Distributed energy storage system multi-scene cooperative control method based on fault location and dynamic communication repair

Abstract

The invention discloses a distributed energy storage system multi-scene cooperative control method based on fault location and dynamic communication repair. The method mainly comprises a fault location module, a communication repair module, a communication module, an SOC equalization module, a current sharing control module, a voltage recovery module and a voltage and current double-closed-loop module. The fault positioning module is used for accurately identifying and positioning the fault energy storage unit; self-adaptive matching of a communication network and a system control topology is realized through the communication repairing module; through the communication module, the adjacent energy storage units exchange information, so that the system SOC and the control state quantity average value can be obtained. Through the SOC equalization module, the current sharing control module and the voltage recovery module, SOC equalization of each unit and equal-proportion distribution of output current according to capacity can be realized without sampling the output current, the bus voltage is maintained at a rated value, multiple scenes such as system starting, steady-state operation and fault recovery are adapted, and stable, efficient and cooperative operation of the distributed energy storage system is realized.

Description

Technical Field

[0001] This invention relates to the field of distributed energy storage systems in DC microgrids, and in particular to a multi-scenario collaborative control method for distributed energy storage systems based on fault location and dynamic communication repair. Background Technology

[0002] With the rapid development of the new energy industry, distributed energy storage systems, as a key support for smoothing fluctuations in new energy output and improving energy utilization efficiency, are widely used in microgrids, smart buildings, and other scenarios. However, distributed energy storage systems, which consist of multiple energy storage units operating collaboratively, face numerous technical challenges in actual operation. On the one hand, energy storage units may fail due to battery aging, power device damage, or other reasons. Traditional control methods struggle to quickly and accurately identify and locate faulty units, easily leading to an expansion of the fault range and affecting the overall stability of the system. On the other hand, the system relies on communication networks to achieve collaborative control between units. When some units fail and exit the network, the original communication topology will be broken. If the communication link cannot be reconstructed and adapted to the current operating state in a timely manner, data interaction will be interrupted, leading to the failure of the control strategy. To address this, this invention proposes a multi-scenario collaborative control method for distributed energy storage systems based on fault location and dynamic communication repair. By constructing a fault location module, it achieves accurate identification of abnormal or faulty units. Combined with a communication repair module, it completes dynamic reconstruction and adaptation of the communication topology. Furthermore, it integrates State-of-Charge (SOC) balancing, current sharing, and voltage recovery control functions. Without relying on output current sampling, it achieves SOC balancing for each energy storage unit and proportional distribution of output current according to the energy storage unit capacity, while maintaining the bus voltage to its rated value. This effectively solves the limitations of traditional control methods in fault response, communication adaptation, and balancing control, enabling stable, efficient, and collaborative operation of the system in various complex scenarios. Summary of the Invention

[0003] To achieve the above objectives, the technical solution provided by this invention is as follows: Step S1: The energy storage unit is connected to the corresponding DC / DC converter and line resistor. R Linep Connected in parallel to the DC bus, and with distributed power sources P DG and constant power load P CPL Energy interaction is performed, and at the beginning of each sampling period, the inductor current of the p-th energy storage unit is... i Lp Output voltage v cp Output current i cp State of charge SOCIETYp and DC bus voltage v bus Sampling is performed separately, where p is the energy storage unit number, p = i, j, k, q. In this invention, only the i-th energy storage unit is selected as an example for illustration. It should be noted that the remaining j-th, k-th, and q-th energy storage units are all applicable under the method framework of this invention. Step S2: In the fault location module, the output current of the p-th energy storage unit is... i cp The original value of the derivative of the state of charge of the p-th energy storage unit SOCIETY dp As input, after being processed by the energy storage unit fault location method, a fault location command is output. L p The specific details of the energy storage unit fault location method are as follows: Step S2-1: First, perform signal preprocessing, that is,... SOCIETY dp A first-order low-pass filter is performed to obtain the derivative of the state of charge of the filtered energy storage unit. SOCIETY dfp Its expression is: (1) In equation (1), τ This is the filtering time constant, used to suppress misjudgments caused by high-frequency noise. T s The sampling period is SOCIETY dfsp This is the derivative of the state of charge of the energy storage unit after filtering at the previous moment, used for recursive calculations; Step S2-2: Set the fault current threshold b Small threshold of the derivative of the state of charge β When either condition 1 or condition 2 in the fault determination expression is met, the p-th energy storage unit is determined to be faulty, and the fault location module outputs a fault location command. L p =1, otherwise, output fault location command. L p =0, where the fault determination expression is: (2) Step S3: In the communication repair module, the fault location command is... L p As input, after processing by the communication network repair and control method, the output is a communication link reconfiguration instruction set. S r This is applied to the consensus algorithm in the communication module. The specific details of the communication network repair control method are as follows: Step S3-1: First, collect fault location commands for each energy storage unit in real time. L p The number of normal energy storage units in the statistical system ,in, N The total number of energy storage units, and V is based on the number of normally functioning energy storage units in the system. normal The communication link reconfiguration logic is defined as follows: When the number of normal energy storage units V in the system... normal When the number of energy storage units is 4, the energy storage system operates normally, and the energy storage units communicate in a four-source ring structure. When the number of normally functioning energy storage units V... normal When the number of normal energy storage units is 3, the communication link with the faulty unit is disconnected, and the remaining three normal energy storage units are reconfigured into a three-source ring communication structure. When the number of normal energy storage units in the system is V... normal When the number of normal energy storage units is 2, the communication link with the faulty unit is disconnected, and the remaining two normal energy storage units are reconfigured to a two-source linear communication structure. When the number of normal energy storage units in the system is V... normal <2. Because the system cannot form an effective communication link, the energy storage system triggers the protection mechanism and stops operating; Step S3-2: Based on the communication link reconfiguration logic in step S3-1, output the communication link reconfiguration instruction set. S r ={ S ij , S jk , S kq , S qi | S ik , S jq}, and directly apply to the consensus algorithm, where, S ij , S jk , S kq , S qi Defined as basic link commands, these correspond to the basic communication links between energy storage units i and j, j and k, k and q, and q and i, respectively. S ik , S jq Defined as a link repair command, corresponding to the link repair between energy storage units i and k, and j and q respectively. The link connection and disconnection rules are as follows: when S ag =1 indicates that the communication link between energy storage units a and g is in a closed state. S ag=0 indicates that the communication link between energy storage units a and g is disconnected, where the values ​​of a and g are i, j, k, and q, and a is not equal to g; Step S4: In the communication module, the state of charge of the energy storage unit is... SOCIETY i Virtual control variables ζ i and communication link reconfiguration instruction set S r As input, the average state of charge of the energy storage unit is obtained through iterative calculation using a consensus algorithm. SOCIETY ai and the average value of virtual control variables ζ ai The expression for the consensus algorithm is: (3) In equation (3), Y ij Let be the average virtual state deviation between the i-th energy storage unit and its adjacent j-th energy storage unit after the communication delay. Y Rij Let be the average virtual state deviation between the i-th and j-th energy storage units after the link update, 1 / ( T t s +1) represents the communication delay stage, where... T t To reduce communication delay between different energy storage units, s For Laplace transform complex variable operators, Y aj Let be the average virtual state variable of the i-th energy storage unit in the four-source ring communication between adjacent j-th energy storage units. Y iq Let be the average virtual state deviation between the i-th energy storage unit and its adjacent q-th energy storage unit after the communication delay. Y Riq Let be the average virtual state deviation after the link update between the i-th and q-th energy storage units. Y aq Let be the average virtual state variable of the i-th energy storage unit in the four-source ring communication with the q-th adjacent energy storage unit. Y ik Let be the average virtual state deviation of the i-th energy storage unit and the j-th energy storage unit that are not adjacent to it after the communication delay. Y Rik Let be the average virtual state deviation after the link update between the i-th and k-th energy storage units. Y ak Let be the average virtual state variable of the i-th energy storage unit in the four-source ring communication system, which is not adjacent to the k-th energy storage unit. Yi =[ SOCIETY i , ζ i [] represents the virtual state variable of the i-th energy storage unit. Y ai =[ SOCIETY ai , ζ ai [ ] represents the average virtual state variable of the i-th energy storage unit. h Communication step size coefficient; When the number of normal energy storage units in the system is V normal When the value is 4, the energy storage system operates normally, and the communication module receives the communication link reconfiguration instruction set. S r for{ S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0}, the basic communication links of the energy storage units are all closed, and the energy storage units form a four-source ring communication according to the connection order of node identifiers ijkqi. At this time, the i-th energy storage unit is connected and communicates with the adjacent j-th and q-th energy storage units. The expression of the consensus algorithm of the i-th energy storage unit is: (4) When the number of normal energy storage units in the system is V normal When =3, the failure of a single energy storage unit in the energy storage system can be mainly divided into two cases: Case 1 is that the i-th energy storage unit fails in the k-th energy storage unit, which is not adjacent to the i-th energy storage unit in the four-source ring communication. In this case, the communication link reconfiguration instruction set... S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =1, S jk =0, Skq =0, S qi =1| S ik =0, S jq =1}, at this time the basic communication link related to the kth energy storage unit is disconnected, the repair link between the jth and qth units is connected, and the remaining normal units reconstruct the three-source ring communication according to the connection order of the node identifier ijqi. At this time, the ith energy storage unit is still connected and communicated with the adjacent jth and qth energy storage units. The consistency algorithm expression of the ith energy storage unit is the same as that of equation (4). Case 2 is when the i-th energy storage unit experiences a failure in its adjacent j-th or q-th energy storage unit within the four-source ring communication, in which case the communication link reconfiguration instruction set is used. S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =0, S jk =0, S kq =1, S qi =1| S ik =1, S jq =0}(unit j fault) or { S ij =1, S jk =1, S kq =0, S qi =0| S ik =1, S jq =0} (unit q failure), at this time, the basic communication link connected to the j-th or q-th energy storage unit is disconnected, the repair link between the i-th and k-th units is reconnected, and the remaining normal units reconstruct the three-source ring communication according to the connection order of node identifier ikqi (unit j failure) or ijki (unit q failure). At this time, the consensus algorithm expression of the i-th energy storage unit is: (5) When the number of normal energy storage units in the system is V normal When =2, two energy storage units in the energy storage system fail. At this time, the failure types can be divided into: simultaneous failure of energy storage units and time-sharing failure of energy storage units. Among them, simultaneous failure of energy storage units can be further divided into two situations: situation (1) is that the i-th energy storage unit and the j-th and q-th energy storage units adjacent to it in the four-source ring communication both fail at the same time. At this time, the communication link reconfiguration instruction set S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =0, S jk =0, S kq =0, S qi =0| S ik =1, S jq =0}, at this time, the basic communication links of all energy storage units are disconnected, the repair link between the i-th and k-th units is reconnected, and the remaining normal units reconstruct the two-source direct communication according to the connection order of node identifier iki. At this time, the consensus algorithm expression of the i-th energy storage unit is: (6) Case (2) is when the i-th energy storage unit is not adjacent to the k-th energy storage unit in the four-source ring communication, and either the j-th or q-th energy storage unit adjacent to the i-th energy storage unit in the four-source ring communication fails simultaneously. In this case, the communication link reconfiguration instruction set is received. S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to {S ij =0, S jk =0, S kq =0, S qi =1| S ik =0, S jq =0}(faults in units k and j) or { S ij =1, S jk =0, S kq =0, S qi =0| S ik =0, S jq =0} (faults in units k and q), at this time, the basic communication link between the k-th energy storage unit and the faulty unit in the j-th or q-th energy storage unit is disconnected. The remaining normal units reconstruct the two-source direct communication according to the connection order of node identifiers iqi (faults in units k and j) or iji (faults in units k and q). At this time, the consensus algorithm expression of the i-th energy storage unit is: (7) Time-of-use failure of energy storage units refers to a situation where, after the first unit fails, the system recovers stability and operates for a period of time, and then the second unit fails, during which the communication link reconfiguration instruction set is used. S r The consensus algorithm needs to be dynamically updated twice. The time-sharing failure of two energy storage units can also be divided into three cases: Case ① is that the i-th energy storage unit fails first in the four-source ring communication, while the k-th energy storage unit, which is not adjacent to it, fails first. In this stage, the communication link reconstruction instruction set... S r The update status and consensus algorithm of the i-th unit are the same as in case 1 of the single-unit failure. The remaining normal units reconstruct the three-source ring communication according to the connection order of node identifiers ijqi. At this time, the system resumes stable operation based on the updated instruction set and algorithm. After running for a period of time, if any one of the j-th or q-th energy storage units adjacent to the i-th energy storage unit in the four-source ring communication fails again, the communication link reconstruction instruction set will be updated during this stage. S r Depend on{ S ij =1, S jk =0, S kq =0, Sqi =1| S ik =0, S jq =1} is updated to { S ij =0, S jk =0, S kq =0, S qi =1| S ik =0, S jq =0}(unit j fault) or { S ij =1, S jk =0, S kq =0, S qi =0| S ik =0, S jq =0}(unit q fault), at this time the basic communication link connected to the j-th or q-th energy storage unit is disconnected, and the repair link between the j-th and q-th units is disconnected. The communication topology of the energy storage unit is reconstructed from the three-source ring communication of ijqi to the two-source straight communication of iqi(unit j fault) or iji(unit q fault). The consensus algorithm of the i-th energy storage unit is updated from equation (4) to equation (7). The initial stages of scenarios ② and ③ are the same: in both cases, the i-th energy storage unit experiences a failure first in the j-th or q-th adjacent energy storage unit in the four-source ring communication. During this stage, the communication link reconfiguration instruction set... S r The update status and the consensus algorithm of the i-th unit are consistent with Case 2 in the above single-unit failure. The remaining normal units reconstruct the three-source ring communication according to the connection order of node identifiers ikqi (unit j failure) or ijki (unit q failure). At this time, the system resumes stable operation based on the updated instruction set and algorithm. After running for a period of time, the failure development of Case 2 and Case 3 diverges, specifically as follows: In scenario ②, the i-th energy storage unit fails again in the k-th energy storage unit, which is not adjacent to the i-th unit in the four-source ring communication. At this stage, the communication link reconfiguration instruction set... S r Depend on{ S ij =0, S jk =0, S kq =1,S qi =1| S ik =1, S jq =0}(unit j fault) or { S ij =1, S jk =1, S kq =0, S qi =0| S ik =1, S jq =0}(cell q fault) updated to { S ij =0, S jk =0, S kq =0, S qi =1| S ik =0, S jq =0}(Unit j fails first, unit k fails later) or { S ij =1, S jk =0, S kq =0, S qi =0| S ik =0, S jq =0} (unit q fails first, unit k fails later), at this time the basic communication link connected to the kth energy storage unit is disconnected, and the repair link between the ith and kth units is disconnected. The communication topology of the energy storage unit is reconstructed from the three-source ring communication of ikqi (unit j fails) or ijki (unit q fails) to the two-source straight communication of iqi (unit j fails first, unit k fails later) or iji (unit q fails first, unit k fails later). During the entire operation of the system, the consistency algorithm of the ith energy storage unit is first updated from equation (4) to equation (5), and then updated from equation (5) to equation (7). In scenario ③, the adjacent unit (either the q-th or j-th unit) of the i-th energy storage unit in the four-source ring communication fails again. At this stage, the communication link reconfiguration instruction set... S r Depend on{ S ij =0, Sjk =0, S kq =1, S qi =1| S ik =1, S jq =0}(Unit j fails first) or { S ij =1, S jk =1, S kq =0, S qi =0| S ik =1, S jq =0}(Unit q fails first) is uniformly updated to { S ij =0, S jk =0, S kq =0, S qi =0| S ik =1, S jq =0}, at this time the basic communication link connected to the qth or jth energy storage unit is disconnected, and the communication topology of the energy storage unit is uniformly reconstructed from the three-source ring communication of ikqi (unit j fails first) or ijki (unit q fails first) to the two-source straight-line communication of iki. During the entire operation of the system, the consensus algorithm of the ith energy storage unit is first updated from equation (4) to equation (5), and then updated from equation (5) to equation (6). When the number of normal energy storage units in the system is V normal When the value is less than 2, the system cannot form an effective communication link, triggering the protection mechanism and stopping operation. Step S5: In the SOC balancing module, the average state of charge of the energy storage units is calculated. SOCIETY ai Subtract the state of charge of the energy storage unit SOCIETY i The standard deviation of the state of charge of the energy storage unit, d, is obtained. SOCIETY i Then, the standard deviation of the state of charge of the energy storage unit, d SOCIETY i Based on the inductor current of the energy storage unit i Li The positive and negative signs are dynamically selected for output, and the specific logic is as follows: If the inductor current of the energy storage unit is positive... i LiIf the value is greater than zero, it indicates that the energy storage system is in a discharging state. At this time, the switching switch in the SOC equalization module points to port 1, and the standard deviation of the state of charge of the energy storage unit is output as d. SOCIETY i If the inductor current of the energy storage unit i Li If the value is less than zero, it indicates that the energy storage system is in a charging state. At this time, the switching switch in the SOC equalization module points to port 2, and the standard deviation of the state of charge of the energy storage unit is d. SOCIETY i Multiply the product by the coefficient -1, invert the output, take the sine of the result (sin), and then multiply the result by the balance adjustment factor. A The results and process coefficients were obtained. w Multiplying them together yields the equilibrium dominant factor. z process coefficients w The expression is: (8) In equation (8), θ To balance the acceleration factor, μ To balance the precision factor; Among them, the dominant factor of equilibrium z The expression is: (9) Equilibrium dominance factor z Take the equilibrium adjustment index the The transition coefficient is obtained by raising the power of . c Then the transition coefficient c Take the exponential function e x To obtain the equilibrium variables y , balance variables y Multiply by the maximum rated capacity of the energy storage unit C max With the rated capacity of the energy storage unit C bat The ratio is taken, and the result is added to the coefficient 1 to obtain the SOC equilibrium factor Δ. m ki, where SOC equilibrium factor Δ m ki The expression is: (10) Step S6: In the current sharing control module, the inductor current of the energy storage unit is... i Li Divide by the maximum rated inductor current of the energy storage unit i Lmax The result is then divided by the current equalization factor. Q Then multiply the result by the SOC equilibrium factor Δ mki The flow control coefficient is obtained. x i Then subtract the flow control coefficient from the coefficient 1. x i The current equalization factor can be obtained. n i Current equalization factor n i Multiply by DC bus voltage v bus Virtual control variables can be obtained ζ i Among them, virtual control variables ζ i The expression is: (11) Step S7: In the voltage recovery module, average the virtual control variable. ζ ai Input, and current equalization factor n i Divide them to obtain the voltage balance. v ai DC bus voltage reference value v ref Subtract voltage balance v ai Then, it goes through a voltage recovery stage controlled by a PI controller. G N (s) yields the voltage recovery regulation amount. v fi ; Step S8: In the voltage and current dual closed-loop module, adjust the voltage recovery amount. v fi As input, and compared with the DC bus voltage reference value v ref Add them together, then subtract the output voltage of the energy storage unit. v ci The result is passed through a voltage outer loop PI controller. G V (s) Obtain the reference current of the inner current loop. i refi The inner loop reference current will be used. i refi With SOC equilibrium factor Δ m ki Multiply the results and subtract the inductor current of the energy storage unit from the result. i Li Then it goes through a current inner loop PI controller. G I (s), the result is passed through a limiting circuit to obtain the driving voltage. vsi , drive voltage v si After passing through PWM Modulation can output a stable and reliable modulated signal. d ti .

[0004] Furthermore, in step S2, the filtering time constant τ The value range is 0.1 < τ <1.5, sampling period T s The value range is 0.0001 < T s <0.01, fault current threshold b The value range is 0.01 < b <0.1, small threshold of the derivative of the state of charge β The value range is 0.0001 < β <0.01; In step S4, the communication step size coefficient h The range of values ​​is 0 < h <1, Communication delay between different energy storage units T t The value range is 0.0001 < T t <0.01; In step S5, the balancing adjustment factor A The value range is 0.3 < A <0.9, equilibrium acceleration factor θ The value range is 0.2 < θ <0.7, Balanced Precision Factor μ The value range is 0.0001 < μ <0.01, equilibrium adjustment index the The value range is 0.1 < the <1; In step S6, the current averaging factor Q The value range is 10 < Q <22.

[0005] Compared with existing technologies, the principles and advantages of this solution are as follows: This invention discloses a multi-scenario collaborative control method for distributed energy storage systems based on fault location and dynamic communication repair. It mainly includes a fault location module, a communication repair module, a communication module, a SOC balancing module, a current sharing control module, a voltage recovery module, and a voltage and current dual closed-loop module. The fault location module accurately identifies and locates faulty energy storage units; the communication repair module achieves adaptive matching between the communication network and the system control topology; the communication module enables adjacent energy storage units to exchange information to obtain the average value of system SOC and control state variables; and the SOC balancing module, current sharing control module, and voltage recovery module achieve SOC balancing of each unit and proportional distribution of output current according to capacity without sampling output current, while maintaining the bus voltage at its rated value. This method adapts to multiple scenarios such as system startup, steady-state operation, and fault repair, enabling stable, efficient, and collaborative operation of the distributed energy storage system. Attached Figure Description

[0006] Figure 1 This is the main circuit diagram of the distributed energy storage system in an embodiment of the present invention; Figure 2 This is a block diagram of a multi-scenario collaborative control method for a distributed energy storage system based on fault location and dynamic communication repair in an embodiment of the present invention; Figure 3 This is a flowchart of the fault location and dynamic communication repair method in an example of the present invention; Figure 4 This is a real-time change diagram of the communication topology of the energy storage unit in an embodiment of the present invention; Figure 5 The state of charge in the embodiments of the present invention SOCIETY p Waveform diagram; Figure 6 DC bus voltage in the embodiments of the present invention v bus Waveform diagram; Figure 7 The DC-side output current in this embodiment of the invention i cp Waveform diagram; Figure 8 This is a waveform diagram of link communication in an embodiment of the present invention. Detailed Implementation

[0007] The present invention will be further described below with reference to specific embodiments: Figure 1 The diagram shown is the main circuit diagram of a distributed energy storage system, including the energy storage unit. FROM p Through the corresponding DC-DC converter and line resistance R linep It is connected in parallel to the DC bus and to the distributed power source. PDG Constant power load P CPL Together they form an energy interaction network. The parameters of the main circuit are defined as follows: p represents the number of the energy storage unit, p = i, j, k, q; i Lp , v cp , i cp , C p These represent the inductor current, output voltage, output current, and supporting capacitor of the p-th energy storage unit, respectively. R CPL This represents the line resistance on the constant power load side. R DG and C DG These are the line resistance and parasitic capacitance of the distributed power source, respectively. The specific values ​​for these parameters are: the line resistance corresponding to the four energy storage units. R linei , R linej , R linek and R lineq The inductance values ​​are 0.7Ω, 0.8Ω, 0.74Ω, and 0.6Ω respectively, and the capacitance values ​​are 6F, 6F, 4F, and 4F respectively. L p Both are 0.009H, capacitance C p All are 0.003F; Distributed power source P DG For 16kW, the corresponding line resistance R DG The parasitic capacitance is 0.3Ω. C DG 0.001F; constant power load P CPL For 8kW, the corresponding line resistance R CPL It is 0.4Ω; in addition, v bus This is the DC bus voltage. v ref Set the voltage reference value to 400V.

[0008] Figure 2 The diagram shown is a control block diagram of a multi-scenario collaborative control method for distributed energy storage systems based on fault location and dynamic communication repair. The specific details are as follows: Step S1: The energy storage unit is connected to the corresponding DC / DC converter and line resistor. R LinepConnected in parallel to the DC bus, and with distributed power sources P DG and constant power load P CPL Energy interaction is performed, and at the beginning of each sampling period, the inductor current of the p-th energy storage unit is... i Lp Output voltage v cp Output current i cp State of charge SOCIETY p and DC bus voltage v bus Sampling is performed separately, where p is the energy storage unit number, p = i, j, k, q. In this invention, only the i-th energy storage unit is selected as an example for illustration. It should be noted that the remaining j-th, k-th, and q-th energy storage units are all applicable under the method framework of this invention. Step S2: In the fault location module, the output current of the p-th energy storage unit is... i cp The original value of the derivative of the state of charge of the p-th energy storage unit SOCIETY dp As input, after being processed by the energy storage unit fault location method, a fault location command is output. L p The specific details of the energy storage unit fault location method are as follows: Step S2-1: First, perform signal preprocessing, that is,... SOCIETY dp A first-order low-pass filter is performed to obtain the derivative of the state of charge of the filtered energy storage unit. SOCIETY dfp Its expression is: (12) In equation (12), τ This is the filtering time constant, used to suppress misjudgments caused by high-frequency noise. T s The sampling period is SOCIETY dfsp This is the derivative of the state of charge of the energy storage unit after filtering at the previous moment, used for recursive calculations; Step S2-2: Set the fault current threshold b Small threshold of the derivative of the state of charge β When either condition 1 or condition 2 in the fault determination expression is met, the p-th energy storage unit is determined to be faulty, and the fault location module outputs a fault location command. L p =1, otherwise, output fault location command. Lp =0, where the fault determination expression is: (13) Step S3: In the communication repair module, the fault location command is... L p As input, after processing by the communication network repair and control method, the output is a communication link reconfiguration instruction set. S r This is applied to the consensus algorithm in the communication module. The specific details of the communication network repair control method are as follows: Step S3-1: First, collect fault location commands for each energy storage unit in real time. L p The number of normal energy storage units in the statistical system ,in, N The total number of energy storage units, and V is based on the number of normally functioning energy storage units in the system. normal The communication link reconfiguration logic is defined as follows: When the number of normal energy storage units V in the system... normal When the number of energy storage units is 4, the energy storage system operates normally, and the energy storage units communicate in a four-source ring structure. When the number of normally functioning energy storage units V... normal When the number of normal energy storage units is 3, the communication link with the faulty unit is disconnected, and the remaining three normal energy storage units are reconfigured into a three-source ring communication structure. When the number of normal energy storage units in the system is V... normal When the number of normal energy storage units is 2, the communication link with the faulty unit is disconnected, and the remaining two normal energy storage units are reconfigured to a two-source linear communication structure. When the number of normal energy storage units in the system is V... normal <2. Because the system cannot form an effective communication link, the energy storage system triggers the protection mechanism and stops operating; Step S3-2: Based on the communication link reconfiguration logic in step S3-1, output the communication link reconfiguration instruction set. S r ={ S ij , S jk , S kq , S qi | S ik , S jq}, and directly apply to the consensus algorithm, where, S ij , S jk , S kq , S qiDefined as basic link commands, these correspond to the basic communication links between energy storage units i and j, j and k, k and q, and q and i, respectively. S ik , S jq Defined as a link repair command, corresponding to the link repair between energy storage units i and k, and j and q respectively. The link connection and disconnection rules are as follows: when S ag =1 indicates that the communication link between energy storage units a and g is in a closed state. S ag =0 indicates that the communication link between energy storage units a and g is disconnected, where the values ​​of a and g are i, j, k, and q, and a is not equal to g; Step S4: In the communication module, the state of charge of the energy storage unit is... SOCIETY i Virtual control variables ζ i and communication link reconfiguration instruction set S r As input, the average state of charge of the energy storage unit is obtained through iterative calculation using a consensus algorithm. SOCIETY ai and the average value of virtual control variables ζ ai The expression for the consensus algorithm is: (14) In equation (14), Y ij Let be the average virtual state deviation between the i-th energy storage unit and its adjacent j-th energy storage unit after the communication delay. Y Rij Let be the average virtual state deviation between the i-th and j-th energy storage units after the link update, 1 / ( T t s +1) represents the communication delay stage, where... T t To reduce communication delay between different energy storage units, s For Laplace transform complex variable operators, Y aj Let be the average virtual state variable of the i-th energy storage unit in the four-source ring communication between adjacent j-th energy storage units. Y iq Let be the average virtual state deviation between the i-th energy storage unit and its adjacent q-th energy storage unit after the communication delay. Y Riq Let be the average virtual state deviation after the link update between the i-th and q-th energy storage units. Y aqLet be the average virtual state variable of the i-th energy storage unit in the four-source ring communication with the q-th adjacent energy storage unit. Y ik Let be the average virtual state deviation of the i-th energy storage unit and the j-th energy storage unit that are not adjacent to it after the communication delay. Y Rik Let be the average virtual state deviation after the link update between the i-th and k-th energy storage units. Y ak Let be the average virtual state variable of the i-th energy storage unit in the four-source ring communication system, which is not adjacent to the k-th energy storage unit. Y i =[ SOCIETY i , ζ i [] represents the virtual state variable of the i-th energy storage unit. Y ai =[ SOCIETY ai , ζ ai [ ] represents the average virtual state variable of the i-th energy storage unit. h Communication step size coefficient; When the number of normal energy storage units in the system is V normal When the value is 4, the energy storage system operates normally, and the communication module receives the communication link reconfiguration instruction set. S r for{ S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0}, the basic communication links of the energy storage units are all closed, and the energy storage units form a four-source ring communication according to the connection order of node identifiers ijkqi. At this time, the i-th energy storage unit is connected and communicates with the adjacent j-th and q-th energy storage units. The expression of the consensus algorithm of the i-th energy storage unit is: (15) When the number of normal energy storage units in the system is V normal When =3, the failure of a single energy storage unit in the energy storage system can be mainly divided into two cases: Case 1 is that the i-th energy storage unit fails in the k-th energy storage unit, which is not adjacent to the i-th energy storage unit in the four-source ring communication. In this case, the communication link reconfiguration instruction set... S r From the system during normal operation { Sij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =1, S jk =0, S kq =0, S qi =1| S ik =0, S jq =1}, at this time the basic communication link related to the kth energy storage unit is disconnected, the repair link between the jth and qth units is connected, and the remaining normal units reconstruct the three-source ring communication according to the connection order of the node identifier ijqi. At this time, the ith energy storage unit is still connected and communicated with the adjacent jth and qth energy storage units. The consistency algorithm expression of the ith energy storage unit is the same as that of equation (15). Case 2 is when the i-th energy storage unit experiences a failure in its adjacent j-th or q-th energy storage unit within the four-source ring communication, in which case the communication link reconfiguration instruction set is used. S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =0, S jk =0, S kq =1, S qi =1| S ik =1, S jq =0}(unit j fault) or { S ij =1, S jk =1, Skq =0, S qi =0| S ik =1, S jq =0} (unit q failure), at this time, the basic communication link connected to the j-th or q-th energy storage unit is disconnected, the repair link between the i-th and k-th units is reconnected, and the remaining normal units reconstruct the three-source ring communication according to the connection order of node identifier ikqi (unit j failure) or ijki (unit q failure). At this time, the consensus algorithm expression of the i-th energy storage unit is: (16) When the number of normal energy storage units in the system is V normal When =2, two energy storage units in the energy storage system fail. At this time, the failure types can be divided into: simultaneous failure of energy storage units and time-sharing failure of energy storage units. Among them, simultaneous failure of energy storage units can be further divided into two situations: situation (1) is that the i-th energy storage unit and the j-th and q-th energy storage units adjacent to it in the four-source ring communication both fail at the same time. At this time, the communication link reconfiguration instruction set S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =0, S jk =0, S kq =0, S qi =0| S ik =1, S jq =0}, at this time, the basic communication links of all energy storage units are disconnected, the repair link between the i-th and k-th units is reconnected, and the remaining normal units reconstruct the two-source direct communication according to the connection order of node identifier iki. At this time, the consensus algorithm expression of the i-th energy storage unit is: (17) Case (2) is when the i-th energy storage unit is not adjacent to the k-th energy storage unit in the four-source ring communication, and either the j-th or q-th energy storage unit adjacent to the i-th energy storage unit in the four-source ring communication fails simultaneously. In this case, the communication link reconfiguration instruction set is received. S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =0, S jk =0, S kq =0, S qi =1| S ik =0, S jq =0}(faults in units k and j) or { S ij =1, S jk =0, S kq =0, S qi =0| S ik =0, S jq =0} (faults in units k and q), at this time, the basic communication link between the k-th energy storage unit and the faulty unit in the j-th or q-th energy storage unit is disconnected. The remaining normal units reconstruct the two-source direct communication according to the connection order of node identifiers iqi (faults in units k and j) or iji (faults in units k and q). At this time, the consensus algorithm expression of the i-th energy storage unit is: (18) Time-of-use failure of energy storage units refers to a situation where, after the first unit fails, the system recovers stability and operates for a period of time, and then the second unit fails, during which the communication link reconfiguration instruction set is used. S r The consensus algorithm needs to be dynamically updated twice. The time-sharing failure of two energy storage units can also be divided into three cases: Case ① is that the i-th energy storage unit fails first in the four-source ring communication, while the k-th energy storage unit, which is not adjacent to it, fails first. In this stage, the communication link reconstruction instruction set... Sr The update status and consensus algorithm of the i-th unit are the same as in case 1 of the single-unit failure. The remaining normal units reconstruct the three-source ring communication according to the connection order of node identifiers ijqi. At this time, the system resumes stable operation based on the updated instruction set and algorithm. After running for a period of time, if any one of the j-th or q-th energy storage units adjacent to the i-th energy storage unit in the four-source ring communication fails again, the communication link reconstruction instruction set will be updated during this stage. S r Depend on{ S ij =1, S jk =0, S kq =0, S qi =1| S ik =0, S jq =1} is updated to { S ij =0, S jk =0, S kq =0, S qi =1| S ik =0, S jq =0}(unit j fault) or { S ij =1, S jk =0, S kq =0, S qi =0| S ik =0, S jq =0}(unit q fault), at this time the basic communication link connected to the j-th or q-th energy storage unit is disconnected, and the repair link between the j-th and q-th units is disconnected. The communication topology of the energy storage unit is reconstructed from the three-source ring communication of ijqi to the two-source straight communication of iqi(unit j fault) or iji(unit q fault). The consensus algorithm of the i-th energy storage unit is updated from equation (15) to equation (18). The initial stages of scenarios ② and ③ are the same: in both cases, the i-th energy storage unit experiences a failure first in the j-th or q-th adjacent energy storage unit in the four-source ring communication. During this stage, the communication link reconfiguration instruction set... S rThe update status and the consensus algorithm of the i-th unit are consistent with Case 2 in the above single-unit failure. The remaining normal units reconstruct the three-source ring communication according to the connection order of node identifiers ikqi (unit j failure) or ijki (unit q failure). At this time, the system resumes stable operation based on the updated instruction set and algorithm. After running for a period of time, the failure development of Case 2 and Case 3 diverges, specifically as follows: In scenario ②, the i-th energy storage unit fails again in the k-th energy storage unit, which is not adjacent to the i-th unit in the four-source ring communication. At this stage, the communication link reconfiguration instruction set... S r Depend on{ S ij =0, S jk =0, S kq =1, S qi =1| S ik =1, S jq =0}(unit j fault) or { S ij =1, S jk =1, S kq =0, S qi =0| S ik =1, S jq =0}(cell q fault) updated to { S ij =0, S jk =0, S kq =0, S qi =1| S ik =0, S jq =0}(Unit j fails first, unit k fails later) or { S ij =1, S jk =0, S kq =0, S qi =0| S ik =0, S jq=0}(unit q fails first, unit k fails later), at this time the basic communication link connected to the kth energy storage unit is disconnected, and the repair link between the ith and kth units is disconnected. The communication topology of the energy storage unit is reconstructed from the three-source ring communication of ikqi (unit j fails) or ijki (unit q fails) to the two-source straight communication of iqi (unit j fails first, unit k fails later) or iji (unit q fails first, unit k fails later). During the entire operation of the system, the consistency algorithm of the ith energy storage unit is first updated from equation (15) to equation (16), and then updated from equation (16) to equation (18). In scenario ③, the adjacent unit (either the q-th or j-th unit) of the i-th energy storage unit in the four-source ring communication fails again. At this stage, the communication link reconfiguration instruction set... S r Depend on{ S ij =0, S jk =0, S kq =1, S qi =1| S ik =1, S jq =0}(Unit j fails first) or { S ij =1, S jk =1, S kq =0, S qi =0| S ik =1, S jq =0}(Unit q fails first) is uniformly updated to { S ij =0, S jk =0, S kq =0, S qi =0| S ik =1, S jq=0}, at this time the basic communication link connected to the qth or jth energy storage unit is disconnected, and the communication topology of the energy storage unit is uniformly reconstructed from the three-source ring communication of ikqi (unit j fails first) or ijki (unit q fails first) to the two-source straight-line communication of iki. During the entire operation of the system, the consensus algorithm of the ith energy storage unit is first updated from equation (15) to equation (16), and then updated from equation (16) to equation (17). When the number of normal energy storage units in the system is V normal When the value is less than 2, the system cannot form an effective communication link, triggering the protection mechanism and stopping operation. Step S5: In the SOC balancing module, the average state of charge of the energy storage units is calculated. SOCIETY ai Subtract the state of charge of the energy storage unit SOCIETY i The standard deviation of the state of charge of the energy storage unit, d, is obtained. SOCIETY i Then, the standard deviation of the state of charge of the energy storage unit, d SOCIETY i Based on the inductor current of the energy storage unit i Li The positive and negative signs are dynamically selected for output, and the specific logic is as follows: If the inductor current of the energy storage unit is positive... i Li If the value is greater than zero, it indicates that the energy storage system is in a discharging state. At this time, the switching switch in the SOC equalization module points to port 1, and the standard deviation of the state of charge of the energy storage unit is output as d. SOCIETY i If the inductor current of the energy storage unit i Li If the value is less than zero, it indicates that the energy storage system is in a charging state. At this time, the switching switch in the SOC equalization module points to port 2, and the standard deviation of the state of charge of the energy storage unit is d. SOCIETY i Multiply the product by the coefficient -1, invert the output, take the sine of the result (sin), and then multiply the result by the balance adjustment factor. A The results and process coefficients were obtained. w Multiplying them together yields the equilibrium dominant factor. z process coefficients w The expression is: (19) In equation (19), θ To balance the acceleration factor, μ To balance the precision factor; Among them, the dominant factor of equilibrium z The expression is: (20) Equilibrium dominance factor z Take the equilibrium adjustment index the The transition coefficient is obtained by raising the power of . c Then the transition coefficient c Take the exponential function e x To obtain the equilibrium variables y , balance variables y Multiply by the maximum rated capacity of the energy storage unit C max With the rated capacity of the energy storage unit C bat The ratio is taken, and the result is added to the coefficient 1 to obtain the SOC equilibrium factor Δ. m ki, where SOC equilibrium factor Δ m ki The expression is: (twenty one) Step S6: In the current sharing control module, the inductor current of the energy storage unit is... i Li Divide by the maximum rated inductor current of the energy storage unit i Lmax The result is then divided by the current equalization factor. Q Then multiply the result by the SOC equilibrium factor Δ m ki The flow control coefficient is obtained. x i Then subtract the flow control coefficient from the coefficient 1. x i The current equalization factor can be obtained. n i Current equalization factor n i Multiply by DC bus voltage v bus Virtual control variables can be obtained ζ i Among them, virtual control variables ζ i The expression is: (twenty two) Step S7: In the voltage recovery module, average the virtual control variable. ζ ai Input, and current equalization factor n i Divide them to obtain the voltage balance. v ai DC bus voltage reference value v ref Subtract voltage balance vai Then, it goes through a voltage recovery stage controlled by a PI controller. G N (s) yields the voltage recovery regulation amount. v fi ; Step S8: In the voltage and current dual closed-loop module, adjust the voltage recovery amount. v fi As input, and compared with the DC bus voltage reference value v ref Add them together, then subtract the output voltage of the energy storage unit. v ci The result is passed through a voltage outer loop PI controller. G V (s) Obtain the reference current of the inner current loop. i refi The inner loop reference current will be used. i refi With SOC equilibrium factor Δ m ki Multiply the results and subtract the inductor current of the energy storage unit from the result. i Li Then it goes through a current inner loop PI controller. G I (s), the result is passed through a limiting circuit to obtain the driving voltage. v si , drive voltage v si After passing through PWM Modulation can output a stable and reliable modulated signal. d ti .

[0009] Furthermore, in step S2, the filtering time constant τ The value range is 0.1 < τ <1.5, sampling period T s The value range is 0.0001 < T s <0.01, fault current threshold b The value range is 0.01 < b <0.1, small threshold of the derivative of the state of charge β The value range is 0.0001 < β <0.01; In step S4, the communication step size coefficient h The range of values ​​is 0 < h <1, Communication delay between different energy storage units T t The value range is 0.0001 < T t<0.01; In step S5, the balancing adjustment factor A The value range is 0.3 < A <0.9, equilibrium acceleration factor θ The value range is 0.2 < θ <0.7, Balanced Precision Factor μ The value range is 0.0001 < μ <0.01, equilibrium adjustment index the The value range is 0.1 < the <1; In step S6, the current averaging factor Q The value range is 10 < Q <22.

[0010] Figure 3 The diagram shows the flowchart of the fault location and dynamic communication repair method, which mainly includes four steps, as follows: Step 1: After the energy storage system starts up, perform a self-test as described in Step 1. Within 0.3 seconds of startup, monitor the output current of the energy storage unit. i cp The original value of the derivative of the state of charge of the energy storage unit SOCIETY dp If either of them approaches 0, the system is deemed to be malfunctioning, the energy storage system is restarted, and step 1 is executed again. If neither of them approaches 0, the next step is performed. Step 2: The system performs step 2 to locate the fault. First, the original value of the derivative of the state of charge of the energy storage unit is obtained. SOCIETY dp Signal preprocessing is performed to obtain the derivative of the state of charge of the filtered energy storage unit. SOCIETY dfp Subsequently, the system sets the fault current threshold. b and the small threshold of the derivative of the state of charge β And monitor the output current of the energy storage unit. i cp and filtered SOCIETY dfp ,like i cp In (- b , b) Within the interval, or SOCIETY dfp The absolute value is less than ζ That is, if any condition is met, the energy storage unit is determined to be a faulty unit, and a corresponding fault location command is output. L p =1; If neither of the two conditions is met, it is determined to be a normal unit, and the output is 1. L p =0, which is the value of V calculated in step 3 for the number of normal energy storage units. normalProvide evidence, then proceed to step 3; Step 3: The system performs communication repair in step 3, first collecting the fault commands output in step 2 in real time. L p The number of normal energy storage units V in the current system is calculated. normal V was subsequently determined. normal Is it less than 2? If V normal ≥2, then according to V normal Execute the corresponding communication link repair operation logic: when V normal =4, then maintain four-source ring communication, when V normal =3, disconnect the faulty unit's associated link and reconstruct a three-source ring structure, when V normal =2, disconnect the faulty unit's associated link and switch to a two-source linear structure, while simultaneously outputting a set of link reconfiguration instructions. S r It is applied to the consensus algorithm, which uses information exchange between adjacent units to synchronize the adjustment of each normal unit and outputs the average state of charge of the energy storage unit. SOCIETY ap And determine whether the SOC equalization error is satisfied. SOCIETY p - SOCIETY ap |<5% and bus voltage deviation| v bus - v ref <5% v ref If the conditions are met, the system is deemed to be in stable condition, enters normal operation mode, and repeats steps 2 and 3 to achieve real-time monitoring of unit faults and dynamic repair of system communication. If the conditions are not met, the system is re-evaluated based on the current V. normal Perform link reconstruction again and output a new set of link reconstruction instructions. S r And it applies to the consensus algorithm, causing all normal units to readjust synchronously until the stability condition is met; in addition, if V normal If the value is less than 2, it indicates that the system can no longer form an effective communication link. A trigger signal is output to step 4, and then the process proceeds to step 4. Step 4: The system performs system protection in step 4. When the trigger signal output in step 3 is received, the system will immediately start the shutdown protection mechanism, stop the charging and discharging operations of all energy storage units, and the energy storage system will stop operating.

[0011] Figure 4 The diagram shown is a real-time change graph of the communication topology of the energy storage unit. FROM i , FROM j , FROM k as well as FROM q The four energy storage units are connected via six communication links (ij, jk, kq, qi and ik, jq), communication switches for each link, and a communication link reconfiguration instruction set. S r ={ S ij , S jk , S kq , S qi | S ik , S jq It consists of four links: ij, jk, kq, and qi, which are the basic communication links. S ij , S jk , S kq , S qi These are basic link commands used to control the on / off state of communication switches on the basic communication link. The ik and jq links are repair links. S ik , S jq The repair link command controls the opening and closing of communication switches on the repair links. When the system is running normally, the four basic communication links are closed, and the other two repair links are open, forming a four-source ring communication. When the system experiences a p-th (e.g., FROM i When a single energy storage unit fails, all basic communication and repair links connected to the failed unit are disconnected. The basic communication links of the remaining normal energy storage units remain closed, and the corresponding repair links change from disconnected to closed. The communication topology is reconstructed from a four-source ring to a three-source ring. When two energy storage units fail, the failure types can be divided into: simultaneous energy storage unit failure and time-sharing energy storage unit failure. Simultaneous energy storage unit failure includes two situations: the first situation is a same-side failure, that is, the p-th energy storage unit and its adjacent energy storage unit (e.g., ...) FROM i and FROM j When both faults occur simultaneously, the basic communication and repair links connected to the two faulty units are completely disconnected, while the basic communication links of the remaining normal energy storage units remain closed. The communication topology is reconstructed from a four-source ring to a two-source line-of-sight communication. The second scenario is a diagonal fault, i.e., the p-th energy storage unit and its non-adjacent energy storage units (such as...) FROM i and FROM k When a fault occurs simultaneously, all four basic links are disconnected, and the repair links between the remaining normal energy storage units change from disconnected to closed. The communication topology is reconstructed from a four-source ring to a two-source straight-line communication. When an energy storage unit experiences a time-sharing fault, it refers to two energy storage units failing sequentially, and there are two scenarios: unit-time-sharing same-side faults and unit-time-sharing diagonal faults. The communication topology changes are the same in both scenarios: the p-th unit fails first, and the communication topology changes in this case are the same as for a single-unit fault, changing from a four-source ring to a three-source ring communication. Subsequently, another unit that is adjacent to or not adjacent to unit p fails, and all basic communication and repair links connected to the failed unit are disconnected. The basic communication links or repair links of the remaining normal energy storage units remain closed, and the communication topology is updated from a three-source ring to a two-source straight-line communication.

[0012] Figure 5 The diagram shows the state of charge of the energy storage unit. SOCIETY p Waveform diagrams showing the initial state of charge of the four energy storage units. SOCIETY i , SOCIETY j , SOCIETY k , SOCIETY q The values ​​were 91%, 88%, 86%, and 84%, respectively. After the energy storage system started, all four energy storage units operated in a discharge state. Under the action of the SOC balancing module in this invention, the four SOC curves converged at a specific rate. When the system had been running for 3.5 seconds, the i-th energy storage unit failed and prematurely exited operation. SOCIETY i The curve forms a horizontal straight line here, remaining stable at 82% of the level at the time of the fault. This sudden change not only altered the original power distribution of the energy storage system but also affected the compatibility of the communication network with the main circuit and control topology. At this point, the remaining three energy storage units need to undertake all the discharge tasks. With the combined efforts of the fault location module, communication repair module, and SOC balancing module, SOCIETY j , SOCIETY k and SOCIETY q The downward slopes of all three curves become steeper, and they reach equilibrium at 4.2 seconds. Thereafter, they continue to discharge at the same rate. When the system reaches 6 seconds, due to external distributed power supply to the energy storage system, the system switches from discharge mode to charging mode. At the instant of mode switching, under the real-time adjustment of the SOC balancing module... SOCIETY j , SOCIETY k and SOCIETY q The slopes of these three curves change from negative to positive, that is, from decreasing to increasing, maintaining a balanced state and continuing to charge and increase at the same rate. When the system has been running for 8 seconds, the k-th energy storage unit malfunctions and prematurely exits operation. SOCIETY k The curve forms a horizontal straight line here, remaining stable at 80.1% of the level at the time of the fault. This exit again alters the system's power distribution and the compatibility between the communication network and the main circuit and control topology. At this point, all charging power is handled by the remaining j-th and q-th energy storage units. SOCIETY j and SOCIETY q The upward slope of these two curves becomes steeper and continues to maintain a balanced state until the energy storage system stops operating. It can be seen that under the coordinated action of the fault location module, communication repair module and SOC balancing module, the system still maintains the SOC balance of the remaining energy storage units in the face of complex operating conditions such as energy storage units exiting operation in stages and system operating mode switching.

[0013] Figure 6 The figure shows the DC bus voltage of the distributed energy storage system. v bus The waveform diagram shows that, thanks to the addition of the voltage recovery module, even when facing complex operating conditions such as the energy storage unit exiting operation in stages and the system switching operating modes, although there are some voltage fluctuations in the DC bus voltage, the voltage fluctuation amplitude can be controlled within 12V. Moreover, after each fluctuation, the DC bus voltage can recover to the voltage reference value of 400V within 0.7s, and can also stabilize at around 400V at other times.

[0014] Figure 7 The figure shows the DC-side output current of the distributed energy storage system. i cp Waveform diagram FROM i , FROM j , FROM k as well as FROM q The rated capacities of the four energy storage units are in a ratio of 3:3:2:2. After the energy storage system starts up, the output currents of the four energy storage units gradually converge proportionally to their respective rated capacities under the action of the current sharing control module. When the system has been running for 3.5 seconds, the i-th energy storage unit malfunctions and prematurely exits operation. The output current of the i-th energy storage unit... i ci The current drops to zero instantaneously, at which point the original current distribution balance of the system is broken, and the remaining... FROMj , FROM k and FROM q They need to share the total output current of the system. Under the action of the fault location module and the communication repair module, the system communication network is adapted to the main circuit and control topology. Under the dynamic adjustment of the current sharing module, the output current of the three energy storage units responds quickly, and within about 4.2 seconds, FROM j , FROM k and FROM q The system achieved current sharing, with output currents of 8.57A, 5.71A, and 5.71A respectively, satisfying a precise 3:2:2 current distribution principle. When the system reached 6 seconds, as the external distributed power source supplied power to the energy storage system, the system switched from discharge mode to charging mode. The output current of the energy storage unit also changed from positive to negative, i.e., from outputting current to absorbing current. Under the dynamic adaptation of the current sharing control module, and around 6.6 seconds... FROM j , FROM k and FROM q The current was once again evenly distributed, with output currents of -8.57A, -5.71A, and -5.71A respectively, satisfying the precise 3:2:2 distribution principle. When the system had been running for 8 seconds, the k-th energy storage unit failed and prematurely shut down. The output current of the k-th energy storage unit... i ck The current drops to zero almost instantly, at which point the original current distribution balance of the system is broken again, and the remaining... FROM j and FROM q The system needs to collectively absorb the total output current of the external distributed power supply. With the assistance of the fault location module and the communication repair module, the system communication network is adapted to the main circuit and control topology. Under the dynamic adjustment of the current sharing module, and around 8.4 seconds later… FROM j and FROM q The system achieves current equalization, with output currents of -12A and -8A respectively, satisfying the principle of precise distribution of output current according to the 3:2 ratio. It can be seen that, with the coordinated action of the fault location module, communication repair module and current equalization control module, the system can still maintain the precise proportional distribution of the output current of the remaining energy storage units even when facing complex operating conditions such as energy storage units exiting operation in stages and system operating mode switching.

[0015] Figure 8The diagram shows the link communication waveforms of a distributed energy storage system. After system startup, the basic communication links ij, jk, kq, and qi have basic values. The fluctuations at time 0 correspond to the system's initialization communication handshake and topology establishment. Each energy storage unit identifies nodes and establishes links, forming a ring communication network according to the connection order of ijkqi. Around 0.3 seconds later, the communication information of the four links converges synchronously to a steady-state value of 2 and remains stable at this value. At this point, the ring communication network enters steady-state operation mode. Each energy storage unit interacts with power allocation commands and SOC status checks in real time through the links. The system discharges based on measured data. When the system runs for 3.5 seconds, the i-th energy storage unit suddenly fails and goes out of operation. The original communication topology unit i breaks, and the communication values ​​of the basic links ij and qi connected to unit i instantly drop to 0, while the communication value of the repair link jq instantly increases from 0 to 2.1. At the same time, the communication values ​​of the jk and kq links also deviate from the steady-state value, and all three communication links experience short-term oscillations. At this time, the system fault location module quickly identifies the faulty unit i, and the communication repair module simultaneously starts the topology reconstruction algorithm to reconstruct the communication topology into a ring communication with the jkqj connection sequence. Around 0.2 seconds, the communication values ​​of the three links jk, kq, and jq converged synchronously to a steady-state value of 2 and maintained this state stably. When the system ran for 6 seconds, it switched from discharge mode to charging mode, and the power flow direction reversed. This change in operating condition had a certain impact on the communication links, and the communication values ​​of the three links jk, kq, and jq all fluctuated briefly. However, under the dynamic adjustment of the communication repair module, they converged again to a steady-state value of 2 around 6.6 seconds and maintained this value stably. This ensured that the three units j, k, and q could exchange charging current commands, energy storage unit charging status, and other data in real time during the charging process. According to reports, when the system was running for 8 seconds, the kth energy storage unit suddenly failed and went out of operation. The original ring communication topology of jkqj was broken due to the failure of unit k. The communication values ​​of links jk and kq connected to unit k dropped to 0 instantly. Only the communication value of the remaining link jq fluctuated significantly. At this time, the system fault location module quickly identified the faulty unit k, and the communication repair module then started the secondary topology reconstruction algorithm to reconstruct the communication topology into a straight-line communication with the jqj connection sequence. Around 8.4 seconds, the communication value of link jq recovered to the steady-state value of 2 and remained stable in this state until the energy storage system stopped operating.

[0016] As can be seen from the above analysis, this invention designs a multi-scenario collaborative control method for distributed energy storage systems based on fault location and dynamic communication repair. By designing a fault location controller, it can accurately identify and locate energy storage units that are malfunctioning or have failed. By designing a communication repair controller, it can achieve rapid reconstruction of the communication topology and restoration of link stability after a fault occurs, ensuring the continuity and reliability of data interaction among the remaining energy storage units. On this basis, by designing an improved SOC equalizer, current sharing, and voltage recovery controller, it can achieve SOC equalization of each energy storage unit and proportional distribution of output current according to the capacity of the energy storage unit without sampling the output current, and maintain the bus voltage to the rated value. This enables the distributed energy storage system to operate stably, efficiently, and collaboratively in complex scenarios such as multiple energy storage unit failures and charging / discharging mode switching.

[0017] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, any changes made in accordance with the shape and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A multi-scenario collaborative control method for distributed energy storage systems based on fault location and dynamic communication repair, characterized in that, including the following steps: Step S1: The energy storage unit is connected to the corresponding DC / DC converter and line resistor. R Linep Connected in parallel to the DC bus, and with distributed power sources P DG and constant power load P CPL Energy interaction is performed, and at the beginning of each sampling period, the inductor current of the p-th energy storage unit is... i Lp Output voltage v cp Output current i cp State of charge SOCIETY p and DC bus voltage v bus Sampling is performed separately, where p is the energy storage unit number, p = i, j, k, q; Step S2: In the fault location module, the output current of the p-th energy storage unit is... i cp The original value of the derivative of the state of charge of the p-th energy storage unit SOCIETY dp As input, after being processed by the energy storage unit fault location method, a fault location command is output. L p The specific details of the energy storage unit fault location method are as follows: Step S2-1: First, perform signal preprocessing, that is,... SOCIETY dp A first-order low-pass filter is performed to obtain the derivative of the state of charge of the filtered energy storage unit. SOCIETY dfp Its expression is: (1) In equation (1), τ This is the filtering time constant, used to suppress misjudgments caused by high-frequency noise. T s The sampling period is SOCIETY dfsp This is the derivative of the state of charge of the energy storage unit after filtering at the previous moment, used for recursive calculations; Step S2-2: Set the fault current threshold b Small threshold of the derivative of the state of charge β When either condition 1 or condition 2 in the fault determination expression is met, the p-th energy storage unit is determined to be faulty, and the fault location module outputs a fault location command. L p =1, otherwise, output fault location command. L p =0, where the fault determination expression is: (2) Step S3: In the communication repair module, the fault location command is... L p As input, after processing by the communication network repair and control method, the output is a communication link reconfiguration instruction set. S r This is applied to the consensus algorithm in the communication module. The specific details of the communication network repair control method are as follows: Step S3-1: First, collect fault location commands for each energy storage unit in real time. L p The number of normal energy storage units in the statistical system ,in, N The total number of energy storage units, and V is based on the number of normally functioning energy storage units in the system. normal The communication link reconfiguration logic is defined as follows: When the number of normal energy storage units V in the system... normal When the number of energy storage units is 4, the energy storage system operates normally, and the energy storage units communicate in a four-source ring structure. When the number of normally functioning energy storage units V... normal When the number of normal energy storage units is 3, the communication link with the faulty unit is disconnected, and the remaining three normal energy storage units are reconfigured into a three-source ring communication structure. When the number of normal energy storage units in the system is V... normal When the number of normal energy storage units is 2, the communication link with the faulty unit is disconnected, and the remaining two normal energy storage units are reconfigured to a two-source linear communication structure. When the number of normal energy storage units in the system is V... normal <2. Because the system cannot form an effective communication link, the energy storage system triggers the protection mechanism and stops operating; Step S3-2: Based on the communication link reconfiguration logic in step S3-1, output the communication link reconfiguration instruction set. S r ={ S ij , S jk , S kq , S qi | S ik , S jq }, and directly apply to the consensus algorithm, where, S ij , S jk , S kq , S qi Defined as basic link commands, these correspond to the basic communication links between energy storage units i and j, j and k, k and q, and q and i, respectively. S ik , S jq Defined as a link repair command, corresponding to the link repair between energy storage units i and k, and j and q respectively. The link connection and disconnection rules are as follows: when S ag =1 indicates that the communication link between energy storage units a and g is in a closed state. S ag =0 indicates that the communication link between energy storage units a and g is disconnected, where the values ​​of a and g are i, j, k, and q, and a is not equal to g; Step S4: In the communication module, the state of charge of the energy storage unit is... SOCIETY i Virtual control variables ζ i and communication link reconfiguration instruction set S r As input, the average state of charge of the energy storage unit is obtained through iterative calculation using a consensus algorithm. SOCIETY ai and the average value of virtual control variables ζ ai The expression for the consensus algorithm is: (3) In equation (3), Y ij Let be the average virtual state deviation between the i-th energy storage unit and its adjacent j-th energy storage unit after the communication delay. Y Rij Let be the average virtual state deviation between the i-th and j-th energy storage units after the link update, 1 / ( T t s +1) represents the communication delay stage, where... T t To reduce communication delay between different energy storage units, s For Laplace transform complex variable operators, Y aj Let be the average virtual state variable of the i-th energy storage unit in the four-source ring communication between adjacent j-th energy storage units. Y iq Let be the average virtual state deviation between the i-th energy storage unit and its adjacent q-th energy storage unit after the communication delay. Y Riq Let be the average virtual state deviation after the link update between the i-th and q-th energy storage units. Y aq Let be the average virtual state variable of the i-th energy storage unit in the four-source ring communication with the q-th adjacent energy storage unit. Y ik Let be the average virtual state deviation of the i-th energy storage unit and the j-th energy storage unit that are not adjacent to it after the communication delay. Y Rik Let be the average virtual state deviation after the link update between the i-th and k-th energy storage units. Y ak Let be the average virtual state variable of the i-th energy storage unit in the four-source ring communication system, which is not adjacent to the k-th energy storage unit. Y i =[ SOCIETY i , ζ i [] represents the virtual state variable of the i-th energy storage unit. Y ai =[ SOCIETY ai , ζ ai [ ] represents the average virtual state variable of the i-th energy storage unit. h Communication step size coefficient; When the number of normal energy storage units in the system is V normal When the value is 4, the energy storage system operates normally, and the communication module receives the communication link reconfiguration instruction set. S r for{ S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0}, the basic communication links of the energy storage units are all closed, and the energy storage units form a four-source ring communication according to the connection order of node identifiers ijkqi. At this time, the i-th energy storage unit is connected and communicates with the adjacent j-th and q-th energy storage units. The expression of the consensus algorithm of the i-th energy storage unit is: (4) When the number of normal energy storage units in the system is V normal When =3, the failure of a single energy storage unit in the energy storage system can be mainly divided into two cases: Case 1 is that the i-th energy storage unit fails in the k-th energy storage unit, which is not adjacent to the i-th energy storage unit in the four-source ring communication. In this case, the communication link reconfiguration instruction set... S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =1, S jk =0, S kq =0, S qi =1| S ik =0, S jq =1}, at this time the basic communication link related to the kth energy storage unit is disconnected, the repair link between the jth and qth units is connected, and the remaining normal units reconstruct the three-source ring communication according to the connection order of the node identifier ijqi. At this time, the ith energy storage unit is still connected and communicated with the adjacent jth and qth energy storage units. The consistency algorithm expression of the ith energy storage unit is the same as that of equation (4). Case 2 is when the i-th energy storage unit experiences a failure in its adjacent j-th or q-th energy storage unit within the four-source ring communication, in which case the communication link reconfiguration instruction set is used. S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =0, S jk =0, S kq =1, S qi =1| S ik =1, S jq =0}(unit j fault) or { S ij =1, S jk =1, S kq =0, S qi =0| S ik =1, S jq =0} (unit q failure), at this time, the basic communication link connected to the j-th or q-th energy storage unit is disconnected, the repair link between the i-th and k-th units is reconnected, and the remaining normal units reconstruct the three-source ring communication according to the connection order of node identifier ikqi (unit j failure) or ijki (unit q failure). At this time, the consensus algorithm expression of the i-th energy storage unit is: (5) When the number of normal energy storage units in the system is V normal When =2, two energy storage units in the energy storage system fail. At this time, the failure types can be divided into: simultaneous failure of energy storage units and time-sharing failure of energy storage units. Among them, simultaneous failure of energy storage units can be further divided into two situations: situation (1) is that the i-th energy storage unit and the j-th and q-th energy storage units adjacent to it in the four-source ring communication both fail at the same time. At this time, the communication link reconfiguration instruction set S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =0, S jk =0, S kq =0, S qi =0| S ik =1, S jq =0}, at this time, the basic communication links of all energy storage units are disconnected, the repair link between the i-th and k-th units is reconnected, and the remaining normal units reconstruct the two-source direct communication according to the connection order of node identifier iki. At this time, the consensus algorithm expression of the i-th energy storage unit is: (6) Case (2) is when the i-th energy storage unit is not adjacent to the k-th energy storage unit in the four-source ring communication, and either the j-th or q-th energy storage unit adjacent to the i-th energy storage unit in the four-source ring communication fails simultaneously. In this case, the communication link reconfiguration instruction set is received. S r From the system during normal operation { S ij =1, S jk =1, S kq =1, S qi =1| S ik =0, S jq =0} is updated to { S ij =0, S jk =0, S kq =0, S qi =1| S ik =0, S jq =0}(faults in units k and j) or { S ij =1, S jk =0, S kq =0, S qi =0| S ik =0, S jq =0} (faults in units k and q), at this time, the basic communication link between the k-th energy storage unit and the faulty unit in the j-th or q-th energy storage unit is disconnected. The remaining normal units reconstruct the two-source direct communication according to the connection order of node identifiers iqi (faults in units k and j) or iji (faults in units k and q). At this time, the consensus algorithm expression of the i-th energy storage unit is: (7) Time-of-use failure of energy storage units refers to a situation where, after the first unit fails, the system recovers stability and operates for a period of time, and then the second unit fails, during which the communication link reconfiguration instruction set is used. S r The consensus algorithm needs to be dynamically updated twice. The time-sharing failure of two energy storage units can also be divided into three cases: Case ① is that the i-th energy storage unit fails first in the four-source ring communication, while the k-th energy storage unit, which is not adjacent to it, fails first. In this stage, the communication link reconstruction instruction set... S r The update status and consensus algorithm of the i-th unit are the same as in case 1 of the single-unit failure. The remaining normal units reconstruct the three-source ring communication according to the connection order of node identifiers ijqi. At this time, the system resumes stable operation based on the updated instruction set and algorithm. After running for a period of time, if any one of the j-th or q-th energy storage units adjacent to the i-th energy storage unit in the four-source ring communication fails again, the communication link reconstruction instruction set will be updated during this stage. S r Depend on{ S ij =1, S jk =0, S kq =0, S qi =1| S ik =0, S jq =1} is updated to { S ij =0, S jk =0, S kq =0, S qi =1| S ik =0, S jq =0}(unit j fault) or { S ij =1, S jk =0, S kq =0, S qi =0| S ik =0, S jq =0}(unit q fault), at this time the basic communication link connected to the j-th or q-th energy storage unit is disconnected, and the repair link between the j-th and q-th units is disconnected. The communication topology of the energy storage unit is reconstructed from the three-source ring communication of ijqi to the two-source straight communication of iqi(unit j fault) or iji(unit q fault). The consensus algorithm of the i-th energy storage unit is updated from equation (4) to equation (7). The initial stages of scenarios ② and ③ are the same: in both cases, the i-th energy storage unit experiences a failure first in the j-th or q-th adjacent energy storage unit in the four-source ring communication. During this stage, the communication link reconfiguration instruction set... S r The update status and the consensus algorithm of the i-th unit are consistent with Case 2 in the above single-unit failure. The remaining normal units reconstruct the three-source ring communication according to the connection order of node identifiers ikqi (unit j failure) or ijki (unit q failure). At this time, the system resumes stable operation based on the updated instruction set and algorithm. After running for a period of time, the failure development of Case 2 and Case 3 diverges, specifically as follows: In scenario ②, the i-th energy storage unit fails again in the k-th energy storage unit, which is not adjacent to the i-th unit in the four-source ring communication. At this stage, the communication link reconfiguration instruction set... S r Depend on{ S ij =0, S jk =0, S kq =1, S qi =1| S ik =1, S jq =0}(unit j fault) or { S ij =1, S jk =1, S kq =0, S qi =0| S ik =1, S jq =0}(cell q fault) updated to { S ij =0, S jk =0, S kq =0, S qi =1| S ik =0, S jq =0}(Unit j fails first, unit k fails later) or { S ij =1, S jk =0, S kq =0, S qi =0| S ik =0, S jq =0} (unit q fails first, unit k fails later), at this time the basic communication link connected to the kth energy storage unit is disconnected, and the repair link between the ith and kth units is disconnected. The communication topology of the energy storage unit is reconstructed from the three-source ring communication of ikqi (unit j fails) or ijki (unit q fails) to the two-source straight communication of iqi (unit j fails first, unit k fails later) or iji (unit q fails first, unit k fails later). During the entire operation of the system, the consistency algorithm of the ith energy storage unit is first updated from equation (4) to equation (5), and then updated from equation (5) to equation (7). In scenario ③, the adjacent unit (either the q-th or j-th unit) of the i-th energy storage unit in the four-source ring communication fails again. At this stage, the communication link reconfiguration instruction set... S r Depend on{ S ij =0, S jk =0, S kq =1, S qi =1| S ik =1, S jq =0}(Unit j fails first) or { S ij =1, S jk =1, S kq =0, S qi =0| S ik =1, S jq =0}(Unit q fails first) is uniformly updated to { S ij =0, S jk =0, S kq =0, S qi =0| S ik =1, S jq =0}, at this time the basic communication link connected to the qth or jth energy storage unit is disconnected, and the communication topology of the energy storage unit is uniformly reconstructed from the three-source ring communication of ikqi (unit j fails first) or ijki (unit q fails first) to the two-source straight-line communication of iki. During the entire operation of the system, the consensus algorithm of the ith energy storage unit is first updated from equation (4) to equation (5), and then updated from equation (5) to equation (6). When the number of normal energy storage units in the system is V normal When the value is less than 2, the system cannot form an effective communication link, triggering the protection mechanism and stopping operation. Step S5: In the SOC balancing module, the average state of charge of the energy storage units is calculated. SOCIETY ai Subtract the state of charge of the energy storage unit SOCIETY i The standard deviation of the state of charge of the energy storage unit, d, is obtained. SOCIETY i Then, the standard deviation of the state of charge of the energy storage unit, d SOCIETY i Based on the inductor current of the energy storage unit i Li The positive and negative signs are dynamically selected for output, and the specific logic is as follows: If the inductor current of the energy storage unit is positive... i Li If the value is greater than zero, it indicates that the energy storage system is in a discharging state. At this time, the switching switch in the SOC equalization module points to port 1, and the standard deviation of the state of charge of the energy storage unit is output as d. SOCIETY i If the inductor current of the energy storage unit i Li If the value is less than zero, it indicates that the energy storage system is in a charging state. At this time, the switching switch in the SOC equalization module points to port 2, and the standard deviation of the state of charge of the energy storage unit is d. SOCIETY i Multiply the product by the coefficient -1, invert the output, take the sine of the result (sin), and then multiply the result by the balance adjustment factor. A The results and process coefficients were obtained. w Multiplying them together yields the equilibrium dominant factor. z process coefficients w The expression is: (8) In equation (8), θ To balance the acceleration factor, μ To balance the precision factor; Among them, the dominant factor of equilibrium z The expression is: (9) Equilibrium dominance factor z Take the equilibrium adjustment index the The transition coefficient is obtained by raising the power of . c Then the transition coefficient c Take the exponential function e x To obtain the equilibrium variables y , balance variables y Multiply by the maximum rated capacity of the energy storage unit C max With the rated capacity of the energy storage unit C bat The ratio is taken, and the result is added to the coefficient 1 to obtain the SOC equilibrium factor Δ. m ki, where SOC equilibrium factor Δ m ki The expression is: (10) Step S6: In the current sharing control module, the inductor current of the energy storage unit is... i Li Divide by the maximum rated inductor current of the energy storage unit i Lmax The result is then divided by the current equalization factor. Q Then multiply the result by the SOC equilibrium factor Δ m ki The flow control coefficient is obtained. x i Then subtract the flow control coefficient from the coefficient 1. x i The current equalization factor can be obtained. n i Current equalization factor n i Multiply by DC bus voltage v bus Virtual control variables can be obtained ζ i Among them, virtual control variables ζ i The expression is: (11) Step S7: In the voltage recovery module, average the virtual control variable. ζ ai Input, and current equalization factor n i Divide them to obtain the voltage balance. v ai DC bus voltage reference value v ref Subtract voltage balance v ai Then, it goes through a voltage recovery stage controlled by a PI controller. G N (s) yields the voltage recovery regulation amount. v fi ; Step S8: In the voltage and current dual closed-loop module, adjust the voltage recovery amount. v fi As input, and compared with the DC bus voltage reference value v ref Add them together, then subtract the output voltage of the energy storage unit. v ci The result is passed through a voltage outer loop PI controller. G V (s) Obtain the reference current of the inner current loop. i refi The inner loop reference current will be used. i refi With SOC equilibrium factor Δ m ki Multiply the results and subtract the inductor current of the energy storage unit from the result. i Li Then it goes through a current inner loop PI controller. G I (s), the result is passed through a limiting circuit to obtain the driving voltage. v si , drive voltage v si After passing through PWM Modulation can output a stable and reliable modulated signal. d ti .

2. The multi-scenario collaborative control method for distributed energy storage systems based on fault location and dynamic communication repair according to claim 1, characterized in that, In step S2, the filtering time constant τ The value range is 0.1 < τ <1.5, sampling period T s The value range is 0.0001 < T s <0.01, fault current threshold b The value range is 0.01 < b <0.1, small threshold of the derivative of the state of charge β The value range is 0.0001 < β <0.

01.

3. The multi-scenario collaborative control method for distributed energy storage systems based on fault location and dynamic communication repair according to claim 1, characterized in that, In step S4, the communication step size coefficient h The range of values ​​is 0 < h <1, Communication delay between different energy storage units T t The value range is 0.0001 < T t <0.

01.

4. The multi-scenario collaborative control method for distributed energy storage systems based on fault location and dynamic communication repair according to claim 1, characterized in that, In step S5, the balancing adjustment factor A The value range is 0.3 < A <0.9, equilibrium acceleration factor θ The value range is 0.2 < θ <0.7, Balanced Precision Factor μ The value range is 0.0001 < μ <0.01, equilibrium adjustment index the The value range is 0.1 < the <1.

5. The multi-scenario collaborative control method for distributed energy storage systems based on fault location and dynamic communication repair according to claim 1, characterized in that, In step S6, the current averaging factor Q The value range is 10 < Q <22.

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