CN-122026588-A - Zero-voltage starting control method for all-vanadium liquid flow energy storage system

CN122026588ACN 122026588 ACN122026588 ACN 122026588ACN-122026588-A

Abstract

The invention relates to the technical field of all-vanadium liquid flow energy storage, in particular to a zero-voltage starting control method for an all-vanadium liquid flow energy storage system. The invention dynamically adjusts the charging current by monitoring the change rate of the voltage of the battery terminal in real time as a sensitive index of the polarization state of the system to form an intelligent closed-loop control system, and simultaneously establishes a collaborative optimization model of the charging current and the electrolyte flow so that the system is always maintained in the state with the highest comprehensive energy efficiency in the whole starting process. The invention realizes the safe, rapid and stable transition of the all-vanadium liquid flow energy storage system from the zero-voltage state to the normal running state by combining a set of controlled and staged dynamic current charging strategies and the cooperative control of the system.

Inventors

Xia Zenggang
YE NA
YANG XINLONG
LIU FEICHAO
ZHANG GUOZHEN
Lv tengfei
ZHANG ZHIQIANG
SONG CHAONAN
DANG KAI
LANG XUEBIN
Hu zhengxi

Assignees

山东电工电气集团科学技术研究有限公司
山东电工电气集团有限公司

Dates

Publication Date: 20260512
Application Date: 20260209

Claims (10)

1. A zero-voltage starting control method for an all-vanadium liquid flow energy storage system is characterized by comprising the following steps of: S01, detecting a zero-voltage state, initializing parameters and starting an electrolyte circulating pump, wherein the initialization parameters comprise minimum starting current and initial current step length, and the converter charges the all-vanadium liquid flow energy storage system by taking the minimum starting current as a starting point; S02, sampling the voltage of a battery end of the energy storage system according to a set period, and calculating the average voltage change rate; S03, comparing the average voltage change rate with a set voltage change rate threshold range, adjusting the current step length when the average voltage change rate exceeds the threshold range, Wherein For the newly calculated current step size, For the last current step used, The coefficient is adjusted for the current step size, For the rate of change of the target voltage, The average voltage change rate obtained by calculation in the step S02 is calculated; s04, adjusting the output current of the converter according to the newly calculated current step length: , In order to regulate the output current of the converter, For adjusting the output current of the converter before, the output current of the converter is the charging current of the all-vanadium redox flow energy storage system; S05, measuring the internal resistance of the battery by a current step method, and correcting the maximum safe current based on the internal resistance of the battery ; S06, the flow of the electrolyte is cooperatively optimized, and after the charging current is adjusted, the optimal flow corresponding to the adjusted charging current is obtained based on the mapping relation between the charging current and the optimal flow of the electrolyte; S07, repeating the steps S02 to S06 until the charging current reaches the maximum safe current Or the voltage of the battery is steadily larger than the safety threshold value, the starting process is ended, and the normal working mode is switched to.
2. The method of claim 1, wherein step S05 comprises collecting voltage jump caused by charging current adjustment Calculating internal resistance of battery by combining known current variation : Obtaining the maximum safe current corresponding to the battery internal resistance based on the mapping relation between the battery internal resistance and the maximum safe current after obtaining the battery internal resistance 。
3. The zero-voltage starting control method for the all-vanadium-oriented liquid flow energy storage system of claim 2, wherein the mapping relation between the internal resistance of the battery and the maximum safe current is: , for the purpose of a safe voltage to be a target, For the open-circuit voltage of the battery, Is the concentration difference overpotential of the electrolyte.
4. The method for zero-voltage start control of an all-vanadium-oriented liquid flow energy storage system as set forth in claim 2, wherein the voltage jump is characterized by The calculation method comprises calculating average value of battery terminal voltage within 10ms after each charge current adjustment, and obtaining difference with average value of battery terminal voltage within 10ms before adjustment 。
5. The method for zero-voltage start control of an all-vanadium-oriented liquid flow energy storage system according to claim 1, wherein in step S06, the mapping relationship between the charging current and the optimal flow of the electrolyte is: , For the optimal flow rate of the electrolyte, In order for the charge current to be sufficient, Is the flow-current co-proportionality coefficient.
6. The zero-voltage starting control method for the all-vanadium-oriented liquid flow energy storage system of claim 5, wherein the method is characterized in that the proportional relation between the charging current and the optimal flow of the electrolyte is obtained through a current-flow collaborative dynamic optimization model, and comprises the following specific processes: Establishing an optimization model and constraint conditions: , , , Will be Carrying out optimization model and solving extremum to obtain an analytical solution: thereby obtaining the proportion relation between the optimal flow and the output current of the converter as follows ; Wherein the method comprises the steps of For the total power of the energy storage system, For the power of the electric pile, In order to pump the power of the pump, The working voltage of the energy storage battery is I is the working current of the energy storage battery, k is the proportionality coefficient of pumping power and flow, Q is the flow of electrolyte, 、 For the minimum and maximum values of the electrolyte flow, For the purpose of a safe voltage to be a target, For the open-circuit voltage of the battery, Is the concentration difference overpotential of the electrolyte, For the internal resistance of the energy storage battery, Is the proportionality coefficient of the power and the flow of the electric pile, As a coefficient of differential proportionality, Is the optimal flow of the electrolyte.
7. The method for zero-voltage start control of an all-vanadium-oriented liquid flow energy storage system of claim 5, wherein the flow-current cooperative proportionality coefficient K is obtained through experimental calibration.
8. The method of zero voltage start control for an all-vanadium redox flow energy storage system of claim 1 wherein the target rate of voltage change is a median of a range of voltage change rate thresholds.
9. The method of claim 1, wherein the threshold range of the voltage change rate is [ alpha, beta ], alpha=0.5V/s, beta=10V/s.
10. The method of zero voltage start control for an all-vanadium redox flow energy storage system of claim 1, wherein the initial current step size =0.5A, minimum start-up current =1A, maximum safe voltage =1000V, safety threshold of 0.9 Maximum safe current The initial value is 5A.

Description

Zero-voltage starting control method for all-vanadium liquid flow energy storage system Technical Field The invention relates to the technical field of all-vanadium liquid flow energy storage, in particular to a zero-voltage starting control method for an all-vanadium liquid flow energy storage system. Background The all-vanadium liquid flow energy storage system has the advantages of capacity expansion, long cycle life, high safety and the like, and is widely applied to the fields of power grid energy storage, renewable energy grid connection and the like. However, the electrolyte charge states of the positive electrode and the negative electrode of the all-vanadium liquid flow energy storage system tend to be consistent after long-term idling, overhauling and maintenance or deep discharging, the open-circuit voltage of the battery is extremely low, a zero-voltage state appears, and the system cannot normally be put into operation at the moment and needs to recover the activity of the system through a specific starting strategy. At present, the starting methods for the zero-voltage state are mainly divided into two types: The constant current starting method adopts a preset and smaller constant current to charge the battery. The method is simple, but has the serious defects that if the preset current is too large, impact current is easy to generate when the internal resistance of the system is low, a galvanic pile is damaged, and if the preset current is too small, the starting time is too long, so that the quick response requirement of a power grid cannot be met. The method cannot perform feedback adjustment according to the real-time state of the battery, is open-loop control, and is difficult to consider both safety and efficiency; The step current starting method sets a current increasing sequence, and gradually increases the charging current according to a fixed time step. The method is improved compared with the constant-current method, but is still an open-loop control of a preset formula. The increment step length and time are fixed, and the battery system with different health States (SOH), temperatures and internal resistances cannot be self-adapted. For a battery with a better state, the starting process is still conservative and slow, and for a battery with a worse state, the protection can be triggered due to too fast polarization in a certain current step, so that the starting failure is caused. In addition, the existing method generally ignores the problem of dynamic matching of electrolyte flow and charging current. During start-up, a fixed electrolyte flow either results in insufficient supply to exacerbate polarization at high currents or in waste of pumping energy at low currents, affecting overall start-up efficiency and economy of the system. Therefore, an intelligent closed-loop starting method capable of sensing the state of a battery in real time, dynamically adjusting a charging strategy and cooperatively optimizing an auxiliary system is urgently needed in the field so as to realize safe, rapid and efficient starting of the all-vanadium redox flow energy storage system from a zero-voltage state. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a zero-voltage starting control method for an all-vanadium liquid flow energy storage system, which realizes the safe, rapid and stable transition from a zero-voltage state to a normal running state of the all-vanadium liquid flow energy storage system through a set of controlled and staged dynamic current charging strategies and the cooperative control of the system. In order to solve the technical problems, the invention adopts the technical scheme that the zero-voltage starting control method for the all-vanadium liquid flow energy storage system comprises the following steps: S01, detecting a zero-voltage state, initializing parameters and starting an electrolyte circulating pump, wherein the initialization parameters comprise minimum starting current and initial current step length, and the converter charges the all-vanadium liquid flow energy storage system by taking the minimum starting current as a starting point; S02, sampling the voltage of a battery end of the energy storage system according to a set period, and calculating the average voltage change rate; S03, comparing the average voltage change rate with a set voltage change rate threshold range, adjusting the current step length when the average voltage change rate exceeds the threshold range, WhereinFor the newly calculated current step size,For the last current step used,The coefficient is adjusted for the current step size,For the rate of change of the target voltage,The average voltage change rate obtained by calculation in the step S02 is calculated; s04, adjusting the output current of the converter according to the newly calculated current step length: , In order to regulate the output current of the converter, For adjusting the out