Flywheel array state-of-charge consistency power distribution method considering loss

Abstract

The invention provides a flywheel array state-of-charge consistency power distribution method considering loss. The flywheel array state-of-charge consistency power distribution method is used for power distribution operation optimization of a flywheel energy storage array. Firstly, an array controller receives a total power instruction, feeds back a system available state, receives a unit operation state fed back by a unit controller, and carries out calculation and allocation preparation. Secondly, setting an optimal operation curve corresponding to the state of charge of the unit, and fitting the corresponding relation between the unit operation loss and the state of charge, which is set in advance; and finally, according to the consistency-efficiency objective function under the set weight, solving the optimal reference power allocated to the unit. According to the method, a solution is provided for array power distribution and optimization, and dual consideration of array operation consistency and efficiency is realized.

Description

Technical Field

[0001] The invention relates to the field of flywheel energy storage technology, and in particular to a method for distributing power in a flywheel array with consistent state of charge taking into account losses. Background Art

[0002] At present, the application scope of flywheel energy storage projects is constantly expanding. The storage capacity of single-unit high-speed energy storage flywheels in my country is developing from 5 to 20 kWh to 50 to 100 kWh, and the power is developing from 200 to 400 kW to 500 to 2000 kW. However, in the fields of grid frequency regulation and new energy power leveling, the power and capacity of single-unit flywheel energy storage cannot meet the needs. The flywheel energy storage system networked in the form of an array is an effective solution. The array mode composed of multiple flywheel energy storage units can significantly increase the scale of energy storage, increase the power and capacity output range of flywheel energy storage, effectively improve the flexibility of traditional thermal power units in power system applications, and smooth the output power fluctuations of new energy such as wind power. When the flywheel energy storage system is networked in the form of an array, due to the different operating states of the flywheel energy storage units in the array, according to the barrel effect, the overall available energy of the system is affected by the charge state of the unit. Therefore, it is necessary to adopt a suitable array power allocation strategy to optimize the reference power of each energy storage unit in the array and achieve the consistency of the energy state of each unit. At the same time, the operating efficiency of each unit in the array is taken into account, and the relationship between the unit speed and loss is converted into the relationship between the state of charge and loss, so that the influence of loss is taken into account when allocating array power, and the consistency-efficiency coordination of array power allocation is achieved. Summary of the invention

[0003] In view of the deficiencies and gaps in the prior art in the relevant field, the present invention provides a method for distributing power to a flywheel array with consistent state of charge considering losses. The purpose of the present invention is achieved through the following technical solutions:

[0004] Step 1: The flywheel energy storage array controller feeds back the system operating status and receives the flywheel energy storage array reference power instruction.

[0005] Step 2: The flywheel energy storage array controller receives the operating status of the flywheel energy storage unit fed back by the flywheel energy storage unit controller, and the flywheel energy storage array controller distributes the energy of the flywheel energy storage array in combination with the reference power command of the flywheel energy storage array, the operating status of the flywheel energy storage unit and the rated power of each flywheel energy storage unit.

[0006] Step 3: Set the expected output power curve of the flywheel energy storage unit at different states of charge.

[0007] Step 4: With the goal of minimizing the root variance of the total flywheel energy storage unit deviation from the expected output power curve value and the total operation loss of the array, a reference power instruction is issued to the flywheel energy storage unit controller.

[0008] Step 5: The flywheel energy storage unit controller controls the flywheel unit to respond to the reference power signal and obtains the array output.

[0009] In step 1, the flywheel energy storage array controller feeds back the system operating status and receives the flywheel energy storage array reference power instruction.

[0010] The step 1 specifically includes the following sub-steps:

[0011] Step 1.1: The array controller PLC uploads the maximum and minimum available power of the array and the charge status of each unit to the energy management system EMS. The array controller PLC receives the array reference power command value issued by the energy management system EMS.

[0012] In step 2, the flywheel energy storage array controller receives the operating status of the flywheel energy storage unit fed back by the flywheel energy storage unit controller, and the flywheel energy storage array controller distributes the energy of the flywheel energy storage array in combination with the flywheel energy storage array reference power instruction, the operating status of the flywheel energy storage unit and the rated power of each flywheel energy storage unit.

[0013] The step 2 specifically includes the following sub-steps:

[0014] Step 2.1: The array controller PLC receives the flywheel unit operating speed and unit output power uploaded by the unit side controller. The array controller PLC completes the array power allocation information collection and performs array power allocation calculation.

[0015] In step 3, the expected output power curve of the flywheel energy storage unit under different charge states is set.

[0016] The step 3 specifically includes the following sub-steps:

[0017] Step 3.1: Set the optimal operating curve for flywheel energy storage:

[0018]

[0019] In the formula, S oc,i is the charge state of the flywheel energy storage unit i, S oc,max ≥S oc,i ≥S oc,min , S oc,max , S oc,min are the maximum and minimum state of charge values ​​allowed by the flywheel energy storage unit; α, β1, β2 are curve parameters, which are 30, 0.3, and 0.7 respectively; P all,ref >0 when discharging, P all,ref <0 when charging.

[0020] In step 4, a reference power instruction is issued to the flywheel energy storage unit controller with the goal of minimizing the root variance of the total flywheel energy storage unit deviation from the expected output power curve value and the total operation loss of the array.

[0021] The step 4 specifically includes the following sub-steps:

[0022] Step 4.1: The corresponding relationship between the flywheel unit operating loss and the state of charge is:

[0023]

[0024] k1, k2, and k3 are the loss coefficients after fitting, which are -1117.16, 5347.20, and 1394.42, respectively.

[0025] Step 4.2: The objective function of array power allocation is:

[0026]

[0027] Where P i,ref is the reference power of flywheel energy storage unit i; P i,exp is the expected power of flywheel energy storage unit i; λ is the loss weight.

[0028] Step 4.3: The array power allocation constraint is:

[0029]

[0030] |P i,ref |≤P i,max

[0031] Where P i,max is the maximum power of flywheel energy storage unit i; P all,ref is the total reference power instruction of the flywheel energy storage array.

[0032] Step 4.4: The array controller PLC calculates the unit reference power instruction P i,ref Send it to the corresponding unit controller.

[0033] In step 5, the flywheel energy storage unit controller controls the flywheel unit to respond to the reference power signal, and the array output is obtained by summarizing.

[0034] The step 5 specifically includes the following sub-steps:

[0035] Step 5.1: Each unit controller controls the machine-side inverter to respond to the power command value issued by the array controller PLC.

[0036] The present invention proposes a flywheel array state of charge consistency power distribution method considering losses for flywheel energy storage array power distribution operation optimization. First, the array controller receives the total power command, feeds back the system available status, receives the unit operation status fed back by the unit controller, and performs calculations and distribution preparations. Secondly, the optimal operation curve corresponding to the unit state of charge is set, and the corresponding relationship between the unit operation loss and the state of charge is fitted. This part is set in advance. Finally, according to the consistency-efficiency objective function under the set weight, the optimal reference power allocated to the unit is solved. This method provides a solution for array power allocation and optimization, and realizes the dual consideration of array operation consistency and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention is a flow chart of a method for distributing power according to the charge state consistency of a flywheel array taking losses into consideration.

[0038] Figure 2 It is the optimal power curve diagram corresponding to the charge state of the unit of the present invention.

[0039] Figure 3 The total reference power instruction of the array and the corresponding curve diagram in Example 1 of the flywheel array charge state consistency power allocation method considering losses of the present invention.

[0040] Figure 4 It is a power distribution curve diagram of each unit in Example 1 of the flywheel array charge state consistency power distribution method taking into account the loss of the present invention.

[0041] Figure 5 It is a curve diagram of the charge state change of each unit in Example 1 of the flywheel array charge state consistency power allocation method taking into account the loss of the present invention.

[0042] Figure 6 This is a curve diagram of the change of the charge state consistency index of each unit in Example 1 of the flywheel array charge state consistency power allocation method taking into account the loss of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the following is a detailed description of the examples in conjunction with the accompanying drawings.

[0044] Reference Figure 1 , a power allocation method for the charge state consistency of a flywheel array considering losses is proposed. By accurately controlling the power output of the flywheel energy storage unit, the overall operating efficiency of the flywheel array is maximized, while ensuring that the state of charge (SOC) of each flywheel energy storage unit remains consistent, thereby extending the service life and reliability of the flywheel energy storage system.

[0045] Step 1: The flywheel energy storage array controller feeds back the system operating status and receives the flywheel energy storage array reference power instruction.

[0046] Step 1 is the starting point of the entire power allocation method, which involves information interaction between the flywheel energy storage array controller (PLC) and the energy management system (EMS). The array controller is responsible for collecting and uploading the array's operating status information, while receiving reference power instructions from the EMS to provide basic data for subsequent energy allocation.

[0047] Step 1.1: The array controller PLC uploads the maximum and minimum available power of the array and the charge status of each unit to the energy management system EMS.

[0048] The array controller calculates the maximum power (maximum value) and minimum power (minimum value) that the entire array can provide under current conditions by monitoring the current status of each flywheel energy storage unit.

[0049] The state of charge (SOC) is an important indicator of the remaining energy of the flywheel energy storage unit. The array controller collects the SOC information of each unit in real time and uploads it to the EMS so that the EMS can understand the energy storage status of each unit and perform accurate power allocation.

[0050] Step 1.2: The array controller PLC receives the array reference power command value issued by the energy management system EMS.

[0051] The EMS calculates the reference power command value that the flywheel energy storage array should provide based on the grid demand, the current state of the flywheel energy storage system, and the preset power allocation strategy. This command value is sent to the array controller through the communication network as the basis for subsequent energy allocation.

[0052] Step 2: The flywheel energy storage array controller receives the operating status of the flywheel energy storage unit fed back by the flywheel energy storage unit controller, and distributes the energy of the flywheel energy storage array.

[0053] Step 2 involves information exchange between the array controller and the flywheel energy storage unit controller, as well as energy allocation strategies based on this information. The array controller calculates the expected power output of each unit based on the received unit operating status information, combined with the reference power command and rated power, and performs energy allocation.

[0054] Step 2.1: The array controller PLC receives the flywheel unit operating speed and unit output power uploaded by the unit side controller.

[0055] The operating speed of the flywheel energy storage unit is an important parameter that reflects its energy storage status. By monitoring the operating speed, the array controller can indirectly understand the energy storage status of each unit and provide a basis for subsequent power allocation.

[0056] The unit output power is the actual power value currently output by the flywheel energy storage unit. The array controller collects this data to understand the actual working status of each unit, so as to make accurate power allocation.

[0057] Step 2.2: The array controller PLC completes the array power allocation information collection and performs array power allocation calculation.

[0058] After receiving the operation status information uploaded by the unit controller, the array controller first integrates and verifies the information to ensure the accuracy and integrity of the data.

[0059] Based on the collected information, the array controller combines the reference power command and the rated power and uses an appropriate algorithm to calculate the expected power output of each unit. The algorithm should be able to fully consider factors such as the energy storage status and output power capacity of each unit to ensure the rationality of power allocation.

[0060] Step 3: Set the expected output power curve of the flywheel energy storage unit at different states of charge.

[0061] Step 3 involves setting the expected output power curve of the flywheel energy storage unit at different states of charge.

[0062] Step 3.1: Set the optimal operating curve of flywheel energy storage.

[0063] The optimal operating curve is derived based on the physical characteristics and operating experience of the flywheel energy storage unit. It reflects the expected power value that the flywheel energy storage unit should output under different charge states.

[0064] Step 4: With the goal of minimizing the root variance of the total flywheel energy storage unit deviation from the expected output power curve value and the total operation loss of the array, a reference power instruction is issued to the flywheel energy storage unit controller.

[0065] Step 4 is the core of the entire power allocation method, which involves the optimization of the power output of the flywheel energy storage unit. The array controller calculates the root variance of each unit's deviation from the desired output power curve and the total array operation loss, and uses an appropriate optimization algorithm to solve the reference power command of each unit to achieve the optimization of power allocation.

[0066] Step 4.1: Correspondence between flywheel unit operating losses and state of charge.

[0067] The operating loss of a flywheel energy storage unit is closely related to its state of charge. In order to accurately describe this relationship, it is necessary to establish a corresponding relationship model between the operating loss of the flywheel unit and the state of charge. This model is usually obtained by fitting experimental data and can reflect the operating loss of the flywheel energy storage unit under different states of charge.

[0068] Step 4.2: Objective function for array power allocation.

[0069] In order to optimize the power distribution of the flywheel energy storage array, an objective function needs to be constructed. This objective function should be able to comprehensively reflect the two optimization goals of the root variance of the flywheel energy storage unit deviation from the expected output power curve value and the total operating loss of the array. By solving the minimum value of this objective function, the optimal power distribution scheme can be obtained.

[0070] Step 4.3: Constraints on array power allocation.

[0071] In the process of solving the objective function, the physical characteristics and operating limitations of the flywheel energy storage unit need to be taken into account. Therefore, a series of constraints need to be set to ensure the feasibility and effectiveness of the solution. These constraints usually include the maximum power limit of the flywheel energy storage unit, the satisfaction of the total reference power instruction, etc.

[0072] Step 4.4: The array controller PLC sends the calculated unit reference power instruction Pi,ref to the corresponding unit controller.

[0073] After solving the objective function and checking the constraints, the array controller sends the calculated unit reference power instructions to the corresponding unit controllers. These instructions will serve as the basis for the subsequent operation of the flywheel energy storage unit and guide it to adjust the power output.

[0074] After receiving the reference power command issued by the array controller, the unit controller will adjust the power output of the flywheel energy storage unit according to the command requirements. Through real-time monitoring and adjustment, the efficiency and stability of the overall operation of the flywheel energy storage array can be ensured.

[0075] Step 5: The flywheel energy storage unit controller controls the flywheel unit to respond to the reference power signal and obtains the array output.

[0076] Step 5 is the last step of the power allocation method, which involves the response of the flywheel energy storage unit controller to the reference power signal and the summary of the array output. By accurately controlling the power output of the flywheel energy storage unit, the efficiency and stability of the overall operation of the flywheel array can be achieved.

[0077] Step 5.1: Each unit controller controls the machine-side inverter to respond to the power command value issued by the array controller PLC.

[0078] The flywheel energy storage unit controller responds to the power command value issued by the array controller by controlling the machine-side inverter. The inverter is a key device for adjusting the power output of the flywheel energy storage unit. By adjusting its operating parameters, the power of the flywheel energy storage unit can be accurately controlled.

[0079] After receiving the power command value, the flywheel energy storage unit controller converts the command value into a control signal that the inverter can recognize and sends it to the inverter for execution. By real-time monitoring and adjusting the operating parameters of the inverter, it can ensure that the flywheel energy storage unit outputs power according to the command requirements.

[0080] Step 5.2: Summarize to get array output.

[0081] After the flywheel energy storage unit outputs power according to the instruction requirements, the power output of each unit will be aggregated to obtain the overall output of the flywheel energy storage array. This output will directly reflect the actual power output capacity of the flywheel energy storage array under the current operating state.

[0082] In order to ensure the stability and accuracy of the flywheel energy storage array output, the array output needs to be monitored in real time. By comparing the difference between the actual output and the expected output, possible problems can be discovered and corrected in time, thereby ensuring the efficiency and reliability of the flywheel energy storage array operation.

[0083] The following is an explanation of the corresponding functions and calculation methods. Figure 1 A power allocation method for a flywheel array state of charge consistency considering losses in the present invention comprises the following steps:

[0084] In step 1, the flywheel energy storage array controller feeds back the system operating status and receives the flywheel energy storage array reference power instruction.

[0085] The step 1 specifically includes the following sub-steps:

[0086] Step 1.1: The array controller PLC uploads the maximum and minimum available power of the array and the charge status of each unit to the energy management system EMS. The array controller PLC receives the array reference power command value issued by the energy management system EMS.

[0087] In step 2, the flywheel energy storage array controller receives the operating status of the flywheel energy storage unit fed back by the flywheel energy storage unit controller, and the flywheel energy storage array controller distributes the energy of the flywheel energy storage array in combination with the flywheel energy storage array reference power instruction, the operating status of the flywheel energy storage unit and the rated power of each flywheel energy storage unit.

[0088] The step 2 specifically includes the following sub-steps:

[0089] Step 2.1: The array controller PLC receives the flywheel unit operating speed and unit output power uploaded by the unit side controller. The array controller PLC completes the array power allocation information collection and performs array power allocation calculation.

[0090] In step 3, the expected output power curve of the flywheel energy storage unit under different charge states is set.

[0091] The step 3 specifically includes the following sub-steps:

[0092] Step 3.1: Set the optimal operating curve for flywheel energy storage:

[0093]

[0094] In the formula, S oc,i is the charge state of the flywheel energy storage unit i, S oc,max ≥S oc,i ≥S oc,min , S oc,max , S oc,min are the maximum and minimum state of charge values ​​allowed by the flywheel energy storage unit; α, β1, β2 are curve parameters, which are 30, 0.3, and 0.7 respectively; P all,ref >0 when discharging, P all,ref <0 when charging.

[0095] In step 4, a reference power instruction is issued to the flywheel energy storage unit controller with the goal of minimizing the root variance of the total flywheel energy storage unit deviation from the expected output power curve value and the total operation loss of the array.

[0096] The step 4 specifically includes the following sub-steps:

[0097] Step 4.1: The corresponding relationship between the flywheel unit operating loss and the state of charge is:

[0098]

[0099] k1, k2, and k3 are the loss coefficients after fitting, which are -1117.16, 5347.20, and 1394.42, respectively.

[0100] Step 4.2: The objective function of array power allocation is:

[0101]

[0102] Where P i,ref is the reference power of flywheel energy storage unit i; P i,exp is the expected power of flywheel energy storage unit i; λ is the loss weight.

[0103] Step 4.3: The array power allocation constraint is:

[0104]

[0105] |P i,ref |≤P i,max

[0106] Where P i,max is the maximum power of flywheel energy storage unit i; Pall,ref is the total reference power instruction of the flywheel energy storage array.

[0107] Step 4.4: The array controller PLC calculates the unit reference power instruction P i,ref Send it to the corresponding unit controller.

[0108] In step 5, the flywheel energy storage unit controller controls the flywheel unit to respond to the reference power signal, and the array output is obtained by summarizing.

[0109] The step 5 specifically includes the following sub-steps:

[0110] Step 5.1: Each unit controller controls the machine-side inverter to respond to the power command value issued by the array controller PLC.

[0111] like Figure 2 As shown, the total reference power instruction of the array and the corresponding curve diagram in Example 1 of the power allocation method for the charge state consistency of the flywheel array considering the loss of the present invention are shown. This curve power instruction is sent to the array controller PLC. The charge state of each unit in the array is [0.55; 0.5; 0.45; 0.4; 0.35; 0.3; 0.25; 0.25; 0.2; 0.2].

[0112] like Figure 3 As shown, it is a power distribution curve diagram of each unit in Example 1 of the power distribution method for charge state consistency of the flywheel array considering the loss of the present invention. There is no obvious step and oscillation in the array power distribution.

[0113] like Figure 4 As shown, the charge state change curve of each unit in Example 1 of the flywheel array charge state consistency power allocation method considering loss.

[0114] like Figure 5 As shown, the charge state consistency index change curve of each unit in the embodiment 1 of the flywheel array charge state consistency power allocation method considering the loss. The consistency index calculation formula is:

[0115]

[0116] It can be seen that the overall trend of the consistency index is gradually decreasing.

[0117] Finally, it should be noted that the above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for distributing power to a flywheel array with consistent state of charge considering losses, characterized in that: The following steps are involved: Step 1: System status feedback and command reception: The flywheel energy storage array controller first feedbacks the current system operating status and receives the flywheel energy storage array reference power command from the upper system; Step 2: Energy allocation strategy formulation: The flywheel energy storage array controller receives the operating status feedback from each flywheel energy storage unit controller, and formulates the energy allocation plan of the flywheel energy storage array in combination with the received reference power command, the operating status of each unit and their rated power; Step 3: Setting the expected output power curve: According to the different charge states of the flywheel energy storage cells, the expected output power curve is preset to ensure the consistency of each cell during the charging and discharging process; Step 4: issuing power instructions under the optimization target; with the dual optimization targets of minimizing the root variance of the overall flywheel energy storage unit deviation from the expected output power curve value and minimizing the total operation loss of the array, the flywheel energy storage array controller issues an optimized reference power instruction to each flywheel energy storage unit controller; Step 5: Response and output summary; The flywheel energy storage unit controller controls the flywheel unit to perform corresponding charging and discharging operations according to the received reference power command, and finally summarizes the overall output of the flywheel energy storage array.

2. The method for distributing power to a flywheel array with consistent state of charge considering losses according to claim 1, characterized in that: The step 1 is specifically as follows: Step 1.1: The array controller PLC uploads the maximum and minimum available power of the array and the charge status of each unit to the energy management system EMS, and the array controller PLC receives the array reference power command value issued by the energy management system EMS.

3. The method for distributing power to a flywheel array with consistent state of charge considering losses according to claim 1, characterized in that: The step 2 is specifically as follows: Step 2.1: The array controller PLC receives the flywheel unit operating speed and unit output power uploaded by the unit side controller, completes the array power allocation information collection, and performs array power allocation calculation.

4. The method for distributing power to a flywheel array with consistent state of charge considering losses according to claim 1, characterized in that: The step 3 is specifically as follows: Step 3.1: Set the optimal operating curve for flywheel energy storage: In the formula, S oc,i is the charge state of the flywheel energy storage unit i, S oc,max ≥S oc,i ≥S oc,min , S oc,max , S oc,min are the maximum and minimum state of charge values ​​allowed by the flywheel energy storage unit; α, β1, β2 are curve parameters, which are 30, 0.3, and 0.7 respectively; P all,ref >0 when discharging, P all,ref <0 when charging.

5. The method for distributing power to a flywheel array with consistent state of charge considering losses according to claim 1, characterized in that: The step 4 is specifically as follows: Step 4.1: The corresponding relationship between the flywheel unit operating loss and the state of charge is: k1, k2, and k3 are the loss coefficients after fitting, which are -1117.16, 5347.20, and 1394.42, respectively; Step 4.2: The objective function of array power allocation is: Where P i,ref is the reference power of flywheel energy storage unit i; P i,exp is the expected power of flywheel energy storage unit i; λ is the loss weight; Step 4.3: The array power allocation constraint is: |P i,ref |≤P i,max Where P i,max is the maximum power of flywheel energy storage unit i; P all,ref is the total reference power instruction of the flywheel energy storage array; Step 4.4: The array controller PLC calculates the unit reference power instruction P i,ref Send it to the corresponding unit controller.

6. The method for distributing power to a flywheel array with consistent state of charge considering losses according to claim 1, characterized in that: The step 5 is specifically as follows: Step 5.1: Each unit controller controls the machine-side inverter to respond to the power command value issued by the array controller PLC.

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