CN115214865B - Ship hybrid power system and energy management method thereof - Google Patents

Abstract

The invention relates to a ship hybrid power system and its energy management method, which includes 1 set of lithium-ion battery pack, 1 set of diesel generator set, 1 set of DC distribution board, 1 set of AC distribution board, 2 sets of propulsion motors, 1 set of DC charging interface and 1 set of energy management system; DC distribution board includes 1 set of DC converter, 1 set of AFE controlled rectifier, 2 sets of daily inverters, 2 sets of propulsion inverters, the energy management system is equipped with pure battery There are three energy supply modes: pure diesel-electric mode and hybrid mode. The energy management system controls the charge and discharge curves of the AFE controllable rectifier and DC converter in real time, and configures multi-strategy mode switching functions and real-time energy management strategies, which effectively solves the problem of slow system response, poor robustness, inflexible mode switching, and problems throughout the ship. Issues such as the risk of power loss. It has the characteristics of long cruising range, high operating efficiency of diesel generator set and good silent effect. Improved safety and reliability of hybrid power systems.

Description

A ship hybrid power system and its energy management method

Technical field

The invention relates to a ship power system, and in particular to a ship hybrid power system and an energy management method thereof.

Background technique

As the country will vigorously control ship pollutant emissions, as well as the advancement of battery technology and the decline in prices, battery power has been widely proposed as a representative of clean power systems, which meets the requirements of "zero emission" and "low noise" At the same time, it will further reduce operating costs, and it will be the first choice for power for small and medium-sized inland ships in the future.

However, currently pure battery-powered ships have a short cruising range, making it difficult to meet the endurance requirements of transportation ships and law enforcement vessels for more than 12 hours a day. Hybrid power systems have the advantages of long cruising time, high operating efficiency of diesel generator sets, and flexible operation modes of the entire ship. , the cost of hybrid power system is also lower than that of pure battery power system, and it is recognized and favored by the above-mentioned ship owners.

At present, marine hybrid power systems are rarely used in ships. In hybrid power mode, the energy management system is mostly used to directly control the output power of the battery pack. This type of hybrid power system has slow response, poor robustness, inflexible mode switching, and the possibility of the entire ship losing power. risk.

Contents of the invention

In view of the current problems of few applications of pure battery-powered ships and the slow response and poor robustness of hybrid power systems, inflexible mode switching, and the risk of complete ship power loss, a ship hybrid power system and its energy management method are proposed. The energy management system controls the charge and discharge curves of the AFE (active front end active front end) controllable rectifier and DC converter in real time, and configures multi-strategy mode switching functions and real-time energy management strategies, which effectively solves the problem of slow system response and poor robustness. Mode switching is inflexible and there is a risk of power loss for the entire ship.

The technical solution of the present invention is: a marine hybrid power system, including 1 set of lithium-ion battery pack, 1 set of diesel generator set, 1 set of DC distribution board, 1 set of AC distribution board, 2 sets of propulsion motors, 1 set of DC Charging interface and 1 set of energy management system; DC distribution board includes 1 set of DC converter, 1 set of AFE controlled rectifier, 2 sets of daily inverters, 2 sets of propulsion inverters, the energy management system has a pure battery mode , three energy supply modes: pure diesel-electric mode and hybrid mode;

When the hybrid ship is operating in pure battery mode during normal navigation, the lithium-ion battery pack is boosted to the DC distribution board bus through the DC converter;

When the hybrid ship is sailing normally in pure diesel-electric mode, the diesel generator set outputs alternating current, which is boosted and transmitted to the DC distribution board bus through the AFE controllable rectifier;

When a hybrid ship is sailing normally in hybrid mode, the diesel generator set transmits electric energy to the DC distribution board bus through the AFE controllable rectifier, and the lithium-ion battery pack is connected to the DC distribution board bus through the DC converter;

The bus power of the DC distribution board transmits energy to the propulsion motor and propeller through the propulsion inverter. The DC power provides three-phase power to the AC load through the daily inverter. The daily inverter is one for use and one for backup;

When the hybrid ship is berthed at the shore, it chooses to enter the shore power charging mode and connects to the DC charging interface through the shore DC charging pile to supply power to the DC distribution board bus. The DC distribution board bus power is used to charge the lithium-ion battery pack through the DC converter. .

Preferably, the energy management system communicates with the DC converter, propulsion inverter and daily inverter through the Profibus communication module for data interaction; the energy management system communicates with the lithium-ion battery pack and shore power DC charging through the CAN module Stake for data interaction;

The energy management system controls and manages the control algorithms and mode switching of pure battery mode, pure diesel-electric mode, hybrid mode, and shore power charging mode.

An energy management method for a marine hybrid power system. The automatic mode switching control management of the energy management system: sets the low power setting value of the lithium-ion battery pack to A% of the rated power, and the high power setting value of the lithium-ion battery pack to C%. Rated power, the power setting value in the lithium battery pack is B% of the rated power;

Hybrid peak clipping mode: If the total load of the whole ship is less than the electric energy corresponding to the current output limit value I _limit of the AFE controllable rectifier, only the AFE controllable rectifier provides electric energy for the whole ship load; if the total load of the whole ship is greater than the current output limit of the AFE controllable rectifier The value I _limit corresponds to the electric energy. The DC converter is under overvoltage control. The AFE controllable rectifier provides the output limit value I _limit corresponding to the electric energy. The remaining electric energy is provided by the lithium-ion battery pack through the DC converter; hybrid power valley filling mode: such as the whole ship If the load is less than the electric energy corresponding to the AFE controllable rectifier current output limit value I _limit , the DC converter is in under-voltage control, and the excess electric energy passes through the DC converter to charge the lithium-ion battery pack; if the total load of the entire ship is greater than the AFE controllable rectifier current output limit The value I _limit corresponds to the electric energy, which limits the propulsion power to ensure that the total ship load is not greater than the AFE controllable rectifier current output limit value I _limit corresponds to the electric energy;

Hybrid peak-shaving and valley-filling mode: If the total ship load is less than the electric energy corresponding to the AFE controllable rectifier current output limit value I _limit , the DC converter is under under-voltage control, and the excess electric energy passes through the DC converter to charge the lithium-ion battery pack; such as The total load of the whole ship is greater than the electric energy corresponding to the current output limit value I _limit of the AFE controllable rectifier. The DC converter is under undervoltage control. The AFE controllable rectifier provides electric energy corresponding to the output limit value I _limit . The remaining electric energy is converted by DC from the lithium-ion battery pack. provided by the device;

When the ship is running in pure battery mode and the SOC is lower than A%, it will automatically switch to the valley filling mode of hybrid power mode;

When the ship is operating in the peak-loading and valley-filling mode of the hybrid power mode, when the SOC is lower than A%, it will automatically switch to the valley-filling mode of the hybrid power mode;

When the ship is running in the peak-loading and valley-filling mode of the hybrid power mode, when the SOC is higher than C%, it will automatically switch to the valley-filling mode of the hybrid power mode;

When the ship is running in the peak-cutting mode of the hybrid power mode, when the SOC is lower than B%, it will automatically switch to the peak-cutting and valley-filling mode of the hybrid power mode;

When the ship is running in the valley-filling mode of the hybrid power mode, when the SOC is higher than B%, it will automatically switch to the peak-cutting and valley-filling mode of the hybrid power mode.

Further, an overvoltage control curve and an undervoltage control curve are set in the DC converter, and the AFE controllable rectifier is set to output a constant voltage and a current output limit;

The overvoltage control curve U ₁ of the DC converter is determined by setting the overvoltage control zero-crossing voltage value U _ov and the overvoltage control curve droop rate K _ov , U ₁ =K _ov *I+U _ov , where I is the DC converter Charge and discharge given value, when the DC converter output DC voltage U reaches the overvoltage control curve U ₁ , the charge and discharge current I given value is calculated based on U ₁ , and the DC converter performs current control according to the I value; the current I is greater than zero It is discharging when the current I is less than zero; it is charging when the current I is less than zero; K _ov is less than zero;

The undervoltage control curve U ₂ of the DC converter is determined by setting the undervoltage control zero-crossing voltage value U _uv and the undervoltage control curve sag rate K _uv , U ₂ =K _uv *I+U _uv , when the DC converter outputs DC When the voltage U reaches the undervoltage control curve U ₂ , the given value of the charging and discharging current I is calculated based on U ₂ , and the DC converter performs current control based on the I value; when the current I is greater than zero, it is discharging, and when the current I is less than zero, it is charging; K _uv is less than zero; the AFE controllable rectifier outputs a constant voltage value U _DC and is set with a current output limit value I _limit ; when the AFE controllable rectifier output current reaches I _limit , the output voltage will not be able to maintain a constant voltage value U _DC and will Enter the corresponding voltage of the overvoltage or undervoltage control curve.

Furthermore, the energy management system uses Profibus to real-time adjust the DC converter charge and discharge current given value I, overvoltage control zero-crossing voltage value U _ov , overvoltage control curve sag rate K _ov , and undervoltage control zero-crossing voltage value U _uv and undervoltage control curve sag rate K _uv , real-time setting of the output constant voltage value U _DC and current output limit value I _limit of the AFE controllable rectifier; the total load of the ship is the sum of the power of the two propulsion motors plus the daily load power.

Further, the output constant voltage value of the AFE controllable rectifier U _DC =750V, the AFE controllable rectifier current output limit value I _limit =0.9I _N2 is set, and the rated current of the AFE controllable rectifier is _IN2 ;

Set the zero-crossing voltage value of the overvoltage control curve U _ov =750V, the droop rate K _ov =-2%*U _ov /I _N1 , the rated current of the DC converter is _IN1 , and the overvoltage control function is U ₁ =K _ov * I+U _ov , I is the given value of the charging and discharging current of the DC converter. When the current I is greater than zero, it is discharging, and when the current I is less than zero, it is charging;

Set the undervoltage control curve zero-crossing voltage value U _uv = 715V, the droop rate K _uv = -2%*U _ov /I _N1 , and the undervoltage control function U ₂ =K _uv *I+U _uv .

The beneficial effects of the present invention are: the marine hybrid system and its energy management method of the present invention have the characteristics of long cruising range, high operating efficiency of the diesel generator set, and good mute effect; the AFE controllable rectifier and DC are controlled in real time through the energy management system The charge and discharge curve of the converter is configured with a multi-strategy mode switching function and a real-time energy management strategy. The entire system has fast response, strong robustness, and flexible mode switching, which improves the safety and reliability of the hybrid power system.

Description of drawings

Figure 1 is a schematic diagram of the marine hybrid power system of the present invention;

Figure 2 is a schematic diagram of the energy control method of the ship hybrid power system of the present invention;

Figure 3 is a control logic diagram of the DC converter of the present invention;

Figure 4 is a control logic diagram of the AFE controllable rectifier of the present invention;

Figure 5 is a schematic diagram of the peak-shaving and valley-filling mode of the ship hybrid power system of the present invention.

Detailed ways

The present invention will be 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 detailed implementation modes and specific operating procedures. However, the protection scope of the present invention is not limited to the following embodiments.

As shown in Figure 1, an example of an embodiment of the present invention that has been applied on a ship is shown. The ship hybrid power system includes a set of 200kWh lithium-ion battery pack, a set of 100kWh diesel generator set, a set of 750VDC DC distribution board, and a set of 400VAC AC Power distribution board, 2 sets of 50kW propulsion motors, 1 set of DC charging interface and 1 set of energy management system; DC power distribution board includes 1 set of 100kW DC converter, 1 set of 100kW AFE controlled rectifier, 2 sets of 50kW daily inverters inverter and two sets of 50kW propulsion inverters, of which one is used for daily use and one is for backup; the rated voltage of the battery pack is 644 volts; the main propulsion motor is rated 380VAC, 1500RPM.

The DC bus of the DC distribution board is redundantly designed, with one in use and one in standby, connected through a controllable switch; the 200kWh lithium-ion battery pack is connected to the second DC bus of the DC distribution board through a DC contactor; the 100kWh diesel generator set It is connected to the first DC bus of the DC distribution board through a 100kW AFE controllable rectifier; the DC charging interface is connected to the two DC buses of the DC distribution board through respective DC contactors; two sets of 50kW propulsion motors are respectively The two DC buses of the DC distribution board are connected to each other through the respective propulsion inverters; the two DC buses of the 400VAC AC distribution board and the DC distribution board are connected through daily inverters respectively, and the two DC buses of the DC distribution board The busbar is connected to the 400VAC AC distribution board through the daily inverter, and the daily load is connected to the 400VAC AC distribution board.

When a hybrid ship is sailing normally, three modes can be selected, namely pure battery mode, pure diesel-electric mode, and hybrid mode. In pure battery mode, the lithium-ion battery pack (644V) increases the power to 750V through the DC converter and transmits it to the DC distribution board bus. In pure diesel-electric mode, the diesel generator set emits 400VAC alternating current, and the electric energy is increased to 750V through the AFE controllable rectifier and transmitted to the DC distribution board bus. In hybrid mode, the diesel generator set transmits electric energy to the DC distribution board bus through the AFE controlled rectifier, and the lithium-ion battery pack is connected to the DC distribution board bus through the DC converter. The bus power of the DC distribution board transmits energy to the propulsion motor and propeller through the propulsion inverter. The DC power provides three-phase 400VAC power to the AC load through the daily inverter. The daily inverter is used for one use and one for backup.

When the hybrid ship is berthed at the shore, it can choose to enter the shore power charging mode. It can connect the DC charging interface through the shore DC charging pile to supply power to the DC distribution board bus. The DC distribution board bus power is supplied to the lithium-ion battery pack through the DC converter. to charge.

1. Specific implementation of energy management system:

The energy management system uses a redundant programmable controller as the main controller and is configured with a Profibus communication module for communicating with the DC converter, AFE controlled rectifier, propulsion inverter and daily inverter, and is configured for the battery pack The CAN module for communication between the BMS and the DC charging pile uses the communication protocol J1939. It is equipped with a network port module for communicating with the ship's integrated control system and an Ethernet module for communicating with the touch screen.

The main contents of the communication between the energy management system and the DC converter, AFE controlled rectifier, propulsion inverter and daily inverter: 1) Control data includes: module start, module stop, bus control mode, charge and discharge mode; 2) Status data includes: module DC voltage, module output voltage, module frequency, module power, module current, module voltage, module temperature, module fault word, module ready, module running, module alarm, module fault.

The main communication contents between the energy management system and the battery pack BMS include: battery pack total voltage, battery pack current, SOC value, SOH value, single cell voltage, battery temperature, three-level alarm code, comprehensive status, contactor status, insulation value , cabin temperature, maximum allowable charge and discharge power value, etc.

The connection process between the energy management system and the shore power DC charging pile: completion of physical connection, low-voltage auxiliary power-on, charging handshake stage, charging parameter configuration stage, charging stage, charging end stage, and end of charging; in the charging stage, the integrated control system and the shore Real-time interactive data of the electric DC charging system. The interactive data includes voltage output value, current output value, battery temperature, battery voltage, charging status, SOC value, insulation status, etc.

The touch screen can display the status and alarm information of all DC converters, AFE controlled rectifiers, propulsion inverters, daily inverters, battery packs, and shore power DC charging piles.

2. DC converter overvoltage control curve and undervoltage control curve

As shown in Figure 2, the overvoltage control curve of the DC converter in this embodiment is set to the zero-crossing voltage value U _ov = 750V, the droop rate K _ov = -2%*U _ov /I _N1 , and the DC converter Rated current I _N1 =133A, the overvoltage control function of formula (1) is U ₁ =K _ov *I+U _ov =-0.02I*U _ov /I _N1 +750, I is the charge and discharge given value of the DC converter; As shown in Figure 2 at point B, U ₁ = 744V = -0.02I*750/I _N +750, I = 0.4*I _N1 = 53.2A. When the current I is greater than zero, it is discharging, and when the current I is less than zero, it is charging. ;

As shown in Figure 2, the under-voltage control curve of the DC converter in this embodiment is set to the zero-crossing voltage value U _uv of the under-voltage control curve = 715V, and the droop rate K _uv = -2%*U _ov /I _N1 , _IN1 = 133A, equation (1) undervoltage control function U ₂ ＝K _uv *I+U _uv ＝-0.02I*U _ov /I _N1 +715, as shown in Figure 2 at point D, U ₂ ＝721V＝-0.02I *750/I _N1 +715, I=-0.4*I _N1 =-53.2A;

As shown in Figure 2, in this embodiment, the AFE controllable rectifier voltage control curve, the AFE controllable rectifier output constant voltage value U _DC =750V, is set with a current output limit value I _limit =0.9I _N2 , the AFE controllable rectifier rated current I _N2 = 133A. When the output current reaches I _limit , the output voltage cannot maintain U _DC and will enter the corresponding voltage of the overvoltage or undervoltage control curve.

Figure 3 is the DC converter control logic block diagram, i _ref is the given value of the charge and discharge current value transmitted to the DC converter by the above energy management system through Profibus. When the given current is greater than the actual current and the voltage U reaches the U1 curve, the DC converter works in overvoltage control. As shown in Figure 3, the given current value is determined by the U1 curve. When the current given is less than the actual current and the voltage U reaches the U2 curve, the DC converter works in undervoltage control. As shown in Figure 3, the current given value is determined by the U2 curve.

As shown in Figure 4, the control logic block diagram of the controllable rectifier is shown. V _dc * is the output constant voltage value U _DC = 750V of the AFE controllable rectifier.

3. Implementation of peak clipping mode

As shown in Figure 2, the energy management system sets U _ov = U _DC = 750V, sets the AFE controllable rectifier output limit value to I _limit = 90% _IN2 , _IN2 = 133A, and sets the control DC converter overvoltage The droop rate of the control curve is K _ov =-2%*U _ov /I _N1 , and the DC converter is set to work at the overvoltage control curve U ₁ ; the total load of the whole ship is the sum of the power of the two propulsion motors plus the daily load power;

When the total ship load is less than I _limit , that is, between U _ov and point A in Figure 2, the diesel generator set provides all electric energy through the AFE controllable rectifier;

When the total load of the whole ship is greater than I _limit , that is, between U _ov and F points in the figure, the diesel generator set provides electric energy corresponding to I _limit through the AFE controlled rectifier, and the remaining electric energy is provided by the lithium-ion battery pack through the DC converter, such as At point B in Figure 2, the diesel generator set provides 90% of the electric energy corresponding to I _N2 through the AFE controlled rectifier, and the lithium-ion battery pack provides 40% of the electric energy corresponding to I _N1 through the DC converter.

4. Implementation of peak-shaving and valley-filling mode

As shown in Figure 2, the energy management system sets U _ov = U _DC = 750V, U _uv = 720V, sets the AFE controllable rectifier output limit value to I _limit = 90% I _N2 , and sets the control DC converter overvoltage The control curve droop rate K _uv =-2%*U _ov /I _N2 , and the DC converter is set to operate under the undervoltage control curve U ₂ ; Figure 5 is a schematic diagram of the peak clipping and valley filling mode;

When the total ship load is less than I _limit , the diesel generator set provides I _limit = 90% I _N2 corresponding electric energy through the AFE controllable rectifier, and the excess electric energy is charged by the DC converter to the lithium-ion battery pack; that is, U _uv and G in Figure 2 Between points, at point C in Figure 2, the diesel generator set provides I _limit = 90% I _N2 corresponding electric energy through the AFE controlled rectifier, and 40% I _N1 corresponding electric energy is charged by the DC converter to the lithium-ion battery pack. At this time The total load of the whole ship is the corresponding electrical energy of two parts;

When the total load of the whole ship is greater than I _limit , the diesel generator set provides electric energy corresponding to I _limit through the AFE controllable rectifier, and the remaining electric energy is provided by the lithium-ion battery pack through the DC converter; that is, between U _uv and H points in Figure 2, such as At point D in Figure 2, the diesel generator set provides I _limit = 90% I _N2 corresponding electric energy through the AFE controlled rectifier, and 40% I _N1 corresponding electric energy is provided by the lithium-ion battery pack through the DC converter. At this time, the total load of the ship It corresponds to the two parts of electrical energy.

5. Implementation of automatic mode switching function

In this embodiment, SOC1 is a low power setting value of 30% of the rated SOC, SOC2 is a high power setting value of 90% of the rated SOC, and SOC3 is a medium power setting value of 60% of the rated SOC;

When the hybrid ship is running in pure battery mode and the SOC is lower than 30%, it will automatically switch to the valley filling mode of the hybrid mode;

When the hybrid ship is operating in the peak-loading and valley-filling mode of the hybrid mode, when the SOC is lower than 30%, it will automatically switch to the valley-filling mode of the hybrid mode;

When the hybrid ship is operating in the peak-loading and valley-filling mode of the hybrid power mode, when the SOC is higher than 90%, it will automatically switch to the valley-filling mode of the hybrid power mode;

When the hybrid ship is operating in the peak-cutting mode of the hybrid mode, and the SOC is lower than 60%, it will automatically switch to the peak-cutting mode of the hybrid mode;

When the hybrid ship is operating in the valley-filling mode of the hybrid mode, and the SOC is higher than 60%, it will automatically switch to the peak-loading and valley-filling mode of the hybrid mode;

The above-mentioned low battery, high battery and medium battery setting values can be appropriately changed according to the actual ship working conditions; they can also be changed from automatic switching to manual switching.

The above-mentioned embodiments only express several implementation modes of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the scope of protection of the patent of the present invention should be determined by the appended claims.

Claims (4)

1. The ship hybrid power system comprises 1 set of lithium ion battery pack, 1 set of diesel generator set, 1 set of direct current distribution board, 1 set of alternating current distribution board, 2 sets of propulsion motors, 1 set of direct current charging interface and 1 set of energy management system; the direct current distribution board comprises 1 set of direct current converter, 1 set of AFE controllable rectifier, 2 sets of daily inverter and 2 sets of propulsion frequency converter, and the energy management system is provided with three energy supply modes of pure battery mode, pure diesel mode and hybrid power mode;

when the hybrid power ship normally sails in the pure battery mode, the lithium ion battery pack is boosted to a direct current distribution board bus through the direct current converter;

when the hybrid power ship normally sails in the pure diesel mode, the diesel generator set outputs alternating current, and the alternating current is boosted through the AFE controllable rectifier and is transmitted to a busbar of the direct current distribution board;

when the hybrid power ship normally sails in the hybrid power mode, the diesel generator set transmits electric energy to the bus of the direct-current distribution board through the AFE controllable rectifier, and the lithium ion battery pack is connected with the bus of the direct-current distribution board through the direct-current converter;

the bus electric energy of the direct-current distribution board transmits energy to a propulsion motor and a propeller through a propulsion inverter, the direct-current electric energy provides three-phase electric energy for an alternating-current load through a daily inverter, and the daily inverter is one-to-one;

when the hybrid power ship berthes alongside, the hybrid power ship is selected to enter a shore power charging mode, a direct current charging pile is connected with a direct current charging interface to supply power for a direct current distribution board bus, and the electric energy of the direct current distribution board bus charges a lithium ion battery pack through a direct current converter;

the energy management system is communicated with the direct current converter, the propulsion inverter and the daily inverter through the Profibus communication module for data interaction; the energy management system performs data interaction with the lithium ion battery pack and the shore power direct current charging pile through the CAN module;

the energy management system controls and manages control algorithms and mode switching of a pure battery mode, a pure diesel mode, a hybrid power mode and a shore power charging mode;

the automatic mode switching control management of the energy management system is characterized in that: setting the low electric quantity set value of the lithium ion battery pack as A% rated electric quantity, setting the high electric quantity set value of the lithium ion battery pack as C% rated electric quantity, and setting the electric quantity set value in the lithium battery pack as B% rated electric quantity;

hybrid peak clipping mode: if the total load of the whole ship is smaller than the current output limit value I of the AFE controllable rectifier _limit Corresponding to the electric energy, only the AFE controllable rectifier provides the electric energy for the whole ship load; if the total load of the whole ship is greater than the current output limit value I of the AFE controllable rectifier _limit Corresponding to the electric energy, the direct-current converter is under overvoltage control, and the AFE controllable rectifier provides a current output limit value I _limit Corresponding to the electric energy, the rest electric energy is provided by the lithium ion battery pack through the direct current converter;

hybrid valley fill mode: if the total load of the whole ship is smaller than the current output limit value I of the AFE controllable rectifier _limit Corresponding to the electric energy, the direct current converter is under-voltage control, and redundant electric energy is supplied to lithium through the direct current converterCharging an ion battery pack; if the total load of the whole ship is greater than the current output limit value I of the AFE controllable rectifier _limit Corresponding to the electric energy, limiting the propulsion power, and ensuring that the total load of the whole ship is not more than the current output limiting value I of the AFE controllable rectifier _limit Corresponding to the electric energy;

hybrid peak clipping and valley filling modes: if the total load of the whole ship is smaller than the current output limit value I of the AFE controllable rectifier _limit Corresponding to the electric energy, the direct current converter is under-voltage control, and redundant electric energy charges the lithium ion battery pack through the direct current converter; if the total load of the whole ship is greater than the current output limit value I of the AFE controllable rectifier _limit Corresponding to the electric energy, the direct-current converter is under-voltage control, and the AFE controllable rectifier provides an output limit value I _limit Corresponding to the electric energy, the rest electric energy is provided by the lithium ion battery pack through the direct current converter;

when the ship runs in the pure battery mode, and the SOC is lower than A%, the ship is automatically switched to a valley filling mode of the hybrid power mode;

when the ship runs in a peak clipping and valley filling mode of the hybrid power mode, and when the SOC is lower than A%, the ship is automatically switched to a valley filling mode of the hybrid power mode;

when the ship runs in a peak clipping and valley filling mode of the hybrid power mode, and when the SOC is higher than C%, the ship is automatically switched to the peak clipping mode of the hybrid power mode;

when the ship runs in a peak clipping mode of the hybrid power mode, and when the SOC is lower than B%, the ship is automatically switched to a peak clipping and valley filling mode of the hybrid power mode;

when the ship runs in the valley filling mode of the hybrid power mode, and when the SOC is higher than B%, the ship is automatically switched to the peak clipping and valley filling mode of the hybrid power mode.

2. The marine hybrid system energy management method of claim 1, wherein an overvoltage control curve and an undervoltage control curve are set in the dc converter, and the AFE controllable rectifier sets output constant voltage and current output limits;

overvoltage control curve U of DC converter ₁ By setting overvoltage control zero-crossing voltage value U _ov And an overpressure control curveSag rate K _ov To determine U ₁ ＝K _ov *I+U _ov Wherein I is the charge and discharge given value of the DC converter, when the output DC voltage U of the DC converter reaches the overvoltage control curve U ₁ When according to U ₁ Calculating a charging and discharging current I given value, and controlling the current by the direct current converter according to the I value; the current I is discharged when being larger than zero, and the current I is charged when being smaller than zero; k (K) _ov Less than zero;

under-voltage control curve U of direct-current converter ₂ By setting the undervoltage to control the zero crossing voltage value U _uv And under-voltage control curve sag rate K _uv To determine U ₂ ＝K _uv *I+U _uv When the output DC voltage U of the DC converter reaches the under-voltage control curve U ₂ When according to U ₂ Calculating a charging and discharging current I given value, and controlling the current by the direct current converter according to the I value; the current I is discharged when being larger than zero, and the current I is charged when being smaller than zero; k (K) _uv Less than zero;

output constant voltage value U of AFE controllable rectifier _DC Setting the current output limit value I of the AFE controllable rectifier _limit The method comprises the steps of carrying out a first treatment on the surface of the When the output current of the AFE controllable rectifier reaches I _limit The output voltage will not maintain the constant voltage value U _DC The overvoltage or undervoltage control curve will be entered to correspond to the voltage.

3. The energy management method of the ship hybrid power system according to claim 2, wherein the energy management system adjusts the charge and discharge current given value I and the overvoltage control zero crossing voltage value U of the direct current converter in real time through Profibus _ov Sag rate K of overvoltage control curve _ov Under-voltage control zero-crossing voltage value U _uv And under-voltage control curve sag rate K _uv Output constant voltage value U of AFE controllable rectifier is set in real time _DC And a current output limit value I _limit The method comprises the steps of carrying out a first treatment on the surface of the The total load of the whole ship is the sum of the power of the two propulsion motors plus the daily load power.

4. A ship hybrid system energy management method according to claim 3, characterized in that theOutput constant voltage value U of AFE controllable rectifier _DC =750v, setting the current output limit value I of the AFE controllable rectifier _limit ＝0.9I _N2 Rated current of AFE controllable rectifier is I _N2 ；

Setting the zero crossing voltage value U of an overvoltage control curve _ov =750v, sagging ratio K _ov ＝-2％*U _ov /I _N1 DC converter rated current I _N1 The overvoltage control function is U ₁ ＝K _ov *I+U _ov I is a given value of charging and discharging current of the direct current converter, the current I is discharged when being larger than zero, and the current I is charged when being smaller than zero;

setting the zero crossing voltage value U of the undervoltage control curve _uv Rate of sagging K =715V _uv ＝-2％*U _ov /I _N1 Under-voltage control function U ₂ ＝K _uv *I+U _uv 。