Offshore hybrid platform lightweight control and collaborative energy management method and system

Abstract

The application discloses a kind of offshore hybrid power platform light weight control and collaborative energy management method and system, method is based on the introduction of virtual damping coefficient based on transformer mathematical model, indirectly estimates reference capacitor current by outer loop PI controller, under the premise of not increasing sensor, not introducing physical damping resistance, suppresses filter resonance;And damping factor is promoted to 2.1 from 0.7, makes resonance frequency upshift, filter inductance is reduced by five times, realizes device light weight;Further, adjust power and battery state of charge as input, coordinate multi-energy flow by fuzzy rule, and seawater desalination unit and methanol cooling pump are used as damping load to realize battery overcharge protection.The application eliminates the continuous loss of damping resistance, significantly reduces the volume and weight of the filter, and improves the reliability and energy efficiency of the offshore platform power supply system.

Description

Technical Field

[0001] This invention belongs to the technical field of energy coordination and integrated control of power systems for offshore operation platforms, and particularly relates to a lightweight control and collaborative energy management method and system for offshore hybrid power platforms. Background Technology

[0002] Offshore independent platforms are far from land-based power grids, and their power supply has long relied solely on diesel generator sets. With the advancement of the International Maritime Organization's (IMO) greenhouse gas emission reduction strategy and the rise of green methanol as a low-carbon alternative fuel for ships, offshore platforms are gradually evolving towards a multi-energy complementary structure combining diesel-methanol dual-fuel generator sets with photovoltaic arrays and energy storage batteries. However, applying this technological system to offshore platforms presents several unresolved technical challenges.

[0003] First, the installation space and load-bearing capacity of offshore platforms are strictly limited. Platform deck area is extremely valuable, and structural load-bearing capacity directly affects platform cost and stability. The LC or LCL filter at the output of the voltage source converter (VSC) is an essential component for power quality regulation, and its inductor components traditionally account for a large proportion of the converter's total volume. Existing technologies often employ lowering the resonant frequency to enhance filtering, resulting in excessively large inductor values ​​and heavy iron cores, which contradicts the lightweight requirements of offshore platforms.

[0004] Secondly, the inherent resonance problem of LC filters is commonly suppressed in engineering by using passive damping resistors. Passive damping resistors have advantages such as simple implementation and good robustness, but they continuously dissipate power and generate a large amount of heat throughout the entire operation of the system. For offshore platforms that operate day and night, the annual losses are significant, and the heat generation increases the burden of heat dissipation and fire prevention in high salt spray environments.

[0005] Third, while traditional active damping solutions can eliminate damping resistance losses, they typically require additional capacitive current or voltage sensors. Offshore platforms operate in environments characterized by high salt spray, high humidity, and strong vibrations; increasing the number of sensors directly reduces the system's mean time between failures (MTBF) and raises maintenance costs.

[0006] Fourth, when facing variable operating conditions such as severe fluctuations in solar radiation, wind and wave disturbances, and emergency load switching, traditional energy management strategies based on lookup tables or fixed rules are difficult to balance fuel economy, battery life, and power quality in offshore diesel-methanol-energy storage-photovoltaic multi-source coupled systems. Meanwhile, when photovoltaic output is high and load demand is low, the energy storage battery is at risk of overcharging, and relying solely on chopper resistors for protection would waste renewable energy and exacerbate the platform's heat dissipation pressure.

[0007] To address the aforementioned issues, there is an urgent need for a comprehensive control method and system for offshore hybrid power platforms that can simultaneously achieve lightweight filters, lossless damping, extremely simplified sensors, and intelligent coordination of multiple energy flows. Summary of the Invention

[0008] Objectives: To achieve active suppression of VSC output LC filter resonance without adding current or voltage sensors; to reduce the value of filter inductor to one-fifth of its original level by shifting the resonant frequency and retuning the damping factor, thereby reducing the size and weight of the offshore platform converter; to construct a multi-energy flow collaborative management strategy based on fuzzy logic for the strong coupling characteristics of offshore platform diesel generator sets, methanol reforming generator sets, photovoltaic arrays, energy storage batteries, and process loads; and to utilize the platform's unique process energy consumption loads (seawater desalination units, methanol system cooling circulation pumps) as damping loads to achieve overcharge protection of energy storage batteries and secondary utilization of renewable energy.

[0009] Technical solution: The present invention provides a lightweight control and collaborative energy management method for offshore hybrid power platforms, comprising the following steps:

[0010] Step S1: Construct an offshore microgrid that includes photovoltaics, dual-fuel generators, energy storage batteries, VSCs, LC filters without physical damping resistors, switchable process energy-consuming loads, and a central control unit.

[0011] Step S2: Establish mathematical models of each distributed power source in the offshore microgrid and complete capacity assessment;

[0012] Step S3: Construct a sensorless adaptive active damping controller based on the VSC mathematical model, and introduce a virtual damping coefficient. Thus, the open-loop transfer function is obtained;

[0013] Step S4: Adjust the virtual damping coefficient and resonant frequency in the sensorless adaptive active damping controller;

[0014] Step S5: Dynamically adjust power using the platform. Using the battery's state of charge (SOC) as input, the power reference of the diesel-methanol dual-fuel generator set is output through fuzzy rules. And the battery terminal voltage exceeds the overcharge threshold. The cooling circulation pumps of the seawater desalination unit and the methanol system are put into operation as damping loads according to priority.

[0015] Step S6: Under the action of the sensorless adaptive active damping controller, coordinated operation control is carried out for typical marine operating conditions such as sunshine fluctuations, cloudy days, emergency response to strong winds and waves, full load, and light load, so as to achieve refined power smoothing and power quality assurance.

[0016] Furthermore, in step S3, the open-loop transfer function is as follows:

[0017]

[0018] Among them, L f For the filter inductor, C f Let be the filter capacitor, and s be the complex frequency domain variable (complex variable, unit rad / s) of the Laplace transform.

[0019] Furthermore, step S4 specifically involves: adjusting the damping factor... Increased from 0.7 to 2.1, according to The virtual damping coefficient is tuned, where The natural resonant frequency of the output filter is shifted upwards to... This causes the filter inductor to change from Reduced to .

[0020] Furthermore, the upward shift of the resonant frequency in step S4 does not exceed... The transfer function poles are located on the left half-real axis of the complex plane or have sufficient phase margin, and the zero-pole locus is used to verify that the transfer function poles are located on the left half-real axis of the complex plane.

[0021] Furthermore, in step S5, the fuzzy rule is specifically: when When the SOC is very low and the negative value is large (typically corresponding to 10% - 20% battery capacity), Take the upright and righteous; when When the SOC is positive or very high (typically corresponding to battery capacity above 90%), Take zero; other values ​​are determined according to the rules given in the rule table.

[0022] Furthermore, in step S5, the fuel blending strategy of the diesel-methanol dual-fuel generator set is as follows: methanol is used preferentially under low load and steady-state conditions, and diesel is switched to under high load, dynamic, emergency, or cold start conditions.

[0023] Furthermore, the battery terminal voltage exceeds the overcharge threshold. The priority is given to activating the cooling circulation pumps of the seawater desalination unit and methanol system as damping loads. Specifically, the switching criteria for process energy consumption loads adopt a dual-threshold hysteresis loop. Timely investment, in The system is cut off in time, and the priority of the seawater desalination unit is higher than that of the methanol system cooling circulation pump. This is the real-time terminal voltage of the battery. This is the upper limit threshold for battery overcharge protection. Hysteresis voltage difference (hysteresis voltage).

[0024] A lightweight control and collaborative energy management system for an offshore hybrid power platform includes: a photovoltaic array and its DC-DC boost converter; a diesel-methanol dual-fuel generator set, which uses diesel as the base fuel to ensure startup and dynamic response under high loads, and methanol as a low-carbon alternative fuel to reduce carbon emissions during operation; an energy storage battery pack and its bidirectional DC-DC converter; a three-phase voltage source converter (VSC) and its output LC filter, wherein the LC filter does not contain physical damping resistors; process energy consumption units used as switchable damping loads, including seawater desalination units and / or methanol system cooling circulation pumps; and a central control unit, which integrates a sensorless active damping controller, a load voltage PI regulator, and a two-input one-output fuzzy logic supervisor. The central control unit replaces the physical damping resistors by introducing a feedback term with a virtual damping coefficient and coordinates the power flow of the aforementioned distributed power sources and process energy consumption units through the fuzzy logic supervisor.

[0025] The present invention also discloses a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method of the present invention.

[0026] The present invention also discloses a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implements the steps of the method of the present invention.

[0027] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: the filter inductor volume of the present invention is reduced, significantly reducing the space and weight occupied by the VSC device; the continuous heat loss caused by the passive damping resistor is eliminated, and in the calculation example, the three-phase heat loss can be reduced by approximately The system continuously dissipates energy; it eliminates the need for additional current or voltage sensors, improving system reliability in marine salt spray environments; it coordinates the power flow of the diesel-methanol dual-fuel unit and photovoltaic-energy storage through a fuzzy logic supervisor, balancing fuel economy and battery life; and it utilizes the platform's process load to produce fresh water or cooling medium, achieving combined energy, fresh water, and cooling. Attached Figure Description

[0028] Figure 1 This is a topology diagram of an independent microgrid system for an offshore hybrid power platform.

[0029] Figure 2 This is a flowchart illustrating the coordination control method described in this invention.

[0030] Figure 3 This is a comparative schematic diagram of an LC output filter structure containing a physical damping resistor and an LC output filter structure of the present invention that does not contain a physical damping resistor and uses sensorless active damping.

[0031] Figure 4 This is a block diagram of the VSC lightweight control based on the virtual damping coefficient.

[0032] Figure 5 For different virtual damping coefficients Bode plot of the output filter under the given values.

[0033] Figure 6 Passive damping resistor With virtual damping coefficient Bode plot comparing two damping methods.

[0034] Figure 7 Damping factor New filter inductor Frequency domain response diagram of the output filter.

[0035] Figure 8 This is a plot of the zero-pole locus of the transfer function before and after the filter size reduction.

[0036] Figure 9 The overall architecture of the fuzzy logic supervisor for energy management on offshore platforms and a schematic diagram of the speed change of the dual-fuel generator set are shown.

[0037] Figure 10 Input variables The membership function graph.

[0038] Figure 11 This is a membership function graph for the input variable SOC.

[0039] Figure 12 For output variables The membership function graph. Detailed Implementation

[0040] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0041] The proposed method for lightweight control and multi-energy collaborative energy management of microgrids for offshore diesel-methanol-energy storage hybrid power platforms has a system topology as shown in Figure 1 and a workflow as shown in Figure 2. The workflow includes steps S1 to S6, with each main step further subdivided into sub-steps.

[0042] Step S1: Construction of an independent microgrid system for the offshore platform;

[0043] Step S1 is used to build the physical structure and control interface of the microgrid of the offshore diesel-methanol-energy storage hybrid power platform described in this invention, providing a controlled object for subsequent steps.

[0044] Step S11: Connect the distributed power source to the DC bus;

[0045] The photovoltaic array is connected to the DC bus via a DC-DC boost converter; the diesel-methanol dual-fuel generator set (GGS) is connected to the DC bus via a rectifier unit to supplement energy when photovoltaic output is insufficient, load demand is high, or emergency conditions are met; the energy storage battery pack is connected to the DC bus via a bidirectional DC-DC converter to smooth power fluctuations and ensure power supply continuity during emergency periods.

[0046] Step S12: Connecting the AC-side VSC to the undamped resistor LC filter;

[0047] The DC bus is connected to the LC output filter via a three-phase voltage source converter (VSC), which does not contain physical damping resistors; the VSC is connected to the platform's AC common coupling point (PCC) via the LC filter to supply power to the platform's AC and DC loads.

[0048] Step S13: Connecting the energy-consuming load of the switchable process;

[0049] The cooling circulation pump of the seawater desalination unit and / or methanol system is connected to the DC bus as a switchable damping load. The process energy-consuming load is triggered by a control signal when the battery voltage exceeds the upper limit, and is used as a damping load to absorb excess power.

[0050] Step S14: Deployment of the central control unit;

[0051] A central control unit is deployed, which integrates a sensorless active damping controller, a load voltage PI regulator, and a two-input, one-output fuzzy logic supervisor; the central control unit collects DC bus voltage and inductor current. PCC voltage Load current Battery terminal voltage and State of Charge (SOC), output VSC modulated signal Power reference for dual-fuel units And the switching signals for process energy consumption load.

[0052] Step S2: Offshore platform load scale assessment and mathematical modeling of each distributed power source;

[0053] Step S2 is used to complete the parameter identification and modeling of the system, providing a model basis for subsequent controller tuning.

[0054] Step S21: Assessment of platform daily energy consumption and power capacity;

[0055] Estimate the platform's total daily energy consumption using the following formula:

[0056]

[0057] In the formula For the first Rated power of such electrical appliances Daily operating hours This refers to the number of electrical appliances.

[0058] Estimate the daily energy required for the photovoltaic array based on a combined efficiency of 0.9025 for the DC-AC and DC-DC converters:

[0059]

[0060] The peak power of photovoltaic power is determined by the following formula:

[0061]

[0062] In the formula Irradiance The average daily equivalent duration (based on the lowest month of the year). This is the comprehensive loss coefficient for power electronics.

[0063] The number of photovoltaic modules connected in series and parallel is determined by the following formula:

[0064]

[0065] In the formula The number of photovoltaic modules connected in series. This refers to the number of photovoltaic modules connected in parallel. Design the DC bus voltage for the photovoltaic array. This refers to the maximum power point voltage of a single photovoltaic module. The rated power of a single photovoltaic module. This indicates rounding up. The capacity of an energy storage battery is determined by the following formula:

[0066]

[0067] in For battery capacity, This is the DC terminal voltage of the battery pack. The overall charge / discharge efficiency of the battery is $DOD$, where $DOD$ represents the depth of discharge. Self-sustaining days without renewable energy output; considering that offshore platforms have dual fuel backups of diesel and methanol, A smaller value can be used compared to remote land-based scenarios.

[0068] Step S22: Photovoltaic array equivalent circuit modeling;

[0069] The equivalent circuit model of a single photovoltaic cell is established as follows:

[0070]

[0071] In the formula For the output current of a single photovoltaic cell, This refers to the output voltage of a single photovoltaic cell. This is the diode voltage. This is the short-circuit current. For saturation current, Thermoelectric voltage, and These are the equivalent resistances in series and parallel, respectively. For the... string The output current model of a photovoltaic cell-based module is extended as follows:

[0072]

[0073] The photovoltaic array operates at MPP via a DC-DC boost converter and the maximum power point tracking algorithm in the central control unit.

[0074] Step S23: Modeling of diesel-methanol dual-fuel generator set;

[0075] Establish the power balance control relationship for GGS:

[0076]

[0077] In the formula This represents the total AC / DC load power of the platform. For the output power of the photovoltaic array, To provide output power for the energy storage battery. To establish mechanical torque. With fuel injection quantity Transfer function between:

[0078]

[0079] In the formula The dead time from fuel injection to mechanical response. , , This represents the unit's dynamic time constant. Controller input. Reference speed The difference between the measured and actual speeds. The switching between diesel and methanol fuels is decided by a fuzzy logic supervisor based on fuel inventory, load demand, and carbon emission strategies.

[0080] Step S24: Establish electrical equations for the VSC output terminal;

[0081] Establish the three-phase output voltage equations for VSC:

[0082]

[0083] In the formula For filtering inductors, The equivalent series resistance of the inductance. For the three-phase control law on the converter side, This refers to the three-phase load voltage on the PCC side. Let the filter inductor current be denoted as . Establish the output capacitor current equation:

[0084]

[0085] In the formula For filtering capacitors, This refers to the three-phase capacitor current. This is the three-phase load current.

[0086] Step S3: Construction and tuning of the sensorless adaptive active damping controller;

[0087] Step S3 is used to construct an active damping controller that is equivalent to real-resistive damping but without power loss, without adding current or voltage sensors. The comparison between the filter structure without physical damping resistors and the structure with physical damping resistors used in this step is as follows: Figure 3 As shown, the overall block diagram of the constructed controller is as follows: Figure 4 As shown.

[0088] Step S31: Quantitative analysis of the loss of traditional passive damping resistor;

[0089] To illustrate the necessity of eliminating the physical damping resistor, we first quantify the damping resistor in traditional passive damping schemes. The power loss is used as a benchmark for the active damping scheme of this invention. For the damping resistor branch connected in series with the filter capacitor, its current is determined by the line voltage. With branch impedance Decide:

[0090]

[0091] The branch impedance is:

[0092]

[0093] by , Power frequency angular frequency Example calculation:

[0094]

[0095] Therefore, the single-phase damping resistor loss is:

[0096]

[0097] The total three-phase loss is:

[0098]

[0099] The aforementioned losses are independent of load conditions and persist throughout the entire system operation period. This invention eliminates these continuous heat losses by canceling the physical damping resistance through sensorless active damping control described in subsequent steps.

[0100] Step S32: Indirect estimation of the reference capacitor current;

[0101] A PI controller is used to regulate the load voltage and estimate the reference capacitor current. The reference filter current is constructed using the following formula:

[0102]

[0103] The estimation process utilizes only existing voltage and inductor current sampling, without requiring additional capacitor current or capacitor voltage sensors.

[0104] Step S33: Introduction of the virtual damping term and derivation of the open-loop transfer function;

[0105] Substituting the reference current loop obtained in step S32 into the voltage equation established in step S24, we obtain the second-order dynamics from the control law to the load voltage:

[0106]

[0107] Ignoring the load current disturbance term, a virtual damping term is introduced on the right side of the control law. :

[0108]

[0109] Considering The new open-loop transfer function is obtained by rearranging the functions:

[0110]

[0111] As can be seen from the above formula, The introduction of this is mathematically equivalent to virtually inserting a resistor with a resistance value in series in the inductor branch. The damping resistor physically does not introduce any resistive element, nor does it have any dissipation loss.

[0112] Step S34: Damping factor tuning and initialization calculate;

[0113] Establish damping factor With virtual damping coefficient Correspondence:

[0114]

[0115] by , , , Example calculation:

[0116]

[0117] Reference Figure 5 ,along with With the increase of [unclear], the resonant peak is effectively suppressed and the passband boundary converges to lower frequencies. This characteristic provides flexibility for subsequent miniaturization of the filter by increasing the resonant frequency. Meanwhile, [unclear], Figure 6 As shown by and A comparison of the two damping methods shows that passive damping resistors... The passband intersection remains unchanged when the frequency changes, while a virtual damping coefficient is used. The time passband can be adjusted accordingly, thus providing flexibility to reduce the filter size.

[0118] Step S35: Load voltage outer loop control and PWM modulation signal generation;

[0119] Based on the active damping inner loop constructed in steps S32 to S34, a load voltage tracking outer loop for VSC is established, forming a complete dual-loop control structure. A reference sinusoidal voltage is used. Compared with the measured load voltage The difference is used as the input to the outer-loop PI controller, and the output reference capacitor current is used. :

[0120]

[0121] in and These represent the proportional and integral gains of the outer-loop PI controller, respectively. The same principle applies to both cases. The reference filter current is obtained by superimposing the reference capacitor current output from the outer loop with the load current according to step S32. Then, the virtual damping term introduced in step S33 is combined with the inner loop. Generate three-phase control law :

[0122]

[0123] Similarly, the resulting control law is used to generate six VSC switch drive signals via sinusoidal pulse width modulation (SPWM), driving the converter to output a low-harmonic sinusoidal voltage. Thus, the active damping inner loop suppresses LC filter resonance, while the voltage outer loop tracks the reference sinusoidal voltage. Together, they achieve high power quality voltage output without physical damping resistors or additional sensors.

[0124] Step S4: LC filter resonant frequency shifted upwards and miniaturized design by five times;

[0125] Step S4 is used to shift the resonant frequency of the LC filter upward and reduce the inductor value to one-fifth of the original scheme, while ensuring the stability margin of the system, so as to achieve the lightweighting of the VSC device.

[0126] Step S41: Calculate the new filter parameters;

[0127] Fixed filter capacitor Increase the target resonant frequency to The new filter inductor is determined by the following formula:

[0128]

[0129] At this time, the inductance value is determined by... Reduced to The reduction ratio is five times.

[0130] Step S42: Damping factor retuning and new calculate;

[0131] If at the new resonant frequency, it is still maintained ,correspond Simulations show that this value does not provide sufficient high-frequency attenuation. Increasing the damping factor to... The new virtual damping coefficient is calculated using the following formula:

[0132]

[0133] Step S43: Stability check;

[0134] Plot the zero-pole locus of the transfer function (refer to) Figure 8 ): Follow As the value increases, the poles of the transfer function initially lie in the complex plane (corresponding to underdampedness), gradually shifting to the real axis (corresponding to overdamped or critically dampedness). For time Since the poles are located on the negative real axis, the system stability is guaranteed.

[0135] Further plotting of the frequency domain response (refer to...) Figure 7 The resonant frequency shifts upward to The phase margin remains in the optimal range, and the proposed method reduces the LC filter inductance by a factor of five without sacrificing stability margin.

[0136] Step S5: Fuzzy logic energy management for oil-electricity-methanol multi-energy flow;

[0137] Step S5 is used to coordinate the power flow of photovoltaic, dual-fuel generator, energy storage battery, and process energy-consuming loads from the system layer after lightweighting and resonance suppression are completed at the converter layer. The overall architecture of the fuzzy logic supervisor described in this step is shown in Figure 9, with input variables... SOC and output variables The membership functions are shown in Figures 10, 11, and 12, respectively.

[0138] Step S51: Define FLS input / output variables and universe of discourse;

[0139] Define a fuzzy logic supervisor (FLS) with two inputs and one output:

[0140]

[0141] in This refers to the power consumption of the process (cooling circulation pump of the seawater desalination unit or methanol system) in operation. The output variable is the power reference of the diesel-methanol dual-fuel generator set. (Corresponding speed reference and fuel injection quantity).

[0142] Step S52: Construct the membership function;

[0143] Will The linguistic variables are divided into five levels: NB (negative), N (negative), Z (zero), P (positive), and PB (positive); the linguistic variables of SOC are divided into five levels: VL (very low, typically corresponding to 10% - 20% battery capacity), L (low, typically corresponding to 20% - 40% battery capacity), M (medium, typically corresponding to 40% - 70% battery capacity), H (high, typically corresponding to 70% - 90% battery capacity), and VH (very high, typically corresponding to over 90% battery capacity); the output... The system is divided into five tiers: PB (suggested value: -40 kW to -25 kW, representing extreme photovoltaic shortage and heavy load, resulting in a significant power generation gap), PM (suggested value: -25 kW to -5 kW), M (suggested value: -5 kW to +5 kW), PS (suggested value: +5 kW to +25 kW), and Z (suggested value: +25 kW to +40 kW, representing severe photovoltaic overcapacity, requiring large-scale absorption through processes such as seawater desalination units). The membership function uses a symmetrical triangular structure, covering offshore platforms. The range of values ​​for peak load and 98% maximum charging SOC.

[0144] Step S53: Establishment of 25 fuzzy rules;

[0145] Press the formula Here are 25 fuzzy inference rules for oil-electricity-methanol energy management on offshore platforms:

[0146]

[0147] Example of the engineering meaning of the rule: When When NB is used and SOC is VL, the output is... PB indicates that the photovoltaic output is severely insufficient and the energy storage is severely depleted. In this case, the dual-fuel unit operates at full power, simultaneously supplying power to the load and charging the battery. When Z is constant and SOC is VL, the photovoltaic system just meets the load demand, and the unit operates at medium power to charge the battery; when When the output is PB, the photovoltaic power output overflows, the unit shuts down, and the excess power is absorbed by the process energy load and the battery.

[0148] formula The following is an example of the explanation of the first line of the fuzzy logic system rule, defining PGGS as the output variable for the GGS (generator system) power (see...). Figure 9 ).

[0149] If Preg is NB and SOC is VL, then PGGS is PB: all loads are fully supplied by GGS;

[0150] If Prec is N and SOC is VL, then PGGS is PB: GGS charges the battery while meeting the load power requirements.

[0151] If Prec is Z and SOC is VL, then PGGS is M: the solar photovoltaic will supply all load power alone, while the battery will be charged by PGGS;

[0152] If Prec is P and SOC is VL, then PGGS is Z: Solar photovoltaic will supply the load demand, and the difference (excess power) will be sent to the battery;

[0153] If Preg is PB and SOC is VL, then PGGS is Z: In this case, the battery and water pump will absorb the additional power provided by the solar PVS.

[0154] It can be deduced that if Preg is negative, and the power generation is insufficient due to the photovoltaic system's inability to provide the required power, then a generator must intervene to make up the power shortfall. If the value is positive, it indicates that the photovoltaic system is providing excess power, which, in some cases, can be used to charge the batteries. The characteristics of the generator system are applied to power management to accurately extract the power required by the load. Figure 9 This demonstrates the two inputs and one output of the Fuzzy Logic Monitor (FLS).

[0155] Figures 10 to 12 The membership functions (MFs) for the two inputs and outputs are shown. The fuzzy logic monitor can be implemented using the Fuzzy Logic Toolbox and Matlab / Simulink software.

[0156] Step S54: Diesel-Methanol Fuel Blending Decision;

[0157] Output FLS The data is sent to the secondary planning layer, where the ratio of diesel to methanol is determined based on fuel inventory status and carbon emission constraints: methanol is prioritized under low load and steady-state conditions to reduce carbon emissions; diesel is switched to under high load, dynamic, emergency, or cold start conditions to ensure the unit's dynamic performance and cold start reliability.

[0158] Step S55: Battery overcharge protection and process energy consumption load switching;

[0159] The switching of process energy-consuming loads is triggered using a dual-threshold hysteresis criterion:

[0160]

[0161] in This refers to the battery overcharge protection threshold. To prevent hysteresis voltage caused by frequent switching operations, the switching priority is as follows: the seawater desalination unit takes precedence over the methanol system cooling circulation pump. The former's byproduct is the freshwater required by the platform, while the latter's byproduct is the cooling medium required for the methanol production process, thus achieving the secondary utilization of renewable energy overflow.

[0162] Step S6: Coordinated operation control under typical sea state conditions;

[0163] Step S6 describes the coordinated operation logic of the complete method constituted by the above steps under varying operating conditions at sea. The method can adaptively respond to several typical operating conditions of offshore platforms. The power flow distribution and control actions of the system under each typical operating condition are described below.

[0164] Step S61: Fluctuating sunshine conditions on sunny days;

[0165] Under clear weather conditions and with photovoltaic output fluctuating intermittently due to cloud cover, the platform load remained relatively stable. The central control unit continuously calculated and adjusted the power. FLS according to The positive and negative changes adaptively adjust the power reference of the dual-fuel generator set This allows for the flexible mitigation of photovoltaic fluctuations. When When the SOC remains positive and is within the VH range, the seawater desalination unit is activated according to the criteria in step S55 to absorb the overflow power and produce fresh water as a byproduct.

[0166] Step S62: Continuous low light conditions on cloudy days;

[0167] Under continuous low-light conditions on cloudy days, photovoltaic output decreases significantly. It falls within the interval N to NB. FLS output. When in the PB range, the dual-fuel unit uses methanol as the main fuel to increase output and undertake the main load power supply; at the same time, it decides whether to take into account the supplementary charging of the energy storage battery based on the range of SOC.

[0168] Step S63: Emergency Response to High Winds and Waves;

[0169] In emergency situations such as high winds and waves, emergency loads such as navigation, communication, and dynamic positioning are instantly activated, causing a step increase in the total load. The energy storage battery, with its rapid response characteristics, first provides instantaneous power support; subsequently, the FLS switches the dual-fuel unit to diesel as the primary fuel, utilizing diesel's excellent dynamic response and cold-start characteristics to quickly increase the unit's output, working in conjunction with the battery to meet emergency load demands. During the load step increase, the sensorless active damping control described in step S3 keeps the point of common coupling (PCC) voltage stable, suppressing filter resonance excited by disturbances.

[0170] Step S64: Full-load continuous operation condition;

[0171] Under full-load conditions with all AC and DC loads continuously operating on the platform, the photovoltaic array and dual-fuel unit jointly supply power, while the energy storage battery is in a shallow charge and discharge state, maintaining the SOC in the M range. (FLS based on...) The rules of the region allow dual-fuel units to operate smoothly near their most efficient operating conditions.

[0172] Step S65: Light load nighttime operation condition;

[0173] Under light-load conditions where photovoltaic output is zero at night and only basic living and lighting loads are maintained, the energy storage battery prioritizes power supply alone; when the SOC drops to the L range, the FLS starts the dual-fuel unit to supplement energy in low-power methanol mode and slowly charges the energy storage battery, taking into account both fuel economy and battery life.

[0174] In summary, the method described in this invention coordinates the diesel-methanol dual-fuel unit, photovoltaic array, energy storage battery, and process energy load through FLS, and ensures power quality with sensorless active damping control. This enables precise power smoothing, overcharge protection of energy storage batteries, and secondary utilization of renewable energy overflow under variable operating conditions at sea.

Claims

1. A lightweight control and collaborative energy management method for offshore hybrid power platforms, characterized in that, Includes the following steps: Step S1: Construct an offshore microgrid that includes photovoltaics, dual-fuel generators, energy storage batteries, VSCs, LC filters without physical damping resistors, switchable process energy-consuming loads, and a central control unit. Step S2: Establish mathematical models of each distributed power source in the offshore microgrid and complete capacity assessment; Step S3: Construct a sensorless adaptive active damping controller based on the VSC mathematical model, and introduce a virtual damping coefficient. Thus, the open-loop transfer function is obtained; Step S4: Adjust the virtual damping coefficient and resonant frequency in the sensorless adaptive active damping controller; Step S5, dynamically adjust the power of the platform. Using the battery's state of charge (SOC) as input, the power reference of the diesel-methanol dual-fuel generator set is output through fuzzy rules. And the battery terminal voltage exceeds the overcharge threshold. The cooling circulation pumps of the seawater desalination unit and the methanol system are put into operation as damping loads according to priority. Step S6: Under the action of the sensorless adaptive active damping controller, coordinated operation control is carried out for typical marine operating conditions such as sunshine fluctuations, cloudy days, emergency response to strong winds and waves, full load, and light load, so as to achieve refined power smoothing and power quality assurance.

2. The lightweight control and collaborative energy management method for a marine hybrid power platform according to claim 1, characterized in that, In step S3, the open-loop transfer function is as follows: ； Among them, L f For the filter inductor, C f Let be the filter capacitor, and s be the complex frequency domain variable of the Laplace transform.

3. The lightweight control and collaborative energy management method for a marine hybrid power platform according to claim 2, characterized in that, Step S4 specifically involves: adjusting the damping factor. Increased from 0.7 to 2.1, according to The virtual damping coefficient is tuned, where The natural resonant frequency of the output filter is shifted upwards to... This causes the filter inductor to change from Reduced to .

4. The lightweight control and collaborative energy management method for a marine hybrid power platform according to claim 2, characterized in that, In step S4, the upward shift of the resonant frequency does not exceed The transfer function poles are located on the left half-real axis of the complex plane or have sufficient phase margin, and the zero-pole locus is used to verify that the transfer function poles are located on the left half-real axis of the complex plane.

5. The lightweight control and collaborative energy management method for a marine hybrid power platform according to claim 1, characterized in that, In step S5, the fuzzy rule is specifically: when When the SOC is large and corresponds to 10% - 20% of the battery capacity, Take the upright and righteous; when When the battery capacity is above 90% (either Zhengda or SOC), Take zero; other values ​​are determined according to the rules given in the rule table.

6. The lightweight control and collaborative energy management method for a marine hybrid power platform according to claim 1, characterized in that, In step S5, the fuel blending strategy of the diesel-methanol dual-fuel generator set is as follows: methanol is used preferentially under low load and steady-state conditions, and diesel is switched to under high load, dynamic, emergency or cold start conditions.

7. The lightweight control and collaborative energy management method for a marine hybrid power platform according to claim 1, characterized in that, The battery terminal voltage exceeds the overcharge threshold. The priority is given to activating the cooling circulation pumps of the seawater desalination unit and methanol system as damping loads. Specifically, the switching criteria for process energy consumption loads adopt a dual-threshold hysteresis loop. Timely investment, in The system is cut off in time, and the seawater desalination unit has a higher priority for switching off than the methanol system cooling circulation pump; This is the real-time terminal voltage of the battery. This is the upper limit threshold for battery overcharge protection. Hysteresis voltage difference.

8. A lightweight control and collaborative energy management system for a marine hybrid power platform, used to implement the method as described in claim 1, characterized in that, include: Photovoltaic arrays and their DC-DC boost converters; diesel-methanol dual-fuel generator sets, with diesel as the base fuel to ensure startup and dynamic response under high loads, and methanol as a low-carbon alternative fuel to reduce carbon emissions during operation; energy storage battery packs and their bidirectional DC-DC converters; three-phase voltage source converters (VSCs) and their output LC filters, with the LC filters containing no physical damping resistors; process energy consumption units used as switchable damping loads, including seawater desalination units and / or methanol system cooling circulation pumps; a central control unit, which integrates a sensorless active damping controller, a load voltage PI regulator, and a two-input, one-output fuzzy logic supervisor; the central control unit replaces physical damping resistors with feedback terms that introduce virtual damping coefficients, and coordinates the power flow of the aforementioned distributed power sources and process energy consumption units through the fuzzy logic supervisor.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method of claim 1.

10. A computer-readable storage medium having a computer program / instructions stored thereon, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the method of claim 1.

Images