Zhejiang Jinhua ± 800KV converter station electrical installation project

The 800kV converter station in Jinhua, Zhejiang Province is a key hub project of the East China UHV AC/DC hybrid power grid, and undertakes the cross-regional conversion and transmission of hydropower in the southwest and new energy power in the east. After the project is completed, it will greatly improve the power receiving capacity of Zhejiang power grid, alleviate the peak power consumption pressure in the province, and provide clean energy guarantee for the integrated development of the Yangtze River Delta.

Core content of electrical installation engineering

1. High voltage DC converter system

• Converter valve group installation:

• It adopts 800kV flexible DC converter valve (based on IGBT devices) to support bidirectional power regulation and black start functions.

• The valve tower is modularly installed, laser positioning ensures verticality error ≤0.05mm, and the valve hall is controlled by constant temperature and humidity (temperature 25±2℃, humidity ≤30%).

• Converter transformer integration:

• The single unit capacity reaches 400MVA, equipped with on-load voltage tap changer (OLTC) and optical fiber temperature measurement system to realize online monitoring of insulating oil chromatography.

2. AC field and DC field equipment

• Equipped with double tuned filter (12/24th), harmonic distortion rate control ≤1.2%, meeting IEEE 519 standard.

• 800kV gas insulated switchgear (GIS), integrated circuit breaker, disconnector and fast earthing switch, partial discharge level ≤5pC.

• Adopt SF6/N2 mixed gas technology to reduce greenhouse gas emissions by 30%.

• GIS equipment installation:

• DC filter bank:

3. Intelligent and digital system

• Differential protection device based on 5G communication, action time ≤20ms, synchronization accuracy reaches microsecond level.

• 3D modeling of all station equipment, real-time mapping of operating data, support for fault prediction and simulation drills.

• Digital Twin Operation and Maintenance Platform:

• Intelligent Control and Protection System:

4. Auxiliary system integration

• Dual redundant power supply architecture, integrated energy storage + photovoltaic backup power supply, to ensure continuous operation of station loads under extreme working conditions.

• Deep well grounding electrode design, depth exceeds 100 meters, equipped with corrosion online monitoring and cathodic protection system.

• Earthing electrode engineering:

• Station power system:

Technical Difficulties and Solutions

1. High-precision installation requirements

• Build a dustproof shed and use high-purity nitrogen to purge to ensure the cleanliness of the conductor contact surface (particles ≤ 0.1μm).

• Use industrial-grade total station and laser tracker to achieve multi-valve layer synchronous calibration, with a cumulative error of ≤ 1mm/10m.

• Converter valve tower installation:

• GIS equipment connection:

2. Electromagnetic compatibility design

• The shielded grounding grid of the entire station adopts copper-clad steel material, the grid density is ≤5m×5m, and the power frequency electric field strength in the station is ≤5kV/m.

3. Seismic and wind-resistant design

• The equipment bracket adopts a steel structure shock-absorbing support, and the seismic fortification intensity is 8 degrees; the wind resistance level of outdoor equipment is designed according to 50m/s.

Implementation capabilities and advantages

1. UHV engineering experience

• The team participated in the Baihetan-Jiangsu ±800kV UHV DC project, Fujian-Guangdong interconnection project, etc., and mastered the core technology of converter station construction in complex environments.

2. Full process technical guarantee

• Design optimization: Jointly with Tsinghua Research Institute to complete electromagnetic transient simulation (RTDS) and optimize the trigger logic of the converter valve.

• Domestic equipment: The localization rate of key equipment such as converter transformer (XD Group) and control protection system (Nanrui Relay Protection) is 100%.

• Construction technology: The hydraulic jacking device is used to install the converter transformer (single unit weighs 400 tons), and the leakage rate of the GIS equipment air chamber is<0.1%/year.

3. Green construction management

• Low-noise equipment and oil mist recovery devices are used during the construction period; the greening rate of the station area exceeds 40%, integrating the concept of sponge city (rainwater recycling rate ≥ 80%).

Project Value

• Power transmission capacity: Rated transmission power 8000MW, annual transmission of clean electricity exceeding 45 billion kWh, equivalent to reducing carbon dioxide emissions by 35 million tons/year.

• Regional impact:

• Support the construction of Jinhua International Hub City and ensure reliable power supply for highly sensitive loads such as Yiwu Trade City and Hengdian Film and Television City.

• Enhance Zhejiang Power Grid's ability to absorb southwestern hydropower and offshore wind power, and help achieve the "dual carbon" goals.