Flywheel energy storage self-recovery control method and system considering unit AGC frequency modulation state

Abstract

The invention discloses a flywheel energy storage self-recovery control method considering the AGC frequency modulation state of a unit, and the method comprises the following steps: S1, obtaining the state information of flywheel energy storage when any step change in an AGC instruction is detected, and calculating a corresponding charge state value; s2, when the charge state value meets a constraint condition, setting two threshold points to divide the charge state into a plurality of regions; s3, based on the rated power of flywheel energy storage and the power deviation of the unit, the output power needed by flywheel energy storage is calculated and output; and S4, virtual AGC instruction control logic is added, a virtual load instruction increment delta AGC of the unit is generated, the size of the load instruction increment delta AGC is adjusted, and the current value of the charge state value is controlled in the optimal charge interval. The virtual AGC instruction of the unit is dynamically adjusted according to the state information of flywheel energy storage, so that the output power of the unit is adjusted, and the flywheel energy storage runs in the optimal charge interval.

Description

Technical Field

[0001] The present invention relates to the technical field of flywheel energy storage and thermal power unit control, and in particular to a flywheel energy storage self-recovery control method and system taking into account the AGC frequency modulation state of the unit. Background Art

[0002] The rapid development of the new energy industry has significantly increased the proportion of clean energy consumption, accelerating the green and low-carbon transition. It is projected that by 2030, the proportion of non-fossil energy consumption will reach approximately 25%, with clean energy accounting for the majority of the increase in energy consumption. As the scale of new energy installed capacity continues to expand, its absorption becomes a key issue. At the same time, due to the volatility and intermittent nature of new energy grid connection, resulting in a "duck curve" load characteristic, the pressure on coal-fired units to participate in deep peak shaving and frequency regulation to achieve a low-carbon energy transition is increasing.

[0003] With the continuous optimization of new energy deployment and the continuous decline in energy storage costs, guided by national policies, energy storage is gaining increasing commercial applications in the power ancillary services market, peak-valley price arbitrage, and addressing wind and solar curtailment. Flywheel energy storage offers the advantages of frequent charging and discharging capabilities and a long cycle life, with over 5 million cycles. A combined flywheel and thermal power generation system can participate in AGC frequency regulation and receive compensation for ancillary services.

[0004] On the other hand, due to the high energy cost of flywheel energy storage, the power generation side often considers the cost investment recovery period when configuring flywheel energy storage, and the flywheel energy storage power is not enough to meet all-weather frequency regulation conditions; thereby reducing the performance of the combined thermal-storage frequency regulation, reducing the participation of flywheel energy storage, and reducing the benefits of the combined system.

[0005] While some self-recovery control strategies enforce self-recovery of the SOC (State of Charge) when it exceeds the normal charge / discharge range, they fail to consider whether the combined system is participating in AGC frequency regulation. This can lead to low frequency regulation performance for combined energy storage systems and even sudden drops in grid frequency. AGC, short for Automatic Generation Control, is a technology used in power systems to maintain grid frequency, control power exchange on inter-regional tie lines, and adjust generator output in response to load changes.

[0006] Currently, the existing technology for the SOC self-recovery problem of flywheel energy storage coupled thermal power units still has the following defects: 1) The importance of the optimal state of charge of flywheel energy storage in the frequency modulation process is not fully considered; 2) Failure to focus on SOC recovery strategies results in flywheel energy storage operating at a boundary state for a long time; 3) The output characteristics of the unit are not fully utilized during the SOC transformation process. Summary of the Invention

[0007] In view of the above three problems, the object of the present invention is to propose a flywheel energy storage self - recovery control method and system considering the AGC frequency modulation state of the unit, which can dynamically adjust the virtual AGC command of the unit according to the state information of the flywheel energy storage, and then adjust the output power of the unit. At the same time, the operation of the flywheel energy storage is made to be in the optimal state of charge, realizing the combined thermal - storage power frequency modulation, improving the adjustable energy of the flywheel energy storage, fully exerting the output characteristics of the unit, meeting the all - weather AGC frequency modulation service, realizing the optimal configuration and control and maximum utilization of the energy storage resources, and improving the project return rate.

[0008] It is achieved through the following technical solutions: First, a flywheel energy storage self - recovery control method considering the AGC frequency modulation state of the unit is proposed, including the following steps: S1. Obtain the AGC command of the power grid. When any step change is detected in the AGC command, obtain the state information of the flywheel energy storage and calculate the state of charge value SOC of the flywheel energy storage at the corresponding step change. S2. Judge whether the state of charge value SOC in step S1 satisfies the constraint condition: 0.2 ≤ SOC ≤ 0.95; if not, prohibit the charging and discharging of the flywheel energy storage; if satisfied, set threshold point A and threshold point B to divide the state of charge of the flywheel energy storage into multiple regions, and then enter step S3; where 0.2 < A < B < 0.95, and (A, B) is the optimal state of charge interval. S3. Obtain the actual power P (t) of the unit, and calculate the power deviation P e (t) = P AGC (t) - P g (t), where P AGC (t) is the current specified power value of the power grid, and P g (t) is the rated power of the unit. Based on the rated power of the flywheel energy storage and the power deviation of the unit, according to formula (1): Calculate the required output power P f (t) of the flywheel energy storage, where P fe is the rated power of the flywheel energy storage; Output the flywheel energy storage according to the calculated output power P f (t). S4. Add virtual AGC command control logic to the unit and generate an incremental virtual load command ΔAGC of the unit, and obtain the current value of the state of charge value SOC of the flywheel energy storage after outputting according to the output power P f [[ID= Adjust the size of the load command increment ΔAGC to control the current value of the state of charge value SOC within the optimal charge range; when the current value of the state of charge value SOC is A or B and ΔAGC=0, stop unit adjustment.

[0009] By treating the step change of the AGC instruction as a frequency modulation instruction, a quick response can be made, and the output power of the flywheel energy storage can be accurately obtained based on the output power of the unit. The virtual AGC instruction control logic is then used to dynamically adjust the load instruction increment, so that the flywheel energy storage can operate stably in the optimal charge range.

[0010] Preferably, the state information obtained in step S1 includes the rated angular velocity of the flywheel energy storage , angular velocity , Rated capacity E e And the current power E, the state of charge value SOC= , where J is the moment of inertia. Combining the rated information with the current actual information can effectively calculate the current state of charge, making it easier to make adjustments based on the state of charge.

[0011] Preferably, in step S2, A = 0.4, B = 0.8; (0.2, 0.4) and (0.8, 0.95) are both secondary charge intervals. Setting A = 0.4 and B = 0.8 provides the flywheel energy storage with sufficient buffer range to cope with sudden changes in energy demand or supply without frequently reaching the limit value, thereby improving system stability and efficiency.

[0012] Preferably, the unit is provided with a dead zone power value, and the dead zone power value is equal to the rated power P of the unit. g The dead-band power value can optimize the response characteristics of the unit. The dead-band power value accounts for only 1% of the unit's rated power, which is small enough to improve the response speed to load changes.

[0013] Preferably, when generating the load command increment ΔAGC of the unit in step S4, ΔAGC does not exceed the dead-band power value. Limiting ΔAGC to not exceed the dead-band power value can maintain stable operation of the unit.

[0014] Preferably, after obtaining the current value of the state of charge SOC in step S4, a charging power rate parameter k is set. d and a discharge power rate parameter k c ; Based on k d and k c Calculate the virtual load command increment ΔAGC of the unit. Charging power rate parameter k d and a discharge power rate parameter k cIt is an important parameter related to the state of charge and can effectively calculate the corresponding load command increment ΔAGC.

[0015] Preferably, , , when ΔP>0, ΔAGC= ; When Δp<0, ΔAGC= ; Among them, ΔP is the updated value of flywheel energy storage, ΔP=P ACG (t1)-P ACG (t0), P ACG (t1) is the ACG command value at time t1, P ACG (t0) is the AGC command value before t1; the virtual AGC command value of the unit is recorded as P * AGC (t), ΔAGC=P * AGC (t)-P AGC (t), by modifying P * AGC (t) Control ΔAGC until the current state of charge (SOC) value is A or B and ΔAGC = 0, at which point the unit regulation is stopped. By modifying the unit's virtual AGC command value, combined thermal-storage power frequency regulation can be achieved, ensuring that the flywheel energy storage is in the optimal charge range while fully utilizing the unit's output characteristics and achieving rapid regulation.

[0016] Secondly, a system is proposed, which operates using a flywheel energy storage self-recovery control method taking into account the AGC frequency regulation state of the unit as described in any of the above items.

[0017] Furthermore, an electronic device is proposed, which is used to support the operation of the aforementioned system.

[0018] In addition, a storage medium is also proposed, which is used to support the operation of the aforementioned electronic device.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The technical solution of the present invention can dynamically adjust the virtual AGC instructions of the unit according to the status information of the flywheel energy storage, thereby adjusting the output power of the unit, and at the same time making the operation of the flywheel energy storage in the optimal charge range, realizing the joint frequency regulation of thermal-storage power, improving the adjustable energy of the flywheel energy storage, giving full play to the output characteristics of the unit, meeting the all-weather AGC frequency regulation service, realizing the optimal configuration, control and maximum utilization of energy storage resources, and improving the project rate of return. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of a flywheel energy storage self-recovery control method considering the AGC frequency regulation state of the unit; Figure 2 It is a schematic diagram of combined thermal energy - energy storage frequency regulation after a step change in AGC command; Figure 3 It is a schematic diagram of the output of a unit when increasing load according to a virtual AGC command; Figure 4 It is a schematic diagram of the output of a unit when decreasing load according to a virtual AGC command. Specific implementation manners

[0021] Next, the technical solutions in the embodiments of the present invention will be described in detail in conjunction with the accompanying drawings in the embodiments of the present invention.

[0022] As Figure 1 shown, it is a flowchart of a flywheel energy storage self - recovery control method considering the AGC frequency regulation state of a unit. According to the state information of the flywheel energy storage, the output power of the unit is dynamically adjusted, that is, the output power of the unit, which can effectively control the flywheel energy storage to operate in the optimal state of charge. The full name of the flywheel energy storage is the flywheel energy storage system. The method specifically includes the following steps: S1. Obtain the AGC command of the power grid. When detecting any step change in the AGC command, obtain the state information of the flywheel energy storage, and calculate the state of charge value SOC of the flywheel energy storage at the corresponding step change. Denote the required command update value of the flywheel energy storage at the step change as ΔP, ΔP = P ACG (t1)-P ACG (t0), P ACG (t1) is the ACG command value at time t1, P ACG (t0) is the ACG command value at time t0, and it is also the ACG command value at the moment before t1. ΔP≠0 means that it is necessary to change the operating condition of the flywheel energy storage.

[0023] In this embodiment, the state information obtained in step S1 includes the rated angular velocity 、angular velocity 、rated electric quantity E e and the current electric quantity E. The state of charge value SOC = ,, where J is the moment of inertia.

[0024] S2. Judge whether the state of charge value SOC in step S1 satisfies the constraint condition: 0.2≤SOC≤0.95; if not, it means that the flywheel energy storage is operating in a relatively extreme situation at this time, and the adjustment difficulty is large and it is not suitable for dynamic change. So, the flywheel energy storage is prohibited from charging and discharging; if it is satisfied, set the threshold point A and threshold point B to divide the state of charge of the flywheel energy storage into multiple regions, and then enter step S3; where, 0.2 < A < B < 0.95, (A, B) is the optimal state of charge interval and also the best operating interval of the flywheel energy storage.

[0025] Specifically, A = 0.4 and B = 0.8 can be set. In this case, (0.4, 0.8) is the optimal charge range, with maximum charge and discharge margin and strong ability to cope with continuous charge and discharge. (0.2, 0.4) and (0.8, 0.95) are both secondary charge ranges, with certain unidirectional charge and discharge capabilities. Setting A = 0.4 and B = 0.8 gives the flywheel energy storage sufficient buffer range to cope with sudden changes in energy demand or supply, without having to frequently reach its limit, thereby improving system stability and efficiency.

[0026] S3. Get the actual power P of the unit g (t), the unit is also a thermal power unit, calculate the power deviation P e (t) = P AGC (t)-P g (t), where P AGC (t) is the current specified power value of the power grid, P g (t) is the rated power of the unit; based on the rated power of the flywheel energy storage and the power deviation of the unit, according to formula (1): Calculate the output power P required for flywheel energy storage f (t), where P fe is the rated power of the flywheel energy storage; the flywheel energy storage is calculated according to the output power P f (t) to output.

[0027] like Figure 2 The figure shows a schematic diagram of thermal-storage combined frequency regulation after a step change in the AGC instruction. Thermal-storage combination refers to the coordination between the thermal power unit and the flywheel energy storage. At time t1, the AGC instruction undergoes a step change, and the unit operates according to the AGC instruction. The flywheel energy storage assists the thermal power unit frequency regulation response curve and performs energy storage discharge. Figure 2 In the figure, the red line is the AGC command line, the black line is the actual power curve of the thermal power unit, also known as the thermal power actual generation curve, and the blue line is the flywheel energy storage power curve, including discharge or charging. At time t3, the thermal power unit tracks the AGC command, that is, the thermal power unit completes the operation of the command, and the flywheel energy storage stops adjusting.

[0028] S4, add virtual AGC command control logic to the unit and generate a virtual load command increment ΔAGC of the unit, obtain the flywheel energy storage output power P in step S3 f (t) The current value of the state of charge (SOC) after output; adjusting the size of the load command increment ΔAGC to control the current value of the state of charge (SOC) within the optimal charge range; when the current value of the state of charge (SOC) is A or B and ΔAGC=0, stopping the unit adjustment.

[0029] In this embodiment, the unit is provided with a dead zone power value, which is equal to the rated power P of the unit. g (t) is 1% of the load command increment ΔAGC of the unit in step S4. ΔAGC does not exceed the dead-band power value. The dead-band power value optimizes the unit's response characteristics. The dead-band power value accounts for only 1% of the unit's rated power, which is small enough to improve the response speed to load changes.

[0030] In this embodiment, after obtaining the current value of the state of charge value SOC in step S4, a charging power rate parameter k is set. d and a discharge power rate parameter k c ;in, , ; Based on k d and k c Calculate the virtual load command increment ΔAGC of the unit. When ΔP>0, ΔAGC= ; When Δp<0, ΔAGC= ; The virtual AGC command value of the unit is recorded as P * AGC (t), ΔAGC=P * AGC (t)-P AGC (t), by modifying P * AGC (t) Control ΔAGC until the current state of charge (SOC) value is A or B and ΔAGC = 0, at which point the unit regulation is stopped. By modifying the unit's virtual AGC command value, combined thermal-storage power frequency regulation can be achieved, ensuring that the flywheel energy storage is in the optimal charge range while fully utilizing the unit's output characteristics and achieving rapid regulation.

[0031] like Figure 3 The figure shows a schematic diagram of the unit's output during load increase according to the virtual AGC instruction. A load increase verification is performed using the above method. At time t1, the AGC instruction changes to a load increase, and the unit begins to operate according to the virtual AGC instruction. The flywheel energy storage assists the thermal power unit's frequency regulation response curve, which continues to be output according to formula (1). The red line is the AGC instruction line, the red dotted line is the virtual AGC instruction, the black line is the thermal power unit's actual output curve, and the blue line is the flywheel energy storage discharge power curve. At time t2, the thermal power unit tracks the AGC instruction, and at time t3, the thermal power unit tracks the virtual AGC instruction. This continues until the flywheel energy storage's state of charge (SOC) reaches 0.4, the virtual AGC increment is 0, and the unit regulation is complete.

[0032] like Figure 4The figure shows a schematic diagram of the unit's output during load reduction according to the virtual AGC instruction. The load reduction verification is continued according to the above method. At time t1, the AGC instruction changes to load reduction, and the unit begins to operate according to the virtual AGC instruction. The flywheel energy storage assists the thermal power unit frequency regulation response curve and continues to be output according to formula (1). The red line is the AGC instruction line, the red dotted line is the virtual AGC instruction, the black line is the actual output curve of the thermal power unit, and the purple line is the flywheel energy storage charging power curve. At time t2, the thermal power unit tracks the AGC instruction, and at time t3, the thermal power unit tracks the virtual AGC instruction. Until the state of charge value (SOC) of the flywheel energy storage reaches 0.8, the virtual AGC increment is 0, and the unit regulation is completed.

[0033] Secondly, a system is also proposed, which operates using a flywheel energy storage self-recovery control method as described above that takes into account the AGC frequency regulation state of the unit.

[0034] Furthermore, an electronic device is proposed, which is used to support the operation of the aforementioned system.

[0035] In addition, a storage medium is also proposed, which is readable and used to support the operation of the aforementioned electronic device.

[0036] In summary, the present invention can dynamically adjust the virtual AGC instructions of the unit according to the status information of the flywheel energy storage, thereby adjusting the output power of the unit, and at the same time making the operation of the flywheel energy storage in the optimal charge range, realizing the combined frequency regulation of thermal-storage power, improving the adjustable energy of the flywheel energy storage, giving full play to the output characteristics of the unit, meeting the all-weather AGC frequency regulation service, realizing the optimal configuration, control and maximum utilization of energy storage resources, improving the project rate of return, and having significant progressiveness.

[0037] The above embodiments are only for illustrating the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A flywheel energy storage self-recovery control method considering the AGC frequency modulation state of the unit, characterized in that: It includes the following steps: S1. Obtain the AGC instruction of the power grid. When any step change is detected in the AGC instruction, obtain the state information of the flywheel energy storage, and calculate the state of charge value SOC of the flywheel energy storage at the corresponding step change. S2. Determine whether the state of charge value SOC in step S1 meets the constraint condition: 0.2 ≤ SOC ≤ 0.95; if not, prohibit charging and discharging of the flywheel energy storage; if it meets, set threshold point A and threshold point B to divide the state of charge of the flywheel energy storage into multiple regions, and then enter step S3; where, 0.2 < A < B < 0.95, (A, B) is the optimal state of charge interval. S3. Get the actual power P of the unit g (t), calculate the power deviation P e (t) = P AGC (t)-P g (t), where P AGC (t) is the current specified power value of the power grid, P g (t) is the rated power of the unit; Based on the rated power of the flywheel energy storage and the power deviation of the unit, according to formula (1): Calculate the output power P required for flywheel energy storage f (t), where P fe The rated power of the flywheel energy storage; The flywheel energy storage is calculated according to the output power P f (t) output; S4, add virtual AGC command control logic to the unit and generate a virtual load command increment ΔAGC of the unit, obtain the flywheel energy storage output power P in step S3 f (t) The current value of the state of charge (SOC) after output; Adjust the magnitude of the load instruction increment ΔAGC to control the current value of the state of charge value SOC within the optimal state of charge interval; when the current value of the state of charge value SOC is A or B and ΔAGC = 0, stop the unit regulation.

2. A flywheel energy storage self-recovery control method considering the AGC frequency modulation state of the unit according to claim 1, characterized in that: The status information obtained in step S1 includes the rated angular velocity of the flywheel energy storage , angular velocity , Rated capacity E e And the current power E, the state of charge value SOC= , where J is the moment of inertia.

3. A flywheel energy storage self-recovery control method considering the AGC frequency modulation state of the unit according to claim 1, characterized in that: In step S2, A = 0.4, B = 0.8; (0.2, 0.4) and (0.8, 0.95) are both secondary state of charge intervals.

4. A flywheel energy storage self-recovery control method considering the AGC frequency modulation state of the unit according to claim 1, characterized in that: The unit is set with a dead zone power value, which is equal to the unit rated power P. g 1% of (t).

5. A flywheel energy storage self-recovery control method considering the AGC frequency modulation state of the unit according to claim 4, characterized in that: When generating the load instruction increment ΔAGC of the unit in step S4, ΔAGC does not exceed the dead zone power value.

6. A flywheel energy storage self-recovery control method considering the AGC frequency modulation state of the unit according to claim 1, characterized in that: After obtaining the current value of the state of charge (SOC) in step S4, a charging power rate parameter k is set. d and a discharge power rate parameter k c ; Based on k d and k c Calculate the unit's virtual load command increment ΔAGC.

7. A flywheel energy storage self-recovery control method considering the AGC frequency modulation state of the unit according to claim 5, characterized in that: , , when ΔP>0, ΔAGC= ; When Δp<0, ΔAGC= ; Among them, ΔP is the updated value of flywheel energy storage, ΔP=P ACG (t1)-P ACG (t0), P ACG (t1) is the ACG command value at time t1, P ACG (t0) is the AGC command value before t1; the virtual AGC command value of the unit is recorded as P * AGC (t), ΔAGC=P * AGC (t)-P AGC (t), by modifying P * AGC (t) Control ΔAGC until the current state of charge (SOC) value is A or B and ΔAGC = 0, then stop the unit regulation.

8. A system, characterized in that: The system operates by using a flywheel energy storage self - recovery control method considering the AGC frequency modulation state of the unit as described in any one of claims 1 to 7.

9. An electronic device, characterized in that: The electronic device is used to support the operation of the system as described in claim 8.

10. A storage medium, characterized in that: The storage medium is used to support the operation of the electronic device as described in claim 9.

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