Longdong-Shandong

Overview

The Longdong–Shandong project is a ±800 kilovolt (kV) ultra-high voltage direct current (UHVDC) transmission line in China, designed to transport electricity across a distance of approximately 926 to 933.9 kilometers. It connects the Qingyang Converter Station in Longdong, Gansu Province, with the Dongping Converter Station in Tai’an, Shandong Province. The transmission line passes through five provinces: Gansu, Shaanxi, Shanxi, Hebei, and Shandong.

System Capacity and Configuration

The UHVDC system is constructed as a ±800 kV bipole line with a rated transmission capacity of 8,000 megawatts (MW). It is capable of transmitting over 36 billion kilowatt-hours (kWh) of electricity annually from western China’s energy-rich regions to the densely populated Shandong load center. The line uses advanced line-commutated converter (LCC) technology and is engineered with conductors measuring 1,250 mm² in cross-sectional area, to ensure minimal resistive losses during transmission.

Converter Stations and Technology

The Qingyang Converter Station acts as the sending terminal, integrating power from a comprehensive energy base that includes wind, solar, thermal, and battery storage. The Dongping Converter Station in Shandong serves as the receiving terminal and is engineered to handle and distribute the high-voltage DC power input to the local AC grid. Both converter stations use state-of-the-art LCC HVDC technology, supplied in part by Hitachi Energy, which delivered HVDC Classic converter valves and advanced high-voltage bushings for the Dongping terminal.

Energy Integration and Storage

A major innovation in the Longdong–Shandong project is the integration of diversified energy sources with large-scale storage. The Longdong energy base includes a 600 MW/2,400 MWh electrochemical energy storage facility, making it the largest of its kind in China dedicated to UHVDC integration. This setup allows for stable output even when renewable energy inputs fluctuate. The storage system uses a distributed battery architecture, where each battery cluster has independent control for cycling, health management, and maintenance, resulting in greater system availability, flexibility, and reduced capacity degradation over time.

Construction

The project was constructed with an investment of 20.2 billion RMB (approximately USD 2.8 billion) and took approximately two years to complete, entering full operation in May 2025.

Environmental and Grid Impact

The UHVDC line delivers a mix of roughly 50% renewable energy and 50% thermal power. It supplies electricity to an estimated 10 million households annually and helps reduce carbon dioxide emissions by between 14.9 and 16 million tons per year. This makes it a component of China’s dual carbon goals and broader energy transition strategy.

Infrastructure Scale and Construction Challenges

The Dongping Converter Station occupies more than 340,000 square meters (over 51 acres) and includes two deep-grounding electrodes to manage system grounding and safety. More than 2,000 transmission towers were built to support the line’s overhead infrastructure along rugged and diverse terrain, requiring complex logistical coordination. Advanced automatic and intelligent systems were incorporated in both construction and operations, especially for the converter stations, enabling real-time control, diagnostics, and predictive maintenance.