinated action. This mechanism precisely matches the power change rate of both at every moment, enabling smooth and disturbance-free joint output to track total demand, effectively preventing power reversal or secondary frequency fluctuations caused by asynchronous adjustment rhythms. This dynamic coordinated command generation method unifies the action logic of the two devices, making them an organic whole. It avoids internal conflicts that may be caused by simple power allocation, achieving a combination of rapid response and sustained support, and improving the adjustment accuracy, dynamic stability, and adaptability to complex disturbances of the joint system. Attached Figure Description
[0016] Figure 1 This is a flowchart illustrating the steps of the control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units according to the present invention. Figure 2 A flowchart for dividing the time sequence stages; Figure 3 A flowchart for the state-of-charge recovery of a supercapacitor; Figure 4 A statistical chart of total power regulation for historical frequency disturbance events; Figure 5 This is a graph showing the calculation of grid frequency deviation and total power regulation. Detailed Implementation
[0017] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] See Figure 1 The system continuously measures the operating frequency of the power grid to obtain real-time grid frequency sampling values. The difference between the grid frequency sampling value and the rated frequency is calculated to obtain the grid frequency deviation. It is then determined whether the absolute value of the grid frequency deviation exceeds a preset dead zone threshold. If the determination result is yes, the coordinated frequency regulation control process of the hydropower unit and the supercapacitor energy storage system is initiated. Based on the grid frequency deviation, the rated capacity of the hydropower unit, and its primary frequency regulation droop coefficient, the total power regulation required under the current operating condition is calculated. According to the preset timing stage division rules, the entire frequency regulation response process is divided into different power allocation stages. For different power allocation stages, the system dynamically generates instantaneous power commands for the supercapacitor energy storage system and target opening commands for the hydropower turbine governor. According to the instantaneous power commands, the supercapacitor energy storage array is controlled to absorb or release corresponding active power from or to the power plant bus via a bidirectional converter. According to the target opening commands, the hydropower turbine governor is controlled to adjust the opening of the guide vanes and blades, thereby changing the active power output of the hydropower unit. Monitor the combined output of the hydropower unit and the supercapacitor energy storage system to ensure that it follows the total power adjustment throughout the frequency regulation process.
[0019] See Figure 2 In one embodiment of the present invention, a power grid frequency disturbance event is used as an example. The power grid frequency sampling value is 49.8 Hz, the rated frequency value is 50 Hz, the rated power of the hydropower unit is 100 MW, the primary frequency regulation droop coefficient is 0.02, the power grid frequency deviation is the rated frequency value minus the power grid frequency sampling value to obtain -0.2 Hz, the relative frequency deviation ratio is the power grid frequency deviation divided by the rated frequency value to obtain -0.004, the power regulation coefficient is the relative frequency deviation ratio divided by the primary frequency regulation droop coefficient to obtain -0.2, and the total power regulation is the power regulation coefficient multiplied by the rated power of the hydropower unit to obtain -20 MW. A negative value indicates that the hydropower unit needs to increase its output to raise the power grid frequency. In some embodiments, the total power regulation is calculated using the following formula:
[0020] in: Indicates the total power adjustment amount. Indicates the power grid frequency deviation. Indicates the rated frequency value. This represents the primary frequency modulation droop coefficient value. The formula represents the rated power value of the hydroelectric generator unit. All characters in the formula have the meanings described above, and the formula symbols do not repeat the formula symbols in other embodiments.
[0021] In specific implementation, the division of timing stages is based on preset rules. The start time of the coordinated frequency regulation control process is recorded as time zero. The end time of the initial rapid response stage is composed of time zero plus a fixed short time period. For example, the short time period ranges from 1 to 2 seconds, so the end time is 2 seconds after time zero. The end time of this stage is composed of the end time of the initial rapid response stage plus a medium time period. The medium time period ranges from 5 to 28 seconds. For example, if the medium time period is set to 10 seconds, the end time is 12 seconds after time zero. The end time of the transition handover stage is composed of the end time of the continuous output stage plus a fixed long time period. The long time period ranges from 20 to 48 seconds. For example, if the long time period is set to 30 seconds, the end time is 42 seconds after time zero. Alternatively, the end time of the transition handover stage is triggered by the condition that the hydropower unit output reaches a stable balance. After the transition handover stage, the steady-state operation and energy storage recovery stage begins. In some embodiments, the specific value of the time period can be adjusted according to the actual system requirements. The range of short time periods is between 1 and 2 seconds, the range of medium time periods is between 5 and 28 seconds, and the range of long time periods is between 20 and 48 seconds. It can be understood that the setting of these time periods needs to adapt to the mechanical response characteristics of the hydropower unit and the frequency regulation requirements of the power grid.
[0022] Optionally, when the grid frequency deviation is positive, the total power regulation is also positive, indicating that the hydropower unit needs to reduce its output. It can be understood that the calculation process for the total power regulation is symmetrically applicable to both rising and falling frequency conditions. Optionally, the primary frequency regulation droop coefficient is set according to the specific model of the hydropower unit and the grid dispatch requirements, with a common value not exceeding 0.03. It can be understood that different coefficient choices will affect the magnitude of the total power regulation. The above example scenarios and data comparisons demonstrate the specific implementation methods for calculation and division. In specific implementations, all terms use complete terminology, such as grid frequency deviation, rated frequency value, rated power value of the hydropower unit, and primary frequency regulation droop coefficient value.
[0023] See Figure 3In one embodiment of the present invention, taking a power grid frequency disturbance event as an example, a total power regulation of -8 MW indicates a need to increase output. During the initial fast response phase, the instantaneous power command of the supercapacitor energy storage system is set to equal the total power regulation, i.e., -8 MW, and a lockout command to maintain the current opening degree is sent to the hydro turbine governor. During the continuous output phase, the instantaneous power command of the supercapacitor energy storage system is maintained equal to the total power regulation, i.e., -8 MW, and lockout commands are continued to be sent to the hydro turbine governor. In some embodiments, the duration of the initial fast response phase is set to 2 seconds, and the duration of the continuous output phase is set to 10 seconds. It is understood that these time settings must be consistent with the phase division in the embodiment.
[0024] In practical implementation, during the transition phase, the instantaneous power command of the supercapacitor energy storage system smoothly decays from the total power regulation to zero according to a preset decay function. Simultaneously, the lock command on the hydropower turbine governor is released, and a target opening command is generated based on the remaining grid frequency deviation. A linear decay slope from the total power regulation to zero is set. In each control cycle, the value of the instantaneous power command is subtracted from the product of the linear decay slope and the cycle duration until the instantaneous power command value decreases to zero. The linear decay process uses the following formula:
[0025] in: This represents the instantaneous power command of the supercapacitor energy storage system during the k-th control cycle. This represents the instantaneous power command of the supercapacitor energy storage system during the (k-1)th control cycle. Indicates the linear decay slope. This indicates the control cycle duration. All characters in the formula have the meanings described above, and the formula symbols do not repeat those in other embodiments. Optionally, a linear decay slope... The calculation method is to divide the absolute value of the total power regulation by the preset duration of the transition phase. For example, if the absolute value of the total power regulation is 8 MW and the preset duration of the transition phase is 30 seconds, then the linear attenuation slope is... Approximately 0.2667 megawatts per second. In some embodiments, during the transition phase, the instantaneous power command value at each moment is calculated according to the dynamic response curve of the first-order inertial element. An inertial time constant is set, and the instantaneous power command value changes with time according to an exponential decay law. It can be understood that the first-order inertial element can achieve smoother power decay.
[0026] In practical implementation, during the steady-state operation and energy storage recovery phases, the instantaneous power command of the supercapacitor energy storage system is set to zero, and a low-power charging command is generated to restore the supercapacitor's state of charge (SOC) to an intermediate value. The real-time SOC value of the supercapacitor energy storage array is monitored, and the difference between the real-time SOC value and the target intermediate SOC value is calculated. When the grid frequency stabilizes near the rated frequency, a constant power charging command with limited amplitude or a proportional adjustment charging command is generated based on the difference. This charging command is used as the new instantaneous power command for the supercapacitor energy storage system until the real-time SOC value is restored to near the target intermediate SOC value. Optionally, the target intermediate SOC value is set to 50%, the power value of the constant power charging command with limited amplitude is set to 5% to 10% of the rated power of the supercapacitor energy storage system, and the power value of the proportional adjustment charging command is proportional to the difference between the real-time SOC value and the target intermediate SOC value. The charging process must avoid causing new power disturbances to the grid.
[0027] In practice, during the transition and handover phase, the method for generating the target opening command after releasing the hydropower turbine governor lock command is based on the current remaining grid frequency deviation. For example, when the remaining grid frequency deviation is -0.1 Hz, the required hydropower unit output increment is calculated based on the frequency regulation characteristics of the hydropower unit and converted into the target opening command of the hydropower turbine governor. It can be understood that the generation of the target opening command needs to take into account the response speed and mechanical limitations of the hydropower unit.
[0028] In one embodiment of the present invention, a grid frequency disturbance event is used as an example for illustration. A total power regulation of -8 MW indicates that an increase in power output is required. In the initial stage, the supercapacitor energy storage system receives a negative instantaneous power command and discharges to increase the active power of the grid. During the entire frequency regulation response process, the actual active power output or absorbed by the supercapacitor energy storage system is calculated in real time to obtain the actual contribution of the supercapacitor. The integral calculation adopts the following formula:
[0029] in: This represents the actual amount of electricity contributed by the supercapacitor up to time t. The active power measured at time τ represents the actual output or absorption of the supercapacitor energy storage system. When discharging, the active power measurement value is negative, indicating the output energy. When charging, the active power measurement value is positive, indicating the absorbed energy. All characters in the formula have the meanings described above, and the formula symbols do not repeat with the formula symbols in other embodiments.
[0030] In specific implementations, the theoretical contribution of the supercapacitor is calculated based on the sign of the total power regulation and the frequency modulation duration. For example, if the sign of the total power regulation is negative and the frequency modulation duration is 15 seconds, the theoretical contribution is the product of the total power regulation and the frequency modulation duration, i.e., -120 megawatt-seconds. The sign of the theoretical contribution is always consistent with the sign of the total power regulation, and the signs of the actual contribution are continuously compared with those of the theoretical contribution. In some embodiments, the theoretical contribution... The calculation method is the total power adjustment amount. Multiply by the time since self-modulation started ,Right now The comparison of the signs of the actual and theoretical power contributions is performed in each control cycle. It can be understood that the actual power contribution reflects the energy actually provided by the supercapacitor energy storage system, while the theoretical power contribution reflects the energy the supercapacitor energy storage system is expected to provide under the current total power regulation requirement.
[0031] In specific implementation, when the sign of the actual contributed power is detected to be about to change in the opposite direction to the sign of the theoretical contributed power, the direction of the instantaneous power command of the supercapacitor energy storage system is immediately reversed. For example, during frequency regulation, the rapid recovery of the grid frequency may cause the theoretical contributed power to remain negative, but the actual contributed power to approach zero due to integral saturation. If discharge continues, the actual contributed power may change from negative to positive, i.e., sign reversal. At this time, the detection mechanism predicts the sign reversal trend and immediately reverses the instantaneous power command of the supercapacitor energy storage system from a discharge command to a charging command. In some embodiments, the detection of the sign reversal trend is achieved by calculating the relationship between the first derivative of the actual contributed power with respect to time and the sign of the theoretical contributed power. When the sign of the first derivative of the actual contributed power is opposite to the sign of the theoretical contributed power, it is determined that a sign reversal is about to occur. Optionally, reversing the direction of the instantaneous power command of the supercapacitor energy storage system means multiplying the instantaneous power command value by negative one, for example, reversing from -5 MW to +5 MW.
[0032] In one embodiment of the present invention, the power station where the hydropower unit is located is equipped with a data recording system to store relevant operating data of past power grid frequency disturbance events. The system analyzes the historical operating data of the power station where the hydropower unit is located and statistically analyzes the maximum total power regulation calculated from the past power grid frequency disturbance events. For example, multiple frequency disturbance events are extracted from the records of the past year, and the total power regulation is calculated for each event based on the power grid frequency deviation, the rated capacity of the hydropower unit, and its primary frequency regulation droop coefficient. These total power regulation values are sorted to find the maximum value. In some embodiments, the historical operating data covers frequency disturbance events under different seasons and load conditions to ensure the comprehensiveness of the statistics. It can be understood that the maximum total power regulation represents the most severe frequency regulation requirements that the power station needs to cope with. The maximum total power regulation is used as the minimum required value for the rated power configuration of the supercapacitor energy storage system. For example, if the statistically obtained maximum total power regulation is 10 MW, then the rated power of the supercapacitor energy storage system should be configured to be at least 10 MW.
[0033] In practical implementation, determining the rated energy parameters requires first determining the typical duration of a primary frequency regulation event. The typical duration is obtained by analyzing the statistical data of the time from when the frequency deviation exceeds the dead zone to when the frequency returns to stability in historical frequency disturbance events. For example, the average or 95th percentile of the duration can be calculated by analyzing multiple events. Multiplying the total power regulation by the typical duration yields a basic energy demand value, calculated using the following formula:
[0034] in: This represents the basic energy requirement. This represents the maximum total power adjustment obtained from statistics. This represents the typical duration of a frequency modulation event. All characters in the formula have the meanings described above, and the formula symbols do not repeat those in other embodiments. Considering that supercapacitors need to be able to complete a full frequency modulation event under both charging and discharging conditions and maintain their initial state of charge at 50%, the base energy requirement is multiplied by two, and the calculated result is used as the minimum required value for the rated energy configuration of the supercapacitor energy storage system. In some embodiments, the typical duration length The value is based on historical data analysis. For example, if the average duration of historical events is calculated to be 30 seconds, then the basic energy requirement value is... 10 megawatts multiplied by 30 seconds equals 300 megawatt-seconds, the minimum required rated energy configuration. With a rated power of 600 megawatt-seconds, it's understandable that the rated energy configuration must ensure that the supercapacitor does not exceed its limits during charge-discharge cycles.
[0035] In practice, the total power adjustment of historical frequency disturbance events can be presented in tabular form. The total power adjustment of historical frequency disturbance events includes columns such as event number, date, and calculated total power adjustment. See Table 1.
[0036] Table 1: Statistics of Total Power Adjustment Amounts During Historical Frequency Disturbance Events
[0037] As can be seen from Table 1, the maximum total power regulation is +10.0 MW. Therefore, the minimum requirement for the rated power configuration of the supercapacitor energy storage system is 10 MW. Optionally, the sign of the total power regulation indicates the direction of power regulation. A positive value indicates a decrease in output, and a negative value indicates an increase in output. However, the rated power configuration takes the largest absolute value. Optionally, in the calculation of the minimum requirement for rated energy configuration, if the duration of the event corresponding to the maximum total power regulation is not a typical value, the actual duration of the event and the maximum total power regulation are used to calculate the basic energy demand value. However, for the sake of unified design standards, the product of the maximum total power regulation and the typical duration is usually used.
[0038] See Figure 4 This is a statistical chart of total power regulation during historical frequency disturbance events, showing the total power regulation required by hydropower units during five grid frequency disturbance events. It serves as the core basis for configuring the rated power of the supercapacitor energy storage system. This chart is the direct data source for determining the rated power of the supercapacitor energy storage system. By extracting the maximum absolute value of the total power regulation in historical events, it can be scientifically used as the minimum configuration requirement for the rated power of the energy storage system. Using the maximum total power regulation as the minimum requirement for the rated power configuration of the supercapacitor energy storage system, the rated power configuration is set at 10 MW. The sign of the total power regulation indicates the direction of power regulation: positive values indicate reduced output, and negative values indicate increased output. The rated power configuration is based on the largest absolute value.
[0039] In one embodiment of the present invention, taking a power grid frequency disturbance event as an example, a total power adjustment of -8 MW indicates that an increase in combined output is required. The actual output measurement value of the hydropower unit and the actual power output measurement value of the supercapacitor energy storage system are collected in real time. The actual output measurement value of the hydropower unit is obtained by a power sensor connected to the outlet of the hydropower unit, and the actual power output measurement value of the supercapacitor energy storage system is obtained by a power sensor connected to the AC side of the bidirectional converter of the supercapacitor energy storage array. The actual output measurement value of the hydropower unit and the actual power output measurement value of the supercapacitor energy storage system are added together to obtain the real-time combined output value. For example, at a certain moment, the actual output measurement value of the hydropower unit is -2 MW, which means that the hydropower unit has increased its output by 2 MW, and the actual power output measurement value of the supercapacitor energy storage system is -5 MW, which means that the supercapacitor energy storage system has output 5 MW of power. The real-time combined output value is -7 MW.
[0040] In specific implementation, the combined output deviation is superimposed as a feedback correction quantity into the generation logic of the instantaneous power command of the supercapacitor energy storage system and the target opening command of the hydropower turbine governor to eliminate the deviation. For the instantaneous power command generation logic of the supercapacitor energy storage system, a correction term proportional to the combined output deviation is added to the original command. For the target opening command generation logic of the hydropower turbine governor, a correction term proportional to the combined output deviation is added to the original opening command. In some embodiments, the proportional coefficient is set according to the dynamic response characteristics of the hydropower unit and the supercapacitor energy storage system respectively. For example, the proportional coefficient can be set larger for the supercapacitor energy storage system with a fast response, and smaller for the hydropower unit with a slow response. It can be understood that the introduction of the feedback correction quantity constitutes closed-loop control, which can suppress the deviation between the combined output and the total power regulation quantity caused by model inaccuracy, equipment response delay, or measurement noise.
[0041] Optionally, the calculation and feedback correction of the combined output deviation are performed in each control cycle. The duration of the control cycle is consistent with the grid frequency sampling control cycle, for example, set to 20 milliseconds or 50 milliseconds. The real-time combined output value is obtained by transmitting the actual output measurement value of the hydropower unit and the actual power output measurement value of the supercapacitor energy storage system to the controller in real time via the communication bus and performing an addition operation. In some embodiments, the superposition method of the feedback correction amount can be direct algebraic superposition, or it can pass through a filtering stage to smooth command changes and prevent sudden command changes from impacting the equipment. It can be understood that monitoring the combined output of the hydropower unit and the supercapacitor energy storage system and using the combined output deviation for feedback correction can improve the tracking accuracy of the entire coordinated frequency regulation system for the total power regulation amount.
[0042] See Figure 5This is a graph showing the calculation of grid frequency deviation and total power regulation. At time 0 seconds, the grid frequency sample value equals the rated frequency, the grid frequency deviation is 0, and the total power regulation is 0 MW. Between 0 and 2.5 seconds, the grid frequency sample value decreases from 50Hz to 49.9Hz, the grid frequency deviation becomes negative, and the total power regulation decreases from 0 MW to -8 MW. Between 2.5 and 7.5 seconds, the grid frequency sample value increases from 49.9Hz to 50.1Hz, the grid frequency deviation changes from negative to positive, and the total power regulation increases from -8 MW to 8 MW. Between 7.5 and 10 seconds, the grid frequency sample value falls back from 50.1Hz to 50Hz, the grid frequency deviation changes from positive to negative, and the total power regulation falls back from 8 MW to 0 MW.
[0043] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.
Claims
1. A control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units, characterized in that, include: Continuously measure the operating frequency of the power grid and obtain real-time power grid frequency sampling values; The difference between the sampled power grid frequency value and the rated frequency is calculated to obtain the power grid frequency deviation. Determine whether the absolute value of the power grid frequency deviation exceeds a preset dead zone threshold; When the judgment result is yes, the coordinated frequency regulation control process of the hydropower unit and the supercapacitor energy storage system is started. Based on the power grid frequency deviation, the rated capacity of the hydropower unit, and its primary frequency regulation droop coefficient, the total power regulation required under the current operating conditions is calculated. Based on the preset timing stage division rules, the entire frequency modulation response process is divided into different power distribution stages; For different power distribution stages, the instantaneous power command of the supercapacitor energy storage system and the target opening command of the hydro turbine governor are dynamically generated. According to the real-time power command, the supercapacitor energy storage array is controlled to absorb or release corresponding active power from the power plant bus through the bidirectional converter. According to the target opening command, the governor of the hydroelectric turbine is controlled to adjust the opening of the guide vanes and blades, thereby changing the active power output of the hydroelectric generator unit. Monitor the combined output of the hydropower unit and the supercapacitor energy storage system to ensure that it follows the total power adjustment throughout the frequency regulation process.
2. The control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units as described in claim 1, characterized in that, Based on the aforementioned power grid frequency deviation, the rated capacity of the hydropower unit, and its primary frequency regulation droop coefficient, the total power regulation required under the current operating conditions is calculated, including: Obtain the preset rated frequency value, rated power value of the hydropower unit, and primary frequency regulation droop coefficient value; Divide the power grid frequency deviation by the rated frequency value to obtain a relative frequency deviation ratio. Divide the relative frequency deviation ratio by the primary frequency modulation droop coefficient value to obtain a power regulation coefficient; The total power regulation is calculated by multiplying the power regulation coefficient by the rated power value of the hydropower unit.
3. The control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units as described in claim 2, characterized in that, Based on the preset timing stage division rules, the entire frequency modulation response process is divided into different power distribution stages, including: From the moment the coordinated frequency modulation control process starts, an end time point for an initial fast response phase is defined, which is composed of the start time plus a fixed short time period. Starting from the end time of the initial rapid response phase, an end time of a continuous output phase is defined, which is composed of the end time of the initial rapid response phase plus a fixed intermediate time period. Starting from the end time of the continuous output phase, a transition phase end time is defined. The end time is composed of the end time of the continuous output phase plus a fixed long period of time, or is triggered by the condition that the hydropower unit output reaches a stable balance. After the transition phase, the system enters the steady-state operation and energy storage recovery phase.
4. The control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units as described in claim 3, characterized in that, For different power distribution stages, the system dynamically generates real-time power commands for the supercapacitor energy storage system and target opening commands for the hydro turbine governor, including: During the initial rapid response phase, the instantaneous power command of the supercapacitor energy storage system is set to be equal to the total power adjustment amount, and a locking command to maintain the current opening degree is sent to the hydro turbine governor. During the continuous output phase, the instantaneous power command of the supercapacitor energy storage system is maintained equal to the total power adjustment amount, and the locking command is continuously sent to the hydro turbine governor. During the transition phase, the instantaneous power command of the supercapacitor energy storage system is smoothly reduced from the total power regulation to zero according to a preset descent function. At the same time, the lock command on the hydro turbine governor is released, and the target opening command is generated based on the current remaining grid frequency deviation. During the steady-state operation and energy storage recovery phase, the instantaneous power command of the supercapacitor energy storage system is set to zero, and a low-power charging command is generated to restore the supercapacitor's state of charge to an intermediate value. The step of smoothly decaying the instantaneous power command of the supercapacitor energy storage system from the total power regulation amount to zero according to a preset decay function includes: Set a linear decay slope from the total power adjustment amount to zero; In each control cycle, the value of the instantaneous power command is subtracted from the product of the linear decay slope and the cycle duration until the value of the instantaneous power command decreases to zero. Alternatively, an inertial time constant can be set, and the instantaneous power command value at each moment can be calculated according to the dynamic response curve of the first-order inertial element.
5. The control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units as described in claim 4, characterized in that, During the steady-state operation and energy storage recovery phase, a low-power charging command is generated to restore the supercapacitor's state of charge to an intermediate value, including: Monitor the real-time state of charge of the supercapacitor energy storage array; Calculate the difference between the real-time state of charge value and the target intermediate state of charge value; When the grid frequency stabilizes near the rated frequency, a constant power charging command or a proportional adjustment charging command with limited amplitude is generated based on the difference. The charging command is used as the new instantaneous power command for the supercapacitor energy storage system until the real-time state of charge value recovers to near the target intermediate state of charge value.
6. The control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units as described in claim 5, characterized in that, It also includes a logic judgment process to prevent power reversal: Throughout the frequency regulation response process, the actual active power output or absorbed by the supercapacitor energy storage system is calculated in real time by integration to obtain the actual power contribution of the supercapacitor. Based on the sign of the total power regulation and the frequency modulation duration, the theoretical power contribution of the supercapacitor is calculated. The sign of the actual contributed electricity is continuously compared with the sign of the theoretical contributed electricity; When it is detected that the sign of the actual contributed power is about to change in the opposite direction to the sign of the theoretical contributed power, the direction of the instantaneous power command of the supercapacitor energy storage system is immediately reversed.
7. The control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units as described in claim 6, characterized in that, The rated power parameters of the supercapacitor energy storage system in the method are determined as follows: Analyze the historical operating data of the power station where the hydropower unit is located, and statistically analyze the maximum total power regulation calculated in each power grid frequency disturbance event; The maximum total power adjustment is taken as the minimum required value for the rated power configuration of the supercapacitor energy storage system.
8. The control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units as described in claim 7, characterized in that, The rated energy parameters of the supercapacitor energy storage system in the method are determined as follows: Determine the typical duration of a frequency modulation event; Multiply the total power adjustment by the typical duration to obtain a basic energy requirement value; Considering that supercapacitors need to be able to complete a full frequency modulation event under both charging and discharging conditions, and that their initial state of charge is maintained at 50%, the basic energy requirement value is multiplied by two, and the calculated result is used as the minimum required value for the rated energy configuration of the supercapacitor energy storage system.
9. The control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units as described in claim 8, characterized in that, Monitoring the combined output of the hydropower unit and the supercapacitor energy storage system to ensure it follows the total power adjustment throughout the frequency regulation process includes: Real-time acquisition of actual power output measurements of hydropower units and actual power output measurements of supercapacitor energy storage systems; The actual output measurement value is added to the actual power output measurement value to obtain the real-time combined output value; The difference between the combined output value and the total power adjustment is calculated to obtain the combined output deviation; The combined output deviation is used as a feedback correction quantity and is superimposed on the generation logic of the real-time power command of the supercapacitor energy storage system and the target opening command of the hydropower turbine governor, respectively, to eliminate the deviation.
10. A supercapacitor energy storage system for improving the frequency regulation performance of hydropower units, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the control method for supercapacitor energy storage to improve the frequency regulation performance of hydropower units as described in any one of claims 1 to 9.