New energy ship battery power control method and system

Abstract

The present invention relates to a new energy ship battery power control method and a system. Each battery pack correspondingly supplies power to one bus, one bidirectional DC-DC converter is arranged between two adjacent buses to form a bus loop, and a load correspondingly draws electrical power from a corresponding bus loop segment; a power supply state of each bus area is checked, and by controlling the bidirectional DC-DC converter between buses, surplus energy of one bus is distributed to another bus having insufficient energy. According to the solution, a low DC-DC capacity configuration is achieved, energy between battery packs can be flexibly scheduled, the remaining electrical power between battery packs can be effectively balanced, the system risk is low and controllable when a bus is short-circuited, the power performance of a ship is not reduced when a single point of failure occurs, and the reliability and safety of the ship are effectively improved.

Description

New energy ship battery power control method and system Technical Field

[0001] The present invention relates to a new energy ship battery system power supply and distribution technology, and in particular to a new energy ship battery power control method and system. Background Art

[0002] Currently, most battery packs on purely battery-powered vessels require DC-DC (Direct-Channel-Driven Device) connections to the vessel's DC grid. This DCDC system is expensive and impacts the vessel's overall efficiency. Furthermore, DCDC equipment requires significant space, and this solution presents challenges such as difficulty calculating DC short-circuit current and difficulty implementing fully selective protection. In this solution, if a single battery pack or DCDC fails, propulsion power or daily load power must be limited to achieve energy balance. Otherwise, the DC bus will collapse.

[0003] Some battery packs on purely battery-powered vessels are not connected to the ship's DC grid using DC-DC (Direct Current Control) technology. This results in uneven remaining battery charge and an inability to effectively regulate it, reducing the vessel's endurance. Furthermore, connecting multiple battery packs in parallel can shorten the battery lifespan. In this solution, if a single battery pack fails, a propulsion system or a daily inverter system on the corresponding busbar will be lost, severely impacting the ship's safety. This solution also provides low redundancy for the ship's propulsion system.

[0004] Summary of the Invention

[0005] In response to the above problems, a new energy ship battery power control method and system are proposed.

[0006] The technical solution of the present invention is: a new energy ship battery power control method, each set of battery packs corresponding to a busbar power supply, bidirectional DC converters are provided between adjacent busbars to form a loop busbar, and the load draws power from the corresponding busbar ring section; the power supply status of each busbar area is checked, and by controlling the bidirectional DC converters between the busbars, the excess energy of the busbar is allocated to the energy-deficient busbar.

[0007] Furthermore, the method of allocating the excess energy of the busbar to the insufficient energy busbar is as follows:

[0008] If there is only one busbar with surplus energy or several adjacent buses with surplus energy, all buses with surplus energy are regarded as the energy configuration subject, and half of the calculated busbar surplus energy is transferred from both sides of the energy configuration subject to the adjacent buses;

[0009] There are three cases of surplus energy between two non-adjacent busbars:

[0010] Case 1: If the energy of the maximum energy bus is greater than half of the propulsion load power value, and the minimum energy bus lacks energy greater than half of the propulsion load power value, the maximum energy bus provides half of the propulsion load power value to the minimum energy bus;

[0011] Case 2: If the energy of the maximum energy bus is greater than half of the propulsion load power value, and the minimum energy bus lacks energy less than half of the propulsion load power value, all the excess power of the maximum energy bus is provided to the minimum energy bus;

[0012] Case 3: If the energy of the maximum energy bus is less than half of the propulsion load, energy is transferred from both sides of the maximum energy bus to the adjacent buses.

[0013] Furthermore, the power supply status of each bus area is checked. When a group of battery packs is lost, the DC bus voltage will drop instantaneously. If the corresponding load of the bus is a propulsion system, the propulsion inverter detects a sudden drop in the bus voltage. When the drop slope and voltage exceed the set value, the propulsion motor speed is controlled to enter the power generation state, which is maintained for about 100 milliseconds, and the bidirectional DC converters on both sides of the bus are triggered to enter the droop control mode; if the corresponding load of the bus is a daily load, the daily inverter detects a sudden drop in the bus voltage. When the drop slope and voltage exceed the set value, the daily inverter is controlled to enter the rectification state to maintain the voltage of the bus from dropping, which is maintained for 100 milliseconds, and the bidirectional DC converters on both sides of the bus are triggered to enter the droop control mode, thereby preventing the DC bus corresponding to the battery pack from losing power.

[0014] A new energy ship battery power system includes four 1000kWh battery packs, two 200kWh propulsion systems, two 200kW daily inverters for powering daily loads, four 100kW bidirectional DC converters, and a power management and control system; battery packs 1 to 4 are connected to busbars 1 to 4 respectively, 1# propulsion system is connected to busbar 1, 1# daily inverter system is connected to busbar 2, 2# daily inverter system is connected to busbar 3, and 2# propulsion system is connected to busbar 4; a bidirectional DC converter 12 is provided between busbar 1 and busbar 2, and busbar 2 is connected to busbar 4. A bidirectional DC converter 23 is provided between busbars 3, a bidirectional DC converter 34 is provided between busbars 3 and 4, and a bidirectional DC converter 41 is provided between busbars 4 and busbar 1, forming a loop bus, and the load draws power from the corresponding bus ring section; each propulsion system includes a 200kW propulsion inverter and a 200kW propulsion motor; each daily inverter system includes a 200kW daily inverter, a sine wave filter and a 250kVA daily transformer; the power management and control system adopts the new energy ship battery power control method to control the power supply of the power system.

[0015] The beneficial effects of the present invention are as follows: The proposed new energy ship battery power control method and system utilizes four battery packs directly connected to the DC bus, bidirectional DC converters between each bus, two propulsion systems and a daily inverter system, and a power management and control system with a multi-strategy algorithm. This solution utilizes a small DC / DC capacity, flexibly dispatches energy between battery packs, effectively balances remaining charge across the packs, minimizes and manages system risk in the event of a busbar short circuit, and maintains controllable single-point failure without degrading ship power performance, effectively improving ship reliability and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a schematic diagram of a ship battery power system according to the present invention;

[0017] Figure 2 is a schematic diagram of a conventional ship battery power system solution 1;

[0018] FIG3 is a schematic diagram of a single battery failure in a ship battery power system according to the present invention;

[0019] Figure 4 is a schematic diagram of a conventional ship battery power system solution 2;

[0020] FIG5 is a schematic diagram of a normal navigation control strategy of a ship battery power system according to the present invention;

[0021] FIG6 is a schematic diagram of a control strategy for a single battery pack in a marine battery power system during locked operation according to the present invention;

[0022] FIG7 is a schematic diagram of the control strategy of the four modes of the ship battery power system of the present invention. DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0024] As shown in Figure 1, an embodiment of the ship's pure battery power control system of the present invention is shown. The ship's pure battery power control system includes four 1000kWh battery packs, two 200kWh propulsion systems, two 200kW daily inverters for powering daily loads, four 100kW bidirectional DC converters, and one power management and control system. Battery packs 1 to 4 are connected to busbars 1 to 4 respectively, 1# propulsion system is connected to busbar 1, 1# daily inverter system is connected to busbar 2, 2# daily inverter system is connected to busbar 3, and 2# propulsion system is connected to busbar 4; a bidirectional DC converter 12 is provided between busbar 1 and busbar 2, a bidirectional DC converter 23 is provided between busbar 2 and busbar 3, a bidirectional DC converter 34 is provided between busbar 3 and busbar 4, and a bidirectional DC converter 41 is provided between busbar 4 and busbar 1, forming a loop bus, and the load draws power from the corresponding busbar ring section;

[0025] Each propulsion system includes a 200kW propulsion inverter and a 200kW propulsion motor; each daily inverter system includes a 200kW daily inverter, a sine wave filter and a 250kVA daily transformer.

[0026] 1. Comparison between the present invention and traditional solutions

[0027] A) Comparison with traditional solution 1 (Figure 2)

[0028] The solution of the present invention is equipped with four sets of 100kW bidirectional DC converters. The traditional battery power system solution 1 (as shown in Figure 2, the battery pack is connected to the bus through a bidirectional DC converter, all busbars are directly connected through switches, and the load draws power from the busbar) requires four 200kW DC converters. The solution of the present invention has the same number of DC converters but reduces the power by half.

[0029] In the conventional battery power system shown in Figure 2, if any battery pack or DC converter fails, the power of the propulsion system or the daily inverter system must be limited, otherwise the DC bus will collapse due to overcurrent. In the solution of the present invention, if any battery pack fails, as shown in Figure 3, two 100kW bidirectional DC converters on either side of the busbar containing the battery pack provide power to a 200kW propulsion system or a 200kW daily inverter system on that busbar, maintaining the power of the propulsion system and the daily inverter system unchanged.

[0030] In the traditional solution 1, the DC bus short-circuit current is difficult to calculate, and the fully selective protection solution is difficult to implement. In the solution of the present invention, the DC bus short-circuit current is easy to calculate, and the fully selective protection solution is easy to implement in a single branch.

[0031] B) Comparison with traditional solution 2 (Figure 4)

[0032] Traditional Solution 2 (Figure 4) directly connects one battery pack to a propulsion system or a daily inverter system. If the battery pack fails and stops functioning, the propulsion system or daily inverter system will be lost, seriously affecting the safety of the ship. Furthermore, this solution makes it difficult to adjust the battery pack capacity, which will affect the ship's range and reliability.

[0033] 2. Implementation of control methods during normal navigation

[0034] As shown in Figure 5, the values ​​of the four battery groups Soc1, Soc2, Soc3, and Soc4 are 90%, 80%, 70%, and 60% respectively. The current of the 1# propulsion inverter I M1 , 1# daily inverter current I S1 , 2# daily inverter current IS2 , 2# propulsion inverter current I M2 The values ​​are 2504, 83A, 83A, and 2504 respectively.

[0035] Because the output current of the 4 battery packs is I b1 :I b2 :I b3 :I b4 =Soc1:Soc2:Soc3:Soc4, derive I b1 :I b2 :I b3 :I b4 They are 200A, 177.5A, 155.3A, and 133.2A respectively. The calculation process is as follows:

[0036] S1: Calculate the regional current value

[0037] Because I A1 =I b1 -I M1 =200-2504=-50A

[0038] Similarly, we can deduce I A2 :I A3 :I A4 94.5A, 72.3A, -116.8A respectively

[0039] S2: Judgment mode

[0040] Because I A1 ~I A4 The number of numbers greater than 0 is 2, recorded as num1=2, and the maximum value is recorded as I Max1 =94.5、I Max2 =72.3; Calculate I A1 ~I A4 The number of values ​​less than 0 is 2, recorded as num2=2, and the minimum value is recorded as I Min1 =-116.8, I Min2 =-50;

[0041] So it is judged as mode 2

[0042] S3: Control Logic

[0043] Initial state equations

[0044] Mode 2 control logic: I Max1 and I Max2 The excess power generated by the DC bus 2 and bus 3 is evenly distributed to the other two areas. The current I dc34Set to 0.5*(I Max1 +I Max2 )=0.5*(94.5+72.3)A=83.4A, the current of the bidirectional DC converter 12 I dc12 Set to -0.5*(I Max1 +I Max2 )A=-83.4A;

[0045] After redistribution, I can be obtained by equation dc41 =-33.4A, I dc23 =-11.1A;

[0046] 3. Implementation of control method when a battery pack is locked during operation

[0047] As shown in FIG6 , the values ​​of Soc1, Soc2, Soc3, and Soc4 of the four battery packs are 90%, 0.01% (the system setting value when the battery pack is locked), 85%, and 80%, respectively. M1 , I S1 , I S2 , I M2 The values ​​are 250A, 83A, 83A, and 250A respectively.

[0048] Because I b1 :I b2 :I b3 :I b4 =Soc1:Soc2:Soc3:Soc4, derive I b1 :I b2 :I b3 :I b4 They are 235A, 0A, 222A, and 209A respectively. The calculation process is as follows:

[0049] S1: Calculate the regional current value

[0050] Because I A1 =I b1 -I M1 =235-250A=-15A

[0051] Similarly, we can deduce I A2 :I A3 :I A4 They are -83A, 139, and -41A respectively

[0052] S2: Judgment mode

[0053] Because I A1 ~I A4 The number of numbers greater than 0 is 1, recorded as num1=1, and the maximum value is recorded as I Max1 =139; Calculate I A1~I A4 The number of values ​​less than 0 is 3, recorded as num2=3, and the minimum value is recorded as I Min1 =-83, I Min2 =-41, I Min3 =-15;

[0054] So it is judged as mode 1

[0055] S3: Control Logic

[0056] Initial state equations

[0057] Mode 1 control logic: I Max1 The excess power generated by the DC bus 3 is evenly distributed to the two adjacent areas. The current I dc34 Set to 0.5*I Max1 =69.5, bidirectional DC converter 23 current I dc23 Set to -0.5*I Max1 =-69.5;

[0058] After redistribution, I can be obtained by equation dc41 =28.5A, I dc12 =13.5A;

[0059] 4. Control strategy diagram

[0060] Figure 7 shows a schematic diagram of the control strategy;

[0061] In mode 1, only one bus has surplus energy, and half of the surplus energy of the bus is transferred from both sides of the bus to the adjacent bus;

[0062] In mode 2, two adjacent buses have surplus energy, and half of the total surplus energy of the two buses is transferred to the two buses lacking energy.

[0063] In mode 3, two non-adjacent buses have surplus energy. If the bus with the largest energy has more than half the propulsion load power value, and the bus with the smallest energy lacks energy more than half the propulsion load, the largest bus provides half the propulsion load power value to the smallest bus.

[0064] In mode 3, if two non-adjacent buses have surplus energy, and if the bus with the largest energy has a power value greater than half of the propulsion load, and the bus with the smallest energy has a power value less than half of the propulsion load, all the surplus power of the largest bus is provided to the smallest bus.

[0065] In mode 3, two non-adjacent buses have surplus energy. If the maximum energy bus is less than half of the propulsion load, energy is transferred from both sides of the maximum energy bus to the adjacent buses.

[0066] In mode 4, the three adjacent buses have surplus energy, and half of the total surplus energy of the three buses is transmitted from the left and right sides to the only bus that lacks energy.

[0067] 5. Instantaneous control implementation when a battery pack fails

[0068] When a battery pack is lost, the DC bus voltage will drop instantaneously. The propulsion inverter detects a sudden drop in bus voltage. When the drop slope and voltage exceed the set value, the propulsion motor speed is controlled to enter the power generation state, which is maintained for about 100 milliseconds, and the bidirectional DC converters on both sides of the bus are triggered to enter the droop control mode. When the daily inverter detects a sudden drop in bus voltage. When the drop slope and voltage exceed the set value, the daily inverter is controlled to enter the rectification state, which can maintain the voltage of the bus from dropping, which is maintained for 100 milliseconds, and the bidirectional DC converters on both sides of the bus are triggered to enter the droop control mode. This prepares the bidirectional DC converter to switch from the energy scheduling mode to the droop control mode to prevent the DC bus from losing power.

[0069] 6. Implementation of droop control for bidirectional DC converters

[0070] During normal operation, the bidirectional DC converter receives current instructions from the power management system to achieve energy scheduling and maintain a balanced SOC state between battery packs.

[0071] When a battery pack fails, the bidirectional DC converter droop control mode is triggered. The droop control method is as follows: As shown in Figure 3, when battery pack 2 fails, bus 1 and bus 3 provide power to it:

[0072] Among them, set U A The droop starting voltage is set to 650V, U B The droop end voltage is set to 550V. dc2 The actual DC voltage of the bus is 600V, P N The rated power of the bidirectional DC converter is 100kW;

[0073] The DC converters 12 and 23 on both sides of the busbar 2 inject current into the busbar 2:

[0074] The above-described embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A new energy ship battery power control method, characterized in that Each battery pack supplies power to a busbar. A bidirectional DC converter is provided between adjacent busbars to form a looped busbar, and the load takes power from the corresponding busbar loop segment. Check the power supply status of each busbar area, and through the control of the bidirectional DC converter between the busbars, allocate the surplus energy of the busbar to the busbar with insufficient energy.

2. The new energy ship battery power control method according to claim 1, wherein The method of allocating the surplus energy of the busbar to the busbar with insufficient energy is as follows: If there is only one busbar with surplus energy or several adjacent busbars with surplus energy, take all the busbars with surplus energy as the main body of energy allocation, and transfer half of the calculated surplus energy of each busbar from both sides of the main body of energy allocation to the adjacent busbars. If there is surplus energy in two non-adjacent busbars, there are three cases. Case 1: If the energy of the busbar with the maximum energy is greater than half of the propulsion load power value, and the busbar with the minimum energy lacks energy greater than half of the propulsion load, the busbar with the maximum energy provides half of the propulsion load power value to the busbar with the minimum energy. Case 2: If the energy of the busbar with the maximum energy is greater than half of the propulsion load power value, and the busbar with the minimum energy lacks energy less than half of the propulsion load, all the surplus power of the busbar with the maximum energy is provided to the busbar with the minimum energy. Case 3: If the energy of the busbar with the maximum energy is less than half of the propulsion load, transfer energy from both sides of the busbar with the maximum energy to the adjacent busbars.

3. The new energy ship battery power control method according to claim 1, characterized in that Check the power supply status of each busbar area. When a battery pack is lost, the DC busbar voltage will drop instantaneously. If the load corresponding to this busbar is the propulsion system, the propulsion inverter detects the sudden drop of the busbar voltage. When the drop slope and voltage exceed the set value, control the speed of the propulsion motor to enter the power generation state for about 100 milliseconds, and trigger the bidirectional DC converters on both sides of this busbar to enter the droop control mode; if the load corresponding to this busbar is the daily load, the daily inverter detects the sudden drop of the busbar voltage. When the drop slope and voltage exceed the set value, control the daily inverter to enter the rectification state to maintain the voltage of this busbar from dropping, for 100 milliseconds, and trigger the bidirectional DC converters on both sides of this busbar to enter the droop control mode; prevent the DC busbar corresponding to the lost battery pack from losing power.

4. A new energy ship battery power system, characterized in that, It includes 4 sets of 1000 kWh battery packs, 2 sets of 200 kWh propulsion systems, 2 sets of 200 kW daily use inverters for power supply of daily loads, 4 sets of 100 kW bidirectional DC converters and 1 set of power management control system; Battery packs 1 to 4 are respectively connected to buses 1 to 4, the 1# propulsion system is connected to bus 1, the 1# daily use inverter system is connected to bus 2, the 2# daily use inverter system is connected to bus 3, and the 2# propulsion system is connected to bus 4; A bidirectional DC converter 12 is provided between bus 1 and bus 2, a bidirectional DC converter 23 is provided between bus 2 and bus 3, a bidirectional DC converter 34 is provided between bus 3 and bus 4, and a bidirectional DC converter 41 is provided between bus 4 and bus 1 to form a loop bus, and the load takes power from the corresponding bus loop segment; Each set of propulsion system includes 1 set of 200 kW propulsion inverter and 1 set of 200 kW propulsion motor; Each set of daily use inverter system includes 1 set of 200 kW daily use inverter, 1 set of sine wave filter and 1 set of 250 kVA daily use transformer; The power management control system controls the power supply of the power system by using the new energy ship battery power control method described in any one of claims 1 to 3.

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