It’s kind of like a shock to the residents of Lone Star State suffer from power outages in unusually severe winters. First, winter in Texas? Second, aren’t the summer heat waves the cause of the continuous eclipses in this region?
If you mentioned Texas to a European, they might think of cowboys, oil, the hit TV show Dallasand if they were European readers of Hakkai, probably the semiconductor giant Texas Instruments. The only country in the United States with a secession clause also turns out to have its own electricity grid, independent of neighboring countries.
Certainly America is a place with such ingenuity that it would be impossible, we cry as we observe in the distance the red squares that spread across the map of interruptions. It turns out that once the independent strip we are told defines Texas, it could be destruction. We are used to our European countries being connected to the rest of the continental network, but because the Texas network is self-contained, it is unable to take energy from its neighbors in times of need.
Let’s dive into the mechanics of maintaining an electrical network, with the unfortunate Texans currently standing as a test object.
A combination of coal, natural gas, nuclear and wind energy generators knocked out by the cold
If the power grid was as simple as a collection of full-time, constant-load generating stations, running it would be a relatively straightforward job of shoveling some kind of fuel at one end and reaping the benefits of electricity at the other. Unfortunately, the reality of powering the human population is never so predictable, and the utility of the network plays a continuous game of predicting variable demand to match it to the generating capacity. There are entire power plants with a specific application to provide almost instantaneous additional power – you may remember our reports on the British Electric Mountain. Network strategists do their business to predict our actions, as they relate to the use of energy to the minute.
Because Texas has hot summer bubbles, they are accustomed to peak periods occurring, while Texans turn on their air conditioners en masse, with relatively mild winters in a country bordering the Gulf of Mexico providing little system stress. But here we have a perfect storm of energy facilities closed by the weather, unable to cope with the additional demand, and Texas turned to electric heat to warm them.
Their current cold replaced the relatively calm with the frozen Arctic, causing ice storms that halted half of the country’s wind energy production from Sunday morning. According to the Texas Electricity Council (ERCOT) network operator, most of the generating plants that were discarded by the cold on Sunday they were a combination of gas, coal or nuclear power. (Interruptions were also reported in Mexico due to frozen gas pipelines coming from Texas.) While wind power accounted for a quarter of Texas power generation in 2020, these turbines are it is reported that it does not work at full capacity during the winter months.
When in need, can you borrow a glass of energy from a neighbor? Mainland North America has two major power grids, one on each side of the Rockies, and several smaller grids, one of which is Texas Interconnect. The reason for its existence is historical and in part its continuation is because as a single state it is not subject to certain federal or international (with Canada) regulations. It has relatively modest DC connections with its neighbors, but they do not have enough capacity to allow generators in warmer countries to take over the release. He has an ambitious plan for a much larger DC interconnect project to connect both the east and west networks to the Texas, which in turn gives us a chance to look at how networks synchronize.
Phase synchronization makes it difficult to connect AC networks
Huge thyristors used in DC link converters between the North and South Islands, New Zealand. Marshal, CC BY-SA 3.0.Connecting two AC mains is not just a case of connecting them together as well their AC frequency and phase must match exactly to make the connection work. The Texas network has the same nominal frequency of 60 Hz as its neighbors, but in practice there will be little difference in frequency and phase, which cannot be matched without the impractical step of shutting down the entire state and synchronizing all its generators. Therefore, the solution when transferring power between networks is to convert to direct current for the intermediate stage, then back to alternating current at the correct frequency and phase of the network. Many submarine cables, such as those connecting the United Kingdom, Scandinavia and continental Europe, adopt this approach, which means that these networks are connected for energy trading purposes, but are not synchronized. Thus, when a political conflict broke out in Kosovo in 2018 caused a load imbalance that sent the frequency of Europe’s network in a downward spiral, the British network was not affected. This is how the ambitious US network connection mentioned earlier should work, with DC connections from the three networks meeting in New Mexico with a superconducting cable interconnect to further increase efficiency.
The electricity on a scale that most Hackaday readers encounter is difficult to control with a switch here and there, or perhaps even with a circuit breaker or two in low-power networks. On a network, country or continent scale, although it is in the order that a single semiconductor switching device can be the size of a small house, and engineers must deal not only with power management issues but also with human behavior and geopolitics. If you are a Texas Hakadei reader who embraces a cold spell, then you have our sympathy and best wishes for a quick thaw, and in the meantime for the rest it is worth remembering that it can just as easily happen anywhere else.
Title image, including US map, Wapcaplet, CC BY-SA 3.0.