A special load power supply system for an extra-high voltage converter station and a standardized testing method

Abstract

The application discloses a kind of special load power supply system of extra-high voltage converter station and standardization test method, belong to offshore wind power project key equipment installation technical field;Its technical scheme is: including load power module, cable connection module, intelligent control module, data acquisition module and safety protection module;The load power module is matched with the modular design of transformer using container type dry load box;The intelligent control module is configured with parallel machine synchronous load distribution logic, for accessing under preset load to be concurrent generator set and synchronously adjusting load distribution.This application has the beneficial effect: through modularization and resistance and inductance integration design, high power density is realized, adapt to offshore converter station limited space;Parallel machine synchronous control logic effectively suppresses the current circulation between units, ensures that the voltage and frequency fluctuation of main generator is stably within the preset high-precision range;System supports automatic gradient loading and remote joint control, improves test efficiency and safety.

Description

Technical Field

[0001] This invention relates to the field of key equipment installation technology for offshore wind power projects, and in particular to a dedicated load power supply system for ultra-high voltage converter stations and a standardized testing method. Background Technology

[0002] As the core power supply equipment of the Qingzhou offshore converter station, the main generator's operational stability and power supply accuracy directly determine the overall operational safety of the converter station. Therefore, it is necessary to verify through professional load tests whether its various performance characteristics meet the design and mooring test procedures. The converter station is equipped with seven main generators: six with specifications of 3850KW / 4812.5KVA (6600V, 50Hz, power factor 0.8) and one with specifications of 1000KW / 1250KVA (400V, 50Hz, power factor 0.8). The load tests must include multiple components such as heating tests, voltage characteristic tests, and load transfer tests, and have extremely high requirements for testing accuracy, load adjustment flexibility, and compatibility with multiple generators operating in parallel.

[0003] Currently, in the field of converter station main generator load testing, there is no dedicated load power supply system or standardized testing method suitable for multi-specification, multi-unit parallel operation scenarios in offshore converter stations. Traditional testing solutions have many technical shortcomings: First, there is a lack of dedicated dry-type load boxes and matching load power supplies suitable for parallel operation of six 3850KW units (maximum load 23100KW). Existing load equipment has insufficient capacity and low adjustment accuracy, and cannot meet the testing requirements of 120 minutes of full load on a single unit, 30 minutes of 10% overload, and load transfer for multiple units in parallel operation. Second, there is no standardized configuration scheme for the load power supply system. Cable selection and transformer matching lack specificity, resulting in problems such as unstable power supply and high electromagnetic interference, which affect the testing. The issues are: 1) Data accuracy; 2) Non-standardized testing procedures, lacking standardized operations throughout the entire process from equipment entry and insulation testing to data acquisition and report generation, and lacking equipment protection measures adapted to the high salt spray and windy / rainy marine environment; 3) Limited load control methods, unable to achieve remote control, simultaneous loading of multiple loads, and customized loading gradients, resulting in poor adaptability and the absence of a synchronous load distribution scheme for parallel testing; 4) This type of dedicated load power system and standardized testing method is being applied for the first time in a converter station scenario, and existing technologies cannot meet the special testing requirements of the Qingzhou offshore converter station, leading to low testing efficiency, insufficient data accuracy, prominent safety hazards, and an inability to effectively verify the actual operating performance of the main generator.

[0004] Therefore, there is an urgent need for a dedicated load power supply system and standardized testing method adapted to the main generator of the Qingzhou offshore converter station, to solve the pain points of existing technologies and ensure that load testing is carried out efficiently, accurately and safely. This solution is the first to be applied in the converter station scenario, filling the technical gap in the field of load testing of main generators in converter stations. Summary of the Invention

[0005] To address the shortcomings of existing converter station main generator load testing, such as the lack of dedicated load power systems adaptable to multiple specifications and parallel operation scenarios, insufficient load equipment capacity, low adjustment accuracy, non-standard testing procedures, single control methods, lack of dedicated marine environmental protection measures, and the absence of related technical solutions in converter stations, this invention provides a dedicated load power system and standardized testing method for the main generator of the Qingzhou offshore converter station, which is being applied for the first time in a converter station. By configuring a dedicated dry-type load box, matching transformer and cables, and designing a standardized testing procedure and multi-mode control scheme, various load tests of the main generator can be achieved, ensuring testing accuracy, efficiency and operational safety.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A dedicated load power supply system for ultra-high voltage converter stations includes:

[0008] Load power supply module: includes several containerized dry load boxes and matching transformers; the dry load boxes adopt an integrated resistive and inductive design to provide adjustable test loads;

[0009] Cable connection module: includes high-voltage cable, low-voltage cable and auxiliary power supply cable, used to realize the electrical connection between generator, transformer and load box;

[0010] Intelligent control module: used to preset test modes and support synchronous parallel control of multiple load cells and gradient loading and unloading;

[0011] Data acquisition module: used to collect electrical operating parameters and environmental parameters in real time during the test process;

[0012] Safety protection module: Used to monitor system fault status and perform load shedding protection.

[0013] The intelligent control module includes a parallel synchronization control unit, which is configured with:

[0014] Parallel connection logic: used to trigger the connection signal of the generator set to be paralleled when the total load is at 20% of the rated power;

[0015] Synchronous loading logic: Used to synchronously issue power compensation commands according to the rated power ratio of each operating unit, so that the load borne by each unit rises synchronously to the rated power according to the preset slope;

[0016] Fluctuation suppression logic: Used to compare the voltage and frequency at the generator terminals in real time, and limit the unit's operating fluctuations within a preset accuracy range by dynamically increasing or decreasing the load step size. That is, when a generator unit is connected to be connected at 20% rated load, the load of each generator is synchronously adjusted to 100% rated power through software control, ensuring balanced load distribution during the paralleling process, controlling the main generator's voltage / frequency fluctuations within ±2.5%, and the emergency generator's fluctuations within ±3.5%.

[0017] The load power supply module includes 6 containerized dry-type load cells and 6 matching transformers, with a total capacity of 27MW. Each dry-type load cell has a capacity of 5625kVA / 4500kW / 3375kvar, a rated voltage of AC440V, and an adjustable power factor of 0.8-1.0. It adopts an integrated resistive / inductive design. The transformers are oil-immersed transformers, with a single unit capacity of 3150kVA, 5500kVA, or 6300kVA and a turns ratio of 6.6kV / 0.44kV.

[0018] The cable connection module includes a high-voltage cable YJV-1×185mm²-8.7 / 15kV, a low-voltage cable YC-1×185mm², and an auxiliary power supply cable; the auxiliary power supply cable includes RVV-3×50mm²+1×16mm² and RVV-3×35mm²+1×10mm².

[0019] The intelligent control module includes three modes: local manual control, local computer control, and remote laptop control. It supports remote control in both manual and automatic modes and synchronous parallel control of up to 30 load boxes.

[0020] It supports one-click automatic loading. After inputting the rated power of the generator set and the loading time, the system will automatically complete the gradient loading / unloading from 0% to 25% to 50% to 75% to 100% to 110%.

[0021] Supports custom loading gradients and sudden loading / unloading tests; a single load cell can be adjusted within the range of 1.25kVA-5625kVA / 1kW-4500kW.

[0022] The data acquisition module includes an industrial computer, sensors, and measurement and control software, used to acquire voltage, current, power, frequency, temperature, and harmonic parameters in real time.

[0023] The safety protection module includes fan fault protection, temperature over-limit protection, overcurrent / overvoltage protection, insufficient wind pressure protection, and on-site warning and protection devices.

[0024] Both the load cell and the transformer adopt a container-type structure;

[0025] The technical parameters of the dry load cell include: minimum active load adjustment range of 1kW, minimum reactive load adjustment range of 0.75kvar, minimum load resolution of 1kW / 1.25kVA; load accuracy of ±3%, three-phase balance and unbalance ≤1.5%; parameter measurement accuracy of voltage ±0.5%, current ±0.5%, frequency ±0.1%, power ±1%, and power factor ±1%.

[0026] The standardized testing method for the dedicated load power supply system of the ultra-high voltage converter station includes the following steps:

[0027] S1. Equipment Arrival and Layout Hoisting: Transport the dry-type load cell, matching transformer, and connecting cables to the offshore converter station test site and complete the hoisting and positioning;

[0028] S2. Insulation test: Use a DC500V megohmmeter to measure the insulation resistance between the armature circuit and the hull, and between the space heater and the hull, to confirm that the insulation resistance is ≥1MΩ;

[0029] S3. Phase sequence detection: Detects the phase sequence consistency between the generator and the load equipment;

[0030] S4. Power-on test: Power is supplied step by step in the order of power supply process: distribution box → load equipment → generator. The load box control system is started and debugged to normal working condition.

[0031] S5. Gradient Loading Test: The generator is subjected to gradient loading through the manual or automatic mode of the intelligent control module, and the operating parameters under each loading state are recorded;

[0032] S6. Parallel load transfer test: When the generator set to be paralleled is connected at 20% rated load, the load of each generator is synchronously adjusted to 100% rated power through the synchronous load distribution control logic to complete the load transfer test;

[0033] S7. Data Acquisition and Report Generation: The data acquisition module automatically collects and records voltage, current, power, frequency, and temperature parameters during the test process, and generates a test report.

[0034] S8. Equipment Dismantling: Disconnect the power in the following order: generator → load equipment → distribution box, dismantle the equipment and clean up the site.

[0035] The steady-state operation test of a single generator in S5 includes:

[0036] Heat generation test: The loading sequence is as follows: 0% no-load operation for 10 minutes → 25% steady-state operation for 15 minutes → 50% steady-state operation for 30 minutes → 75% steady-state operation for 30 minutes → 100% steady-state operation for 120 minutes → 110% overload operation for 30 minutes;

[0037] Voltage characteristic test: Under full load, adjust the voltage and frequency to the rated values, and change the load in the following steps: 100%→75%→25%→0→25%→50%→75%→100%;

[0038] After each loading step is completed, record the generator output power, frequency, voltage, current and temperature of each part to confirm that there is no abnormal temperature rise and the voltage change rate meets the standard.

[0039] The loading sequence for the parallel operation test of multiple generators in S6 is: 20%→50%→75%→100%→75%→100%→75%→50%→20%; the parallel combination includes parallel combinations of 2, 3, 4, 5, and 6 generators, with a maximum parallel capacity of 23100kW.

[0040] The data acquisition in S7 includes: steady-state parameter acquisition, with a sampling frequency of 1 second / time; waveform and harmonic analysis, analyzing the 2nd to 50th harmonic content of voltage / current and the total harmonic content; transient testing, recording the instantaneous values ​​of voltage and frequency and the recovery time when the load is suddenly applied / removed; data output, saving the test data and curves in Excel and Word formats, and generating a generator set performance test report.

[0041] In S7, the data acquisition module compares the generator output power with the load box input power in real time. When the deviation between the two exceeds ±3%, the system automatically marks the data as invalid data and triggers an alarm, while pausing the test process until the fault is resolved.

[0042] The power supply process in S4 is distribution box → load equipment → generator, and the power outage process in S8 is generator → load equipment → distribution box, forming a safety mechanism for reverse operation.

[0043] The standardized test method for the dedicated load power supply system of ultra-high voltage converter stations is applied to offshore converter stations, booster stations, and wind power projects. It is suitable for load testing of six main generators with a rated power of 3850kW, apparent power of 4812.5kVA, voltage of 6600V, frequency of 50Hz, and power factor of 0.8, and one main generator with a rated power of 1000kW, apparent power of 1250kVA, voltage of 400V, frequency of 50Hz, and power factor of 0.8.

[0044] To achieve the above objectives, this invention proposes the following core technological improvements in control methods, loading strategies, parallel allocation, and process flow:

[0045] The system features a dual-mode remote control design, combining manual and automatic operation. Three control methods are available: local manual knob control, local computer control, and remote control via laptop (control distance ≥ 100 meters). Remote control allows for synchronized control of multiple load cells via data cable. It supports one-click automatic loading; after inputting the generator set's rated power and loading time, the system automatically completes gradient loading / unloading from 0% to 25% to 50% to 75% to 100% to 110%, requiring no manual intervention.

[0046] The adaptive control method with flexible loading strategy supports custom loading gradients (such as 10%-20%-30%…110%), sudden loading and unloading tests (0%-50%-100%-0%), and the loading time can be freely set. A single load box can be adjusted arbitrarily within the range of 1.25kVA-5625kVA / 1kW-4500kW. At the same time, it supports synchronous loading control of multiple units in parallel (up to 30 units), adapting to different needs of single / multiple generator parallel testing.

[0047] The synchronous load distribution method for parallel operation testing is designed for scenarios involving 2-6 generators operating in parallel. It incorporates load synchronization distribution control logic, which connects the generator set to be paralleled at 20% of its rated load, and then synchronously adjusts the load of each generator to 100% of its rated power. This ensures balanced load distribution during parallel operation and keeps voltage / frequency fluctuations within the standard range (±2.5% for the main generator and ±3.5% for the emergency generator).

[0048] The standardized process design for generator load testing at the Qingzhou offshore converter station involves a complete standardized operation method covering "equipment arrival - arrangement and hoisting - insulation testing - phase sequence testing - power-on testing - gradient loading - parallel testing - data acquisition - report generation - equipment removal". This method clarifies the loading sequence, time parameters, and data recording requirements for single-unit / parallel testing. Simultaneously, it establishes a reverse operation procedure for power-on / power-off (power-on: distribution box - load equipment - generator; power-off: generator - load equipment - distribution box), thus achieving the standardization and normalization of load testing at the Qingzhou offshore converter station.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] (1) High power density and space adaptability: By adopting a modular design that matches the containerized dry load box with the transformer, combined with the integrated resistance and inductance structure, the power density of the system is significantly improved. This solution can achieve a large-capacity load test of up to 27MW in a relatively small footprint, which meets the layout requirements of UHV converter stations (especially offshore platforms) under space constraints, and the standard container structure greatly facilitates the hoisting and transportation of equipment.

[0051] (2) High-precision parallel load balancing control: This invention achieves dynamic response during parallel testing of multiple generator sets through the parallel synchronous load distribution logic of the intelligent control module. After the 20% rated load is switched in, the system can automatically and synchronously adjust the load of each unit to the rated power, effectively suppressing the circulating current risk between units. Experiments have shown that this logic can stably control the voltage and frequency fluctuations of the main generator within ±2.5%, which is far superior to the accuracy of traditional manual adjustment, ensuring the stability of the power grid during the testing process.

[0052] (3) Standardized process and high-efficiency automation: The system integrates remote control functions in both manual and automatic modes, supports multiple gradient loading modes such as 0%-110%, and realizes the standardization of the test process. This automated control method not only eliminates the safety hazards caused by human error, but also enables real-time and synchronous data acquisition and recording, improving test efficiency by more than 30% compared with the traditional method.

[0053] (4) Extreme environmental tolerance and reliability: In response to the extreme working conditions of high salt spray and high humidity at sea, this system significantly enhances the chemical stability and electrical insulation performance of the equipment through a sealed waterproof structure, a ship-specific anti-corrosion coating, and the selection of corrosion-resistant alloy materials for the inductive components. Combined with the side air intake and top air exhaust heat dissipation design, it effectively solves the problem of cooling efficiency fluctuations caused by the changing wind direction at the dock, and greatly extends the continuous operation time of the equipment in harsh environments.

[0054] (5) Comprehensive operational safety assurance: The system is equipped with multi-dimensional safety protection modules, which can monitor the fan status, temperature rise, wind pressure and electrical parameters in real time. Once a fault characteristic is identified, the system can immediately perform automatic load shedding protection, which effectively prevents equipment burnout or electrical chain reaction that may occur under high current and high voltage test conditions, and ensures the safety of key tests of the converter station. Attached Figure Description

[0055] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0056] Figure 1 This is an electrical connection diagram according to an embodiment of the present invention.

[0057] Figure 2 This is a diagram showing the routing of the converter station according to an embodiment of the present invention.

[0058] Figure 3 This is a hoisting arrangement diagram of the load box according to an embodiment of the present invention.

[0059] Figure 4 This is a control system diagram of the load box according to an embodiment of the present invention. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] Example 1

[0062] This invention is the first application of a main generator load testing technology solution in a converter station scenario. The core of the solution is to construct a dedicated load power system adapted to the seven main generators (six 3850KW and one 1000KW) of the Qingzhou offshore converter station. It clarifies the load equipment configuration, testing process, control method, safety protection, and the working scope of both parties. It achieves all the requirements such as steady-state testing of a single generator and load transfer testing of 2-6 generators in parallel operation, ensuring that ordinary technicians in the field can implement it completely. It guarantees the accuracy of test data and the safety of operation throughout the process, and is adapted to the special environment of high salt spray and frequent wind and rain at sea.

[0063] The core of this project is to conduct load tests on the main generator of the Qingzhou offshore converter station. This requires the rental of dry-type load cells, cables, transformers, and other accessories. (See attached document.) Figures 1 to 2 The generator load test was conducted strictly in accordance with the mechanical installation mooring test procedure and requirements. The specific test requirements are as follows:

[0064] Basic generator parameters: 6 units of 3850KW / 4812.5KVA (voltage 6600V, frequency 50Hz, power factor 0.8); 1 unit of 1000KW / 1250KVA (voltage 400V, frequency 50Hz, power factor 0.8).

[0065] Test load requirements: The test load for the main generator shall be a dry resistance load (power factor = 0.9).

[0066] Insulation resistance test: Before and after the generator set heating test, use a DC500V MΩ resistance meter to measure the insulation resistance between the armature circuit and the hull, and between the space heater and the hull, to ensure that the insulation resistance is ≥1MΩ.

[0067] Heating test (continuous load test): The generator is gradually loaded from no load to full load and runs continuously for 120 minutes under full load, and then runs for 30 minutes under 10% overload. The output power (kW), frequency (Hz), voltage (V), current (A) and the temperature of air, casing, stator, bearings and nacelle are recorded (measured by thermometer method) to confirm that there is no abnormal temperature rise in each component.

[0068] Voltage characteristic test (load characteristic test): Under full load, adjust the voltage and frequency to the rated values; change the load in the steps of (100%-75%-25%-0-25%-50%-75%-100%), and record the voltage and frequency under each state to ensure that the voltage change rate of the main generator is within ±2.5% and that of the emergency generator is within ±3.5%.

[0069] Load transfer test: Complete the parallel load transfer test of two, three, and four machines to ensure that the load distribution is balanced and the voltage and frequency fluctuations meet the standards during the parallel operation.

[0070] Equipment requirements: The dry load box must be equipped with a test power cable and corresponding control equipment, and the test load must meet the requirements of the technical solution.

[0071] To meet the demand of 100% maximum load (23100KW / 6600V / 3P / PF:0.8) for six 3850KW units operating in parallel, a complete dedicated load power system with a total dry-type load capacity of 27MW / AC440V / PF:0.8-1.0 adjustable is provided. This system includes dry-type load boxes, transformers, cables, and other accessories. The specific configuration and parameters are shown in Table 1. All equipment is adapted to the high salt spray and windy and rainy marine environment to ensure a stable power supply for the load.

[0072] Table 1

[0073]

[0074] Based on the main generator parameters and testing requirements of the Qingzhou offshore converter station, a standardized load testing technical solution was developed. This solution clarifies the load requirements, loading sequence, and testing procedures for steady-state testing of a single generator and parallel testing of multiple generators, ensuring a standardized testing process and accurate data. The details are as follows:

[0075] Single generator steady-state operation test

[0076] For six 3850kW generators, with each generator operating at a maximum steady-state load of 100%, the active power is 3850kW, the reactive power is 2887.5kvar, and the apparent power is 4812.5kVA. Dry-type load equipment and commissioning technicians are required, with a power factor of 0.8.

[0077] The loading order is as follows:

[0078] 0% (10 minutes of no-load operation) → 25% (15 minutes of steady-state operation) → 50% (30 minutes of steady-state operation) → 75% (30 minutes of steady-state operation) → 100% (120 minutes of steady-state operation) → 110% (30 minutes of overload operation); After each loading step is completed, record the generator output power, frequency, voltage, current and temperature of each part to confirm that there is no abnormal temperature rise and the insulation resistance meets the requirements.

[0079] Multiple generators running in parallel test

[0080] For scenarios involving 2-6 3850kW generators operating in parallel, the load equipment should be configured as follows, with the loading sequence as follows: 20%→50%→75%→100%→75%→100%→75%→50%→20%. During operation, when each generator is at 20% of its rated load, it should be connected to the generator set to be paralleled. Then, the load on each generator should be adjusted to 100% of its rated power until stable, completing the load transfer test. This ensures balanced load distribution and that voltage and frequency fluctuations meet standards during paralleling. The specific combination is as follows: 2 generators in parallel: 3850 + 3850 = 7700kW, active power 7700kW, reactive power... The power output is 5775 kvar, and the apparent power is 9625 kVA; 3 units in parallel: 3850 × 3 = 11550 kW, active power 11550 kW, reactive power 8662.5 kvar, apparent power 14437.5 kVA; 4 units in parallel: 3850 × 4 = 15400 kW, active power 15400 kW, reactive power 11550 kvar, apparent power 19250 kVA; 5 units in parallel: 3850 × 5 = 19250 kW, active power 19250 kW, reactive power 14437.5 kvar, apparent power 24062.5 kVA;

[0081] Six units operating in parallel: 3850 × 6 = 23100 kW, active power 23100 kW, reactive power 17325 kvar, apparent power 28875 kVA.

[0082] Core testing functionality implementation

[0083] Relying on a dedicated load power supply system, it realizes various functions of generator load testing, ensuring accurate and comprehensive test data. The specific functions are as follows:

[0084] Steady-state testing: Real-time acquisition of parameters such as voltage (U:V), current (I:A), active power (P:W), power factor (PF), apparent power (S:VA), and reactive power (Q:Var), with a sampling frequency of 1 second / time to ensure real-time and accurate data.

[0085] Waveform and Harmonic Analysis: Collect all waveforms and phase waveforms, analyze the 2nd to 50th harmonic content of voltage and current and the total harmonic content, display data such as voltage modulation rate, peak value, crest coefficient, and distortion rate, and verify the power supply quality of the generator.

[0086] Setting test, fluctuation test, and sudden load / unload test: Complete voltage and frequency setting tests, record the maximum and minimum values ​​of fluctuating voltage and frequency and steady-state deviation; test the instantaneous values ​​of voltage and frequency and recovery time when the load is suddenly applied or removed to verify the generator's regulation capability.

[0087] Parallel operation test: Supports load transfer test of 2-6 generators in parallel operation. Through synchronous load distribution control, it ensures balanced load distribution during parallel operation and keeps voltage and frequency fluctuations within the standard range.

[0088] Data recording and report generation: Automatically records all parameters during the test process, stores and displays them in tabular and curve formats, and can generate generator set performance test reports, inspection reports, and data detection reports. It supports saving and printing in Excel and Word formats, and the data is authentic, valid, standardized and authoritative.

[0089] Standardized testing procedures (first application at a converter station)

[0090] Establish standardized operating procedures for the entire process from equipment arrival to equipment dismantling, clearly defining the operational requirements, process parameters, and safety precautions for each stage to ensure that the testing process is standardized, safe, and efficient. The specific procedures are as follows:

[0091] Equipment Arrival Preparation: Party A shall notify Party B of the specific arrival time and location 10 days in advance. Party B shall be responsible for the transportation of equipment, personnel, and tools, as well as all related matters concerning their entry and exit (including transportation insurance, accommodation, and transportation). Party A shall be responsible for on-site hoisting and positioning, providing sufficient placement space, and nighttime lighting facilities. The hoisting layout diagram of the load cell is as follows: Figure 3 As shown.

[0092] Equipment layout and cable laying: Party B shall be responsible for the laying, wiring and dismantling of all connecting cables for the load equipment. The cables shall be laid and bundled in a triangular pattern, giving priority to the use of idle ladders and existing cable trays. If there are no existing facilities, the cables shall be laid on scaffolding. The cables shall be secured with plastic-coated wire every 1m and rotated every 15m. Rubber insulation material shall be laid along the cable route, and warning lines shall be set up around the perimeter and high-voltage danger warning signs shall be hung.

[0093] Insulation and phase sequence testing: Party B shall be responsible for providing insulation withstand voltage tests on medium and high voltage generator load boxes, cables, and transformers after installation and commissioning. The insulation resistance shall be measured using a DC 500V MΩ resistance meter (≥1MΩ), and phase sequence testing shall be conducted at the same time. After the test is qualified, a test report shall be issued, and the equipment can only be put into use after confirmation by Party A.

[0094] Power-on test: Follow the power-on procedure (distribution box → load equipment → generator), confirm that all power switches are in the off state, complete the line insulation test, gradually supply power, start the load box control system, and debug it to normal operating condition. The control system diagram of the load box is shown below. Figure 4 As shown.

[0095] Gradient loading test: Following the loading sequence of single-unit and parallel-unit tests, the load is gradually loaded through the manual or automatic control mode of the load box. After each loading step is completed, the unit is kept stable for a specified time, and various test data are collected and recorded synchronously to confirm that there are no abnormal temperature rises, and that voltage and frequency fluctuations of the generator components meet the standards.

[0096] Parallel load transfer test: Complete the parallel load transfer test of two, three, and four generators. When the generator is connected to the generator set to be connected at 20% of the rated load, the load of each generator is adjusted to 100% of the rated power. Record the various parameters during the load transfer process to ensure balanced load distribution.

[0097] Test completion: After the test is completed, follow the power outage procedure (generator → load equipment → distribution box) to confirm that the equipment has stopped running and that the power outage is safe. Then, remove the cables, warning lines and support facilities, retrieve the equipment, and clean up the construction area.

[0098] Load control method (core innovation, first application in converter station)

[0099] The design incorporates a manual and automatic dual-mode remote control method, supporting simultaneous control of multiple load cells to meet the needs of different testing scenarios. The specific control method is as follows:

[0100] Control modes include three modes: local manual knob control, local computer control, and remote control via laptop (control distance ≥ 100 meters). Remote control can achieve synchronous control of multiple load boxes via data cable, making operation flexible and convenient.

[0101] Automatic loading control: After inputting the rated power of the generator set and the loading time, the system automatically completes the gradient loading / unloading from 0% to 25% to 50% to 75% to 100% to 110% without manual intervention; it supports custom loading gradients (such as 10% to 20% to 30% to 110%) and sudden loading and unloading tests (0% to 50% to 100% to 0%), and the loading time can be set freely.

[0102] Flexible loading capability: The load cell can be adjusted arbitrarily within the range of 1.25kVA-5625kVA / 1kW-4500kW, and supports synchronous loading control of multiple units in parallel (up to 30 units), adapting to different needs of single / multiple generator parallel testing.

[0103] Parallel Synchronization Control: For parallel testing scenarios of 2-6 generators, load synchronization distribution control logic is designed to ensure balanced load distribution during parallel operation and to control voltage / frequency fluctuations within the standard range (main generator ±2.5%, emergency generator ±3.5%).

[0104] Safety protection measures (adapted to offshore converter station scenarios, first application in converter stations)

[0105] In light of the characteristics of high salt spray, frequent wind and rain, and multiple overlapping construction operations at sea, specific safety protection measures have been formulated to ensure the safety of personnel and equipment during the load testing process, as follows:

[0106] Equipment protection: The load box and transformer adopt a container design, and the box body is painted with marine-grade paint, which is resistant to salt spray, acid and alkali and seawater corrosion; the internal components are made of waterproof, salt spray and mildew-proof materials, the resistors are made of high temperature resistant alloy materials, and the cooling fans are waterproof fans, which can be used in all weather; the resistor cooling fan area adopts a sealed waterproof structure to prevent rainwater intrusion.

[0107] Load protection function: The load box is equipped with multiple safety protections, including automatic shedding in case of fan failure, automatic shedding in case of temperature over-limit, short circuit / overcurrent / overvoltage, and insufficient wind pressure, to ensure the safe operation of the load equipment.

[0108] On-site protection: During the test, a warning line will be set up in the area of ​​the load equipment to prevent unauthorized personnel from approaching; the client is strictly prohibited from performing work such as welding, water spraying, etc. on the deck or at high altitude around the equipment area, and shall assume the responsibility of guarding and protecting the equipment at night; wire mesh fences will be set up around the primary distribution cabinet and safety barriers and warnings will be set up.

[0109] Personnel protection: Operators must wear insulated safety shoes, insulated gloves and other PPE protective equipment, complete safety training before construction, and be familiar with the commissioning process and emergency response measures; the contractor's operators shall strictly abide by the client's rules and regulations and follow the client's testing work arrangements.

[0110] Electrical protection: Before powering on the distribution board, the commissioning personnel must conduct insulation and safety checks to confirm that there are no faults in the lines before wiring and powering on; all cables are bound with insulated cable ties to avoid leakage hazards caused by metal cable ties; the equipment is reliably grounded and all metal casings are grounded to prevent leakage and electric shock accidents.

[0111] Emergency protection: Deploy emergency equipment on site to deal with sudden safety incidents; keep electrical control boxes away from open flames, and regularly check the integrity of cables to avoid sparks burning the cable insulation layer.

[0112] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A dedicated load power supply system for an ultra-high voltage converter station, characterized in that, include: Load power supply module: includes several containerized dry load boxes and matching transformers; the dry load boxes adopt an integrated resistive and inductive design to provide adjustable test loads; Cable connection module: includes high-voltage cable, low-voltage cable and auxiliary power supply cable, used to realize the electrical connection between generator, transformer and load box; Intelligent control module: used to preset test modes and support synchronous parallel control of multiple load cells and gradient loading and unloading; Data acquisition module: used to collect electrical operating parameters and environmental parameters in real time during the test process; Safety protection module: Used to monitor system fault status and perform load shedding protection.

2. The dedicated load power supply system for ultra-high voltage converter stations according to claim 1, characterized in that, The intelligent control module includes a parallel synchronization control unit, which is configured with: Parallel connection logic: used to trigger the connection signal of the generator set to be paralleled when the total load is at 20% of the rated power; Synchronous loading logic: Used to synchronously issue power compensation commands according to the rated power ratio of each operating unit, so that the load borne by each unit rises synchronously to the rated power according to the preset slope; Fluctuation suppression logic: Used to compare the voltage and frequency at the generator terminals in real time, and limit the fluctuation of unit operation within a preset accuracy range by dynamically increasing or decreasing the load step size.

3. The dedicated load power supply system for ultra-high voltage converter stations according to claim 2, characterized in that, The load power supply module includes 6 containerized dry-type load cells and 6 matching transformers, with a total capacity of 27MW. Each dry-type load cell has a capacity of 5625kVA / 4500kW / 3375kvar, a rated voltage of AC440V, and an adjustable power factor of 0.8-1.

0. It adopts an integrated resistive / inductive design. The transformers are oil-immersed transformers, with a single unit capacity of 3150kVA, 5500kVA, or 6300kVA and a turns ratio of 6.6kV / 0.44kV. The cable connection module includes a high-voltage cable YJV-1×185mm²-8.7 / 15kV, a low-voltage cable YC-1×185mm², and an auxiliary power supply cable; the auxiliary power supply cable includes RVV-3×50mm²+1×16mm² and RVV-3×35mm²+1×10mm². The intelligent control module includes three modes: local manual control, local computer control, and remote laptop control. It supports remote control in both manual and automatic modes and synchronous parallel control of up to 30 load boxes. It supports one-click automatic loading. After inputting the rated power of the generator set and the loading time, the system will automatically complete the gradient loading / unloading from 0% to 25% to 50% to 75% to 100% to 110%. Supports custom loading gradients and sudden loading / unloading tests; a single load cell can be adjusted within the range of 1.25kVA-5625kVA / 1kW-4500kW. The data acquisition module includes an industrial computer, sensors, and measurement and control software, used to acquire voltage, current, power, frequency, temperature, and harmonic parameters in real time. The safety protection module includes fan fault protection, temperature over-limit protection, overcurrent / overvoltage protection, insufficient wind pressure protection, and on-site warning and protection devices. Both the load cell and the transformer adopt a container-type structure; The technical parameters of the dry load cell include: minimum active load adjustment range of 1kW, minimum reactive load adjustment range of 0.75kvar, minimum load resolution of 1kW / 1.25kVA; load accuracy of ±3%, three-phase balance and unbalance ≤1.5%; parameter measurement accuracy of voltage ±0.5%, current ±0.5%, frequency ±0.1%, power ±1%, and power factor ±1%.

4. A standardized test method for a dedicated load power supply system for an ultra-high voltage converter station as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Equipment Arrival and Layout Hoisting: Transport the dry-type load cell, matching transformer, and connecting cables to the offshore converter station test site and complete the hoisting and positioning; S2. Insulation test: Use a DC500V megohmmeter to measure the insulation resistance between the armature circuit and the hull, and between the space heater and the hull, to confirm that the insulation resistance is ≥1MΩ; S3. Phase sequence detection: Detects the phase sequence consistency between the generator and the load equipment; S4. Power-on test: Power is supplied step by step in the order of power supply process: distribution box → load equipment → generator. The load box control system is started and debugged to normal working condition. S5. Gradient Loading Test: The generator is subjected to gradient loading through the manual or automatic mode of the intelligent control module, and the operating parameters under each loading state are recorded; S6. Parallel load transfer test: When the generator set to be paralleled is connected at 20% rated load, the load of each generator is synchronously adjusted to 100% rated power through the synchronous load distribution control logic to complete the load transfer test; S7. Data Acquisition and Report Generation: The data acquisition module automatically collects and records voltage, current, power, frequency, and temperature parameters during the test process, and generates a test report. S8. Equipment Dismantling: Disconnect the power in the following order: generator → load equipment → distribution box, dismantle the equipment and clean up the site.

5. The standardized testing method for the dedicated load power supply system of the UHV converter station according to claim 4, characterized in that, The steady-state operation test of a single generator in S5 includes: Heat generation test: The loading sequence is as follows: 0% no-load operation for 10 minutes → 25% steady-state operation for 15 minutes → 50% steady-state operation for 30 minutes → 75% steady-state operation for 30 minutes → 100% steady-state operation for 120 minutes → 110% overload operation for 30 minutes; Voltage characteristic test: Under full load, adjust the voltage and frequency to the rated values, and change the load in the following steps: 100%→75%→25%→0→25%→50%→75%→100%; After each loading step is completed, record the generator output power, frequency, voltage, current and temperature of each part to confirm that there is no abnormal temperature rise and the voltage change rate meets the standard.

6. The standardized testing method for the dedicated load power supply system of the UHV converter station according to claim 4, characterized in that, The loading sequence for the parallel operation test of multiple generators in S6 is: 20%→50%→75%→100%→75%→100%→75%→50%→20%; the parallel combination includes parallel combinations of 2, 3, 4, 5, and 6 generators, with a maximum parallel capacity of 23100kW.

7. The standardized testing method for the dedicated load power supply system of the UHV converter station according to claim 4, characterized in that, The data acquisition in S7 includes: steady-state parameter acquisition, with a sampling frequency of 1 second / time; waveform and harmonic analysis, analyzing the 2nd to 50th harmonic content of voltage / current and the total harmonic content; transient testing, recording the instantaneous values ​​of voltage and frequency and the recovery time when the load is suddenly applied / removed; data output, saving the test data and curves in Excel and Word formats, and generating a generator set performance test report.

8. The standardized testing method for the dedicated load power supply system of the UHV converter station according to claim 4, characterized in that, In S7, the data acquisition module compares the generator output power with the load box input power in real time. When the deviation between the two exceeds ±3%, the system automatically marks the data as invalid data and triggers an alarm, while pausing the test process until the fault is resolved.

9. The standardized testing method for the dedicated load power supply system of an ultra-high voltage converter station according to claim 4, characterized in that, The power supply process in S4 is distribution box → load equipment → generator, and the power outage process in S8 is generator → load equipment → distribution box, forming a safety mechanism for reverse operation.

10. The standardized test method for the dedicated load power supply system of the UHV converter station according to claim 4, characterized in that, It is used in offshore converter stations and booster stations for wind power projects, and is suitable for load testing of 6 main generators with rated power of 3850kW, apparent power of 4812.5kVA, voltage of 6600V, frequency of 50Hz, and power factor of 0.8, and 1 main generator with rated power of 1000kW, apparent power of 1250kVA, voltage of 400V, frequency of 50Hz, and power factor of 0.8.

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