Frequency division control management strategy of network construction type hybrid energy storage power station

Abstract

The invention discloses a frequency division control management strategy for a network construction type hybrid energy storage power station, and the strategy comprises the steps: building corresponding control models for different energy storage units in the network construction type hybrid energy storage power station, decomposing the total power demand into four characteristic frequency band components based on the dynamic response characteristics of different energy storage units, and carrying out the frequency division control management of the network construction type hybrid energy storage power station. And finally, applying the decomposed characteristic frequency band component to a corresponding control model according to a frequency division control management strategy to perform energy storage cooperative control, thereby decomposing the total power demand of the system into frequency band components of different time scales, and realizing accurate distribution and cooperative control.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy management of energy storage systems, and particularly relates to a frequency division control management strategy of a grid-constructed hybrid energy storage power station. BACKGROUND

[0002] With high proportion of renewable energy connected to the grid, the system faces many challenges such as power fluctuation aggravation and frequency stability decline. The grid-constructed hybrid energy storage power station, as a key means to improve the flexibility and resilience of the grid, can enhance the response ability of the system to disturbances by actively providing power support and frequency regulation. However, the traditional control strategy often fails to fully utilize the dynamic characteristics of different types of energy storage, resulting in insufficient coordination optimization between response speed, regulation accuracy and equipment life.

[0003] Existing researches are mostly focused on the combination of battery-super capacitor, and the collaborative control of multi-element composite energy storage system containing flywheel and hydrogen energy is insufficient, which fails to fully utilize the complementary advantages of different media. Secondly, most control strategies use simple logic threshold or filtering distribution method, which lacks deep mining of the frequency domain characteristics of system power demand, and it is difficult to achieve accurate matching and dynamic optimization of power components. Thirdly, the existing methods fail to fully consider the dynamic response characteristics and equipment constraints of different energy storage elements, which may lead to overuse of some equipment and underuse of other equipment under frequent power fluctuations. At the same time, most control strategies lack deep integration with grid-constructed converter control, and fail to realize closed-loop optimization from power distribution to converter control, which affects the overall response performance and control accuracy of the system. SUMMARY

[0004] In view of the above problems, the present application provides a frequency division control management strategy of a grid-constructed hybrid energy storage power station, which aims to decompose the total power demand into frequency components of different time scales according to the dynamic response capabilities of multi-element energy storage units such as lithium ion battery, super capacitor, flywheel energy storage, hydrogen fuel cell and electrolytic cell, and realize accurate allocation and coordinated control.

[0005] To solve the above technical problems, the technical scheme of the present application is as follows:

[0006] A frequency division control management strategy of a grid-constructed hybrid energy storage power station, comprising the following steps:

[0007] Control models are established for different energy storage units in the grid-constructed hybrid energy storage power station, and the energy storage units at least include lithium ion battery, super capacitor, flywheel energy storage, hydrogen fuel cell and hydrogen electrolytic cell;

[0008] Based on the dynamic response characteristics of lithium ion battery, super capacitor, flywheel energy storage, hydrogen fuel cell and hydrogen electrolytic cell, the total power demand is decomposed into four characteristic frequency band components;

[0009] The four decomposed characteristic frequency band components are applied to the corresponding control model according to the frequency control management strategy, and energy storage collaborative control is performed.

[0010] In some embodiments, the control model of the lithium ion battery and the super capacitor are both established based on the same flow, including:

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

[0012] In some embodiments, the control model of the flywheel energy storage includes:

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

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

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

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

[0017] The control system generates a converter PWM voltage reference signal based on the power reference value, the terminal voltage and the current feedback of the hydrogen electrolyzer, and the PI regulator.

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

[0019] The four frequency ranges (50Hz, ~Hz), (10Hz, 50Hz), (1Hz, 10Hz) and (0Hz, 1Hz) are set, respectively defined as high frequency power demand P t dc,high , secondary high frequency power demand P t dc,midh , medium frequency power demand P t dc,midand low frequency power demand P t dc,low wherein, high frequency power demand P t dc,high processed by super capacitor, second high frequency power demand P t dc,midh processed by flywheel energy storage, medium frequency power demand P t dc,mid processed by lithium ion battery, low frequency power demand P t dc,low processed by hydrogen fuel cell and hydrogen electrolyzer.

[0020] In some embodiments, the frequency division control management strategy comprises:

[0021] judging the current power state of the system according to preset conditions, the power state being power deficiency or power excess;

[0022] if the current power state is power deficiency, the hydrogen fuel cell is started to supplement the basic power gap, and the remaining power demand is redistributed to other energy storage units for discharging, and if the current power state is power excess, the hydrogen fuel cell is closed first, each energy storage unit absorbs the excess power, and finally the hydrogen electrolyzer is started to absorb the remaining low frequency power;

[0023] each frequency band power in the current power difference is discharged or charged according to the frequency characteristics of each type of energy storage unit;

[0024] each type of energy storage unit is controlled according to a preset power reference value, and the power command is converted into a duty cycle signal of a full-controlled power switch device of a converter of each type of energy storage unit.

[0025] The present application has the beneficial effects that: by establishing a corresponding control model for different energy storage units in a network-constructed hybrid energy storage power station, then based on the dynamic response characteristics of different energy storage units, the total power demand is decomposed into four characteristic frequency band components, and finally the decomposed characteristic frequency band components are applied to the corresponding control model according to the frequency division control management strategy for energy storage collaborative control, so as to decompose the total power demand of the system into frequency band components of different time scales, and realize accurate allocation and coordinated control. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 a flowchart of the frequency division control management strategy of the network-constructed hybrid energy storage power station disclosed in the embodiments of the present application;

[0027] Figure 2 a flowchart of the frequency division control management strategy disclosed in the embodiments of the present application;

[0028] Figure 3The key parameter response curve of a certain network-constructed hybrid energy storage power station in a normal operation condition in an application example of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present application more clear and explicit, the content of the present application is further described in detail below in combination with the drawings and specific embodiments. It can be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that only the parts related to the present application are shown in the drawings for the convenience of description, but not all the contents.

[0030] The present embodiment proposes a frequency division control management strategy for a network-constructed hybrid energy storage power station, as shown in Figure 1 The steps include the following steps:

[0031] Step 1: Establishing a corresponding control model for different energy storage units in the network-constructed hybrid energy storage power station, the energy storage units at least including lithium ion batteries, super capacitors, flywheel energy storage, hydrogen fuel cells and hydrogen electrolytic cells.

[0032] The control models of the lithium ion batteries and the super capacitors are both established based on the same flow.

[0033] Specifically, the control model of the lithium ion battery adopts a bidirectional synchronous Buck-Boost converter as a power bidirectional regulation basis, cooperatively controls the fully controlled power switching devices in the converter through a pulse width modulation method (PWM), and the control system generates a PWM voltage reference signal based on the power reference value and the terminal current feedback of the lithium ion battery through a PI regulator, and the complex frequency domain control equation is:

[0034]

[0035] In the formula: is the voltage reference signal of the BAT in the s domain; is the power reference value of the BAT in the s domain; is the actual power value of the lithium ion battery in the s domain; is the terminal current of the lithium ion battery in the s domain; are the proportional coefficient and the integral coefficient of the PI control, respectively.

[0036] The control model of the super capacitor adopts a bidirectional synchronous Buck-Boost converter as a power bidirectional regulation basis, cooperatively controls the fully controlled power switching devices in the converter through a pulse width modulation method (PWM), and the control system generates a PWM voltage reference signal based on the power reference value and the terminal current feedback of the super capacitor through a PI regulator, and the complex frequency domain control equation is:

[0037]

[0038] wherein: is the voltage reference signal of the SCP in s domain; is the power reference value of the SCP in s domain; is the actual power value of the super capacitor in s domain; is the terminal current of the super capacitor in s domain; are the proportional coefficient and the integral coefficient of the PI control, respectively.

[0039] The control model of the flywheel energy storage includes the following steps:

[0040] The motor-side converter adopts a three-phase full-bridge topology as the basis of AC / DC bidirectional power conversion, and the full-controlled power switching devices in the motor-side converter are cooperatively controlled by the space vector pulse width modulation (SVPWM) method. The control system is based on a power-current double closed-loop control architecture, and generates the SVPWM voltage reference signal in the d-q synchronous rotating coordinate system by PI regulator based on the flywheel energy storage power reference value and the terminal current feedback. The complex frequency domain control equation is:

[0041]

[0042] wherein: are the d-q axis components of the voltage reference signal of the flywheel energy storage in s domain, respectively; are the d-q axis components of the terminal current of the flywheel energy storage in s domain, respectively; is the power reference value of the flywheel energy storage in s domain; is the electromagnetic torque of the flywheel energy storage in s domain; and are the electrical angular velocity and the rotor rotation angular velocity of the flywheel energy storage in s domain, respectively; is the rotor flux of the flywheel energy storage in s domain; are the proportional coefficient and the integral coefficient of the PI control, respectively.

[0043] The control model of the hydrogen fuel cell includes the following steps:

[0044] According to the output power reference value, the terminal voltage and the current of the hydrogen fuel cell, the utilization rate of hydrogen and oxygen is dynamically adjusted. The control system generates the converter PWM voltage reference signal by PI regulator based on the hydrogen fuel cell power reference value, the terminal voltage and the current feedback. The complex frequency domain control equation is:

[0045]

[0046] wherein: is the voltage reference signal of the hydrogen fuel cell in s domain; is the output power reference value of the hydrogen fuel cell in s domain; VH(s) is the terminal voltage of HFC in s domain; IH(s) is the terminal current of HFC in s domain; hfc,fuel , p hfc ,air Pf and Pa are the absolute pressure of fuel and air supply, respectively; Vf and Va are the volume flow rate of input fuel and air, respectively; hfc %, y hfc % are the volume concentration percentage of hydrogen and oxygen, respectively; Kp and Ki are the proportional coefficient and integral coefficient in PI control, respectively.

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

[0048] Based on the power reference value, terminal voltage and current feedback of hydrogen electrolyzer, the PWM voltage reference signal of the converter is generated through the PI regulator, and the complex frequency domain control equation is:

[0049]

[0050] In the formula: VH*(s) is the voltage reference signal of hydrogen electrolyzer in s domain; PH*(s) is the output power reference value of hydrogen electrolyzer in s domain; VH(s) is the terminal voltage of hydrogen electrolyzer in s domain; IH(s) is the terminal current of hydrogen electrolyzer L in s domain; Kp and Ki are the proportional coefficient and integral coefficient in PI control, respectively.

[0051] In summary, each energy storage unit in step 1 is realized by high-precision power electronic converter (such as Buck-Boost topology, three-phase full-bridge structure, etc.) to realize bidirectional power regulation, and PWM, SVPWM and other modulation techniques are used with PI control loop to realize fast tracking of reference power and dynamic adjustment of system state, effectively improving the adaptability of hybrid energy storage system to wide frequency domain power disturbance.

[0052] Step 2, based on the dynamic response characteristics of lithium ion battery, super capacitor, flywheel energy storage, hydrogen fuel cell and hydrogen electrolyzer, the total power demand is decomposed into four characteristic frequency band components, as shown in Table 1.

[0053] The decomposition conditions of the four characteristic frequency band components are: setting (50Hz, ~Hz), (10Hz, 50Hz), (1Hz, 10Hz) and (0Hz, 1Hz) four frequency ranges, which are defined as high frequency power demand P t dc,high , secondary high frequency power demand P t dc,midh , medium frequency power demand P t dc,mid and low frequency power demand Pt dc,low wherein the high frequency power demand P t dc,high is handled by supercapacitors, the next high frequency power demand P t dc,midh is handled by flywheel energy storage, the medium frequency power demand P t dc,mid is handled by lithium ion batteries, and the low frequency power demand P t dc,low is handled by hydrogen fuel cells and hydrogen electrolysis.

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

[0055] Device Processing band Response characteristics Main functions Super capacitor High frequency power P t dc,high (>50Hz)]]> Millisecond response Suppressing transient power fluctuations Flywheel energy storage P t dc,midh (10-50 Hz) Second response Adjusting short-term power fluctuations Lithium-ion battery Intermediate frequency power P t dc,mid (1-10 Hz) Minute response Balancing medium-term power demand Hydrogen fuel cell Low frequency power P t dc,low (<1 Hz) Hour response Basic power supply Hydrogen electrolyzer Low frequency power P t dc,low (<1 Hz) Hour response Excess energy consumption

[0056] Step 3, the four decomposed characteristic band components are applied to the corresponding control model according to the frequency control management strategy, and energy storage collaborative control is performed, and a flowchart is as shown in Figure 2 .

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

[0058] Step 301, judging the system power state: judging the current power state of the system according to a preset condition, the power state being power generation deficiency or power generation excess. Specifically, the total power demand P t total is equal to the sum of the power of the four characteristic bands, and also equal to the system load consumption power P t load minus the photovoltaic power generation power P t pv , according to the positive and negative of the total power demand, it is judged whether the system is in a power generation deficiency (P t total > 0) or power generation excess (P t total < 0) state.

[0059] Step 302, switching the working mode according to the state: if the current power state is power generation deficiency, the hydrogen fuel cell is preferentially started to supplement the basic power gap, and the remaining power demand P t rem is allocated to other energy storage units for discharging:

[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 power surplus, first close the hydrogen fuel cell, each energy storage unit absorbs excess power, and finally start the hydrogen electrolyzer 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] wherein P t bat,ref , P t fes,ref , P t scp,ref , P t hfc,ref and P t hel,ref are the output power reference values of lithium ion battery, flywheel energy storage, super capacitor, hydrogen fuel cell and hydrogen electrolyzer respectively.

[0070] Step 303, layering processing of each frequency band power according to equipment characteristics: according to the frequency characteristics of each type of energy storage unit, the power of each frequency band in the current power difference is discharged or charged in layers.

[0071] Step 304, adjusting the internal control strategy of the energy storage system based on the power reference value: controlling each type of energy storage unit according to the preset power reference value, and realizing accurate adjustment and stable operation of the system output power by converting the power command into the duty cycle signal of the full-controlled power switch device of each type of energy storage unit converter.

[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 of a network-constructed hybrid energy storage power station, characterized in that, The method comprises the following steps: Control models are established for different energy storage units in a networked hybrid energy storage power station, the energy storage units including at least lithium ion batteries, super capacitors, flywheel energy storage, hydrogen fuel cells and hydrogen electrolyzers; Based on the dynamic response characteristics of lithium ion batteries, super capacitors, flywheel energy storage, hydrogen fuel cells and hydrogen electrolyzers, total power demand is decomposed into four characteristic frequency band components; The four characteristic frequency band components are applied to the corresponding control models according to a frequency division control management strategy for collaborative control of energy storage.

2. The frequency division control management strategy of the network-constructed hybrid energy storage power station according to claim 1, characterized in that, The control models of the lithium ion batteries and the super capacitors are both established based on the same process, which comprises: A bidirectional synchronous Buck-Boost converter is used as a basis for bidirectional power regulation, and the full-controlled power switching devices in the converter are cooperatively controlled by a pulse width modulation method, and the control system generates a PWM voltage reference signal based on the power reference value and the terminal current feedback of the current energy storage unit through a PI regulator.

3. The frequency division control management strategy of the network-constructed hybrid energy storage power station according to claim 1, characterized in that, The control model of the flywheel energy storage comprises: A three-phase full-bridge topology structure is used as a basis for AC / DC bidirectional power conversion of the motor side converter, and the full-controlled power switching devices in the motor side converter are cooperatively controlled by a space vector pulse width modulation method, and the control system generates a SVPWM voltage reference signal in the d-q synchronous rotating coordinate system based on the power-current double closed loop control architecture, the flywheel energy storage power reference value and the terminal current feedback through a PI regulator.

4. The frequency division control management strategy of the network-constructed hybrid energy storage power station according to claim 1, characterized in that, The control model of the hydrogen fuel cell comprises: The utilization rates of hydrogen and oxygen are dynamically adjusted according to the output power reference value, the terminal voltage and the current of the hydrogen fuel cell, and the control system generates a converter PWM voltage reference signal based on the hydrogen fuel cell power reference value, the terminal voltage and the current feedback through a PI regulator.

5. The frequency division control management strategy of the network-constructed hybrid energy storage power station according to claim 1, characterized in that, The control model of the hydrogen electrolyzer comprises: A converter PWM voltage reference signal is generated based on the power reference value, the terminal voltage and the current feedback of the hydrogen electrolyzer through a PI regulator.

6. The frequency division control management strategy of the network-constructed hybrid energy storage power station according to claim 1, wherein, The decomposition conditions of the four characteristic frequency band components are: Four frequency ranges, (50 Hz, ~ Hz), (10 Hz, 50 Hz), (1 Hz, 10 Hz) and (0 Hz, 1 Hz) are set, respectively defined as high frequency power demand P t dc,high , second high frequency power demand P t dc,midh , medium frequency power demand P t dc,mid and low frequency power demand P t dc,low , wherein the high frequency power demand P t dc,high is handled by super capacitor, t dc,midh the second high frequency power demand P t dc,mid is handled by flywheel energy storage, t dc,low the medium frequency power demand P is handled by lithium ion battery, and the low frequency power demand P is handled by hydrogen fuel cell and hydrogen electrolyzer.

7. The frequency division control management strategy of the network-constructed hybrid energy storage power station according to claim 6, characterized in that, The frequency division control management strategy comprises: The current power state of the system is determined according to a preset condition, and the power state is power deficiency or power excess; If the current power state is power deficiency, the hydrogen fuel cell is preferentially started to supplement the basic power gap, and the remaining power demand is distributed to other energy storage units for discharging, and if the current power state is power excess, the hydrogen fuel cell is first closed, each energy storage unit absorbs the excess power, and finally the hydrogen electrolyzer is started to absorb the remaining low-frequency power; Each frequency band power in the current power difference is discharged or charged according to the frequency characteristics of each type of energy storage unit; Each type of energy storage unit is controlled according to a preset power reference value, and the power command is converted into a duty cycle signal of the full-controlled power switching devices of the converter of each type of energy storage unit.

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