Controller of ship shaft brushless doubly-fed motor independent / grid-connected power generation system

Abstract

The invention discloses a controller of a ship shaft brushless doubly-fed motor independent / grid-connected power generation system, and belongs to the field of ship power systems, and the controller comprises a signal monitoring and processing module which is used for collecting signals of a ship shaft in real time; the operation mode switching module is used for monitoring a ship power grid parameter signal, and the operation mode switching module can judge whether a ship power grid enters an island mode or not; the wide-area energy efficiency optimization module is composed of an independent mode control unit and a grid-connected mode control unit. And the multi-physical-field coupling protection module is used for monitoring the stator winding temperature, the shafting torsional vibration amplitude and the direct-current link voltage of the power electronic converter in real time. By adopting the controller of the ship shaft brushless doubly-fed motor independent / grid-connected power generation system, intelligent switching between independent power generation and grid-connected power generation is realized through the operation mode switching module, transient response characteristics are optimized by adopting a double-closed-loop control strategy, a fault protection mechanism is designed in combination with a ship environment, and the reliability of the ship shaft brushless doubly-fed motor independent / grid-connected power generation system is improved. The system stability and the energy utilization rate are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ship power systems, and in particular to a controller for a ship shaft-belt brushless double-fed motor independent / grid-connected power generation system. Background Art

[0002] As a key energy-saving device of the ship's integrated power system, the ship's shaft drive power recovery power generation system achieves clean power generation by capturing the rotational kinetic energy of the main engine's tail shaft, which has significant benefits in reducing auxiliary engine fuel consumption. The current mainstream technical solutions mainly use traditional synchronous generators or conventional double-fed generator architectures, but they still face the following key technical challenges in actual engineering applications:

[0003] 1. The reliability of mode coordination control needs to be improved: In the process of switching between off-grid power generation and grid-connected operation modes, the traditional technology relies on mechanical circuit breakers for hard switching operations, resulting in bus voltage sag (transient fluctuation amplitude can reach more than 25% of the rated voltage) and frequency phase mismatch, which seriously affects the power supply reliability of ship precision navigation equipment and refrigerated containers. Although some improved schemes realize soft switching function through dual PWM converters, they do not establish a dynamic coupling model of mechanical torsional vibration and electromagnetic torque of the shaft system, which is easy to cause power pulsation (measured fluctuation amplitude exceeds 15%) under the emergency speed change condition of the main engine, resulting in frequent overvoltage protection of the converter DC link.

[0004] 2. Insufficient coordinated optimization of transient response characteristics and power quality: Conventional doubly-fed motor control systems mostly use fixed parameter PI adjustment mechanisms. In the case of random fluctuations in shaft speed (±5% rated speed) and load step changes (such as thruster start and stop) caused by complex sea conditions, there are problems of voltage regulation response delay (>200ms) and weakened harmonic suppression capabilities. Experimental data show that the total spectrum distortion index (THD) of the output voltage of existing systems generally remains in the range of 5.2%-6.8%, which is difficult to meet the current "Steel Seagoing Ship Classification Code" for the mandatory requirement that the harmonic content of ship power grids does not exceed 4%. In addition, during grid-connected operation, the traditional feedforward compensation strategy has poor adaptability to the impedance diversity of port ship power grids, resulting in a significant increase in the circulating current component (the measured imbalance is 12%-18%).

[0005] 3. The design of adaptability to harsh working conditions has shortcomings: The ship's power compartment has unique composite environmental stress (temperature 60°C+ / humidity 95%RH+ / salt spray concentration 3mg / m 3 ) poses a severe test to the reliability of controllers. The circuit protection level of mainstream equipment in the industry (such as JY-9000 series controllers) is generally lower than the IP54 standard, which is easy to cause oxidation corrosion of circuit boards in a hot and humid salt spray environment. The average trouble-free operation period of key components is only about 7,500 hours, which is significantly lower than the 20,000-hour MTBF reliability index of ship equipment.

[0006] 4. Wide-range operation energy efficiency urgently needs to be improved: When the main engine is in low-speed sailing mode (40%-60% rated speed), the traditional flux control strategy causes the power generation efficiency to drop sharply due to the air gap magnetic field distortion (from 92% under rated conditions to 65%-70%). This is in obvious conflict with the latest energy efficiency framework requirements of the International Maritime Organization (IMO) - the standard clearly requires that the ship power system must maintain an energy conversion efficiency of more than 85% in the range of 30%-120% rated speed. The existing technical solutions have not yet reached the regulatory threshold in terms of the ability to maintain energy efficiency in a wide speed range. Summary of the invention

[0007] The purpose of the present invention is to provide a controller for a ship shaft-driven brushless double-fed motor independent / grid-connected power generation system to solve the above technical problems.

[0008] To achieve the above object, the present invention provides a controller for a ship shaft-driven brushless double-fed motor independent / grid-connected power generation system, comprising:

[0009] Signal monitoring and processing module: used to collect the shaft rotation speed monitoring signal of the ship shaft belt, the main power winding voltage of the brushless double-fed motor, the stator side current signal, the control winding excitation component signal, and the voltage, frequency and phase signal of the ship power grid side in real time;

[0010] Operation mode switching module: It is used to monitor the ship power grid parameter signal. The operation mode switching module can determine whether the ship power grid has entered the island mode. When it is detected that the ship power grid voltage amplitude deviation exceeds ±5% or the frequency deviation exceeds ±0.5Hz, it triggers the switch from the grid-connected mode to the independent mode. Conversely, when the ship power grid parameters are restored to within the rated value ±2%, it switches back to the grid-connected mode.

[0011] The wide-range energy efficiency optimization module consists of an independent mode control unit and a grid-connected mode control unit. The independent mode control unit ensures that the voltage amplitude at the stator end is maintained at 400V±1% and the frequency is stabilized at 50Hz±0.1Hz by adjusting the excitation current component of the rotor-side converter. The grid-connected mode control unit adopts a double closed-loop structure of a power outer loop and a current inner loop. The outer loop dynamically adjusts the active or reactive power command according to the change of the ship's main engine speed, and the inner loop suppresses the circulating current caused by the dynamic change of the ship's power grid line impedance through a dynamic decoupling compensation strategy.

[0012] Multi-physics field coupling protection module: used to monitor the stator winding temperature, shaft torsional vibration amplitude and DC link voltage of the power electronic converter in real time. When it is detected that the temperature exceeds 150°C, the torsional vibration amplitude is greater than 0.15°, or the DC bus voltage exceeds the range of 600V-800V, a fault-tolerant protection mechanism based on multi-level confidence intervals is established.

[0013] Preferably, the switching process of the operation mode switching module includes a transition state, and within 50ms after the start of the switching, a seamless transition is achieved by:

[0014] When switching from independent to grid-connected, first adjust the stator voltage phase to synchronize with the ship's power grid to Δθ<2°, and then close the static switch;

[0015] When switching from grid-connected to independent operation, the virtual synchronous machine control of the rotor-side converter is started first, and then the static switch is disconnected.

[0016] Preferably, the dynamic decoupling compensation strategy satisfies:

[0017] V′ d =V d +ω s L q I q -ΔV d ;

[0018] V′ q =V q -ω s L s I d -ΔV q ;

[0019] Where V′ d and V′ q is the motor voltage output command after adjustment by dynamic decoupling compensation strategy; V d and V q is the current inner loop output instruction; ΔV d and ΔV q is the ship power grid impedance feedforward compensation; ω s is the synchronous angular frequency; L d and L q is the DC inductance and AC inductance of the motor; I d and L q is the current of the motor in the d-axis and q-axis directions.

[0020] Therefore, the present invention adopts the above-mentioned controller of the ship shaft-belt brushless double-fed motor independent / grid-connected power generation system, which has the following beneficial effects:

[0021] 1. Dynamically compensate for load changes through excitation current to maintain stable output voltage;

[0022] 2. Use the coordinated control of the power outer loop and the current inner loop to achieve fast synchronization and low harmonic output;

[0023] 3. Design fault monitoring in combination with the ship's vibration environment to prevent overpressure, overcurrent and shaft torsional vibration.

[0024] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a flow chart of a control method of a controller for a ship shaft-driven brushless double-fed motor independent / grid-connected power generation system. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not used to limit the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0027] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or devices.

[0028] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0029] A controller for a ship shaft-driven brushless double-fed motor independent / grid-connected power generation system, comprising:

[0030] Signal monitoring and processing module: used to collect the shaft rotation speed monitoring signal of the ship shaft belt, the main power winding voltage of the brushless double-fed motor, the stator side current signal, the control winding excitation component signal, and the voltage, frequency and phase signal of the ship power grid side in real time;

[0031] Operation mode switching module: It is used to monitor the ship power grid parameter signal. The operation mode switching module can determine whether the ship power grid has entered the island mode. When it is detected that the ship power grid voltage amplitude deviation exceeds ±5% or the frequency deviation exceeds ±0.5Hz, it triggers the switch from the grid-connected mode to the independent mode. Conversely, when the ship power grid parameters are restored to within the rated value ±2%, it switches back to the grid-connected mode.

[0032] The wide-range energy efficiency optimization module consists of an independent mode control unit and a grid-connected mode control unit. The independent mode control unit ensures that the voltage amplitude at the stator end is maintained at 400V±1% and the frequency is stabilized at 50Hz±0.1Hz by adjusting the excitation current component of the rotor-side converter. The grid-connected mode control unit adopts a double closed-loop structure of a power outer loop and a current inner loop. The outer loop dynamically adjusts the active or reactive power command according to the change of the ship's main engine speed, and the inner loop suppresses the circulating current caused by the dynamic change of the ship's power grid line impedance through a dynamic decoupling compensation strategy.

[0033] Multi-physics field coupling protection module: used to monitor the stator winding temperature, shaft torsional vibration amplitude and DC link voltage of the power electronic converter in real time. When it is detected that the temperature exceeds 150°C, the torsional vibration amplitude is greater than 0.15°, or the DC bus voltage exceeds the range of 600V-800V, a fault-tolerant protection mechanism based on multi-level confidence intervals is established.

[0034] The switching process of the operating mode switching module includes a transition state. Within 50ms after the start of switching, a seamless transition is achieved in the following ways: when switching from independent to grid-connected, the stator voltage phase is first adjusted to synchronize with the ship power grid to Δθ<2°, and then the static switch is closed; when switching from grid-connected to independent, the virtual synchronous machine control of the rotor-side converter is started first, and then the static switch is disconnected.

[0035] The dynamic decoupling compensation strategy satisfies:

[0036] V′ d =V d +ω s L q I q -ΔV d ;

[0037] V′ q =V q -ω s L d I d -ΔV q ;

[0038] Where V′ d and V′ q is the motor voltage output command after adjustment by dynamic decoupling compensation strategy; V d and W q is the current inner loop output instruction; ΔV d and ΔV q is the ship power grid impedance feedforward compensation; ω s is the synchronous angular frequency; L d and L q is the DC inductance and AC inductance of the motor; I d and I qis the current of the motor in the d-axis and q-axis directions.

[0039] like Figure 1 As shown, the control method of the controller of the ship shaft-driven brushless double-fed motor independent / grid-connected power generation system includes the following steps:

[0040] S1, collecting ship shaft speed, stator voltage, current and ship power grid voltage signals;

[0041] S2. Calculate the phase difference of the ship power grid voltage synchronization signal, and determine that when the phase difference of the ship power grid voltage synchronization signal is greater than the set phase threshold or the duration exceeds 100ms, it is determined to be an island state and trigger mode switching;

[0042] In step S2, the calculation formula of the phase difference Δθ of the ship power grid voltage synchronization signal is as follows:

[0043] Δθ=θ g -θ s ;

[0044] In the formula, θ g Represents the phase angle of the ship power grid voltage synchronization signal; θ s Represents the phase angle of the power generation system;

[0045] In step S2, the phase threshold is set to 5°;

[0046] In the independent mode in step S2, based on the load current I L The fuzzy adaptive algorithm is used to adjust the excitation current I r The d / q axis components make the output voltage U s The following relations are satisfied:

[0047]

[0048] In the formula, X s is the stator equivalent reactance; U ref is the rated voltage reference value;

[0049] In grid-connected mode, power control is achieved through the following steps:

[0050] The first step is to calculate the shaft belt speed ω m With rated speedω rated The ratio of the active power command P is calculated ref =K p ×(ω m / ω rated ) 3 , K p is the proportional gain;

[0051] Step 2: Use the enhanced sliding mode state observer to estimate the ship power grid impedance Z g , and generate a feedforward compensation term ΔU to inject into the current inner loop:

[0052] ΔU=I g ×Z g ;

[0053] In the formula, I g is the injected current.

[0054] S3: When it is detected that the shaft system torsional vibration frequency is greater than the set frequency threshold and lasts for 200ms, the torsional vibration suppression algorithm is activated to offset the mechanical vibration energy by injecting a reverse harmonic current compensation component into the rotor current.

[0055] In step S3, the frequency threshold is set to 10 Hz;

[0056] Reverse harmonic current compensation component f h The calculation formula is as follows:

[0057] f h =f v I g ±k×f s ;

[0058] In the formula, f s is the fundamental frequency of the motor; f v is the frequency component; k is the adjustment coefficient.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A controller for a ship shaft-driven brushless double-fed motor independent / grid-connected power generation system, characterized in that: include: Signal monitoring and processing module: used to collect the shaft rotation speed monitoring signal of the ship shaft belt, the main power winding voltage of the brushless double-fed motor, the stator side current signal, the control winding excitation component signal, and the voltage, frequency and phase signal of the ship power grid side in real time; Operation mode switching module: It is used to monitor the ship power grid parameter signal. The operation mode switching module can determine whether the ship power grid has entered the island mode. When it is detected that the ship power grid voltage amplitude deviation exceeds ±5% or the frequency deviation exceeds ±0.5Hz, it triggers the switch from the grid-connected mode to the independent mode. Conversely, when the ship power grid parameters are restored to within the rated value ±2%, it switches back to the grid-connected mode. The wide-range energy efficiency optimization module consists of an independent mode control unit and a grid-connected mode control unit. The independent mode control unit ensures that the voltage amplitude at the stator end is maintained at 400V±1% and the frequency is stabilized at 50Hz±0.1Hz by adjusting the excitation current component of the rotor-side converter. The grid-connected mode control unit adopts a double closed-loop structure of a power outer loop and a current inner loop. The outer loop dynamically adjusts the active or reactive power command according to the change of the ship's main engine speed, and the inner loop suppresses the circulating current caused by the dynamic change of the ship's power grid line impedance through a dynamic decoupling compensation strategy. Multi-physics field coupling protection module: used to monitor the stator winding temperature, shaft torsional vibration amplitude and DC link voltage of the power electronic converter in real time. When it is detected that the temperature exceeds 150°C, the torsional vibration amplitude is greater than 0.15°, or the DC bus voltage exceeds the range of 600V-800V, a fault-tolerant protection mechanism based on multi-level confidence intervals is established.

2. The controller of the ship shaft-driven brushless double-fed motor independent / grid-connected power generation system according to claim 1, characterized in that: The switching process of the running mode switching module includes a transition state. Within 50ms after the switching starts, a seamless transition is achieved through the following methods: When switching from independent to grid-connected, first adjust the stator voltage phase to synchronize with the ship's power grid to Δθ<2°, and then close the static switch; When switching from grid-connected to independent operation, the virtual synchronous machine control of the rotor-side converter is started first, and then the static switch is disconnected.

3. The controller of the ship shaft-driven brushless double-fed motor independent / grid-connected power generation system according to claim 2, characterized in that: The dynamic decoupling compensation strategy satisfies: V′ d =V d +oh s L q I q -ΔV d ; V′ q =V q -oh s L d I d -ΔV q ; Where V′ d and V′ q is the motor voltage output command after adjustment by dynamic decoupling compensation strategy; V d and V q is the current inner loop output instruction; ΔV d and ΔV q is the ship power grid impedance feedforward compensation; ω s is the synchronous angular frequency; L d and L q is the DC inductance and AC inductance of the motor; I d and I q is the current of the motor in the d-axis and q-axis directions.

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