Power Grid: What Is It and How Does It Work? (2024)

Until we’re faced with power outages, we tend to take the electric power that we receive from our power grid for granted.

We expect on-demand electricity, and many of us are surprised, dismayed, and sometimes at a loss as to how to respond when we don’t have power.

The power grid delivers electricity from power plants to homes and businesses across the nation. Its vast network of power generation, transmission, and delivery ensures we can function in the modern world. The electrical grid provides us with electrical power on demand.

While this grid is such an integral part of our daily lives, most folks don’t know much about it or how it functions. We hope to demystify our electricity system, explaining how the power grid works, its vulnerabilities, and how it could be improved.

What Is a Power Grid and Its Function?

Whether you call it the power grid, power distribution grid, electrical grid, or national grid, this electrical network generates and distributes electricity across a large area. The network includes energy utility companies and energy suppliers that deliver electricity to your home or business.

The power grid also consists of the infrastructure to generate and distribute power.

When people talk about the grid, they generally refer to one of three smaller regional grids, also called interconnections. The Eastern, Western, and Texas Interconnection systems make up the power grid. These three networks are linked in a limited way at grid stations but mostly work independently. The Eastern and Western interconnections also include parts of Canada.

The power grid does three things: It ensures best practice use of energy resources, provides greater power supply capacity, and makes power system operations more economical and reliable. The generating stations are interconnected to reduce the reserve generation capacity, known as a spinning reserve, in each area.

How Many Power Grids Are in the Continental United States?

The power grid in the continental U.S. is a tiered system that encompasses three major interconnections. The Eastern and Western grids tend to operate independently, although they permit power to be transferred between grids. Not to be confused with utility companies, who are the balancing authorities (grid operators) who work within the Eastern and Western Interconnections.

Grid operators ensure the balance between supply and demand in real-time. This allows for safe, reliable power system operation. Without the supply and demand balance, there is a risk of local and regional blackouts.

• Everything east of the Rocky Mountains and part of northern Texas is in the Eastern Interconnection. The Eastern Interconnection has 36 balancing authorities, which includes five in Canada.
• The Western Interconnection extends west of the Rockies and has 37 grid operators, including two in Canada and one in Mexico.
• The Electric Reliability Council of Texas (ERCOT), the name of the grid operator and the regulatory body’s name, is solely responsible for most of Texas.

Why Does Texas Have a Separate Electric Grid?

The Texas Interconnection, which the Electric Reliability Council of Texas (ERCOT) manages, is mostly limited to Texas. According to the Texas Tribune, Texas controls a separate power grid to avoid federal regulation.

In 1935, when the Federal Power Act became law, Texas’ northern and southern systems joined together. Further, Texas utility companies realized they could avoid regulation if they didn’t cross state lines. ERCOT came into being following one of the nation’s worst power outages in 1965, which resulted in further federal regulation.

The drawback to Texas’ regulatory independence is the isolation of the Texas Interconnection. It’s challenging for Texas to import electricity from the nation’s other power grids in a power outage like the February 2021 grid failure.

That said, the state’s deregulated energy market allows Texans to choose their own electricity company and gives them the power to choose the best plan for their needs.

How Does an Electric Grid Work?

An electrical grid is a complex power generation, transmission, and distribution network. Grid operators — the entities that manage energy production and delivery — are regional entities that control electrical energy as it travels through a fixed infrastructure.

That infrastructure — consisting of power stations, transmission lines, and distribution lines — is spread out across America. Sometimes called system operators or balancing authorities, grid operators manage the power grid to deliver your electricity.

Seven balancing authorities are known as independent system operators (ISOs) or regional transmission authorities (RTOs). These authorities are often called grid operators. Grid operators monitor the power grid, signaling to power plants when more power is needed and maintaining the power grid‘s electrical flow to the transmission lines and distribution network.

A power grid has three functions: generation, transmission, and distribution. Within each step, complex processes are at work.

How Does a Power Plant Produce Electricity?

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Your electric utility company‘s power plant generates electricity from three types of energy resources:

• Fossil fuels, such as natural gas and coal
• Nuclear power
• Renewable energy sources, including solar, wind, and hydropower

Power plant output is measured in megawatts, and a megawatt (M.W.) is one million watts. Electrical output, the amount of electricity generated, varies depending on the size of a power plant. The average coal-fired plant generates about 750MW of electricity.

Power plants use energy sources to generate electricity. Turbine generators produce electricity at the power plant using fuels from one of the three classes above, steam, water, or fossil fuels. Wind turbines and solar photovoltaics can also produce electricity. Respectively, they use kinetic energy and chemical energy to generate electricity.

To make the turbine blades spin and rotate, a turbine generator works by pushing fluid, whether water, steam, air, or combustion gases (the exhaust from combustion). Next, the turbine’s rotor shaft, connected to a generator, converts the rotor’s kinetic energy (also known as mechanical energy) to electrical energy.

What Do Transformers Do?

A transformer is an electrical device that moves electrical energy from one electric circuit to another using the principles of electromagnetic induction. Transformers don’t generate electricity; instead, transformers transfer power from one alternating current to another.

Transformers can increase or decrease AC voltage, which is called stepping up or stepping down the voltage. For example, when the electricity leaves the power plant, it passes through a transformer to step up the voltage.

Why Are High-Voltage Transmission Lines Necessary?

High-voltage transmission lines carry high-voltage electricity over long distances, and they are instrumental in delivering electricity to the power grid‘s distribution networks. These high-voltage power lines carry up to 500,000 volts. A large industrial plant might also require high-voltage lines directly from overhead transmission lines. Without high-voltage transmission lines, the complexity and vulnerability of the power grid become more expensive and difficult to manage.

Power is conveyed at a high voltage to increase efficiency by preventing energy loss. Higher voltage means lower current. In turn, lower current decreases resistance loss in conductors. Decreased resistance translates to less lost energy as electricity moves over long distances, making transmission lines an essential part of the power grid.

There are two kinds of electrical lines. High-voltage lines carry power from the power plants to substations, often over long distances. From the substation, distribution lines send energy to residential and business consumers. Distribution lines have a much lower voltage.

What Are Substations and What Do They Do?

When electricity from high-voltage transmission lines comes into a substation, transformers step down the voltage for distribution to homes and businesses. This happens at substations.

Substations are equipped with fuses that split the current into multiple distribution lines. Through circuit breakers, switches, and capacitors, grid operators can also isolate and control the interface between high-voltage power lines and distribution lines.

When the electricity supply leaves the substation via the distribution lines, it’s ready for delivery to homes and businesses.

What Are the Two Connection Types for Interconnections?

Interconnection links between networks can be High Voltage Alternating Current (HVAC) or High Voltage Direct Current (HVDC).

An HVAC link is a rigid, synchronous connection between the two connecting systems, which must have nearly the same frequency control. However, there are limitations or problems associated with AC synchronous interconnections:

• If there are frequency disturbances in one system, it transfers to the other system.
• Power swings in one system affect the other system and may cause increased tripping. In turn, that causes the whole interconnected system to fail.
• If grid operators use an alternating current tie line, the fault level increases.

A direct current tie loosely connects two alternating systems, and it is a nonsynchronous (or asynchronous) connection. A direct current link has some advantages:

• A direct current tie permits two systems to connect at the same frequency or a different frequency, allowing each to operate independently while maintaining their respective frequency standards.
• HVDC links enable the quick, reliable control of magnitude and direction of power flow, which increases transient stability limits.
• Power swings in alternating current networks are modulated by regulating the direct current’s power flow through the direct current tie.

What Causes Power Grid Failure?

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A single event doesn’t cause a power grid blackout; grid failure can also result from a series of accidents and missteps that culminate in cascading failure. Cascading failure occurs when an element of the system partially or wholly fails. The collapse creates a power surge load on other nearby system elements, which are stressed beyond capacity, causing them to fail.

For example, a power grid can fail if the frequency plunges below the lower limit of the (49.5-50.2Hz) band or shoots up beyond the upper limit. When that happens, transmission lines no longer accept the power supply, which means other grid constituents, including the power generation plants, go offline.

So how can we address these issues? First, Congress directed the installation of a smart grid to secure the power grid when they passed the Energy Independence and Security Act of 2007.

In addition, a recent Scientific American article discusses the ways a smart grid can automatically regulate the production and flow of electricity. Such improvements, the authors assert, will make the power grid more efficient and safer.

How Secure Is Our Power Grid?

The nation’s power grid is vulnerable to cyberattacks because its infrastructure uses a two-part system. First, the transmission network has to meet stringent federal protection standards. However, the distribution system, regulated by state entities, has very little protection against cyberattacks because those entities don’t have robust protection standards.

Crashing the nation’s power grids would take a great deal of money and sophistication, but the possibility isn’t being ignored. As the Edison Electric Institute Vice President for Security and Preparedness Scott Aaronson says, “we are preparing for that possibility today.” Also, weather and wildfire can threaten all parts of the power grid.

What Factors Threaten the Electric Grid?

Climate change-induced extreme weather events such as heatwaves, blizzards, or hurricanes can impact the electric grid. For example, 96% of power outages (blackouts) were weather-related or natural disaster events that damaged the electricity distribution systems infrastructure.

Surprisingly, the growth in renewable power sources also threatens the grid. This is because solar and wind power can sometimes produce more electricity than grid operators incorporate into the power grid system.

The increasing age of the power grid‘s infrastructure is another threat to the grid. Metal fatigue and equipment deterioration increasingly play a role in the grid’s aging process. As of this year, the power grid‘s average age is 31 years.

Can the Power Grid Be Hacked?

According to a Republican senatorial policy paper, the power grid‘s Industrial Control Systems (ICS) are at risk for cyberattacks. The ICS manages the electrical processes, and physical functions used to run the electric grid. Hostile foreign governments, criminal organizations, terrorists, and “hacktivists” can potentially target the ICS because it’s increasingly connected to the internet.

What Happens If an Electric Grid Goes Down?

When a portion of the electric grid goes down, somebody somewhere is without electricity. In most cases, it’s a relatively simple matter of rerouting electricity from another grid sector or even another grid interconnection.

However, as Texans experienced during the February 2021 winter storm, it may not be possible to import electricity from another interconnection or even another sector within one interconnection.

Unfortunately, large-scale energy storage isn’t possible because electricity is a binary commodity (you have it or you don’t). However, many utilities use lithium-ion batteries as a short-term energy storage solution. In addition, hydroelectricity relies on abundant water resources, a potential energy resource that is easily accessed in response to increased demand.

The Power Grid: A Necessity in Modern Life

America’s power grid is an extensive array of power plants and transmission lines, divided into three geographic areas called interconnections. The Eastern and Western Interconnections can transfer power, on a limited basis, from one to another. Yet, Texas stands alone, relying almost entirely on ERCOT for the state’s power needs.

Our modern way of life is possible because the power grid exists. As it ages and technology advances, that way of life is increasingly vulnerable. Many of the systems and infrastructure were built in the last century, making them overdue for upgrades and replacement.

Even as technology improves the efficiency of day-to-day operations, the power grid is at risk from weather-related events and cyberattacks. However, with improvements in security and technical management processes, a smart grid can safeguard the power grid.

Brought to you by justenergy.com

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