Ship electric propulsion system, ship and control method

Abstract

The invention discloses a ship electric propulsion system, a ship and a control method, and relates to the technical field of ship electric power coordination control. The ship electric propulsion system comprises a propulsion motor, a propeller, a generator cut-off switch, a main transmission shaft and a load distribution board, the propulsion motor is connected with the propeller through the main transmission shaft, the propulsion motor is in driving connection with a steam turbine generator unit, and the steam turbine generator unit is electrically connected with a steam turbine control system. The steam turbine generator set module is connected with the switchboard through a generator circuit breaker switch, a power source of the propulsion motor is realized based on the switchboard, and a steam turbine generator set is connected into a ship power grid. According to the method, severe disturbance to the steam generator set during switching of complex working conditions of an electric propulsion ship is avoided, a large delay system of a primary loop can operate stably, safety of a power source is guaranteed, rotating speed fluctuation of the steam generator set in isolated network operation is within an allowable range, and safe operation of ship alternating current electric appliances is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of ship electric power coordinated control, and in particular to a ship electric propulsion system, a ship and a control method. Background Art

[0002] The electric propulsion ship uses pure electric drive, and the driving power comes entirely from the steam turbine generator set on the ship, which is connected to the propeller through the motor to provide navigation power for the ship. The pure electric drive has many advantages such as large starting torque, fast starting speed, flexible propulsion mechanism layout, high efficiency and quietness. The disadvantage is that the steam turbine generator set on the ship cannot be connected to the large power grid. When the propulsion motor is running under variable conditions, it has a great impact on the load torque of the steam generator set, resulting in the stable frequency operation of the steam generator set becoming the key to the smooth operation of the unit. The frequency of the steam generator set directly affects the frequency of the AC power output by the generator. If the power frequency exceeds the standard, all AC power-consuming equipment will not work properly or even be damaged.

[0003] In addition, the power level of the ship's AC load is low, the load fluctuation is small, and it has almost no impact on the ship's power grid; while the propulsion motor is a high-power electrical equipment. With the different working conditions of the ship (rapid acceleration, escape, etc.), the power of the propulsion motor changes dramatically and frequently, bringing huge load fluctuations to the ship's power grid.

[0004] Since the steam turbine generator set is the only power generation equipment on the power grid, and the capacity of the steam turbine generator set is equivalent to that of the propulsion motor, the kinetic energy and thermal potential energy stored in the turbine's rotational inertia are relatively small. The direct impact of the drastic fluctuation of the power grid load on the steam turbine generator set is to cause a drastic change in the unit's speed, that is, the frequency. The drastic fluctuation of the unit's frequency will cause damage to the steam turbine, generator failure, abnormal operation of the excitation equipment, etc., resulting in unstable power grid voltage, and ultimately causing power outages or electrical damage to the entire ship, endangering the safety of all personnel and equipment on the ship.

[0005] The existing technology sets the steam turbine generator set to the frequency regulation operation mode. In this mode, all changes in the load in the isolated grid are absorbed by the frequency regulation unit, and the frequency setting value is a fixed value (50Hz). As the load fluctuates, the unit frequency will fluctuate around this set value. The advantage of this mode is that the frequency of the isolated grid can be controlled during small load disturbances, the power supply quality is high, and it is conducive to the healthy operation of the steam turbine generator set.

[0006] However, due to the physical limitations of the mechanical components of the steam distribution mechanism, even if the frequency modulation mode is running, it is impossible to ensure that the speed (frequency) of the frequency modulation unit is stable near the rated value when the load changes greatly. Even if DC power distribution is used (some ship power stations use DC power generation, which has the advantage that the change of the unit frequency does not affect the grid frequency), the drastic change of the unit frequency will also affect the health of the unit, which may cause failure and damage to the power generation equipment, and the voltage stabilization ability of the excitation system can only play a regulatory role within a limited unit frequency range. Since the steam generating unit is a large inertia link, when the load changes greatly, the steam generator cannot meet the instantaneous supply of sufficient quality power steam, which affects the safe operation of the unit itself and is also very likely to cause failure and shutdown of the steam generating unit. Therefore, there are unavoidable deficiencies in the coordinated control of the traditional steam turbine generator set matching load. Summary of the invention

[0007] In view of the deficiencies in the prior art, the present invention provides a ship electric propulsion system, a ship and a control method, which solve the problems raised in the above background technology.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: a ship electric propulsion system, a ship and a control method, wherein the propulsion system includes a propulsion motor, a propeller, a generator circuit breaker, a main drive shaft, and a load distribution board, wherein the propulsion motor is connected to the propeller through the main drive shaft, and the propulsion motor drive is connected to a steam turbine generator set, the steam turbine generator set is electrically connected to a steam turbine control system, and the steam turbine generator set module is connected to a distribution board through a generator circuit breaker switch, the propulsion motor power source is realized based on the distribution board, and the steam turbine generator set is incorporated into the ship power grid.

[0009] A further improvement of the technical solution of the present invention is that: the control mode of the steam turbine generator set adopts a speed PID closed-loop strategy, and the output current I of the steam turbine generator set is determined based on the input signal of the propulsion system.

[0010] A further improvement of the technical solution of the present invention is that: the working current I ’ Real-time tracking of the output current of the steam turbine generator set is the feedback signal of the propulsion system.

[0011] A further improvement of the technical solution of the present invention is that a control method for a ship electric propulsion system is also provided, comprising the following specific steps:

[0012] S1: Introduce the power signal inside the steam turbine and connect the steam turbine generator set to the ship's power grid. The propulsion system quickly generates propulsion power. After balancing the power inside the steam turbine, the power model is used to calculate the power inside the steam turbine at this time.

[0013] S2: Calculate the power of the steam turbine unit according to the instrument measurement to obtain the shaft end output torque of the steam turbine in the steam turbine generator unit;

[0014] S3: The output torque at the control shaft end is the same as the electromagnetic torque T, and the available current I generated by the generator in the steam turbine generator set in real time and the working current I required by the propulsion motor in the ship propulsion system are obtained. ’ ; Thus completing the working current I of the propulsion motor ’ Real-time tracking of steam turbine generator output current I and operating current I ’作为 Feedback signals from the propulsion system;

[0015] S4: Finally, the speed PID control is mainly used, which is a 50Hz electrical system, that is, the speed of the steam turbine unit is 3000 rpm, and the given speed is a fixed value of 3000 rpm. When the actual speed of the steam turbine is greater than 3000 rpm, the steam inlet regulating valve is closed. When the actual speed of the steam turbine is less than 3000 rpm, the steam inlet regulating valve is opened to balance the power of the generator and the propulsion motor.

[0016] Furthermore, because the given speed remains unchanged, the active power generated by the steam turbine generator set is not restricted by the power load, but only related to the air intake of the steam turbine. Therefore, in order to ensure that the steam turbine generator set can better track the given speed of 3000 rpm, it is necessary to balance the power of the generator and the propulsion motor. The stator winding current of the generator is used as the given value of the second closed-loop PID in the schematic diagram, and the stator current of the propulsion motor is used as the feedback value of the closed loop. In this way, the propulsion motor electric power can be matched with the generator electric power by changing the current of the propulsion motor in real time. This method can make the marine isolated grid AC generator set always run smoothly at around 3000 rpm like the grid-connected unit. The speed control loop adjustment process is gentle, and the power adjustment is handed over to the propulsion motor to complete;

[0017] Therefore, this control strategy in which the ship propulsion system follows the operation of the steam turbine generator set solves the problem of severe disturbances to the steam turbine generator set caused by the switching of complex working conditions of electric propulsion ships. It can make the large delay system of one circuit run smoothly, ensure the safety of the power source, and make the speed fluctuation of the steam turbine generator set under isolated grid operation within the allowable range, thereby ensuring the safe operation of the ship's AC electrical appliances.

[0018] A further improvement of the technical solution of the present invention is that the power model in S1 is specifically:

[0019] Ne=D×Hs×ηe / 3600=G×Hs×ηe=M×ω=2π×M×ns;

[0020] Where Ne is the turbine effective power, D is the steam flow rate, Hs is the adiabatic enthalpy drop, G is the steam flow rate, ηe is the effective efficiency of the turbine, M is the shaft end torque of the turbine, ω is the turbine rotor angular velocity, and ns is the turbine rotor speed.

[0021] A further improvement of the technical solution of the present invention is that the instrument measurement in S2 includes the following specific values: the instantaneous steam flow entering the turbine, the instantaneous adiabatic enthalpy drop and the turbine efficiency curve, wherein the shaft end output torque of the turbine in the steam turbine generator set is completed according to M=Ne / ω.

[0022] A further improvement of the technical solution of the present invention is that the electromagnetic torque T in S3 is calculated as follows: T is the electromagnetic torque, K is the proportional coefficient, B is the magnetic field strength, I is the current of the energized coil, A is the cross-sectional area of ​​the coil, θ is the angle between the coil axis and the magnetic field axis, and the output torque at the control shaft end is the same as the electromagnetic torque T, that is, M=T.

[0023] A further improvement of the technical solution of the present invention is that a ship is also provided, wherein the ship uses the ship electric propulsion system as described in any one of claims 1-3 to achieve stable frequency operation.

[0024] Compared with the prior art, the present invention has the following beneficial effects: the ship electric propulsion system, ship and control method solve the severe disturbance to the steam generator set caused by the switching of complex working conditions of the electric propulsion ship, can make the large delay system of one circuit run smoothly, ensure the safety of the power source, make the speed fluctuation of the steam generator set under isolated grid operation within the allowable range, and ensure the safe operation of the ship's AC electrical appliances. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the schematic diagram of the electric propulsion system control of this ship;

[0026] Figure 2 The graph is a graph of the rotation speed and adjustment time of the electric propulsion system of the ship;

[0027] Figure 3 This is a schematic diagram of the isolated grid frequency when the frequency regulating unit in the ship electric propulsion system is in an isolated grid state;

[0028] Figure 4 Schematic diagram of the control method of the ship electric propulsion system. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings.

[0030] The present invention provides a ship electric propulsion system, which includes a propulsion motor, a propeller, a generator circuit breaker switch, a main transmission shaft, and a load distribution board, wherein the propulsion motor is connected to the propeller through the main transmission shaft, and the propulsion motor is drivingly connected to a steam turbine generator set, the steam turbine generator set is electrically connected to a steam turbine control system, and the steam turbine generator set module is connected to a distribution board through a generator circuit breaker switch, the propulsion motor power source is realized based on the distribution board, and the steam turbine generator set is incorporated into the ship power grid.

[0031] The steam turbine generator set control method adopts a speed PID closed-loop strategy, and the output current I of the steam turbine generator set is determined based on an input signal of a propulsion system.

[0032] The working current I of the propulsion motor ’ Real-time tracking of the output current of the steam turbine generator set is the feedback signal of the propulsion system.

[0033] The present invention also provides a control method for a ship electric propulsion system, S1: introducing a power signal in a steam turbine, and incorporating a steam turbine generator set into a ship power grid, so that the propulsion system quickly generates propulsion power, and after balancing the power in the steam turbine, the power in the steam turbine at this time is calculated by a power model;

[0034] S2: Calculate the power of the steam turbine unit according to the instrument measurement to obtain the shaft end output torque of the steam turbine in the steam turbine generator unit;

[0035] S3: The output torque at the control shaft end is the same as the electromagnetic torque T, and the available current I generated by the generator in the steam turbine generator set in real time and the working current I required by the propulsion motor in the ship propulsion system are obtained. ’ ; Thus completing the working current I of the propulsion motor ’ Real-time tracking of steam turbine generator output current I and operating current I ’作为 Feedback signals from the propulsion system;

[0036] S4: Finally, the speed PID control is mainly used, which is a 50Hz electrical system, that is, the speed of the steam turbine unit is 3000 rpm, and the given speed is a fixed value of 3000 rpm. When the actual speed of the steam turbine is greater than 3000 rpm, the steam inlet regulating valve is closed. When the actual speed of the steam turbine is less than 3000 rpm, the steam inlet regulating valve is opened to balance the power of the generator and the propulsion motor.

[0037] Furthermore, because the given speed remains unchanged, the active power generated by the steam turbine generator set is not restricted by the power load, but only related to the air intake of the steam turbine. Therefore, in order to ensure that the steam turbine generator set can better track the given speed of 3000 rpm, it is necessary to balance the power of the generator and the propulsion motor. The stator winding current of the generator is used as the given value of the second closed-loop PID in the schematic diagram, and the stator current of the propulsion motor is used as the feedback value of the closed loop. In this way, the propulsion motor electric power can be matched with the generator electric power by changing the current of the propulsion motor in real time. This method can make the marine isolated grid AC generator set always run smoothly at around 3000 rpm like the grid-connected unit. The speed control loop adjustment process is gentle, and the power adjustment is handed over to the propulsion motor to complete;

[0038] Therefore, this control strategy in which the ship propulsion system follows the operation of the steam turbine generator set solves the problem of severe disturbances to the steam turbine generator set caused by the switching of complex working conditions of electric propulsion ships. It can make the large delay system of one circuit run smoothly, ensure the safety of the power source, and make the speed fluctuation of the steam turbine generator set under isolated grid operation within the allowable range, thereby ensuring the safe operation of the ship's AC electrical appliances.

[0039] The power model in S1 is specifically:

[0040] Ne=D×Hs×ηe / 3600=G×Hs×ηe=M×ω=2π×M×ns;

[0041] Where Ne is the turbine effective power, D is the steam flow rate, Hs is the adiabatic enthalpy drop, G is the steam flow rate, ηe is the effective efficiency of the turbine, M is the shaft end torque of the turbine, ω is the turbine rotor angular velocity, and ns is the turbine rotor speed.

[0042] The instrument measurements in S3 include the following specific values: instantaneous steam flow entering the turbine, instantaneous adiabatic enthalpy drop and turbine efficiency curve, wherein the shaft end output torque of the turbine in the turbine generator set is completed according to M=Ne / ω.

[0043] In S3, the electromagnetic torque T=k×B×I×A×sin(θ), wherein T is the electromagnetic torque, K is the proportional coefficient, B is the magnetic field strength, I is the current of the energized coil, A is the cross-sectional area of ​​the coil, and θ is the angle between the coil axis and the magnetic field axis. The output torque at the control shaft end is the same as the electromagnetic torque T, that is, M=T.

[0044] The present invention also provides a ship, which uses the ship electric propulsion system as described in any one of claims 1 to 3 to achieve stable frequency operation.

[0045] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art, and the model parameters of each electrical appliance are not specifically limited, and conventional equipment can be used.

[0046] When in use, the control of the steam turbine is still mainly based on the speed PID control, which is a 50Hz electrical system, that is, the speed of the steam turbine unit is 3000 rpm, and the given speed is a fixed value of 3000 rpm. When the actual speed of the steam turbine is greater than 3000 rpm, the steam inlet regulating valve is closed, and when the actual speed of the steam turbine is less than 3000 rpm, the steam inlet regulating valve is opened. Because the given speed is unchanged, the active power generated by the steam turbine generator set is not restricted by the power load, but only related to the air intake of the steam turbine. Therefore, in order to ensure that the steam turbine generator set can better track the given speed of 3000 rpm, it is necessary to balance the power of the generator and the propulsion motor. The stator winding current of the generator is used as the given value of the second closed-loop PID in the schematic diagram, and the stator current of the propulsion motor is used as the feedback value of the closed loop. In this way, the electric power of the propulsion motor can be matched with the electric power of the generator by changing the current of the propulsion motor in real time.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A ship electric propulsion system, characterized in that: The propulsion system includes a propulsion motor, a propeller, a generator circuit breaker switch, a main drive shaft, and a load distribution board, wherein the propulsion motor is connected to the propeller through the main drive shaft, and the propulsion motor driving connection is connected to a steam turbine generator set, the steam turbine generator set is electrically connected to a steam turbine control system, and the steam turbine generator set module is connected to a distribution board through a generator circuit breaker switch, the propulsion motor power source is realized based on the distribution board, and the steam turbine generator set is incorporated into the ship's power grid.

2. A ship electric propulsion system according to claim 1, characterized in that: The steam turbine generator set control method adopts a speed PID closed-loop strategy, and the output current I of the steam turbine generator set is determined based on an input signal of a propulsion system.

3. A ship electric propulsion system according to claim 1, characterized in that: The working current I of the propulsion motor ’ Real-time tracking of the output current of the steam turbine generator set is the feedback signal of the propulsion system.

4. A control method for a ship electric propulsion system, applied to the ship electric propulsion system according to any one of claims 1 to 3, characterized in that: The specific steps include: S1: Introduce the power signal inside the steam turbine and connect the steam turbine generator set to the ship's power grid. The propulsion system quickly generates propulsion power. After balancing the power inside the steam turbine, the power model is used to calculate the power inside the steam turbine at this time. S2: Calculate the power of the steam turbine unit according to the instrument measurement to obtain the shaft end output torque of the steam turbine in the steam turbine generator unit; S3: The output torque at the control shaft end is the same as the electromagnetic torque T, and the available current I generated by the generator in the steam turbine generator set in real time and the working current I required by the propulsion motor in the ship propulsion system are obtained. ’ ; Thereby completing the working current I of the propulsion motor ’ Real-time tracking of steam turbine generator output current I and operating current I ’作为 Feedback signals from the propulsion system; S4: Finally, the speed PID control is mainly used, which is a 50Hz electrical system, that is, the speed of the steam turbine unit is 3000 rpm, and the given speed is a fixed value of 3000 rpm. When the actual speed of the steam turbine is greater than 3000 rpm, the steam inlet regulating valve is closed. When the actual speed of the steam turbine is less than 3000 rpm, the steam inlet regulating valve is opened to balance the power of the generator and the propulsion motor.

5. A control method for a ship electric propulsion system according to claim 4, characterized in that: The power model in S1 is specifically: Ne=D×Hs×ηe / 3600=G×Hs×ηe=M×ω=2π×M×ns; Where Ne is the turbine effective power, D is the steam flow rate, Hs is the adiabatic enthalpy drop, G is the steam flow rate, ηe is the effective efficiency of the turbine, M is the shaft end torque of the turbine, ω is the turbine rotor angular velocity, and ns is the turbine rotor speed.

6. A control method for a ship electric propulsion system according to claim 5, characterized in that: The instrument measurements in S3 include the following specific values: instantaneous steam flow entering the turbine, instantaneous adiabatic enthalpy drop and turbine efficiency curve, wherein the shaft end output torque of the turbine in the turbine generator set is completed according to M=Ne / ω.

7. A control method for a ship electric propulsion system according to claim 4, characterized in that: In S3, the electromagnetic torque T=k×B×I×A×sin(θ), wherein T is the electromagnetic torque, K is the proportional coefficient, B is the magnetic field strength, I is the current of the energized coil, A is the cross-sectional area of ​​the coil, and θ is the angle between the coil axis and the magnetic field axis. The output torque at the control shaft end is the same as the electromagnetic torque T, that is, M=T.

8. A ship, characterized in that: The ship applies the ship electric propulsion system as described in any one of claims 1-3 to achieve stable frequency operation.

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