A method for PCS droop control based on electrochemical state perception

Abstract

The present application relates to the technical field of energy storage converter control, and discloses a PCS droop control method based on electrochemical state sensing, which introduces the SOP dynamic margin of BMS into PCS transient droop control, fills the control gap between EMS steady-state scheduling and PCS transient response, realizes the differentiated allocation of batteries through the comprehensive adjustment factor of the fusion of battery internal resistance and dynamic margin, adopts steady-state / transient split mode control, and gives consideration to steady-state accuracy and transient safety through hysteresis mechanism smooth switching, adds SOP hard constraint real-time verification and collaborative derating mechanism to avoid passive protection of "first limit, then trip", opens the BMS-PCS transient control channel to realize millisecond-level deep cooperation and reduce high-rate impact to prolong battery life. In addition, only a software algorithm module needs to be added in the PCS controller without changing the main circuit topology, so the engineering compatibility is good and the implementation cost is low.

Description

Technical Field

[0001] This invention relates to the field of energy storage converter control technology, and in particular to a PCS droop control method based on electrochemical state sensing. Background Technology

[0002] As the interface device between the battery energy storage system and the power grid, the PCS (Power Conversion System) directly affects the operational reliability of the energy storage system and the grid's support capability. In energy storage systems with multiple units operating in parallel, droop control is the core control strategy for achieving power distribution among the PCS units. Traditional droop control simulates the active-frequency (Pf) and reactive-voltage (QU) droop characteristics of synchronous generators to achieve power sharing when multiple PCS units are operating in parallel.

[0003] However, existing droop control strategies still have the following technical shortcomings:

[0004] (i) Traditional droop control cannot distinguish between steady-state scheduling and transient disturbances. When the power grid experiences frequency disturbances or load changes, each PCS automatically assumes the disturbance power according to its droop characteristics. This process is not directly intervened by the EMS (Energy Management System). Some existing solutions have introduced SOC into droop control to achieve battery power balancing, but these solutions are all aimed at steady-state power allocation and have not solved the adaptive problem of droop control under transient disturbance scenarios.

[0005] (ii) Fixed droop factor causes aging batteries to easily approach the SOP (State of Power) upper limit under transient disturbances. In the traditional scheme using a fixed droop factor, when the grid frequency shifts, all parallel PCS share the disturbance power equally. Taking two PCS as an example: PCS-A is connected to a healthy battery (good SOH, high SOP upper limit), and PCS-B is connected to an aging battery (decreased SOH, low SOP upper limit). After the EMS issues a steady-state command, when the grid frequency drops sharply and each PCS needs to generate additional power, the fixed droop factor causes both PCS to bear the same incremental power, resulting in the total output of the aging PCS approaching or even exceeding the SOP upper limit, triggering the BMS (Battery Management System) protective trip, and in severe cases, causing the system to disconnect from the grid.

[0006] (iii) Existing adaptive droop solutions do not incorporate SOP dynamic margin into transient control. Existing technologies have attempted to use SOH as a weighting factor for power allocation, or to dynamically adjust the droop coefficient based on traditional droop control to avoid overcharging and over-discharging. However, these solutions do not distinguish between the control requirements of "steady-state power scheduling" and "transient disturbance response" at two different time scales, nor do they use the SOP dynamic margin issued by the BMS in real time as the basis for adjusting the droop coefficient, resulting in the risk of overloading of aging batteries under transient disturbances.

[0007] (iv) Lack of coordination between BMS and PCS in transient time scale. In the prior art, EMS performs minute-level steady-state scheduling based on SOPs provided by BMS, while PCS lacks SOP constraints in millisecond-level transient responses. The SOP information calculated by BMS does not directly participate in the transient response decision of PCS, resulting in information gaps.

[0008] Therefore, improvements to existing technologies are necessary. Summary of the Invention

[0009] This invention provides a PCS droop control method based on electrochemical state sensing to solve the problems existing in the prior art.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A PCS sag control method based on electrochemical state sensing, the method comprising:

[0012] S1. Real-time acquisition of electrochemical state parameters and power state boundary information of the battery clusters connected to each PCS; wherein, the electrochemical state parameters include battery state of charge (SOC), battery state of health (SOH), and battery DC internal resistance R. bat Current real-time output power P of the battery out and battery temperature T bat The power state boundary information includes the upper limit of the battery's current available charge / discharge power (SOP). max ;

[0013] S2. Based on the current available charge / discharge power limit SOP of the battery max and the current real-time output power P of the battery out Calculate the dynamic power margin factor κ for each PCS. i ;

[0014] S3. Based on the DC internal resistance R of each battery cluster bat and the dynamic power margin coefficient κ i Construct the comprehensive adjustment factor δ for each PCS i ;

[0015] S4. Real-time detection of grid frequency deviation Δf, and determination of system operating mode based on the grid frequency deviation Δf; when determined to be in steady state, each PCS calculates the transient disturbance power of each PCS using the rated droop coefficient m0; when determined to be in transient disturbance state, the integrated adjustment factor δ is used. i Adaptive correction is performed on the droop coefficient of each PCS, and the transient disturbance power of each PCS is calculated.

[0016] S5. Real-time verification of whether the transient disturbance power of each PCS exceeds the upper limit of SOP. If it does, implement safety protection measures.

[0017] Furthermore, in the electrochemical state-aware energy storage PCS droop control method, in S2, the dynamic power margin coefficient κ... i The calculation formula is:

[0018] ;

[0019] Among them, κ i ∈[0,1], representing the remaining capacity of the i-th PCS at the current operating point to cope with subsequent power disturbances, κ i The closer to 1, the greater the margin; κ i The closer it is to 0, the closer it is to the upper limit of SOP (Standard Operating Procedure), and the weaker its ability to cope with disturbances; SOP max,i This represents the maximum available charge / discharge power (SOP) of the battery cluster connected to the i-th PCS. max P out,i This represents the current real-time output power P of the battery cluster connected to the i-th PCS. out ;

[0020] When the system is charging, SOP max,i Take the absolute value of the maximum charging power limit, P out,i Take the absolute value of the current charging power.

[0021] Furthermore, in the electrochemical state-aware energy storage PCS droop control method, step S3 includes:

[0022] S31. Based on the DC internal resistance R of each battery cluster bat Calculate the average DC internal resistance R of the batteries for all PCS operating in parallel. avg :

[0023] ;

[0024] Where n is the number of PCS operating in parallel, R bat,i R represents the DC internal resistance of the battery cluster connected to the i-th PCS. bat ;

[0025] S32. Construct the comprehensive adjustment factor δ of the i-th PCS. i :

[0026] ;

[0027] Where ε is a preset positive decimal number used to prevent division by zero errors; δ i The larger the value, the more severe the PCS aging and the smaller the dynamic margin, and the less additional power it should bear in transient disturbances.

[0028] Furthermore, in the electrochemical state-aware energy storage PCS droop control method, step S4 includes:

[0029] S41. Real-time detection of power grid frequency deviation Δf=|f-f0|, where f is the real-time frequency of the power grid and f0 is the rated frequency;

[0030] S42, when Δf ≤ Δf th When the system is determined to be in steady state, each PCS adopts a rated droop coefficient m0 ​​to ensure the accurate execution of steady-state power dispatch commands issued by the EMS; where Δf th This indicates the preset frequency deviation threshold;

[0031] S43, when Δf > Δf th When the system is determined to be in a transient disturbance state, the droop coefficient of each PCS is determined according to the comprehensive adjustment factor δ. i Perform adaptive correction:

[0032] m i =m0×δ i ;

[0033] Where, m i This represents the droop coefficient after adaptive correction;

[0034] S44. Under the same grid frequency deviation Δf, calculate the transient disturbance power ΔP of each PCS according to the following formula. i To achieve differentiated allocation of transient disturbance power among different PCS:

[0035] .

[0036] Furthermore, in the electrochemical state-aware energy storage PCS droop control method, in step S42, when Δf changes from less than or equal to Δf... th Rise to greater than Δf th +Δf hys When Δf occurs, the system transitions from a steady state to a transient disturbance state; where Δf hys Indicates the hysteresis width;

[0037] In S43, when Δf is greater than Δf th Decrease to less than or equal to Δf th -Δf hys At this time, the system switches from a transient disturbance state to a steady state.

[0038] Furthermore, in the electrochemical state-aware energy storage PCS droop control method, step S5 includes:

[0039] S51. Real-time verification of whether the transient disturbance power of each PCS exceeds the upper limit of SOP. max,i :

[0040] If it's the discharge direction, then check if P... out,i +ΔPi≤SOP max,i ;

[0041] If it's the charging direction, then check if |P out,i +ΔPi|≤|SOP max,i |;

[0042] S52. If the verification passes, the droop coefficient after the adaptive correction in S4 is maintained.

[0043] S53. If the verification fails, the comprehensive adjustment factor δ of the corresponding PCS will be forcibly adjusted. i Converge towards 1, so that its droop coefficient is restored to m0 or higher than m0, thereby reducing its disturbance power load;

[0044] S54. If the SOP limit is still exceeded after adjustment in S53, the coordinated derating mode is triggered, and the total disturbance power demand of all parallel PCS is redistributed according to the SOP margin ratio of each PCS.

[0045] S55. If the total disturbance support capacity of the system still cannot meet the grid demand after coordinated derating, the power limiting operation mode is triggered, and the power command is actively limited to SOP. max,i Within this range, a power-limited status signal is reported to the EMS.

[0046] Furthermore, in the electrochemical state-aware energy storage PCS droop control method, after step S5, the method further includes:

[0047] S6: Return to execute S1-S5, and dynamically update the comprehensive adjustment factor δ. i The droop coefficient of each PCS.

[0048] Furthermore, in the electrochemical state-aware energy storage PCS droop control method, step S6 includes:

[0049] S61. Employing a dual update mechanism of event triggering and periodic updates, return to execute steps S1-S5 to dynamically update the comprehensive adjustment factor δ. i The droop coefficient of each PCS;

[0050] S62. The droop coefficients of each PCS are updated smoothly using a first-order inertial filter:

[0051] ;

[0052] Where, m i (t) represents the droop coefficient of the i-th PCS actually put into use at the current time t; t represents the current time; α represents the filter coefficient; Δt represents the control period; m i,target This represents the target sagging coefficient.

[0053] Furthermore, in the electrochemical state-aware energy storage PCS droop control method, the event triggering conditions include at least one of the following:

[0054] The change in the state of charge (SOC) of any battery cluster exceeds a preset SOC threshold ΔSOC. th ;

[0055] The change in the state of health (SOH) of any battery cluster exceeds the preset SOH threshold ΔSOH. th ;

[0056] The maximum available charge / discharge power (SOP) of any battery cluster. max The amount of change exceeds the preset SOP max Threshold ΔSOP th ;

[0057] The DC internal resistance R of any battery cluster bat The change exceeds the preset R bat Threshold ΔR th ;

[0058] The system's charging and discharging states have switched.

[0059] Furthermore, in the electrochemical state-aware energy storage PCS droop control method, the periodic update is performed every fixed time interval T. update .

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] 1. It fills the control gap between EMS steady-state scheduling and PCS transient response. This invention is the first to introduce the SOP dynamic margin of BMS into the transient droop control of PCS. By reflecting the degree to which each PCS approaches the upper limit of SOP in real time through the dynamic power margin coefficient, it realizes battery capability perception and control adaptation across the entire time scale, fundamentally solving the control blind spot problem of "constrained in steady state, unconstrained in transient state".

[0062] 2. It achieves differentiated allocation under transient disturbances, avoiding overload of aging batteries. By comprehensively adjusting the factor to integrate battery internal resistance (reflecting the degree of aging) and dynamic margin (reflecting the degree of approaching the upper limit of SOP), healthy batteries contribute more power during transient disturbances, while aging batteries contribute less, eliminating the "weakest link" risk in parallel systems.

[0063] 3. Steady-state and transient control modes operate independently. In steady-state mode, a fixed droop coefficient is maintained to ensure accurate execution of EMS scheduling commands. In transient mode, the droop coefficient is adaptively adjusted to achieve intelligent disturbance allocation. The two modes switch smoothly through a hysteresis mechanism, ensuring both steady-state accuracy and transient optimization.

[0064] 4. Real-time verification of SOP hard constraints ensures absolute safety. Based on adaptive adjustment, a real-time verification mechanism for the SOP upper limit is added to ensure that the PCS transient power does not exceed the SOP hard limit given by the BMS under any circumstances, avoiding the passive protection mode of "limit exceeding first, then tripping" in traditional solutions.

[0065] 5. Enabled collaboration between BMS and PCS on the transient time scale. The SOP information of BMS was expanded from "only used for EMS steady-state scheduling" to "also used for PCS transient control", opening up a direct control channel between BMS and PCS, and realizing deep collaboration between the battery management system and the converter control system on the transient time scale.

[0066] 6. Effectively extends battery life and enhances the system's overall lifecycle value. When the battery is in poor condition, it proactively reduces the transient disturbance load on the PCS, minimizing the impact of high-rate shocks and excessive stress on the battery, effectively slowing down battery aging and extending the effective service life of the energy storage system.

[0067] 7. Quantitative effect verification shows that after adopting the present invention, under the same frequency drop scenario, the SOP margin of the aged PCS can be kept within a safe range, successfully avoiding the risk of tripping, and the system continues to operate stably.

[0068] 8. Excellent engineering compatibility and low implementation cost. This invention does not rely on modifications to the main circuit of the energy storage converter or the hardware topology of the battery system. It only requires adding corresponding software algorithm modules to the PCS controller, thus possessing excellent engineering compatibility and portability. Attached Figure Description

[0069] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0070] Figure 1 This is one of the flowcharts of a PCS droop control method based on electrochemical state sensing provided in an embodiment of the present invention;

[0071] Figure 2 This is the second schematic flowchart of a PCS droop control method based on electrochemical state sensing provided in an embodiment of the present invention. Detailed Implementation

[0072] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0073] Please refer to Figure 1 This is a schematic flowchart illustrating a PCS sag control method based on electrochemical state sensing provided in an embodiment of the present invention. The method specifically includes the following steps:

[0074] S1. Real-time acquisition of electrochemical state parameters and power state boundary information of the battery clusters connected to each PCS; wherein, the electrochemical state parameters include battery state of charge (SOC), battery state of health (SOH), and battery DC internal resistance R. bat Current real-time output power P of the battery out and battery temperature T bat The power state boundary information includes the upper limit of the battery's current available charge / discharge power (SOP). max .

[0075] It should be noted that this step aims to establish a real-time data channel between the PCS controller and the BMS, providing fundamental data support for subsequent dynamic power margin calculations and the construction of integrated regulation factors. By moving the BMS's electrochemical state sensing capability forward to the PCS transient control layer, the technical gap in traditional control architectures where BMS information is only used for EMS steady-state scheduling and does not participate in PCS transient response is filled.

[0076] The battery's state of charge (SOC) ranges from 0% to 100%; the battery's state of health (SOH) ranges from 0% to 100%; the battery's DC internal resistance R... bat Real-time acquisition through online identification can employ recursive least squares or extended Kalman filtering; the current available charge / discharge power limit (SOP) of the battery. max The current real-time output power P of the battery is calculated and distributed in real time by the BMS. out A positive value indicates discharge, and a negative value indicates charging; battery temperature T bat These parameters are used as monitoring parameters to assist in judgment; they are acquired in real time through the communication bus between the PCS and BMS (such as CAN bus or Modbus); the sampling period is consistent with the control period (typically 10ms), ensuring the real-time response to transient disturbances.

[0077] Online identification of the battery's DC internal resistance Rbat is a key technical step in this process, and its accuracy directly affects the accuracy of the subsequent comprehensive adjustment factor.

[0078] The definition of power direction (positive discharge, negative charge) provides a unified mathematical benchmark for the calculation of the dynamic power margin coefficient in S2.

[0079] S2. Based on the current available charge / discharge power limit SOP of the battery max and the current real-time output power P of the battery out Calculate the dynamic power margin factor κ for each PCS. i .

[0080] It should be noted that this step aims to quantify the remaining capacity of each PCS to cope with subsequent power disturbances at the current operating point, providing a first dimension of adjustment basis for subsequent differentiated power allocation.

[0081] In S2, the dynamic power margin coefficient κ i The calculation formula is:

[0082] ;

[0083] Among them, κ i ∈[0,1], representing the remaining capacity of the i-th PCS at the current operating point to cope with subsequent power disturbances, κ i The closer to 1, the greater the margin; κ i The closer the coefficient is to 0, the closer it is to the SOP (Start of Production) limit, and the weaker its ability to cope with disturbances. This coefficient enables real-time quantitative perception of the battery power boundary state and is a key bridge connecting the BMS power state boundary and the PCS transient control; SOP max,i This represents the maximum available charge / discharge power (SOP) of the battery cluster connected to the i-th PCS. max P out,iThis represents the current real-time output power P of the battery cluster connected to the i-th PCS. out ;

[0084] When the system is charging, SOP max,i Take the absolute value of the maximum charging power limit, P out,i Take the absolute value of the current charging power to ensure consistency in the calculation.

[0085] S3. Based on the DC internal resistance R of each battery cluster bat and the dynamic power margin coefficient κ i Construct the comprehensive adjustment factor δ for each PCS i .

[0086] It should be noted that this step aims to integrate the degree of battery aging (reflected by DC internal resistance) with the dynamic power margin (reflected by κ). i (Reflection), construct a comprehensive adjustment factor that can fully characterize the transient power carrying capacity of the PCS, and provide a unified adjustment variable for the adaptive correction of the droop coefficient.

[0087] S3 can be further refined to include the following sub-steps:

[0088] S31. Based on the DC internal resistance R of each battery cluster bat Calculate the average DC internal resistance R of the batteries for all PCS operating in parallel. avg :

[0089] ;

[0090] Where n is the number of PCS operating in parallel, R bat,i R represents the DC internal resistance of the battery cluster connected to the i-th PCS. bat ;

[0091] S32. Construct the comprehensive adjustment factor δ of the i-th PCS. i :

[0092] ;

[0093] Where ε is a preset positive decimal number used to prevent division by zero errors; δ i A larger value indicates more severe PCS aging (relatively higher battery internal resistance) and a smaller dynamic margin, meaning it should bear less additional power during transient disturbances.

[0094] By using the product of internal resistance normalization and the inverse of the margin, a dual weighted fusion of aging degree and power boundary state is achieved.

[0095] S4. Real-time detection of grid frequency deviation Δf, and determination of system operating mode based on the grid frequency deviation Δf; when determined to be in steady state, each PCS calculates the transient disturbance power of each PCS using the rated droop coefficient m0; when determined to be in transient disturbance state, the integrated adjustment factor δ is used. i The droop coefficient of each PCS is adaptively corrected, and the transient disturbance power of each PCS is calculated.

[0096] It should be noted that S4 can be further refined to include the following sub-steps:

[0097] It should be noted that this step aims to achieve mode-specific control for steady-state operation and transient disturbances: ensuring accurate execution of EMS scheduling commands in steady state, and implementing differentiated power allocation based on battery status in transient state.

[0098] S41. Real-time detection of power grid frequency deviation Δf=|f-f0|, where f is the real-time frequency of the power grid and f0 is the rated frequency.

[0099] It should be further noted that the real-time frequency of the power grid is obtained through the phase-locked loop or frequency measurement unit inside the PCS; the rated frequency is 50Hz or 60Hz.

[0100] S42, when Δf ≤ Δf th When the system is determined to be in steady state, each PCS adopts a rated droop coefficient m0 ​​to ensure the accurate execution of steady-state power dispatch commands issued by the EMS; where Δf th This indicates the preset frequency deviation threshold.

[0101] It should be further noted that the typical value for the frequency deviation threshold is 0.02Hz.

[0102] In one implementation, to prevent frequent switching of control modes due to small frequency fluctuations near the threshold, a hysteresis mechanism is introduced. In S42, when Δf changes from less than or equal to Δf... th Rise to greater than Δf th +Δf hys When Δf occurs, the system transitions from a steady state to a transient disturbance state; where Δf hys This indicates the hysteresis width, with a typical value of 0.005Hz;

[0103] S43, when Δf > Δf th When the system is determined to be in a transient disturbance state, the droop coefficient of each PCS is determined according to the comprehensive adjustment factor δ. i Perform adaptive correction:

[0104] m i =m0×δ i ;

[0105] Where, mi This represents the droop coefficient after adaptive correction.

[0106] It should be further explained that, namely .

[0107] In one implementation, in S43, when Δf is greater than Δf th Decrease to less than or equal to Δf th -Δf hys At this time, the system switches from a transient disturbance state to a steady state.

[0108] S44. Under the same grid frequency deviation Δf, calculate the transient disturbance power ΔP of each PCS according to the following formula. i To achieve differentiated allocation of transient disturbance power among different PCS:

[0109] .

[0110] It should be further explained that δ i The larger the PCS (severe aging, small margin), the greater the sag factor m. i The larger the value (the "softer" the droop characteristic), the greater the disturbance power ΔP it bears under the same grid frequency deviation. i The smaller; δ i The smaller the PCS (healthier, larger margin), the greater the droop factor m. i The smaller the droop (the "stiffer" the droop characteristic), the greater the disturbance power ΔP it can handle. i The larger the value, the more differentiated the allocation of transient disturbances, allowing for the principle of "the capable to do more work and the weak to do less work."

[0111] Steady-state fixed droop ensures scheduling accuracy, while transient adaptive droop achieves optimized allocation. The two modes switch smoothly through a hysteresis mechanism without interfering with each other.

[0112] When the grid frequency drops, each PCS responds differently according to its own capabilities, which not only ensures the frequency support effect, but also avoids overload of individual PCS.

[0113] S5. Real-time verification of whether the transient disturbance power of each PCS exceeds the upper limit of SOP. If it does, implement safety protection measures.

[0114] It should be noted that a real-time verification mechanism for SOP hard constraints is added on the basis of adaptive adjustment to ensure that the PCS transient power does not exceed the SOP hard limit given by the BMS under any circumstances, thus avoiding the passive protection mode of "first exceeding the limit, then tripping" in the traditional scheme.

[0115] S5 can be further refined to include the following sub-steps:

[0116] S51. Real-time verification of whether the transient disturbance power of each PCS exceeds the upper limit of SOP. max,i :

[0117] If it's the discharge direction, then check if P... out,i +ΔPi≤SOP max,i ;

[0118] If it's the charging direction, then check if |P out,i +ΔPi|≤|SOP max,i |

[0119] S52. If the verification passes, the droop coefficient after the adaptive correction in S4 is maintained.

[0120] It should be further noted that this step involves continuing the differential allocation process.

[0121] S53. If the verification fails, the comprehensive adjustment factor δ of the corresponding PCS will be forcibly adjusted. i Converge towards 1, so that its droop coefficient is restored to m0 or higher, thereby reducing its disturbance power load.

[0122] S54. If the SOP limit is still exceeded after adjustment in S53, the coordinated derating mode is triggered, and the total disturbance power demand of all parallel PCS is redistributed according to the SOP margin ratio of each PCS.

[0123] It should be further noted that this step ensures that none of the PCS exceed the limits. Specifically, the disturbance power of each PCS is redistributed as follows:

[0124] .

[0125] S55. If the total disturbance support capacity of the system still cannot meet the grid demand after coordinated derating, the power limiting operation mode is triggered, and the power command is actively limited to SOP. max,i Within this range, a power-limited status signal is reported to the EMS.

[0126] It should be further explained that a complete protection gradient can be formed by adaptive adjustment of a single PCS → coordinated derating and redistribution → power-limited operation and reporting.

[0127] These steps also ensure that all PCS do not exceed limits, fundamentally eliminating the risk of tripping due to transient overload.

[0128] Because the power redistribution among parallel PCS is considered in the protection action, the excessive weakening of the overall frequency support capability of the system by a single-point protection action is avoided.

[0129] Please refer to Figure 2In one embodiment, after S5, the method further includes:

[0130] S6: Return to execute S1-S5, and dynamically update the comprehensive adjustment factor δ. i The droop coefficient of each PCS.

[0131] It should be noted that this step aims to establish a closed-loop iterative mechanism for the control method, enabling the droop coefficient of the PCS to be continuously updated with the dynamic evolution of the battery's electrochemical state, thus avoiding the control mismatch problem caused by "one-time calculation and long-term fixation" of control parameters. By periodically or event-wise re-executing S1-S5, it is ensured that the power allocation strategy under transient disturbances always matches the latest battery state, thereby maintaining a differentiated allocation effect of "more work for the capable and less work for the weak" across the entire time scale.

[0132] Specifically, after each safety protection verification in S5 is completed, the control process does not terminate, but returns to S1 to re-collect the latest electrochemical state parameters and power state boundary information of the battery clusters connected to each PCS, and then recalculates the dynamic power margin coefficient κ sequentially. i Comprehensive regulating factor δ i droop coefficient m i and transient disturbance power ΔP i This forms a closed-loop control circuit of "sensing-computing-execution-verification-re-sensing".

[0133] S6 can be further refined to include the following sub-steps:

[0134] S61. Employing a dual update mechanism of event triggering and periodic updates, return to execute steps S1-S5 to dynamically update the comprehensive adjustment factor δ. i The droop coefficient of each PCS.

[0135] It should be further explained that this step aims to address the "when to update" triggering strategy. Simple periodic updates may lag when the battery state changes drastically; simple event triggering may not update in a timely manner when the state drifts slowly. This dual mechanism balances timeliness of response with economical use of computational resources.

[0136] The conditions for triggering the event include at least one of the following:

[0137] The change in the state of charge (SOC) of any battery cluster exceeds a preset SOC threshold ΔSOC. th ;

[0138] The change in the state of health (SOH) of any battery cluster exceeds the preset SOH threshold ΔSOH. th ;

[0139] The maximum available charge / discharge power (SOP) of any battery cluster. max The amount of change exceeds the preset SOP max Threshold ΔSOP th ;

[0140] The DC internal resistance R of any battery cluster bat The change exceeds the preset R bat Threshold ΔR th ;

[0141] The system's charging and discharging states have switched.

[0142] The periodic update is performed every fixed time interval T. update That is, regardless of whether the above events occur, a fixed time interval T is used. update Force a re-execution of S1-S5 as a fallback update strategy when the state drifts slowly.

[0143] It is understandable that when the battery state changes rapidly (such as a sudden drop in SOC due to high-power charging and discharging, or a sudden rise in temperature leading to SOP), the battery will be in a state of emergency. max (Shrinkage), the event-triggered mechanism ensures that the droop coefficient is updated within milliseconds to seconds, avoiding the risk of overload due to control lag;

[0144] In scenarios such as slow battery aging or self-discharge during rest, the periodic update mechanism ensures that the droop coefficient will not stagnate for a long time, maintaining the long-term accuracy of control.

[0145] The dual mechanism reduces unnecessary frequent calculations, lowering the computational burden on the PCS controller and the load on the communication bus.

[0146] S62. The droop coefficients of each PCS are updated smoothly using a first-order inertial filter:

[0147] ;

[0148] Where, m i (t) represents the droop coefficient of the i-th PCS actually put into use at the current time t; t represents the current time; α represents the filter coefficient; Δt represents the control period; m i,target This represents the target sagging coefficient.

[0149] It should be further explained that this step aims to address the smoothness issue of "how to update". The droop coefficient of each PCS is updated continuously and smoothly as the battery state changes, and system oscillations caused by abrupt coefficient changes are avoided through first-order inertial filtering.

[0150] This filtering process limits the rate of change of the droop coefficient to a physically feasible range, avoiding power surges caused by sudden changes in the coefficient.

[0151] Although this invention uses terms such as PCS and periodic updates frequently, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of this invention; interpreting them as any additional limitation would contradict the spirit of this invention.

[0152] This invention provides a droop control method for energy storage PCS based on electrochemical state perception. By acquiring the electrochemical state parameters and power state boundary information of the battery management system in real time, a dynamic power margin coefficient and a comprehensive adjustment factor are constructed to achieve steady-state and transient mode control and differentiated power allocation. It is supplemented by real-time verification and safety protection mechanism of SOP hard constraint, thereby achieving intelligent transient disturbance allocation with more power output from healthy batteries and less power output from aged batteries while ensuring system safety.

[0153] Finally, it should be noted that although the above embodiments have been described in the description and drawings of this invention, this should not limit the scope of patent protection of this invention. Any technical solutions that are based on the essential concept of this invention, utilize the content described in the description and drawings of this invention to make equivalent structural or procedural substitutions or modifications, as well as the direct or indirect application of the technical solutions of the above embodiments to other related technical fields, are all included within the scope of patent protection of this invention.

Claims

1. A PCS sag control method based on electrochemical state sensing, characterized in that, The method includes: S1. Real-time acquisition of electrochemical state parameters and power state boundary information of the battery clusters connected to each PCS; wherein, the electrochemical state parameters include battery state of charge (SOC), battery state of health (SOH), and battery DC internal resistance R. bat Current real-time output power P of the battery out and battery temperature T bat The power state boundary information includes the upper limit of the battery's current available charge / discharge power (SOP). max ; S2. Based on the current available charge / discharge power limit SOP of the battery max and the current real-time output power P of the battery out Calculate the dynamic power margin factor κ for each PCS. i ; S3. Based on the DC internal resistance R of each battery cluster bat and the dynamic power margin coefficient κ i Construct the comprehensive adjustment factor δ for each PCS i ; S4. Real-time detection of grid frequency deviation Δf, and determination of system operating mode based on the grid frequency deviation Δf; when determined to be in steady state, each PCS calculates the transient disturbance power of each PCS using the rated droop coefficient m0; when determined to be in transient disturbance state, the integrated adjustment factor δ is used. i Adaptive correction is performed on the droop coefficient of each PCS, and the transient disturbance power of each PCS is calculated. S5. Real-time verification of whether the transient disturbance power of each PCS exceeds the upper limit of SOP. If it does, implement safety protection measures.

2. The method for controlling the droop of an energy storage PCS based on electrochemical state sensing according to claim 1, characterized in that, In S2, the dynamic power margin coefficient κ i The calculation formula is: ； Among them, κ i ∈[0,1], representing the remaining capacity of the i-th PCS at the current operating point to cope with subsequent power disturbances, κ i The closer to 1, the greater the margin; κ i The closer it is to 0, the closer it is to the upper limit of SOP (Standard Operating Procedure), and the weaker its ability to cope with disturbances; SOP max,i This represents the maximum available charge / discharge power (SOP) of the battery cluster connected to the i-th PCS. max P out,i This represents the current real-time output power P of the battery cluster connected to the i-th PCS. out ; When the system is charging, SOP max,i Take the absolute value of the maximum charging power limit, P out,i Take the absolute value of the current charging power.

3. The method for controlling the droop of an energy storage PCS based on electrochemical state sensing according to claim 1, characterized in that, S3 includes: S31. Based on the DC internal resistance R of each battery cluster bat Calculate the average DC internal resistance R of the batteries for all PCS operating in parallel. avg : ； Where n is the number of PCS operating in parallel, R bat,i R represents the DC internal resistance of the battery cluster connected to the i-th PCS. bat ; S32. Construct the comprehensive adjustment factor δ of the i-th PCS. i : ； Where ε is a preset positive decimal number used to prevent division by zero errors; δ i The larger the value, the more severe the PCS aging and the smaller the dynamic margin, and the less additional power it should bear in transient disturbances.

4. The method for controlling the droop of an energy storage PCS based on electrochemical state sensing according to claim 1, characterized in that, S4 includes: S41. Real-time detection of power grid frequency deviation Δf=|f-f0|, where f is the real-time frequency of the power grid and f0 is the rated frequency; S42, when Δf ≤ Δf th When the system is determined to be in steady state, each PCS adopts a rated droop coefficient m0 ​​to ensure the accurate execution of steady-state power dispatch commands issued by the EMS; where Δf th This indicates the preset frequency deviation threshold; S43, when Δf > Δf th When the system is determined to be in a transient disturbance state, the droop coefficient of each PCS is determined according to the comprehensive adjustment factor δ. i Perform adaptive correction: m i =m0×δ i ; Where, m i This represents the droop coefficient after adaptive correction; S44. Under the same grid frequency deviation Δf, calculate the transient disturbance power ΔP of each PCS according to the following formula. i To achieve differentiated allocation of transient disturbance power among different PCS: 。 5. The method for controlling the droop of an energy storage PCS based on electrochemical state sensing according to claim 4, characterized in that, In S42, when Δf is less than or equal to Δf th Rise to greater than Δf th +Δf hys When Δf occurs, the system transitions from a steady state to a transient disturbance state; where Δf hys Indicates the hysteresis width; In S43, when Δf is greater than Δf th Decrease to less than or equal to Δf th -Δf hys At this time, the system switches from a transient disturbance state to a steady state.

6. The method for controlling the droop of an energy storage PCS based on electrochemical state sensing according to claim 1, characterized in that, S5 includes: S51. Real-time verification of whether the transient disturbance power of each PCS exceeds the upper limit of SOP. max,i : If it's the discharge direction, then check if P... out,i +ΔPi≤SOP max,i ; If it's the charging direction, then check if |P out,i +ΔPi|≤|SOP max,i |; S52. If the verification passes, the droop coefficient after the adaptive correction in S4 is maintained. S53. If the verification fails, the comprehensive adjustment factor δ of the corresponding PCS will be forcibly adjusted. i Converge towards 1, so that its droop coefficient is restored to m0 or higher than m0, thereby reducing its disturbance power load; S54. If the SOP limit is still exceeded after adjustment in S53, the coordinated derating mode is triggered, and the total disturbance power demand of all parallel PCS is redistributed according to the SOP margin ratio of each PCS. S55. If the total disturbance support capacity of the system still cannot meet the grid demand after coordinated derating, the power limiting operation mode is triggered, and the power command is actively limited to SOP. max,i Within this range, a power-limited status signal is reported to the EMS.

7. The method for controlling the droop of an energy storage PCS based on electrochemical state sensing according to claim 1, characterized in that, Following S5, the method further includes: S6: Return to execute S1-S5, and dynamically update the comprehensive adjustment factor δ. i The droop coefficient of each PCS.

8. The method for controlling the droop of an energy storage PCS based on electrochemical state sensing according to claim 7, characterized in that, S6 includes: S61. Employing a dual update mechanism of event triggering and periodic updates, return to execute steps S1-S5 to dynamically update the comprehensive adjustment factor δ. i The droop coefficient of each PCS; S62. The droop coefficients of each PCS are updated smoothly using a first-order inertial filter: ； Where, m i (t) represents the droop coefficient of the i-th PCS actually put into use at the current time t; t represents the current time; α represents the filter coefficient; Δt represents the control period; m i,target This represents the target sagging coefficient.

9. The method for controlling the droop of an energy storage PCS based on electrochemical state sensing according to claim 8, characterized in that, The conditions for triggering the event include at least one of the following: The change in the state of charge (SOC) of any battery cluster exceeds a preset SOC threshold ΔSOC. th ; The change in the state of health (SOH) of any battery cluster exceeds the preset SOH threshold ΔSOH. th ; The maximum available charge / discharge power (SOP) of any battery cluster. max The amount of change exceeds the preset SOP max Threshold ΔSOP th ; The DC internal resistance R of any battery cluster bat The change exceeds the preset R bat Threshold ΔR th ; The system's charging and discharging states have switched.

10. The method for controlling the droop of an energy storage PCS based on electrochemical state sensing according to claim 8, characterized in that, The periodic update is performed every fixed time interval T. update .

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