Electrical safety reconstruction, path interlocking and capacity adaptive frequency response control method of discrete gravity energy storage system

Abstract

The application discloses an electrical safety reconstruction, path interlocking and capacity adaptive frequency response control method of a discrete gravity energy storage system, and belongs to the technical field of gravity energy storage. The method comprises the following steps: judging a current task direction according to a scheduling power instruction, a frequency deviation and a frequency change rate, and calculating a capacity that can be used to increase power generation and a capacity that can be used to increase absorbed power; calculating a health state quantity of each energy storage unit, a path occupation state quantity of each candidate path, a residual travel time quantity, an energy matching quantity and a wear balancing quantity of each energy storage unit-candidate path combination; calculating a weighted cost of a residual feasible energy storage unit-candidate path combination; setting and updating a state matrix; selecting one or more energy storage units to execute a current task according to a comprehensive evaluation value; and performing energy storage unit access, exit and emergency fault control based on an energy storage unit access control method, an energy storage unit normal zero-flow exit control method and an energy storage unit emergency fault isolation control method.

Description

Technical Field

[0001] This invention belongs to the field of gravity energy storage technology, specifically a method for electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control of discrete gravity energy storage systems. Background Technology

[0002] With the continuous expansion of new energy grid connection, the demand for large-capacity, long-life, and dispatchable energy storage resources in the power system is increasing. Discrete and modular gravity energy storage systems have demonstrated good engineering application value due to their excellent adaptability. Existing discrete gravity energy storage systems mainly consist of gravity blocks, lifting mechanisms, drive motors, power converters, and grid connection interfaces. The mainstream solutions are divided into two categories: fixed paired systems and matrix modular systems. They meet the power regulation needs of the power grid by operating independent energy storage units or by multiple energy storage units working in concert. However, this system integrates electrical power regulation with the mechanical movement of gravity blocks in a confined space, and there are many technical shortcomings in practical engineering applications.

[0003] On the one hand, multiple force blocks are prone to resource contention issues related to shafts, tracks, and transfer platforms. Traditional fixed-sequence polling and single-power-priority control methods cannot guarantee the safe and efficient operation of the system. Simultaneously, when switching energy storage units on and off the bus, challenges arise regarding voltage matching, inductive current and mechanical inertia release, and fault isolation. Improper operation can easily lead to overvoltage, overcurrent, device damage, and even bus short-circuit faults. On the other hand, under grid frequency disturbance conditions, the available capacity of discrete gravity energy storage changes dynamically in real time with equipment operating conditions. Traditional fixed droop coefficient and virtual inertia coefficient control modes can easily cause overload or insufficient power response of the energy storage units.

[0004] Based on this, in order to solve the above problems, the present invention provides an electrical safety reconfiguration, path interlocking and capacity adaptive frequency response control method for discrete gravity energy storage systems. Summary of the Invention

[0005] To address the problems of the above solutions, this invention provides an electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for discrete gravity energy storage systems.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control of a discrete gravity energy storage system, comprising: Step 1: Construct a discrete gravity energy storage system and perform system initialization; Furthermore, the discrete gravity energy storage system includes several discrete gravity energy storage units, several cluster-level DC buses, one or more station-level grid-connected converters, station-level controllers, cluster-level combiner controllers, unit controllers, an intra-station communication network, and a finite set of candidate paths; Each discrete gravity energy storage unit includes at least a gravity block, a lifting mechanism, a lifting motor M, a unit-level power converter, a connection switch K1, a fault freewheeling / braking protection branch K2, a pre-charge branch K3, a position sensor, a speed sensor, a load sensor, a temperature sensor, a vibration sensor, a lock-up status detector, and a unit controller.

[0007] In this invention, except for terms that explicitly indicate components such as "unit controller" and "unit-level power converter", the term "energy storage unit" refers to a discrete gravity energy storage unit, hereinafter referred to as "energy storage unit".

[0008] Step 2: Perform status acquisition to obtain multi-dimensional status data; the station-level controller determines the current task direction based on the dispatch power command, frequency deviation, and frequency change rate. The task direction includes distributing power generation and enhancing energy storage; the station-level controller calculates the current capacity available for increasing power generation and the current capacity available for increasing power absorption.

[0009] Furthermore, the formulas for calculating the current available capacity for increasing power generation and the current available capacity for increasing power absorption are as follows: ; ; in, For the current capacity available to increase power generation, For the current capacity available to increase absorbed power, P N,i The rated power of the i-th unit, Let be the availability coefficient of the i-th energy storage unit for power generation at the current moment. Let be the availability factor of the i-th energy storage unit at the current moment for improving energy storage.

[0010] Step 3: The cluster-level combiner controller calculates the health status of each energy storage unit, the path occupancy status of each candidate path, the remaining travel time of each energy storage unit-candidate path combination, the energy matching quantity, and the wear leveling quantity.

[0011] The energy storage unit-candidate path combination described in this invention refers to the combination formed by the i-th candidate energy storage unit and the k-th candidate path in the finite set of candidate paths; the combination before screening is called the initial energy storage unit-candidate path combination, and the combination that meets the preset screening conditions and is retained is called the feasible energy storage unit-candidate path combination.

[0012] Furthermore, the health status parameters of the energy storage unit: The health status of the i-th energy storage unit is denoted as H. i Defined as: ; Among them, H T,iFor healthy temperature, H V,i For vibrational health parameters, H F,i H represents the health status of the fault history. η,i For efficient and healthy quantities, w T w V w F w η These are the weighting coefficients; Path occupancy status variables: The path occupancy state of the k-th candidate path is denoted as O. k Defined as: ; Among them, B k The path is in Boolean occupancy status; B indicates the path is idle. k =0, path occupied when B k =1; L k L is the path queue length; max The maximum allowed queue length; J k J represents the number or occupancy rate of interlocked nodes; max This is the maximum reference value for the interlocked node's occupancy. Remaining travel time: The remaining travel time required for the i-th energy storage unit to reach the target location via the k-th candidate path is denoted as T. ik Let the current position of the i-th energy storage unit be x. i The target position is x target,k The path distance is: ; Using trapezoidal velocity programming, when: ; At that time, the remaining travel time was: ; when: ; At that time, the remaining travel time was: ; Where, v max For the maximum allowed speed of the path, a max To allow maximum acceleration, T lock,k The time required for mechanical locking or unlocking.

[0013] The remaining travel time is normalized as follows: ; Among them, T max The maximum travel time allowed for the current task; Energy matching amount: The height normalization value of the i-th energy storage unit is defined as: ; Among them, h i h represents the current height of the gravity block. min h is the minimum allowable height. max Maximum permissible height; When the task direction is to generate electricity from below, the energy matching quantity is defined as: E match,i =z i ; When the mission objective is to enhance energy storage, the energy matching quantity is defined as: E match,i =1-z i ; If the current task has a target energy requirement E req It shall be in the following form: ; Among them, E avail,i Let ξ be the energy that the i-th energy storage unit can currently release or absorb. E To prevent positive numbers with a denominator of zero; Wear leveling amount: Wear leveling amount W i Calculated by weighting the following normalized components: ; ; ; ; ; Among them, T run,i N lift,i and E through,i These represent the cumulative operating time, cumulative number of lifting or lowering actions, and cumulative energy throughput of the i-th energy storage unit within a preset statistical period; T ref N ref and E ref This corresponds to the normalized reference value; λ T , λ N and λ E W represents the weighting coefficient. i The larger the value, the higher the cumulative utilization rate of the energy storage unit.

[0014] Step 4: Eliminate energy storage unit-candidate path combinations that do not meet the preset screening conditions, calculate the weighted cost of the remaining feasible energy storage unit-candidate path combinations, and set and update the state matrix.

[0015] Furthermore, the screening criteria are as follows: the energy storage unit has no fault signs or fault isolation signs; the current position, mechanical locking state, and release state of the energy storage unit meet the requirements of the current task action; the electrical state of the energy storage unit meets the requirements for pre-charging, connection, operation, or deactivation; the candidate path is reachable, there is no occupancy state that conflicts with the current movement of the energy storage unit, and the corresponding interlock node allows entry; the current height of the energy storage unit and the energy that can be released or absorbed meet the current task direction; and the temperature, vibration, and load states of the energy storage unit do not exceed the corresponding limits.

[0016] Furthermore, the weighted cost C of the remaining feasible energy storage unit-candidate path combination is calculated. ik : Define the weighted cost function when the i-th energy storage unit selects the k-th candidate path to execute the task as follows: ; Among them, H i O is a health status parameter for energy storage units. k τ is the path occupancy state quantity. ik E represents the remaining travel time. match,i For energy matching quantity, W i α represents the wear equalization factor; α, β, γ, δ, and ε are weighting coefficients.

[0017] Furthermore, the comprehensive evaluation value S in the state matrix S(t) ik (t) is defined as: ; Among them, S ik (t) represents the comprehensive evaluation value of the i-th energy storage unit for the k-th candidate path task at time t, ρ is the historical attenuation coefficient, and ξ is a positive constant to prevent the denominator from being zero.

[0018] Step 5: Sort feasible energy storage unit-candidate path combinations from largest to smallest based on their comprehensive evaluation value. Select one or more combinations ranked first according to the current task power requirement until the cumulative executable power of the selected energy storage units meets the current task power requirement. When the comprehensive evaluation values ​​are the same, prioritize them in the following order: smaller weighted cost, shorter remaining travel time, larger health status of the energy storage unit, and smaller path occupancy status. Within the same scheduling cycle, the same energy storage unit can correspond to at most one candidate path, and combinations with interlocking conflicts cannot be released simultaneously.

[0019] Step Six: Perform energy storage unit access, exit, and emergency fault control based on the preset energy storage unit access control method, energy storage unit normal zero-current exit control method, and energy storage unit emergency fault isolation control method.

[0020] Furthermore, the energy storage unit access control method: When the target energy storage unit selected in step five meets the mechanical position conditions and task direction conditions, and the candidate path (hereinafter referred to as "target path") that forms the selected feasible combination with the target energy storage unit and its interlocking nodes meet the release conditions, the cluster-level combiner controller allows the target energy storage unit to enter the access process; Before connecting the energy storage unit, first detect the DC side voltage U of the unit. dc,i With cluster-level DC bus voltage U bus The absolute value of the difference; the closing of the access switch K1 is permitted when the following conditions are met: |U dc,i - U bus |≤ΔU set ; Where, ΔU set The preset voltage difference threshold; When the DC side voltage of the unit meets the pre-charge condition, and the unit output current meets the access constraints, the energy storage unit has no fault flag, the mechanical lock-up state has been released, and the interlock node on the target path is allowed to enter, the access switch K1 is closed to connect the energy storage unit to the cluster-level DC bus; the cluster-level combiner controller sends the generator torque setpoint or power setpoint to the unit controller, and the energy storage unit enters the controlled operation state; Normal zero-current exit control method for energy storage units: SA1: The cluster-level combiner controller sends a torque reduction or current reduction command to the target energy storage unit, causing the output current of the energy storage unit to gradually decrease; SA2: Unit controller detects unit current I i The energy storage unit is considered to have entered a near-zero current state when the following conditions are met: |I i |≤I zero ; Among them, I zero Zero-flow exit threshold; SA3: The unit controller blocks the drive pulses of the unit-level power converter, putting the hoisting motor into a safe and controlled state; SA4: Disconnect the access switch K1 to isolate the energy storage unit from the cluster-level DC bus; SA5: If the gravity block needs to be kept in its current position, control the lifting mechanism to move it to the mechanical locking waiting position and confirm the mechanical locking status; if the energy storage unit needs maintenance, write the fault or maintenance flag into the status matrix. Emergency fault isolation and control methods for energy storage units: The system enters an emergency fault isolation process when any of the following conditions are detected: overcurrent, overvoltage, drive failure, or bridge arm abnormality occurs in the unit-level power converter; the hoisting motor current fails to decrease according to the normal current reduction command; the hoisting mechanism experiences abnormal speed, braking, or load; or the unit's DC side voltage U... dc,i The overvoltage protection threshold has been exceeded; the energy storage unit's mechanical state prevents it from continuing to perform its original task. The emergency fault isolation process includes the following steps: SC1: The unit controller immediately reports the fault flag, the cluster-level combiner controller freezes the path assignment status of the energy storage unit, and prohibits other energy storage units from entering the corresponding interlock node; SC2: The unit-level power converter performs current limiting control or blocks the drive pulse of a faulty bridge arm; SC3: Activate fault freewheeling / braking protection branch K2; if K2 is the AC side freewheeling / braking branch of the motor, the motor inductance current and mechanical inertial energy are released through the motor side braking resistor, controlled short-circuit branch or equivalent damping branch; if K2 is the DC side braking chopper branch of the unit, the DC side overvoltage energy is absorbed through the braking resistor. SC4: Detection unit current I i Unit DC side voltage U dc,i and motor speed ω i When the safety isolation conditions are met, disconnect the connection switch K1; the safety isolation conditions include: |I i |≤I safe ; U dc,i ≤U safe ; Among them, I safe U is the fault isolation current threshold. safe The fault isolation voltage threshold; SC5: After disconnecting the access switch K1, mark the energy storage unit as a fault isolation state and remove the energy storage unit from the subsequent candidate energy storage unit set in the state matrix.

[0021] Step 7: When the energy storage unit needs to move to the target location or waiting station, the mechanical path interlock module determines whether the target path and its interlock nodes determined in Step 5 are allowed to enter; if allowed, it is allowed; if not allowed, the energy storage unit enters the mechanical lock waiting station or maintains the existing lock state.

[0022] Step 8: If a frequency disturbance is detected, the station-level controller generates a target active power regulation based on the current available capacity for increasing power generation, the current available power absorption, the frequency deviation, and the frequency change rate. It then performs torque regulation of the operating energy storage unit, activation of the hot standby energy storage unit, suspension of the rising task, or reactive power support according to the response level.

[0023] Furthermore, the target active power adjustment is defined as: ; in: ; ; This represents the real-time available capacity corresponding to the current frequency disturbance direction; when the system needs to increase power generation, When the system needs to increase the absorbed power, ;Δf ref For the reference frequency deviation, R ref k is the reference frequency change rate. f and k R This is a dimensionless adjustment coefficient.

[0024] Furthermore, based on the response level, the following actions are taken: torque adjustment of operating energy storage units, activation of hot standby energy storage units, suspension of rising tasks, or reactive power support, including: Assume that the additional power generation provided by the currently operating energy storage units is The current operational energy storage units can provide an additional absorption power of [missing information]. The number of additional decentralized power generation and energy storage units required is: ; The number of additional energy storage units required is as follows: ; Among them, P unit The rated power of the unit. The average availability factor of candidate decentralized power generation and energy storage units. To improve the average availability factor of candidate energy storage units; When the calculated results of the number of newly invested decentralized power generation and energy storage units and the number of newly invested upgraded energy storage units are not integers, they are rounded up to the nearest integer.

[0025] Hierarchical frequency response strategy: Set three frequency change rate thresholds a, b, and c, and satisfy the following: 0 < a < b < c; Level 1 Response: when: |R(t)|<a; At that time, the system does not change the number of energy storage units put into operation, but only makes adjustments through the motor torque correction of the operating energy storage units and the power control of the station-level grid-connected converter; Level 2 Response: when: a≤|R(t)|<b; At that time, based on the first-level response, the system selects energy storage units from the set of hot standby energy storage units that meet the electrical pre-charging conditions, mechanical lock-up release conditions, and path interlock conditions for operation; Hot standby energy storage units must meet the following conditions: The energy storage unit has no fault indicators; The energy storage unit is in a mechanically locked waiting position or can reach the access position within a limited time. The DC side of the unit has completed pre-charging, or can complete pre-charging within a preset time. Interlocked nodes on the target path are allowed to proceed; The current altitude meets the requirements of the mission direction; Level 3 Response: when: b≤|R(t)|<c; When the system is in a state of underfrequency, it will suspend unnecessary boosting tasks on the basis of the level 2 response. If the system is in an underfrequency state, it will prioritize suspending boosting energy storage tasks and increase the distribution of power generation tasks. If the system is in an overfrequency state, it will prioritize suspending unnecessary power generation tasks and increase boosting energy storage tasks. Level 4 Response: when: |R(t)|≥c; When necessary, the system executes an emergency frequency response strategy, including locking non-essential tasks, calling up high-potential or low-potential thermal backup energy storage units, reallocating paths, increasing the power response priority of the station-level grid-connected converter, and performing reactive power support by the station-level grid-connected converter when needed.

[0026] Step 9: The controller writes the results of access, exit, fault, lockout, path occupancy and power execution into the state matrix, and re-executes steps 2 to 9 in the next scheduling cycle.

[0027] Compared with the prior art, the beneficial effects of the present invention are: Improving the online reconfiguration capability of energy storage units: This invention enables discrete gravity energy storage units to complete connection, disconnection, fault isolation and backup replacement without stopping the station by coordinating the work of the access switch K1, the pre-charge branch K3 and the fault freewheeling / braking protection branch K2.

[0028] To avoid confusion between normal exit and fault exit logic: This invention clearly distinguishes between normal zero-current exit and emergency fault isolation. During normal exit, K1 is directly disconnected after the current drops to the near-zero threshold; during emergency faults, K2 is activated for freewheeling or braking energy release. This avoids redundant actions and topology risks caused by additional bypass branch closures under near-zero current conditions.

[0029] Reduce the risk of DC bus short circuit: This invention clearly stipulates that K2 is not a bypass switch that directly connects to the positive and negative poles of the cluster-level DC bus, but rather a motor AC side freewheeling / braking branch or a unit DC side braking chopper branch, thereby structurally reducing the risk of bus short circuit.

[0030] Improving the engineering feasibility of path scheduling: This invention incorporates candidate paths, interlocked nodes, and mechanical locking waiting stations into a unified control framework, so that path planning no longer remains at the level of abstract scheduling algorithms, but is combined with the actual mechanical structure, locking status, and path occupancy status.

[0031] To avoid overload caused by fixed frequency response parameters: This invention is based on adaptive tuning of droop control coefficient and virtual inertia control coefficient according to real-time available capacity, so that the frequency response intensity changes dynamically with the online available capacity, thereby reducing the risk of overload of in-operation energy storage units.

[0032] To avoid misjudgment of power direction: This invention clearly defines the downward generation of power as positive power and the boosting of energy storage as negative power, and calculates the number of newly added power generation and energy storage units and the number of newly added power absorption and energy storage units respectively, so as to avoid the use of the absolute value of power deviation leading to incorrect control direction.

[0033] Improve system continuous operation capability: When some energy storage units fail, their efficiency decreases, or their paths are blocked, the system can reselect backup energy storage units and candidate paths through state matrix and path interlock control, thereby improving the system's continuous operation capability and fault tolerance. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a diagram of the overall electrical-mechanical-control architecture of the discrete gravity energy storage system of the present invention; Figure 2 This is a schematic diagram of an existing fixed-connection discrete gravity energy storage system; Figure 3 This is a topology diagram of the safe access and fault follow current protection of the discrete gravity energy storage unit of the present invention; Figure 4 This is a schematic diagram of the limited candidate paths, interlocking nodes, and mechanical locking waiting stations of the present invention; Figure 5 This is a flowchart illustrating the energy storage unit connection, normal zero-current exit, and emergency fault isolation processes of the present invention. Figure 6This is a flowchart of the state variable normalization, state matrix update and path assignment process of the present invention; Figure 7 This is a flowchart of the hierarchical frequency response and task redistribution based on real-time available capacity of the present invention. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] like Figures 1 to 7 As shown, an electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for a discrete gravity energy storage system is presented. The method includes: Step 1: Construct a discrete gravity energy storage system and perform system initialization; like Figure 1 As shown, the discrete gravity energy storage system includes several discrete gravity energy storage units, several cluster-level DC buses, one or more station-level grid-connected converters, station-level controllers, cluster-level combiner controllers, unit controllers, an intra-station communication network, and a finite set of candidate paths. Each discrete gravity energy storage unit includes at least a gravity block, a lifting mechanism, a lifting motor M, a unit-level power converter, a connection switch K1, a fault freewheeling / braking protection branch K2, a pre-charge branch K3, a position sensor, a speed sensor, a load sensor, a temperature sensor, a vibration sensor, a lock-up status detector, and a unit controller.

[0038] In this invention, except for terms that explicitly indicate components such as "unit controller" and "unit-level power converter", the term "energy storage unit" refers to a discrete gravity energy storage unit, hereinafter referred to as "energy storage unit".

[0039] Multiple unit-level power converters connect their DC sides to their respective cluster-level DC buses via their respective access switches K1. The cluster-level DC buses are then connected to the AC grid via station-level grid-connected converters. The station-level controller generates station-level control targets based on grid frequency, dispatch power commands, and real-time available system capacity. The cluster-level combiner controller performs energy storage unit selection, path assignment, and access / exit control based on the station-level control targets, state matrix, and path interlock status. The unit controller performs motor torque control, pre-charge control, switching actions, sensor acquisition, and fault reporting.

[0040] The system control is divided into three levels: Station-level control layer: responsible for grid-connected power control, frequency response control, real-time available capacity calculation, inter-cluster power allocation, and reactive power support control.

[0041] Cluster-level control layer: responsible for updating the state matrix of discrete gravity energy storage units within the cluster, path optimization, interlock release, access and exit control, and task reallocation.

[0042] Energy storage unit control layer: responsible for the acquisition and execution control of unit-level voltage, current, torque, speed, position, temperature, vibration, lock-up status and fault status.

[0043] like Figure 3 As shown, the lifting motor M is connected to the AC side of the unit-level power converter. The unit-level power converter preferably adopts a bidirectional three-phase full-bridge topology, and its power devices can be IGBTs, MOSFETs, SiC MOSFETs, or other controllable power semiconductor devices. The DC side of the unit-level power converter is connected to the cluster-level DC bus via a connection switch K1.

[0044] The pre-charge branch K3 is located between the DC side of the unit-level power converter and the cluster-level DC bus. The pre-charge branch K3 includes a pre-charge switch and a series current-limiting resistor. Before the energy storage unit is connected, the pre-charge branch K3 is closed to ensure the unit's DC side voltage U... dc,i Gradually approaching the cluster-level DC bus voltage U bus .

[0045] The fault freewheeling / braking protection branch K2 is only activated under emergency fault conditions. K2 is not directly connected to the positive and negative terminals of the cluster-level DC bus. Depending on the implementation, K2 can adopt one of the following two structures: AC side freewheeling / braking branch of motor: set on the AC side of the lifting motor M, used to provide a path for releasing the inductor current on the motor side when the converter is blocked or fails, and to consume the remaining electromagnetic energy through braking resistor or controlled short circuit.

[0046] Unit DC-side braking chopper branch: Located across the DC-side capacitor of the unit-level power converter, it includes a controlled switch and a braking resistor, used to absorb braking energy when the unit's DC-side voltage abnormally rises. This branch must not form a short-circuit path to the DC bus with no impedance.

[0047] With the above configuration, K1 is used for connection isolation between the energy storage unit and the bus, K3 is used for pre-charging before connection, and K2 is used for freewheeling and braking protection in case of emergency faults. The functions of the three are independent of each other, avoiding the problem of mistakenly interpreting the bypass switch as a DC bus short-circuit switch.

[0048] System initialization: The station-level controller reads the system's rated parameters and the unit's rated power P. N,i Rated current I N,i Rated bus voltage U bus,N Candidate path set Set of interlocked nodes and set of mechanically locked waiting workstations.

[0049] Step 2: Perform status acquisition to obtain multi-dimensional status data; the station-level controller determines the current task direction based on the dispatch power command, frequency deviation, and frequency change rate, including both power generation and energy storage enhancement; the station-level controller calculates the current available capacity for increasing power generation. and the current capacity available to increase absorbed power .

[0050] Perform status collection: The unit controller uploads voltage, current, speed, position, height, temperature, vibration, load, locking status, and fault flags; the cluster-level bus controller uploads path occupancy status, queue length, interlock node status, and waiting station status, which are then aggregated into multi-dimensional status data.

[0051] If the task requires the system to output active power to the grid, the task direction is to distribute power to the grid; if the task requires the system to absorb active power, the task direction is to improve energy storage.

[0052] like Figure 7 As shown, the station-level controller collects the grid connection point frequency f(t) in real time and calculates the frequency deviation Δf(t) and the frequency change rate R(t).

[0053] Frequency deviation is defined as: Δf(t) = f(t) - f0; Where f0 is the rated power grid frequency.

[0054] The rate of change of frequency is defined as: ; The direction of active power is as follows: P > 0: The system outputs active power to the grid, that is, the gravity block generates electricity when it is lowered. P < 0: The system absorbs active power from the grid, i.e., gravity blocks enhance energy storage.

[0055] The station-level controller calculates the real-time available capacity in both directions based on the current status of available energy storage units: ; ; in, For the current capacity available to increase power generation, For the current capacity available to increase absorbed power, P N,i The rated power of the i-th unit, Let be the availability coefficient of the i-th energy storage unit for power generation at the current moment. Let be the availability factor of the i-th energy storage unit at the current moment for improving energy storage.

[0056] in, and The value is determined based on a comprehensive consideration of energy storage unit height, fault status, path feasibility, electrical connection status, mechanical locking status, and temperature limits, and the range is as follows: ; ; Step 3: The cluster-level combiner controller calculates the health status quantity H of each energy storage unit. i Path occupancy state O for each candidate path k The remaining travel time τ for each energy storage unit-candidate route combination ik Energy matching quantity E match,i and wear equalization amount W i .

[0057] The energy storage unit-candidate path combination described in this invention refers to the combination formed by the i-th candidate energy storage unit and the k-th candidate path in the finite set of candidate paths; the combination before screening is called the initial energy storage unit-candidate path combination, and the combination that meets the preset screening conditions and is retained is called the feasible energy storage unit-candidate path combination.

[0058] Health status parameters of energy storage units: The health status of the i-th energy storage unit is denoted as H. i Defined as: ; Among them, H T,i For healthy temperature, H V,i For vibrational health parameters, H F,i H represents the health status of the fault history. η,i For efficient and healthy quantities, w T w V w F w η Let be the weighting coefficients, and satisfy: w T +w V +w F +w η =1; Temperature health status is defined as: ; Among them, T i T represents the current temperature of the motor windings or power devices. nom For normal operation reference temperature, T max The maximum permissible temperature.

[0059] Vibration health quantity is defined as: ; Where Vibi is the root mean square value of bearing vibration or the characteristic value of the vibration spectrum, Vib max The permissible vibration threshold.

[0060] The fault history health quantity is defined as: ; Where, N fault,i N is the number of failures in the most recent statistical period, and N0 is the normalization constant for the number of failures.

[0061] Efficient health quantity is defined as: ; Where, η i Let η be the recent operating efficiency of the i-th energy storage unit. ref For reference efficiency.

[0062] In a preferred embodiment, the following is taken: w T =0.30, w V =0.30, w F =0.20, w η =0.20; Path occupancy state variables: The path occupancy state of the k-th candidate path is denoted as O. k Defined as: ; Among them, B k The path is in Boolean occupancy status; B indicates the path is idle. k =0, path occupied when B k =1; L k L is the path queue length; max The maximum allowed queue length; J k J represents the number or occupancy rate of interlocked nodes; max This is the maximum reference value for the interlocked node's occupancy. The weighting coefficients satisfy: q1 + q2 + q3 = 1; In a preferred embodiment, the values ​​are: q1 = 0.50, q2 = 0.30, and q3 = 0.20. Path occupancy state quantity O k The larger the value, the higher the level of path congestion, and the less suitable it is to be selected by the current task.

[0063] Remaining travel time: The remaining travel time required for the i-th energy storage unit to reach the target location via the k-th candidate path is denoted as T. ik Let the current position of the i-th energy storage unit be x.i The target position is x target,k The path distance is: ; If trapezoidal velocity programming is used, when: ; At that time, the remaining travel time was: ; when: ; At that time, the remaining travel time was: ; Among them, v max For the maximum allowed speed of the path, a max To allow maximum acceleration, T lock,k The time required for mechanical locking or unlocking.

[0064] The remaining travel time is normalized as follows: ; Among them, T max The maximum travel time allowed for the current task.

[0065] Energy matching amount: The height normalization value of the i-th energy storage unit is defined as: ; Among them, h i h represents the current height of the gravity block. min h is the minimum allowable height. max This is the maximum permissible height.

[0066] When the mission direction is power generation, the energy matching quantity is defined as: E match,i =z i ; When the mission objective is to enhance energy storage, the energy matching quantity is defined as: E match,i =1-z i ; If the current task has a target energy requirement E req Alternatively, the following forms may be used: ; Among them, E avail,i Let ξ be the energy that the i-th energy storage unit can currently release or absorb. E To prevent positive numbers with a denominator of zero.

[0067] Wear leveling amount: ; ; ; ; ; Among them, T run,i N lift,i and E through,i These represent the cumulative operating time, cumulative number of lifting or lowering actions, and cumulative energy throughput of the i-th energy storage unit within a preset statistical period, respectively; T ref N ref and E ref This corresponds to the normalized reference value; λ T , λ N and λ E W represents the weighting coefficient. i The larger the value, the higher the cumulative utilization of the energy storage unit, and the greater the corresponding cost in the weighted cost function.

[0068] In a preferred embodiment, λ is taken. T =0.4、λ N =0.3、λ E =0.3; If the normalized values ​​of the cumulative operating time, cumulative number of actions, and cumulative energy throughput of a certain energy storage unit are 0.6, 0.4, and 0.5, respectively, then: W i =0.4×0.6+0.3×0.4+0.3×0.5=0.51; Therefore, the wear equalization amount of the energy storage unit is 0.51.

[0069] Task priority P task Defined as:

[0070] Among them, P freq P is the normalization quantity for the frequency response level. dispatch P is the normalized quantity for station-level scheduling priority. deadline P is a normalized measure of the urgency of the task deadline. balance For load balancing adjustments, the weights satisfy: r1+r2+r3+r4=1; In a preferred embodiment, for the frequency response task, the following is taken: r1=0.50, r2=0.20, r3=0.20, r4=0.10; For regular scheduled tasks, take: r1=0.10, r2=0.40, r3=0.30, r4=0.20; Step 4: Eliminate energy storage unit-candidate path combinations that do not meet the preset screening criteria, and calculate the weighted cost C of the remaining feasible energy storage unit-candidate path combinations. ik Set and update the comprehensive evaluation value S in the state matrix S(t). ik (t).

[0071] The path planning in this invention is not free-roaming in continuous space, but rather performs path filtering and optimization from a pre-defined set of finite candidate paths. For example... Figure 4 As shown, the set of limited candidate paths may include multiple shafts, multiple parallel tracks, multiple transfer channels, multiple lifting stations, multiple waiting stations, or combinations thereof.

[0072] Let the set of candidate paths be: ; Where M is the number of candidate paths.

[0073] Let the set of candidate energy storage units be: ; Where N is the number of candidate energy storage units.

[0074] Each candidate path P k This includes path entry, path exit, path length, speed limit parameters, interlock nodes, waiting positions, and occupancy status. Each interlock node allows only one or a group of non-conflicting energy storage units that meet the release conditions to enter. When multiple energy storage units compete for the same interlock node, the cluster-level combiner controller determines the release order based on a comprehensive evaluation value.

[0075] The mechanical locking waiting station is located in a position with mechanical support capacity, including the end of the track, the upper docking area of ​​the shaft, the lower docking area of ​​the shaft, the intermediate support platform, or a dedicated locking platform. The mechanical locking waiting station includes a support seat, locking pin, wedge, pawl, motor brake, or a combination thereof, and is equipped with locking position sensors and release position sensors.

[0076] After the gravity block enters the mechanical locking waiting position, the gravity load is borne by the support or locking component, and the lifting motor does not continuously output hovering torque. The locking and unlocking times are included in the remaining travel time τ. ik When the locked state is not confirmed or the released state is not confirmed, the energy storage unit shall not enter the next path, nor shall it perform an electrical connection task.

[0077] The selection criteria are as follows: the energy storage unit has no fault signs or fault isolation signs; the current position, mechanical locking status, and release status of the energy storage unit meet the requirements of the current task action; the electrical status of the energy storage unit meets the requirements for pre-charging, connection, operation, or deactivation; the candidate path is reachable, there is no occupancy status that conflicts with the current movement of the energy storage unit, and the corresponding interlock node allows entry; the current height of the energy storage unit and the energy that can be released or absorbed meet the current task direction; and the temperature, vibration, and load status of the energy storage unit do not exceed the corresponding limits.

[0078] This means eliminating any initial energy storage unit-candidate path combination that does not meet the screening criteria.

[0079] Calculate the weighted cost C of the remaining feasible energy storage unit-candidate path combination. ik : Define the weighted cost function when the i-th energy storage unit selects the k-th candidate path to execute the task as follows: ; Among them, H i O is a health status parameter for energy storage units. k τ is the path occupancy state quantity. ik E represents the remaining travel time. match,i For energy matching quantity, W i This is the amount of wear equalization.

[0080] The weighting coefficients satisfy: α+β+γ+δ+ε=1; In a preferred embodiment, the values ​​are: α = 0.25, β = 0.25, γ = 0.20, δ = 0.20, ε = 0.10; Among them, C ik The smaller the value, the lower the overall cost for the i-th energy storage unit to perform the current task via the k-th candidate path.

[0081] The comprehensive evaluation value S in the state matrix S(t) ik (t) is defined as: ; Among them, S ik (t) represents the comprehensive evaluation value of the i-th energy storage unit for the k-th candidate path task at time t, ρ is the historical attenuation coefficient, and ξ is a positive constant to prevent the denominator from being zero.

[0082] Preferably: 0.60≤ρ≤0.95; 0.001≤ξ≤0.05; In a preferred embodiment, ρ = 0.80 and ξ = 0.01 are selected. When an energy storage unit is in a fault isolation state, a mechanical lockout unconfirmed state, a path unreachable state, or an electrical access condition not met, its corresponding comprehensive evaluation value is set to an unselectable state and it is not included in the current scheduling cycle sorting.

[0083] like Figure 6 As shown, the cluster-level bus controller performs path assignment and interlock release according to the following steps.

[0084] Step S41: Collect candidate energy storage unit set The location, height, voltage, current, temperature, vibration, fault signs, lock-up status, and recent efficiency of each energy storage unit.

[0085] Step S42: Collect candidate path set The occupancy status, queue length, interlock node status, path length, speed limit parameters, and waiting station status of each candidate path are displayed.

[0086] Step S43: Perform feasibility screening for each initial energy storage unit-candidate path combination according to the aforementioned screening conditions, and retain only feasible energy storage unit-candidate path combinations that meet all screening conditions.

[0087] Step S44: Calculate H for each feasible combination i O k τ ik E match,i W i and C ik .

[0088] Step S45: Update the comprehensive evaluation value S in the state matrix S(t). ik (t).

[0089] Step S46: For all feasible combinations, according to S ik (t) Sort from largest to smallest and determine the feasible energy storage unit-candidate path combination for executing the current task according to the selection rules in step five.

[0090] Step S47: When multiple energy storage units compete for the same interlock node, the energy storage unit with the highest comprehensive evaluation value is given priority in release; when the comprehensive evaluation values ​​are the same, the release order is determined according to the secondary sorting rules specified in Step 5; the energy storage units that are not released enter the mechanical lock-up waiting position or remain in the original lock-up state, and the comprehensive evaluation value is recalculated in the next scheduling cycle.

[0091] Step S48: After the interlock is released, the cluster-level combiner controller sends the path action command, electrical access command and motor torque setpoint to the unit controller of the corresponding energy storage unit.

[0092] Step 5: Combine feasible energy storage units and candidate routes according to the comprehensive evaluation value S.ik (t) Sort from largest to smallest; when the executable power of one energy storage unit can meet the power requirement of the current task, select one energy storage unit; when one energy storage unit cannot meet the requirement, add the energy storage units ranked higher in the order until the cumulative executable power meets the power requirement of the current task or reaches the current available capacity limit; when the comprehensive evaluation values ​​are the same, select the energy storage unit according to the weighted cost C. ik Smaller, remaining travel time T ik Shorter, health status quantity H of energy storage unit i Larger and path occupancy state quantity O k Priority is determined by the smaller order; if they are still the same, they are determined by the preset rotation order. Within the same scheduling cycle, the same energy storage unit can correspond to at most one candidate path, and combinations with interlocking conflicts cannot be allowed to pass at the same time.

[0093] Step Six: Perform energy storage unit access, exit, and emergency fault control based on preset energy storage unit access control methods, energy storage unit normal zero-current exit control methods, and energy storage unit emergency fault isolation control methods.

[0094] Energy storage unit access control method: When the target energy storage unit selected in step five meets the mechanical position conditions and task direction conditions, and the candidate path (hereinafter referred to as "target path") that forms the selected feasible combination with the target energy storage unit and its interlocking nodes meet the release conditions, the cluster-level combiner controller allows the target energy storage unit to enter the access process; Before connecting the energy storage unit, first detect the DC side voltage U of the unit. dc,i With cluster-level DC bus voltage U bus The absolute value of the difference; the closing of the access switch K1 is permitted when the following conditions are met: |U dc,i -U bus |≤ΔU set ; Wherein, ΔU set This is a preset voltage difference threshold. Preferably, ΔU set Take the rated voltage U of the cluster-level DC bus bus,N 1%~3%, that is: ΔU set =k U U bus,N ; in: 0.01≤k U ≤0.03; In a preferred embodiment, if the rated voltage of the cluster-level DC bus is 1500V, then ΔU set 15V to 45V can be used.

[0095] When the DC-side voltage of the unit meets the aforementioned pre-charge conditions, and the unit output current meets the access constraints, the energy storage unit has no fault flag, the mechanical lockout state has been released, and the interlock node on the target path is allowed to enter, the access switch K1 is closed, allowing the energy storage unit to connect to the cluster-level DC bus. Afterwards, the cluster-level combiner controller sends the generator torque or power setpoint to the unit controller, and the energy storage unit enters a controlled operating state.

[0096] Normal zero-current exit control method for energy storage units: When a discrete gravity energy storage unit needs to exit the main operating sequence due to reduced efficiency, balanced rotation, task completion, or planned maintenance, a normal zero-flow exit process is adopted.

[0097] The normal zero-flow exit process includes the following steps: SA1: The cluster-level combiner controller sends a torque reduction or current reduction command to the target energy storage unit, causing the output current of the energy storage unit to gradually decrease; SA2: Unit controller detects unit current I i The energy storage unit is considered to have entered a near-zero current state when the following conditions are met: |I i |≤I zero ; Among them, I zero This is the zero-flow exit threshold. Preferably, I zero Take the rated current I of the unit N,i 3%~8%, that is: I zero =k1I N,i ; in: 0.03≤k1≤0.08; SA3: The unit controller blocks the drive pulses of the unit-level power converter, putting the hoisting motor into a safe and controlled state.

[0098] SA4: Disconnect the access switch K1 to isolate the energy storage unit from the cluster-level DC bus.

[0099] SA5: If the gravity block needs to be kept in its current position, control the lifting mechanism to move it to the mechanical locking waiting position and confirm the mechanical locking status; if the energy storage unit needs maintenance, write the fault or maintenance flag into the status matrix.

[0100] During the normal zero-current exit process, the fault freewheeling / braking protection branch K2 is not closed. Since the unit current has already dropped below the zero-current threshold, safety isolation can be achieved by directly disconnecting the connection switch K1, without the need to establish an additional freewheeling branch.

[0101] Emergency fault isolation and control methods for energy storage units: The system enters the emergency fault isolation process when any of the following conditions are detected: The unit-level power converter experiences overcurrent, overvoltage, drive failure, or bridge arm abnormality. The motor current cannot be reduced according to the normal current reduction command; The lifting mechanism exhibits abnormal speed, abnormal braking, or abnormal load. Unit DC side voltage U dc,i Exceeding the overvoltage protection threshold; The energy storage unit is not allowed to continue performing its original task due to its mechanical state.

[0102] The emergency fault isolation process includes the following steps: SC1: The unit controller immediately reports a fault flag, the cluster-level combiner controller freezes the path assignment status of the energy storage unit, and prohibits other energy storage units from entering the relevant interlock node.

[0103] SC2: The unit-level power converter performs current limiting control or blocks the drive pulse of a faulty bridge arm.

[0104] SC3: Activate fault freewheeling / braking protection branch K2. If K2 is the AC side freewheeling / braking branch of the motor, the motor inductive current and mechanical inertial energy are released through the motor side braking resistor, controlled short-circuit branch or equivalent damping branch; if K2 is the DC side braking chopper branch of the unit, the DC side overvoltage energy is absorbed through the braking resistor.

[0105] SC4: Detection unit current I i Unit DC side voltage U dc,i and motor speed ω i When the safety isolation conditions are met, disconnect the connection switch K1. The safety isolation conditions include: |I i |≤I safe ; U dc,i ≤U safe ; Among them, I safe U is the fault isolation current threshold. safe This is the fault isolation voltage threshold. Preferably, I safe Take 5% to 10% of the unit's rated current, U safe Take 105% to 115% of the rated voltage on the DC side of the unit.

[0106] SC5: After disconnecting the access switch K1, mark the energy storage unit as a fault isolation state and remove the energy storage unit from the subsequent candidate energy storage unit set in the state matrix.

[0107] SC6: If a faulty energy storage unit affects the current power task, the cluster-level combiner controller will select an energy storage unit from the set of hot standby energy storage units that meets the electrical access conditions, mechanical path conditions, and comprehensive evaluation value ranking conditions to fill the gap.

[0108] Step 7: When the energy storage unit needs to move to the target location or waiting station, the mechanical path interlock module determines whether the target path and its interlock nodes determined in Step 5 are allowed to enter; if allowed, it is allowed; if not allowed, the energy storage unit enters the mechanical lock waiting station or maintains the existing lock state.

[0109] Step 8: If a frequency disturbance is detected, the station-level controller will... , The target active power regulation ΔP*(t) is generated from Δf(t) and R(T), and the torque adjustment of the operating energy storage unit, the activation of the hot standby energy storage unit, the suspension of the rising task, or the reactive power support are executed according to the response level.

[0110] The droop control coefficient and virtual inertia control coefficient are no longer fixed constants, but are adaptively tuned based on the real-time available capacity: ; ; in, This represents the real-time available capacity corresponding to the current frequency disturbance direction. When the system needs to increase power generation... When the system needs to increase the absorbed power, Δf ref For the reference frequency deviation, R ref k is the reference frequency change rate. f and k R This is a dimensionless adjustment coefficient.

[0111] The target active power regulation is defined as: ; Where, sat(x,x min ,x max ) indicates that x is restricted to [x min ,x max Within the range.

[0112] When ΔP*(t) > 0, it means that the system needs to increase the power output; when ΔP*(t) < 0, it means that the system needs to increase the energy storage power or decrease the current power output.

[0113] Assume that the additional power generation provided by the currently operating energy storage units is The current operational energy storage units can provide an additional absorption power of [missing information]. The number of additional decentralized power generation and energy storage units required is: ; The number of additional energy storage units required is as follows: ; Among them, P unit The rated power of the unit. The average availability factor of candidate decentralized power generation and energy storage units. To improve the average availability factor of candidate energy storage units.

[0114] When the calculated results of the number of newly invested decentralized power generation and energy storage units and the number of newly invested upgraded energy storage units are not integers, they are rounded up to the nearest integer.

[0115] Hierarchical frequency response strategy: Set three frequency change rate thresholds a, b, and c, and satisfy the following: 0 < a < b < c; In a preferred embodiment, the following may be taken: a=0.10Hz / s, b=0.30Hz / s, c=0.50Hz / s; the specific thresholds can be adjusted according to grid connection specifications, grid strength and rated capacity of the energy storage system.

[0116] Level 1 Response: when: |R(t)|<a; At the same time, the system does not change the number of energy storage units put into operation, but achieves rapid fine-tuning only by correcting the motor torque of the operating energy storage units and controlling the power of the station-level grid-connected converter.

[0117] Level 2 Response: when: a≤|R(t)|<b; At that time, based on the first-level response, the system selects energy storage units from the set of hot standby energy storage units that meet the electrical pre-charging conditions, mechanical lock-up release conditions, and path interlock conditions for operation.

[0118] Hot standby energy storage units must meet the following conditions: The energy storage unit has no fault indicators; The energy storage unit is in a mechanically locked waiting position or can reach the access position within a limited time. The DC side of the unit has completed pre-charging, or can complete pre-charging within a preset time. Interlocked nodes on the target path are allowed to proceed; The current altitude meets the requirements of the mission direction.

[0119] Level 3 Response: when: b≤|R(t)|<c; When the system is in a state of underfrequency response, it will suspend some non-essential boosting tasks based on the secondary response level, freeing up more capacity for the current frequency response direction. If the system is in an underfrequency state, it will prioritize suspending energy storage boosting tasks and increasing power generation tasks; if the system is in an overfrequency state, it will prioritize suspending non-essential power generation tasks and increasing energy storage boosting tasks.

[0120] Level 4 Response: when: |R(t)|≥c; When necessary, the system executes an emergency frequency response strategy, including locking non-essential tasks, calling up high-potential or low-potential thermal backup energy storage units, reallocating paths, increasing the power response priority of the station-level grid-connected converter, and performing reactive power support by the station-level grid-connected converter when needed.

[0121] Level 4 response does not require the instantaneous deployment of ordinary stationary gravity blocks; instead, it prioritizes the use of energy storage units already in hot standby mode. Energy storage units that have not yet completed mechanical preparation or electrical pre-charging will only participate in scheduling as subsequent continuous power replenishment energy storage units.

[0122] Step 9: The controller writes the results of access, exit, fault, lockout, path occupancy and power execution into the state matrix, and re-executes steps 2 to 9 in the next scheduling cycle.

[0123] The central controller in this invention can be composed of a station-level controller and a cluster-level combiner controller, or it can be implemented by a centralized controller with multiple processing modules. The central controller includes at least the following functional modules.

[0124] Status acquisition module: The status acquisition module is used to periodically acquire the position, height, speed, current, voltage, temperature, vibration, load, mechanical locking status, fault signs and communication status of each discrete gravity energy storage unit. At the same time, it acquires the occupancy status, interlock node status, waiting station status and path queue length of each candidate path.

[0125] Electrical reconfiguration control module: The electrical reconfiguration control module is used to perform pre-charge access of energy storage units, normal zero-current exit, emergency fault isolation, and backup energy storage unit replenishment control. This module is based on U... dc,i U bus I i The states of K1, K2, and K3 determine the sequence of switch actions.

[0126] Mechanical path interlock module: The mechanical path interlock module is used to maintain a finite set of candidate paths. The module monitors the status of interlock nodes and mechanical locking waiting stations. Before releasing a path, this module confirms that there are no conflicts with the target path, that the interlock nodes are allowed to enter, and that the locking components have been released or locked in place.

[0127] State normalization module: The state normalization module is used to convert temperature, vibration, number of failures, efficiency, path occupancy, queue length, interlock status, remaining travel time and altitude energy status into dimensionless indices in the range of 0 to 1.

[0128] State matrix update module: The state matrix update module is used to update the state matrix according to the weighted cost function C. ik and task priority P task Update the comprehensive evaluation value S in the state matrix S(t) ik (t), and output the sorting results of candidate energy storage unit-candidate path combinations.

[0129] Frequency response module: The frequency response module is used to acquire the grid connection point frequency f(t), calculate the frequency deviation Δf(t), the frequency change rate R(t), and the real-time available capacity. and And generate the target active power adjustment ΔP*(t).

[0130] Task assignment module: The task allocation module is used to determine the torque correction amount of operating energy storage units, the number of hot standby energy storage units to be put into operation, the list of suspended tasks and the replacement scheme of faulty energy storage units based on the station-level power demand, the ranking results of comprehensive evaluation values, the path interlock status and the real-time available capacity.

[0131] Security protection module: The safety protection module is used to perform overvoltage, overcurrent, overtemperature, abnormal vibration, abnormal mechanical locking, communication interruption, and path conflict protection. In the event of an emergency fault, the safety protection module takes precedence over the ordinary scheduling module in performing fault follow-up / braking protection and energy storage unit isolation.

[0132] Example 1: In this embodiment, the system includes 24 discrete gravity energy storage units, divided into 4 clusters, with each cluster containing 6 energy storage units. The system is equipped with 3 vertical shaft channels, and each energy storage unit is equipped with a hoisting motor, a unit-level bidirectional three-phase full-bridge power converter, a connection switch K1, a pre-charge branch K3, a fault freewheeling / braking protection branch K2, a unit controller, and a mechanical locking waiting station.

[0133] Cluster-level DC bus rated voltage U bus,N The voltage is 1500V. Pre-charge voltage difference coefficient k U If we take 0.02, then: ΔU set =0.02×1500V=30V; The rated current of the unit is I N,i If the zero-flow exit coefficient k1 is taken as 0.05, then: I zero =0.05I N,i ; Under normal operating conditions, some energy storage units are in a power generation state, some are in a boosted energy storage state, and some are in a mechanically locked, thermal standby state. The station-level controller issues target power and task direction to the cluster-level combiner controller based on external dispatch instructions.

[0134] When the temperature of an energy storage unit in cluster 2 continues to rise and exceeds the temperature warning threshold, the unit controller reports a temperature anomaly to the cluster-level bus controller. The cluster-level bus controller determines that the energy storage unit needs to be scheduled for shutdown, and therefore issues a torque reduction command to gradually decrease its output current. When the following is detected: |I i |≤0.05I N,i ; At this time, the unit controller blocks the drive pulse of the unit-level power converter and disconnects the connection switch K1. Since this process is a normal zero-current exit, the fault freewheeling / braking protection branch K2 is not activated.

[0135] Subsequently, the cluster-level combiner controller writes the energy storage unit's state into the state matrix and selects a backup energy storage unit from the hot standby energy storage unit set that has a high health status, an idle path, and a high degree of satisfaction with the task direction. This backup energy storage unit first completes pre-charging through the pre-charging branch K3, when the following conditions are met: |U dc,i -U bus ≤30V; When the connection switch K1 is closed, the system enters a controlled operating state.

[0136] Through this embodiment, the system can complete the shutdown of low-health energy storage units and the connection of hot standby energy storage units without stopping the station.

[0137] Example 2: In this embodiment, the system includes 30 discrete gravity energy storage units, 4 parallel tracks, and 2 interlocking nodes. Each track is equipped with a path entrance, path exit, path occupancy detector, speed limit parameters, and a mechanical locking waiting station. Each interlocking node is configured with an occupancy detector and a release controller.

[0138] Mechanical locking waiting stations are located at the ends of the track and shaft, not in suspended positions without mechanical support. Each waiting station includes a support, a locking pin, a locking position sensor, and a release position sensor. After the gravity block enters the waiting station, the support and locking pin bear the gravity load, and the lifting motor does not continuously output hovering torque.

[0139] During a certain scheduling cycle, two energy storage units G5 and G 12 Both requests to enter the same interlocked node. The cluster-level merge controller calculates the combined evaluation value of both requests executing the current task via the target path. Assumptions: S 5,2 (t)>S 12,2 (t); Then; the system prioritizes allowing energy storage unit G5 to enter the corresponding interlock node, and energy storage unit G... 12 Enter the mechanical lock-up waiting station and wait for the next scheduling cycle to participate in the evaluation again.

[0140] For energy storage unit G 12 The remaining travel time T in the next cycle 12,2 The waiting time T for the workstation to unlock will be included. lock,2 This affects its overall evaluation value. Therefore, the waiting workstation is not an abstract queuing point, but a real engineering location with mechanical support, locking confirmation, and time costs.

[0141] Through this embodiment, the system can avoid path conflict under limited track and interlocking node conditions, and avoid the additional energy consumption caused by relying on motor hovering.

[0142] Example 3: Capacity adaptive response control under frequency disturbance; In this embodiment, the system's rated frequency f0 is 50Hz, and the frequency change rate threshold is: a=0.01Hz / s, b=0.30Hz / s, c=0.50Hz / s; The system currently has 12 energy storage units in operation, 4 in hot standby mode, and the remaining units in normal waiting or maintenance mode. The station-level controller calculates in real-time the current potential for increased power generation capacity as follows: ; The current increase in power absorption capacity is: ; When the power grid experiences an underfrequency disturbance, Δf(t) < 0 and R(t) < 0. The station-level controller determines that the system needs to increase the active power output to the power grid, therefore, it takes: ; And calculate K based on the real-time available capacity. f(t) and K R (t), generating the target active power adjustment ΔP*(t).

[0143] If at this time: a≤|R(t)|<b; The system then enters a level-two response. The station-level controller first adjusts the torque of the operating energy storage units, while the cluster-level combiner controller selects an energy storage unit from the hot standby energy storage units that is at a higher elevation, has completed pre-charging, has releaseable mechanical lockouts, and whose path interlocks are permitted, to be put into operation for power generation.

[0144] If further detection is detected: b≤|R(t)|<c; The system then enters a Level 3 response, suspending some non-essential energy storage upgrades to release more power generation capacity. Ordinary waiting energy storage units that have not yet completed pre-charging or whose paths have not been cleared are not considered instantaneous response energy storage units, but rather serve as subsequent continuous backup energy storage units.

[0145] Through this embodiment, the system can adaptively adjust the frequency response intensity according to the real-time online capacity, avoiding overload or insufficient response of the operating energy storage unit caused by a fixed control coefficient.

[0146] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. A method for electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control of a discrete gravity energy storage system, characterized in that, The methods include: Step 1: Construct a discrete gravity energy storage system comprising several discrete gravity energy storage units, perform system initialization, and mark the discrete gravity energy storage units as energy storage units; Step 2: Perform status acquisition to obtain multi-dimensional status data; the station-level controller determines the current task direction based on the dispatch power command, frequency deviation, and frequency change rate. The task direction includes distributing power generation and enhancing energy storage; the station-level controller calculates the current capacity available for increasing power generation and the current capacity available for increasing power absorption. Step 3: The cluster-level combiner controller calculates the health status of each energy storage unit, the path occupancy status of each candidate path, and the remaining travel time, energy matching, and wear leveling of the energy storage unit-candidate path combination consisting of the i-th candidate energy storage unit and the k-th candidate path in the finite set of candidate paths. Step 4: Eliminate energy storage unit-candidate path combinations that do not meet the preset screening conditions, calculate the weighted cost of the remaining feasible energy storage unit-candidate path combinations; set and update the state matrix; Step 5: Sort feasible energy storage unit-candidate path combinations from largest to smallest based on their comprehensive evaluation value. Select one or more combinations sequentially according to the current task power requirement and the ranking, until the cumulative executable power of the selected energy storage units meets the current task power requirement. When the comprehensive evaluation values ​​are the same, prioritize them in the following order: lower weighted cost, shorter remaining travel time, larger health status of the energy storage unit, and smaller path occupancy status. Within the same scheduling cycle, there should be no more than one candidate path for the same energy storage unit, and combinations with interlocking conflicts should not be allowed to proceed simultaneously. Step Six: Perform energy storage unit access, exit, and emergency fault control based on the preset energy storage unit access control method, energy storage unit normal zero-current exit control method, and energy storage unit emergency fault isolation control method; Step 7: When the energy storage unit needs to move to the target location or waiting station, determine whether the target path and its interlock nodes determined in Step 5 are allowed to enter; if allowed, then allow passage; if not allowed, then the energy storage unit enters the mechanically locked waiting station or maintains the existing locked state. Step 8: If a frequency disturbance is detected, the station-level controller generates a target active power regulation based on the current available capacity for increasing power generation, the current available power absorption, the frequency deviation, and the frequency change rate, and executes torque regulation of the operating energy storage unit, activation of the hot standby energy storage unit, suspension of the rising task, or reactive power support according to the response level. Step 9: The controller writes the results of access, exit, fault, lockout, path occupancy and power execution into the state matrix, and re-executes steps 2 to 9 in the next scheduling cycle.

2. The electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for a discrete gravity energy storage system according to claim 1, characterized in that, The discrete gravity energy storage system includes several discrete gravity energy storage units, several cluster-level DC buses, one or more station-level grid-connected converters, station-level controllers, cluster-level combiner controllers, unit controllers, an intra-station communication network, and a finite set of candidate paths. Each discrete gravity energy storage unit includes at least a gravity block, a lifting mechanism, a lifting motor M, a unit-level power converter, a connection switch K1, a fault freewheeling / braking protection branch K2, a pre-charge branch K3, a position sensor, a speed sensor, a load sensor, a temperature sensor, a vibration sensor, a lock-up status detector, and a unit controller.

3. The electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for a discrete gravity energy storage system according to claim 1, characterized in that, The formulas for calculating the current available capacity for increasing power generation and the current available capacity for increasing power absorption are as follows: ； ； in, For the current capacity available to increase power generation, For the current capacity available to increase absorbed power, P N,i The rated power of the i-th unit, Let be the availability factor of the i-th energy storage unit for power generation at the current moment. Let be the availability factor of the i-th energy storage unit at the current moment for improving energy storage.

4. The electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for a discrete gravity energy storage system according to claim 1, characterized in that, Health status parameters of energy storage units: The health status of the i-th energy storage unit is denoted as H. i Defined as: ； Among them, H T,i For healthy temperature, H V,i For vibrational health parameters, H F,i H represents the health status of the fault history. η,i For efficient and healthy quantities, w T w V w F w η These are the weighting coefficients; Path occupancy state variables: The path occupancy state of the k-th candidate path is denoted as O. k Defined as: ； Among them, B k The path is in Boolean occupancy status; B indicates the path is idle. k =0, path occupied when B k =1; L k L is the path queue length; max The maximum allowed queue length; J k J represents the number or occupancy rate of interlocked nodes; max This is the maximum reference value for the interlocked node's occupancy. Remaining travel time: The remaining travel time required for the i-th energy storage unit to reach the target location via the k-th candidate path is denoted as T. ik Let the current position of the i-th energy storage unit be x. i The target position is x target,k The path distance is: ； Using trapezoidal velocity programming, when: ； At that time, the remaining travel time was: ； when: ； At that time, the remaining travel time was: ； Among them, v max For the maximum allowed speed of the path, a max To allow maximum acceleration, T lock,k The time required for mechanical locking or unlocking; The remaining travel time is normalized as follows: ； Among them, T max The maximum travel time allowed for the current task; Energy matching amount: The height normalization value of the i-th energy storage unit is defined as: ； Among them, h i h represents the current height of the gravity block. min h is the minimum allowable height. max Maximum permissible height; When the task direction is to generate electricity from below, the energy matching quantity is defined as: E match,i =with i ; When the mission objective is to enhance energy storage, the energy matching quantity is defined as: E match,i =1-z i ; If the current task has a target energy requirement E req The following forms shall be adopted: ； Among them, E avail,i Let ξ be the energy that the i-th energy storage unit can currently release or absorb. E To prevent positive numbers with a denominator of zero; Wear leveling amount: Wear leveling amount W i Calculated by weighting the following normalized components: ； ； ； ； ； Among them, T run,i N lift,i and E through,i These represent the cumulative operating time, cumulative number of lifting or lowering actions, and cumulative energy throughput of the i-th energy storage unit within a preset statistical period, respectively; T ref N ref and E ref This corresponds to the normalized reference value; λ T , λ N and λ E W represents the weighting coefficient. i The larger the value, the higher the cumulative utilization rate of the energy storage unit.

5. The electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for a discrete gravity energy storage system according to claim 1, characterized in that, The screening criteria are: the energy storage unit does not have fault signs or fault isolation signs; The current position, mechanical locking state, and release state of the energy storage unit meet the requirements of the current task action; The electrical status of the energy storage unit meets the requirements for pre-charging, connection, operation, or decommissioning; the candidate path is reachable, there is no occupancy status that conflicts with the current movement of the energy storage unit, and the corresponding interlock node allows entry; the current height of the energy storage unit and the energy that can be released or absorbed meet the current mission direction; the temperature, vibration, and load status of the energy storage unit do not exceed the corresponding limits.

6. The electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for a discrete gravity energy storage system according to claim 1, characterized in that, Calculate the weighted cost of the remaining feasible energy storage unit-candidate path combination: Define the weighted cost function when the i-th energy storage unit selects the k-th candidate path to execute the task as follows: ； Among them, H i O is a health status parameter for energy storage units. k τ is the path occupancy state quantity. ik E represents the remaining travel time. match,i For energy matching quantity, W i α represents the wear equalization factor; α, β, γ, δ, and ε are weighting coefficients.

7. The electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for a discrete gravity energy storage system according to claim 1, characterized in that, The comprehensive evaluation value S in the state matrix S(t) ik (t) is defined as: ； Among them, S ik (t) represents the comprehensive evaluation value of the i-th energy storage unit for the k-th candidate path task at time t, ρ is the historical attenuation coefficient, and ξ is a positive constant to prevent the denominator from being zero; C ik The weighted cost of selecting the k-th candidate path to execute the task for the i-th energy storage unit; P task Prioritize tasks; Task priority P task Defined as: ； Among them, P freq P is the normalization quantity for the frequency response level. dispatch P is the normalized quantity for station-level scheduling priority. deadline P is a normalized measure of the urgency of the task deadline. balance The load balancing adjustment is given by weights that satisfy r1+r2+r3+r4=1.

8. The electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for a discrete gravity energy storage system according to claim 1, characterized in that, Energy storage unit access control method: When the target energy storage unit selected in step five meets the mechanical position condition and mission direction condition, and the candidate path and its interlocking nodes that form the selected feasible combination with the target energy storage unit meet the release condition, the corresponding candidate path is marked as the target path. The cluster-level combiner controller allows the target energy storage unit to enter the access process; Before connecting the energy storage unit, first detect the DC side voltage U of the unit. dc,i With cluster-level DC bus voltage U bus The absolute value of the difference; the closing of the access switch K1 is permitted when the following conditions are met: |In dc,i -IN bus |≤ΔU set ; Where, ΔU set The preset voltage difference threshold; When the DC side voltage of the unit meets the pre-charge condition, and the unit output current meets the access constraints, the energy storage unit has no fault flag, the mechanical lock-up state has been released, and the interlock node on the target path is allowed to enter, the access switch K1 is closed to connect the energy storage unit to the cluster-level DC bus; the cluster-level combiner controller sends the generator torque setpoint or power setpoint to the unit controller, and the energy storage unit enters the controlled operation state; Normal zero-current exit control method for energy storage units: SA1: The cluster-level combiner controller sends a torque reduction or current reduction command to the target energy storage unit, causing the output current of the energy storage unit to gradually decrease; SA2: Unit controller detects unit current I i The energy storage unit is considered to have entered a near-zero current state when the following conditions are met: |I i |≤I zero ; Among them, I zero Zero-flow exit threshold; SA3: The unit controller blocks the drive pulses of the unit-level power converter, putting the hoisting motor into a safe and controlled state; SA4: Disconnect the access switch K1 to isolate the energy storage unit from the cluster-level DC bus; SA5: If the gravity block needs to be kept in its current position, control the lifting mechanism to move it to the mechanical locking waiting position and confirm the mechanical locking status; if the energy storage unit needs maintenance, write the fault or maintenance flag into the status matrix. Emergency fault isolation and control methods for energy storage units: The system enters the emergency fault isolation process when any of the following conditions are detected: The unit-level power converter experiences overcurrent, overvoltage, drive failure, or bridge arm abnormality. The motor current cannot be reduced according to the normal current reduction command; The lifting mechanism exhibits abnormal speed, abnormal braking, or abnormal load. Unit DC side voltage U dc,i Exceeding the overvoltage protection threshold; The energy storage unit is not allowed to continue performing its original task due to its mechanical state. The emergency fault isolation process includes the following steps: SC1: The unit controller immediately reports the fault flag, the cluster-level combiner controller freezes the path assignment status of the energy storage unit, and prohibits other energy storage units from entering the corresponding interlock node; SC2: The unit-level power converter performs current limiting control or blocks the drive pulse of a faulty bridge arm; SC3: Activate fault freewheeling / braking protection branch K2; if K2 is the AC side freewheeling / braking branch of the motor, the motor inductance current and mechanical inertial energy are released through the motor side braking resistor, controlled short-circuit branch or equivalent damping branch; if K2 is the DC side braking chopper branch of the unit, the DC side overvoltage energy is absorbed through the braking resistor. SC4: Detection unit current I i Unit DC side voltage U dc,i and motor speed ω i When the safety isolation conditions are met, disconnect the connection switch K1; the safety isolation conditions include: |I i |≤I safe ; IN dc,i ≤U safe ; Among them, I safe U is the fault isolation current threshold. safe The fault isolation voltage threshold; SC5: After disconnecting the access switch K1, mark the energy storage unit as a fault isolation state and remove the energy storage unit from the subsequent candidate energy storage unit set in the state matrix.

9. The electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for a discrete gravity energy storage system according to claim 1, characterized in that, The target active power regulation is defined as: ； in: ； ； This represents the real-time available capacity corresponding to the current frequency disturbance direction; when the system needs to increase power generation, When the system needs to increase the power absorbed, ;Δf ref For the reference frequency deviation, R ref k is the reference frequency change rate. f and k R This is a dimensionless adjustment coefficient.

10. The electrical safety reconfiguration, path interlocking, and capacity adaptive frequency response control method for a discrete gravity energy storage system according to claim 1, characterized in that, Depending on the response level, the following actions will be taken: torque adjustment of operating energy storage units, activation of hot standby energy storage units, suspension of rising tasks, or reactive power support. Assume that the additional power generation provided by the currently operating energy storage units is The current operational energy storage units can provide an additional absorption power of [missing information]. The number of additional decentralized power generation and energy storage units required is: ； The number of additional energy storage units required is as follows: ； Among them, P unit The rated power of the unit. The average availability factor of candidate decentralized power generation and energy storage units. To improve the average availability factor of candidate energy storage units; When the calculated results of the number of newly invested decentralized power generation and energy storage units and the number of newly invested upgraded energy storage units are not integers, they are rounded up to the nearest integer. Hierarchical frequency response strategy: Set three frequency change rate thresholds a, b, and c, and satisfy the following: 0 < a < b < c; Level 1 Response: when: |R(t)|<a; At that time, the system does not change the number of energy storage units put into operation, but only makes adjustments through the motor torque correction of the operating energy storage units and the power control of the station-level grid-connected converter; Level 2 response: when: a≤|R(t)|<b; At that time, based on the first-level response, the system selects energy storage units from the set of hot standby energy storage units that meet the electrical pre-charging conditions, mechanical lock-up release conditions, and path interlock conditions for operation; Hot standby energy storage units must meet the following conditions: The energy storage unit has no fault indicators; The energy storage unit is in a mechanically locked waiting position or can reach the access position within a limited time. The DC side of the unit has completed pre-charging, or can complete pre-charging within a preset time. Interlocked nodes on the target path are allowed to proceed; The current altitude meets the requirements of the mission direction; Level 3 Response: when: b≤|R(t)|<c; When the system is in a state of underfrequency, it will suspend unnecessary boosting tasks on the basis of the level 2 response. If the system is in an underfrequency state, it will prioritize suspending boosting energy storage tasks and increase the distribution of power generation tasks. If the system is in an overfrequency state, it will prioritize suspending unnecessary power generation tasks and increase boosting energy storage tasks. Level 4 Response: when: |R(t)|≥c; When necessary, the system executes an emergency frequency response strategy, including locking non-essential tasks, calling up high-potential or low-potential thermal backup energy storage units, reallocating paths, increasing the power response priority of the station-level grid-connected converter, and performing reactive power support by the station-level grid-connected converter when needed.

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