When:
1962, Hydro‑Quebec began to acquire the shares of all private electric power enterprises in the Quebec region and carried out a large merger and undertook the construction of the Manicouagan-Outardes hydroelectric complex. The hydroelectric complex was originally expected to generate 30 billion kilowatt-hours of electricity per year and is located more than 700km from the population center of Quebec. In the context of the era, the standard high-voltage voltage did not exceed 400kV, which required too many repeated lines to be built for transmission over this distance, and the loss was huge. Hydro Quebec decided to make a breakthrough by building the first 735kV AC high-voltage transmission line to meet the power needs of the Quebec region. On November 29, 1965, the line was officially put into use, which marked that the voltage of the highest practical high-voltage line in the world broke through to more than 700kV, laying a solid foundation for the future long-distance low-loss transmission.
Scope:
In the two decades since the first 735kV high-voltage transmission line came into operation, Hydro Quebec has worked with other companies to gradually expand the transmission intensity of the Quebec grid. So far, the project has about 34000km of transmission lines, of which a third is operated at very high voltage (735 kV or 735,000 volts). 533 substations (44 kV to 735 kV), 15 cross-border interconnections allowing power interchanges with the maritime provinces, Ontario and the U.S. Northeast. Interconnection capacity: Imports: 6,025 MW Exports: 7,974 MW.
The high-voltage AC power network established by Hydro Quebec does not strictly belong to the category of ultra-high voltage. At present, according to the requirements for ultra-high voltage transmission lines, the operating voltage is not less than 800kV. But in the 1960s, it’s known to the world as “hyper pressure.” Since its inception, Hydro Quebec’s goal has been to reduce land use along Quebec by using higher voltage lines as much as possible, while utilizing the electricity generated by dam with minimal loss. At the peak of hydropower production, 25,000 megawatts of electricity were delivered annually to population centers via 735 kV power lines. Hydro Quebec puts the loss ratio at 4.5% to 8% over a distance of 1,000 kilometers, depending on weather and temperature. Such low losses (compared with traditional 315kV high-voltage transmission) on a quarter of the floor area were a breakthrough in the 1960s.
Success?
Overall, the project was very successful. First of all, Hydro Quebec is different from China’s State Grid in that it is a private company and needs to be a for-profit company. The most basic reason for the success of Chinese projects is that they are led by the government, regardless of the profit and loss of the initial investment, so they can be developed and built quickly to serve the people. As a private company from the beginning, they need to consider the pros and cons of establishing a high-voltage grid. The grid is still in the hands of Hydro Quebec from 1965 to this day and we can conclude that the project has been a great success.
The reason for the success of this project is actually the existence of many coincidences. One is that the Quebec region is large and sparsely populated, with most people concentrated in one area, which allows the large substations of the high-voltage grid to serve multiple cities simultaneously. If people are scattered in various areas of Quebec (such as some of the major agricultural provinces of the United States), then the disadvantages of the coverage of the high-voltage grid will be exposed. There are also few pylons occupying private space along the way, so there are no high demolition/compensation costs, which makes the Quebec grid the cheapest high voltage grid in the world.
The second is that hydroelectric power in Quebec is a prerequisite for a high-voltage grid. In a region like Quebec, which is so large and sparsely populated, there would not have been much agreement to build a high-voltage grid for coal-fired power stations. Hydropower is clean and immobile and requires only basic maintenance once the plant is built, rather than the continuous cost of coal and natural gas, as with thermal power. Hydropower costs less and is best suited to high-voltage grids because it is immobile. It’s not just Quebec, Brazil’s high-voltage power lines, and China’s ultra-high-voltage grid that took their first steps with hydroelectric DAMS.
What can we learn?
Quebec is an example of a highly successful private local high voltage grid. High voltage power grids are born out of the right geographical conditions and needs. However, for SuperGrid, the scale of Quebec power grid is too small, the connection scope is too single, and the power source is too common, which leads to low reference value. What we can learn instead are some of the same technical problems that we face at high latitudes. In 1998, North America was hit by a massive ice storm. Cold temperatures and humidity quickly brought down the power grid. Five to six days of freezing rain and precipitation have crippled Quebec’s hydroelectric grid in Montreal and the South Shore region. About 116 transmission lines were out of service, including several major 735 kV power lines. Through a continuous wave of freezing precipitation, more than 75 mm of radial ice accumulates on the electrical conductors and the tower itself. The ice coating adds an additional weight of 15 to 20 kilograms per meter of conductor. Although the wires can withstand this extra weight, when combined with the effects of wind and precipitation, these conductors can break and fall. After the outage ended, Hydro Quebec made several upgrades to its systems to improve the grid. Examples include strengthening pylons and poles, and increasing the supply of electricity. And an upgrade to the grid’s heating system could melt ice on power lines more quickly. These approaches are useful, especially in today’s increasingly unstable climate. Supergrid spans a large area and has a variety of climate types. It needs to adjust the function of pylons and wires according to local climate changes, while using intelligent detection systems to quickly repair the power grid when problems occur.