Frequency division control management strategy for network-constructed hybrid energy storage power station

Abstract

The application discloses a frequency division control management strategy for a network-constructed hybrid energy storage power station, and the method comprises the following steps: establishing a corresponding control model for different energy storage units in the network-constructed hybrid energy storage power station; based on the dynamic response characteristics of the different energy storage units, decomposing the total power demand into four characteristic frequency band components; and finally applying the decomposed characteristic frequency band components to the corresponding control model according to the frequency division control management strategy for energy storage collaborative control, so that the total power demand of the system is decomposed into frequency band components of different time scales, and precise allocation and coordinated control are realized.

Description

Technical Field

[0001] This invention relates to the field of energy management technology for energy storage systems, and in particular to a frequency division control management strategy for a grid-type hybrid energy storage power station. Background Technology

[0002] With a high proportion of renewable energy being integrated into the grid, the system faces numerous challenges, including increased power fluctuations and decreased frequency stability. Grid-based hybrid energy storage power stations, as a key means to enhance grid flexibility and resilience, can strengthen the system's ability to respond to disturbances by actively providing power support and frequency regulation. However, traditional control strategies often fail to fully leverage the dynamic characteristics of different types of energy storage, resulting in insufficient synergistic optimization between response speed, regulation accuracy, and equipment lifespan.

[0003] Existing research largely focuses on binary energy storage combinations such as batteries and supercapacitors, with insufficient research on the coordinated control of multi-element composite energy storage systems including flywheels and hydrogen energy, failing to fully leverage the complementary advantages of different media. Secondly, most control strategies employ simple logic thresholds or filtering allocation methods, lacking in-depth exploration of the frequency domain characteristics of system power demand, making it difficult to achieve accurate matching and dynamic optimization of power components. Furthermore, existing methods fail to fully consider the dynamic response characteristics and equipment constraints of different energy storage components, easily leading to overuse of some equipment and underutilization of others under frequent power fluctuations. At the same time, most control strategies lack deep integration with grid-type converter control, failing to achieve closed-loop optimization from power allocation to converter control, affecting the overall response performance and control accuracy of the system. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a frequency division control management strategy for a grid-type hybrid energy storage power station. The strategy aims to decompose the total power demand of the system into frequency band components at different time scales based on the dynamic response capabilities of various energy storage units such as lithium-ion batteries, supercapacitors, flywheel energy storage, hydrogen fuel cells, and electrolyzers, and to achieve precise allocation and coordinated control.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A frequency division control management strategy for a grid-connected hybrid energy storage power station includes the following steps:

[0007] Establish corresponding control models for different energy storage units in a grid-type hybrid energy storage power station. The energy storage units include at least lithium-ion batteries, supercapacitors, flywheel energy storage, hydrogen fuel cells, and hydrogen electrolyzers.

[0008] Based on the dynamic response characteristics of lithium-ion batteries, supercapacitors, flywheel energy storage, hydrogen fuel cells and hydrogen electrolyzers, the total power demand is decomposed into four characteristic frequency band components.

[0009] The four characteristic frequency band components after decomposition are applied to the corresponding control model according to the frequency division control management strategy to carry out energy storage coordinated control.

[0010] In some implementations, the control models for both the lithium-ion battery and the supercapacitor are established based on the same process, including:

[0011] A bidirectional synchronous Buck-Boost converter is used as the basis for bidirectional power regulation. The fully controlled power switching devices in the converter are controlled in a coordinated manner through pulse width modulation. Furthermore, the control system generates a PWM voltage reference signal through a PI regulator based on the current power reference value of the energy storage unit and the terminal current feedback.

[0012] In some implementations, the process of establishing the control model for the flywheel energy storage includes:

[0013] The motor-side converter adopts a three-phase full-bridge topology as the basis for AC / DC bidirectional power conversion. The fully controlled power switching devices in the motor-side converter are coordinated and controlled by the space vector pulse width modulation method. Furthermore, the control system is based on a power-current dual closed-loop control architecture. The SVPWM voltage reference signal in the dq synchronous rotating coordinate system is generated by the PI regulator using the flywheel energy storage power reference value and terminal current feedback.

[0014] In some embodiments, the process of establishing the control model for the hydrogen fuel cell includes:

[0015] The utilization rate of hydrogen and oxygen is dynamically adjusted based on the hydrogen fuel cell output power reference value, terminal voltage and current. Furthermore, the control system generates the converter PWM voltage reference signal through a PI regulator based on the hydrogen fuel cell power reference value, terminal voltage and current feedback.

[0016] In some embodiments, the process of establishing the control model of the hydrogen electrolyzer includes:

[0017] Based on the power reference value, terminal voltage, and current feedback of the hydrogen electrolyzer, a PWM voltage reference signal for the converter is generated via a PI regulator.

[0018] In some implementations, the decomposition conditions for the four characteristic frequency band components are:

[0019] Four frequency ranges are defined: (50Hz, ~Hz), (10Hz, 50Hz), (1Hz, 10Hz), and (0Hz, 1Hz), each defined as the high-frequency power demand P. t dc,high Sub-high frequency power demand P t dc,midh Intermediate frequency power requirement P t dc,midand low-frequency power demand P t dc,low Among them, the high-frequency power demand P t dc,high Processed by supercapacitors, sub-high frequency power demand P t dc,midh Energy storage by flywheel, medium frequency power demand P t dc,mid Low-frequency power demand P is handled by lithium-ion batteries. t dc,low It is processed by hydrogen fuel cells and hydrogen electrolyzers.

[0020] In some implementations, the frequency division control management strategy includes:

[0021] The current power status of the system is determined based on preset conditions, wherein the power status is either insufficient power generation or excessive power generation.

[0022] If the current power status is insufficient power generation, the hydrogen fuel cell will be started first to supplement the basic power gap, and the remaining power demand will be allocated to other energy storage units for discharge. If the current power status is excessive power generation, the hydrogen fuel cell will be shut down first, each energy storage unit will absorb the excess power, and finally the hydrogen electrolyzer will be started to consume the remaining low-frequency power.

[0023] Based on the frequency characteristics of each type of energy storage unit, the power in each frequency band of the current power difference is discharged or charged in layers.

[0024] Based on the preset power reference value, the system controls various types of energy storage units by converting power commands into duty cycle signals of the fully controlled power switching devices of the converters of various types of energy storage units.

[0025] The beneficial effects of this invention are as follows: By establishing corresponding control models for different energy storage units in a grid-type hybrid energy storage power station, and then decomposing the total power demand into four characteristic frequency band components based on the dynamic response characteristics of different energy storage units, the decomposed characteristic frequency band components are finally applied to the corresponding control models for energy storage coordinated control according to the frequency division control management strategy, thereby decomposing the total power demand of the system into frequency band components of different time scales and achieving precise allocation and coordinated control. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the frequency division control management strategy of a grid-type hybrid energy storage power station disclosed in an embodiment of the present invention;

[0027] Figure 2 This is a flowchart of the frequency division control management strategy disclosed in an embodiment of the present invention;

[0028] Figure 3This is a response curve of key parameters of a grid-type hybrid energy storage power station under normal operating conditions, as shown in an application example of this invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the content of this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to this invention are shown in the accompanying drawings, not all of them.

[0030] This embodiment proposes a frequency division control management strategy for a grid-type hybrid energy storage power station, such as... Figure 1 As shown, it includes the following steps:

[0031] Step 1: Establish corresponding control models for different energy storage units in a grid-type hybrid energy storage power station. The energy storage units include at least lithium-ion batteries, supercapacitors, flywheel energy storage, hydrogen fuel cells, and hydrogen electrolyzers.

[0032] The control models for both lithium-ion batteries and supercapacitors are based on the same process.

[0033] Specifically, the control model for the lithium-ion battery uses a bidirectional synchronous Buck-Boost converter as the basis for bidirectional power regulation. Pulse Width Modulation (PWM) is used to collaboratively control the fully controlled power switching devices in the converter. Furthermore, the control system generates a PWM voltage reference signal based on the lithium-ion battery's power reference value and terminal current feedback via a PI regulator. Its complex frequency domain control equation is as follows:

[0034]

[0035] In the formula: This is the voltage reference signal of BAT in the s-domain; This is the power reference value for BAT in the s-domain; This represents the actual power of the lithium-ion battery in the s-domain. Let be the terminal current of the lithium-ion battery in the s-domain; These are the proportional and integral coefficients for PI control, respectively.

[0036] The control model of the supercapacitor uses a bidirectional synchronous Buck-Boost converter as the basis for bidirectional power regulation. Pulse Width Modulation (PWM) is used to coordinate the control of fully controlled power switching devices in the converter. Furthermore, the control system generates a PWM voltage reference signal based on the supercapacitor's power reference value and terminal current feedback via a PI regulator. Its complex frequency domain control equation is as follows:

[0037]

[0038] In the formula: The voltage reference signal for SCP in the s-domain; This is a power reference value for the SCP in the s domain; This represents the actual power of the supercapacitor in the s-domain. Let be the terminal current of the supercapacitor in the s-domain; These are the proportional and integral coefficients for PI control, respectively.

[0039] The process of establishing a control model for flywheel energy storage includes:

[0040] The motor-side converter adopts a three-phase full-bridge topology as the basis for AC / DC bidirectional power conversion. It uses Space Vector Pulse Width Modulation (SVPWM) to collaboratively control the fully controlled power switching devices in the motor-side converter. Furthermore, the control system is based on a power-current dual closed-loop control architecture. Using the flywheel energy storage power reference value and terminal current feedback, a PI regulator generates an SVPWM voltage reference signal in the dq synchronous rotating coordinate system. Its complex frequency domain control equation is:

[0041]

[0042] In the formula: These are the dq-axis components of the flywheel energy storage voltage reference signal in the s-domain, respectively. These are the dq-axis components of the flywheel energy storage current in the s-domain, respectively. This is the power reference value for flywheel energy storage in the s-domain; Electromagnetic torque in the s-domain for storing energy in the flywheel; and These are the electric angular velocity and rotor rotational angular velocity of the flywheel energy storage in the s-domain, respectively. Rotor flux for flywheel energy storage in the s-domain; These are the proportional and integral coefficients for PI control, respectively.

[0043] The process of establishing a control model for a hydrogen fuel cell includes:

[0044] Based on the hydrogen fuel cell output power reference value, terminal voltage, and current, the utilization rate of hydrogen and oxygen is dynamically adjusted. Furthermore, based on the hydrogen fuel cell power reference value, terminal voltage, and current feedback, the control system generates a converter PWM voltage reference signal via a PI regulator. Its complex frequency domain control equation is as follows:

[0045]

[0046] In the formula: This is the voltage reference signal for the hydrogen fuel cell in the s-domain; This is a reference value for the output power of a hydrogen fuel cell in the s-domain. Let be the terminal voltage of the HFC in the s-domain; The terminal current of the hydrogen fuel cell in the s-domain; p hfc,fuel p hfc ,air These are the absolute pressures supplied for fuel and air, respectively. These are the volumetric flow rates of the input fuel and air, respectively; x hfc % y hfc The percentages represent the volume concentrations of hydrogen and oxygen, respectively. These are the proportional coefficient and integral coefficient in PI control, respectively.

[0047] The process of establishing the control model for a hydrogen electrolyzer includes:

[0048] Based on the power reference value, terminal voltage, and current feedback of the hydrogen electrolyzer, a PWM voltage reference signal for the converter is generated via a PI regulator. Its complex frequency domain control equation is as follows:

[0049]

[0050] In the formula: This is the voltage reference signal for the hydrogen electrolyzer in the s-domain; This is a reference value for the output power of the hydrogen electrolyzer in the s-domain; The terminal voltage of the hydrogen electrolyzer in the s-domain; Let L be the terminal current of the hydrogen electrolyzer L in the s domain; These are the proportional coefficient and integral coefficient in PI control, respectively.

[0051] In summary, in step 1, each energy storage unit achieves bidirectional power regulation through high-precision power electronic converters (such as Buck-Boost topology, three-phase full-bridge structure, etc.), and adopts modulation technologies such as PWM and SVPWM with PI control loop to achieve rapid tracking of reference power and dynamic adjustment of system state, effectively improving the hybrid energy storage system's adaptability to wide-frequency power disturbances.

[0052] Step 2: Based on the dynamic response characteristics of lithium-ion batteries, supercapacitors, flywheel energy storage, hydrogen fuel cells, and hydrogen electrolyzers, the total power demand is decomposed into four characteristic frequency band components, as shown in Table 1.

[0053] The decomposition conditions for the four characteristic frequency band components are as follows: Four frequency ranges are set: (50Hz, ~Hz), (10Hz, 50Hz), (1Hz, 10Hz), and (0Hz, 1Hz), which are defined as the high-frequency power demand P. t dc,high Sub-high frequency power demand P t dc,midh Intermediate frequency power requirement P t dc,mid and low-frequency power demand Pt dc,low Among them, the high-frequency power demand P t dc,high Processed by supercapacitors, sub-high frequency power demand P t dc,midh Energy storage by flywheel, medium frequency power demand P t dc,mid Low-frequency power demand P is handled by lithium-ion batteries. t dc,low It is processed by hydrogen fuel cells and hydrogen electrolyzers.

[0054] Table 1 Multi-band power allocation of coupled energy storage units

[0055] Supercapacitor <![CDATA[High-frequency power P t dc,high (>50 Hz)]]> Millisecond response Smoothing instantaneous power fluctuations Flywheel energy storage <![CDATA[Sub-high frequency power P t dc,midh (10 - 50 Hz)]]> Second-level response Adjusting short-term power fluctuations Lithium-ion batteries <![CDATA[Intermediate frequency power P t dc,mid (1 - 10 Hz)]]> Minute-level response Balancing medium-term power demand hydrogen fuel cells <![CDATA[Low-frequency power P t dc,low (<1 Hz)]]> Hourly response Basic power supply hydrogen electrolyzer <![CDATA[Low-frequency power P t dc,low (<1 Hz)]]> Hourly response Excess energy absorption

[0056] Step 3: The four decomposed characteristic frequency band components will be applied to the corresponding control model according to the frequency division control management strategy to perform energy storage coordinated control. The flowchart is as follows: Figure 2 As shown.

[0057] In one example, the frequency division control management strategy described above includes:

[0058] Step 301, Determine the system power status: Based on preset conditions, determine the current power status of the system, which is either insufficient power generation or excessive power generation. Specifically, the total power demand P... t total It equals the sum of the power in the four characteristic frequency bands, and also equals the power consumed by the system load P. t load Subtract photovoltaic power generation P t pv The value of P is used to determine whether the system is underpowered (P0) based on the sign of the total power demand. t total >0) or overcapacity in power generation (P) t total <0) state.

[0059] Step 302, switch operating modes according to status: If the current power status is insufficient power generation, prioritize starting the hydrogen fuel cell to supplement the basic power gap, and the remaining power demand P t rem The energy is then redistributed to other energy storage units for discharge.

[0060] P t hfc,ref =min(P t dc,low ,P t hfc,max )

[0061] P t hel,ref=0

[0062] P t rem =P t total -P t hfc,ref

[0063] If the current power state is one of excess power generation, the hydrogen fuel cells will be shut down first, the energy storage units will absorb the excess power, and finally the hydrogen electrolyzer will be started to consume the remaining low-frequency power.

[0064] P t hfc,ref =0

[0065] P t hel,ref =-P t dc,low

[0066] P t bat,ref =-P t dc,mid

[0067] P t fes,ref =-P t dc,midh

[0068] P t scp,ref =-P t dc,high

[0069] Among them, P t bat,ref P t fes,ref P t scp,ref P t hfc,ref and P t hel,ref These are the reference values ​​for the output power of lithium-ion batteries, flywheel energy storage, supercapacitors, hydrogen fuel cells, and hydrogen electrolyzers, respectively.

[0070] Step 303, process the power of each frequency band in layers according to the characteristics of the equipment: Based on the frequency characteristics of each type of energy storage unit, perform layered discharge or charging of the power of each frequency band in the current power difference.

[0071] Step 304: Adjust the internal control strategy of the energy storage system based on the power reference value: Control each type of energy storage unit according to the preset power reference value. By converting the power command into the duty cycle signal of the fully controlled power switching device of each type of energy storage unit converter, the system output power can be accurately adjusted and the system output power can be stably operated.

[0072] Application Examples

[0073] In this example, a frequency division control management strategy is applied to the grid-type hybrid energy storage power station according to steps 1-3 of the above embodiment. The response curves of key parameters of the power station under normal operating conditions are as follows: Figure 3 As shown. DC bus voltage The initial value is 0V, and it reaches steady-state operation in about 0.04s, with the steady-state voltage stabilizing around 1500V. The system AC side frequency f t normal The frequency remained consistently near the 50Hz reference value, with a maximum frequency deviation of 50.14Hz and a relative deviation of only 0.28%. The system's active power P... t total,normal and reactive power The system enters steady-state operation in approximately 0.12 seconds, during which the steady-state active power output remains consistently at 300kW. The system's three-phase AC voltage... During the initial startup phase at t=0s, the instantaneous values ​​of the three-phase voltages exhibit a significantly asymmetrical distribution, among which... The imbalance reached 62.3%. After adjustment using the voltage control strategy proposed in Section 2.6.1, the system reached a stable operating state in 0.03s, with the steady-state voltage amplitude stabilizing at around 590V. Analysis of the above data shows that the entire transient adjustment process lasted ≤0.04s. The initial stage of fluctuations was due to the dynamic adjustment process during grid connection, including power balancing, voltage regulation, and frequency synchronization. This meets the requirements of the T / CES243-2023 group standard "Technical Specification for Grid Connection of Grid-connected Energy Storage Systems," which stipulates that the active power frequency regulation adjustment time for grid-connected energy storage systems should be ≤1s, and the reactive power voltage regulation response time should be ≤50ms. This fully verifies the effectiveness of the stability control strategy proposed in this invention.

[0074] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made based on the essence of the content of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A frequency division control management strategy for a grid-type hybrid energy storage power station, characterized in that, Includes the following steps: Establish corresponding control models for different energy storage units in a grid-type hybrid energy storage power station. The energy storage units include at least lithium-ion batteries, supercapacitors, flywheel energy storage, hydrogen fuel cells, and hydrogen electrolyzers. Based on the dynamic response characteristics of lithium-ion batteries, supercapacitors, flywheel energy storage, hydrogen fuel cells, and hydrogen electrolyzers, the total power demand is decomposed into four characteristic frequency band components. The decomposition conditions for these four characteristic frequency band components are as follows: four frequency ranges are set: (50Hz, ~Hz), (10Hz, 50Hz), (1Hz, 10Hz), and (0Hz, 1Hz), which are defined as high-frequency power demands. Sub-high frequency power requirements Intermediate frequency power requirements and low-frequency power requirements Among them, high-frequency power demand Processed by supercapacitors, sub-high frequency power requirements Energy storage by flywheel, medium frequency power demand Low-frequency power requirements handled by lithium-ion batteries Processed by hydrogen fuel cells and hydrogen electrolyzers; The four characteristic frequency band components after decomposition are applied to the corresponding control model according to the frequency division control management strategy to carry out energy storage coordinated control. The frequency division control management strategy includes: determining the current power state of the system based on preset conditions, where the power state is either insufficient power generation or excessive power generation; if the current power state is insufficient power generation, prioritizing the activation of hydrogen fuel cells to supplement the basic power gap, and redistributing the remaining power demand to other energy storage units for discharge; if the current power state is excessive power generation, first shutting down the hydrogen fuel cells, with each energy storage unit absorbing the excess power, and finally activating the hydrogen electrolyzer to absorb the remaining low-frequency power; performing tiered discharge or charging of power in each frequency band within the current power difference based on the frequency characteristics of each type of energy storage unit; controlling each type of energy storage unit according to preset power reference values ​​by converting power commands into duty cycle signals of the fully controlled power switching devices of each type of energy storage unit converter.

2. The frequency division control management strategy for a grid-type hybrid energy storage power station as described in claim 1, characterized in that, The control models for both the lithium-ion battery and the supercapacitor are established based on the same process, including: A bidirectional synchronous Buck-Boost converter is used as the basis for bidirectional power regulation. The fully controlled power switching devices in the converter are controlled in a coordinated manner through pulse width modulation. Furthermore, the control system generates a PWM voltage reference signal through a PI regulator based on the current power reference value of the energy storage unit and the terminal current feedback.

3. The frequency division control management strategy for a grid-type hybrid energy storage power station as described in claim 1, characterized in that, The process of establishing the control model for flywheel energy storage includes: The motor-side converter adopts a three-phase full-bridge topology as the basis for AC / DC bidirectional power conversion. The fully controlled power switching devices in the motor-side converter are coordinated and controlled by the space vector pulse width modulation method. Furthermore, the control system is based on a power-current dual closed-loop control architecture. The SVPWM voltage reference signal in the dq synchronous rotating coordinate system is generated by the PI regulator using the flywheel energy storage power reference value and terminal current feedback.

4. The frequency division control management strategy for a grid-type hybrid energy storage power station as described in claim 1, characterized in that, The process of establishing the control model for the hydrogen fuel cell includes: The utilization rate of hydrogen and oxygen is dynamically adjusted based on the hydrogen fuel cell output power reference value, terminal voltage and current. Furthermore, the control system generates the converter PWM voltage reference signal through a PI regulator based on the hydrogen fuel cell power reference value, terminal voltage and current feedback.

5. The frequency division control management strategy for a grid-type hybrid energy storage power station as described in claim 1, characterized in that, The process for establishing the control model of the hydrogen electrolyzer includes: Based on the power reference value, terminal voltage, and current feedback of the hydrogen electrolyzer, a PWM voltage reference signal for the converter is generated via a PI regulator.

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