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CN-122026585-A - Marine energy storage active follow-up charge and discharge control method and verification method

CN122026585ACN 122026585 ACN122026585 ACN 122026585ACN-122026585-A

Abstract

The invention relates to a marine energy storage active follow-up charge and discharge control method and a verification method, wherein a generator set and a battery pack in an energy storage system are connected in parallel to a bus to supply power to the bus, the battery pack is used as a voltage source, the bus is independently supported in a control mode of a virtual synchronous generator, in the follow-up mode, the battery pack is equivalent to a controllable current source, charge and discharge control is performed based on two-dimensional criteria of a battery state of charge (SOC) and bus voltage, and the energy storage system is efficiently, safely and flexibly operated under different working conditions by introducing an active and follow-up dual-mode cooperative operation mode and combining intelligent control logic based on the battery state of charge (SOC) and the bus voltage.

Inventors

  • JI XINKE
  • LI JING
  • DING FENG
  • HU RONGHUI
  • ZHANG KUN

Assignees

  • 中国船舶集团有限公司第七〇四研究所

Dates

Publication Date
20260512
Application Date
20260129

Claims (10)

  1. 1. The method is characterized in that the method is applied to a marine direct-current power grid system, the system comprises a generator set, a battery pack and a bidirectional DCDC converter, and the battery pack is connected in parallel to a direct-current bus through the bidirectional DCDC converter; the method comprises the following steps of (1) setting two operation modes of a battery pack, namely an active mode and a follow-up mode, (2) in the follow-up mode, the battery pack is equivalent to a controllable current source, charge and discharge control is performed based on two-dimensional criteria of a battery charge state SOC and a bus voltage, wherein when the battery charge state SOC is less than or equal to 50%, a power command PD=0 of a bidirectional DCDC converter is set, the battery pack is in a hot standby state, when the SOC is less than or equal to 50%, the bidirectional DCDC converter is set to charge with constant power PD1, when the SOC is more than or equal to 80%, the bidirectional DCDC converter is set to discharge with constant power PD2, when the bus voltage is more than or equal to Umax, umax=110% Un, un is the rated voltage of the generator set, high-power charging is started, the charging power is P3, umin=90% Un is started, the discharging power is Pmax, in a voltage transition interval, the charging and discharging power is smoothly switched according to a preset slope, (3) when the bus voltage is 70% Un, the bidirectional DCDC converter is set to charge with constant power PD1, when the SOC is less than or equal to 80%, when the bus voltage is more than or equal to 80%, the bus voltage is set to 95% and the equivalent voltage is set to the active mode, the active mode is set to be equal to or equal to 95%, the battery pack is automatically switched from the active mode back to the slave mode.
  2. 2. The marine energy storage active follow-up charge-discharge control method according to claim 1, wherein in the step (2), the voltage transition section includes a first voltage section [ Un1, umax ] and a second voltage section [ Umin, un2], wherein Un1 = 105% Un and Un2 = 95% Un, wherein in the first voltage section, the charging power is linearly increased from 0 to P3, and wherein in the second voltage section, the discharging power is linearly increased from 0 to Pmax.
  3. 3. The method for controlling the active follow-up charge and discharge of the marine energy storage according to claim 1 or 2, wherein in the step (2), the absolute values of the constant charge power PD1 and the constant discharge power PD2 are equal, the value range is 5kw to 20kw, the high-power charge power P3 is 30% -60% of the rated power of the battery pack, and the high-power discharge power Pmax is the rated power of the battery pack.
  4. 4. The method according to claim 1, wherein in the step (4), the sagging coefficient of the active mode is set to 2% -5%, corresponding to the virtual impedance rv=Δu/Pn, where Δu is a rated voltage drop value, and Pn is the rated power of the battery pack.
  5. 5. The method for controlling the active follow-up charge and discharge of the marine energy storage according to claim 1, wherein in the step (4), the triggering condition of the active mode further comprises an energy management system EMS sending a battery protection command, and the exiting condition further comprises an energy management system EMS returning to the follow-up mode.
  6. 6. The marine energy storage system is characterized by comprising a generator set, a battery pack, a bidirectional DCDC converter, a controller and an energy management system EMS, wherein the generator set is used for providing electric energy for a direct-current bus, the battery pack has a capacity of 200-500 kWh, the maximum charge-discharge multiplying power is 1-3C, the bidirectional DCDC converter is connected between the battery pack and the direct-current bus and has an undervoltage protection function, the undervoltage protection threshold value is set to be 70% Un, the controller is configured to execute the marine energy storage active follow-up charge-discharge control method according to any one of claims 1-5, and the energy management system EMS is used for monitoring the state of SOC of the battery pack and sending a mode switching instruction to the controller.
  7. 7. A verification method of an energy storage active follow-up charge-discharge control method is characterized by comprising the following steps of (1) constructing a verification platform, wherein the verification platform comprises N generator sets with rated power of P0, a battery pack with capacity of C and adjustable direct current loads, N is more than or equal to 3, C is more than or equal to 200kWh, all devices are connected in parallel to a direct current bus with rated voltage of Un, (2) setting initial SOC of the battery pack in a range of 50% -80%, 3) carrying out 100% load dump test, namely enabling a system to operate under the condition that total power is approximately equal to N multiplied by P0, suddenly cutting off all loads, recording the time of bus voltage fluctuation peak value and recovering the rated voltage, 4) carrying out 100% load dump test, enabling the system to operate under the condition that total power is approximately equal to N multiplied by P0, recording the lowest value of bus voltage drop and time of recovering the rated voltage, and (5) verifying standard, namely controlling the bus voltage fluctuation range within +/-10% Un and enabling the voltage recovery time to be less than 200ms.
  8. 8. The method according to claim 7, wherein in the step (3), when the bus voltage exceeds Umax, the battery pack is verified to be switched to a charged state and absorb power within 20ms, and in the step (4), when the bus voltage is lower than uman, the battery pack is verified to be switched to a discharged state and output power within 150 ms.
  9. 9. The method according to claim 7, further comprising a comparison verification step of testing the voltage fluctuation characteristics of the bus when the battery pack is connected and when the battery pack is not connected under the same working condition, respectively, and verifying the suppression effect of the battery pack on the voltage fluctuation and the improvement amplitude of the recovery speed.
  10. 10. The marine energy storage active follow-up charge and discharge control method according to claim 1, wherein the method enables an SOC effective working window of a battery pack to be expanded to 20% -95%, and when a + -100%Pn/10 ms step load disturbance is handled, bus voltage fluctuation is controlled within + -6%Un, and voltage recovery time is shortened by more than 80% compared with a traditional control strategy.

Description

Marine energy storage active follow-up charge and discharge control method and verification method Technical Field The invention relates to the technical field of energy storage control of a direct-current power grid system, in particular to a marine energy storage active follow-up charge and discharge control method and a verification method. Background Along with the rapid development of energy conversion requirements of various complex working conditions and distributed intelligent power grid technologies under different task modes of ships, the energy storage system is used as key equipment for stabilizing power fluctuation, realizing energy space-time transfer and improving the stability and power supply reliability of a power grid system, and the importance of the energy storage system is increasingly highlighted. However, the existing energy storage system control strategies still have a plurality of defects, so that the full play and wider application of the performance of the energy storage system are limited. The marine direct current bus simultaneously faces three types of severe disturbance, namely (1) a high-power cable winch, a side pushing and other load steps (+ -100% Pn/10 ms), and (2) Chai Fa unit switching and (3) short circuit faults. The traditional constant-power energy storage strategy is off-grid under 70% Un, deep drop cannot be restrained, and the utilization rate of the SOC section is low. The control strategy of the energy storage system in the current market is multifunctional and single, is difficult to adapt to complex and changeable operation conditions, and is mainly characterized in the following aspects: 1) The flexibility of single mode control is not enough, and many existing energy storage systems are only designed into a single operation mode, for example, only used as a current source or a voltage source, and the single mode design makes the energy storage system have poor adaptability under different application scenes, so that the waste of equipment resources is further caused. 2) The capability of bus voltage fluctuation is limited, and traditional energy storage control strategies tend to not respond quickly or effectively to bus voltage fluctuation. For example, some energy storage systems may require long detection and switching times when the grid voltage suddenly drops, and in addition, some control strategies only take simple shutdown or power limiting measures when coping with the bus voltage being over-limited, and none of them fully utilize the regulation capability of the energy storage system to maintain the stability of the bus voltage. 3) The mode switching logic is complex and has low reliability, namely, the mode switching of the energy storage system is a technical difficulty, and the system is unstable, equipment is damaged and even power supply of the system is interrupted due to improper switching logic. In the existing switching strategy, although mode switching is realized, the control logic is often complex, and the control logic depends on accurate detection and judgment of a plurality of electric quantities such as power grid voltage, frequency and the like, and is easily interfered by factors such as power grid harmonic waves, instantaneous disturbance and the like, so that misoperation or switching failure is caused. Disclosure of Invention Aiming at the problems, the method for controlling the active follow-up charge and discharge of the energy storage for the ship and the verification method are provided, the energy storage self-adaptive charge/discharge is realized to stabilize load fluctuation, the busbar voltage fluctuation is relatively smaller, the voltage recovery is faster, and the system is more stable. The technical scheme is that the marine energy storage active follow-up charge-discharge control method is applied to a marine direct current power grid system, the system comprises a generator set, a battery pack and a bidirectional DCDC converter, the battery pack is connected in parallel to a direct current bus through the bidirectional DCDC converter, and the method comprises the following steps: (1) Setting two operation modes of the battery pack, namely an active mode and a follow-up mode; (2) In the follow-up mode, the battery pack is equivalent to a controllable current source, and charge and discharge control is performed based on two-dimensional criteria of the battery state of charge (SOC) and bus voltage: When the SOC is more than or equal to 50% and less than or equal to 80%, setting a power command PD=0 of the bidirectional DCDC converter, and enabling the battery pack to be in a hot standby state; When the SOC is less than 50%, the bidirectional DCDC converter is set to charge at constant power PD 1; When SOC >80%, the bidirectional DCDC converter is set to discharge at constant power PD 2; When the busbar voltage is more than or equal to Umax, umax=110%Un, un is the rated voltage of the generator set, high-power ch