How Grid Operators Manage Power Transfers

How does power flow in the grid and can it be controlled? What are the components of power flows? Real power is the portion of the power that flows on the grid that does work—turning motors, lighting lights, anything that is doing something. Imaginary power is power that moves back and forth on the grid reactance and capacitance or generators. This imaginary power is directly related to the magnetic fields created from current flowing through lines and magnetic loads like motors. Both of these components are controlled differently and make up portions of the Apparent Power Triangle: How do they flow? Real power flows from a higher voltage angle to a lower voltage angle. As real power is drawn by loads, the voltage angle changes at the nodes from the generation to the load due to how the voltage angle changes as real power passes over the grid reactance, like lines or through transformers. This angle difference between nodes directs the flow of real power, in the direction from the generation to the load. Imaginary power flows in the direction of higher voltage to lower voltage. The equation for imaginary power flow is mostly dependent on the voltage magnitude difference between two nodes, rather than the angle. Imaginary power can be looked at as the flow of voltage support from higher to lower voltage. How are these components controlled on the grid? Real power flow on the grid can be directed by a phase-shifting transformers. This transformer induces an artificial phase angle shift to redirect the flow of real power in the direction needed. This is often done to prevent real power from flowing in such a way that it overloads a line that no one wants to upgrade. These transformers are not common. Real power flows are still generally controlled through how generation is dispatched. Power flow simulations are done to determine how the dispatch of generation should be adjusted if choke points are an issue. Once real power is put into the grid, it flows usually without control, based on the math, in the direction of the loads. Imaginary power can be controlled with transformer taps, which will pull the imaginary power from the higher to lower per-unit voltage side. This helps the lower-voltage side at the expense of the high-voltage side. VAR flow generally doesn't overload lines, since flows are mostly real power. The issue that can be caused by poor VAR flow is high or low voltages. Like with real power, the control of imaginary power flow is generally managed by the dispatch of shunt capacitors. Once the shunt cap banks are switched in, the VAR flow is uncontrolled toward low voltage. Generators can inject vars, too, but they can't redirect them in the grid once injected. Power flows are generally controlled by strategically dispatching resources, rather than actively redirecting the flow of electricity. #utilities #renewables #energystorage #electricalengineering

For TSOs, the energy transition has moved decisively from strategy to execution. Recent expert discussions on grid reliability highlighted a reality every system operator now faces: power systems are being operated closer to their physical limits, with less inertia, higher volatility, and far greater uncertainty than legacy planning frameworks were designed to manage. In this environment, deterministic capacity limits and offline security studies are no longer sufficient. Executives need operational answers in real time: How much load can the grid safely carry right now? For how long? And with what confidence level? This is why probabilistic, real-time prediction of load and network capacity is becoming a core operational capability. It allows operators to replace conservative static margins with quantified risk, enabling higher asset utilisation, reduced congestion costs, and safer integration of renewables — without compromising security of supply. This shift is not optional. Under the EU regulatory framework led by ACER, advanced probabilistic and real-time approaches to capacity calculation and operational security become mandatory by end-2027. Compliance will be assessed not on intent, but on demonstrable operational capability. For TSO leadership, the message is clear: • Reliability is now a probabilistic outcome, not a deterministic assumption • Regulatory compliance and real-time operations are converging • Competitive advantage will accrue to operators who can safely run closer to true system limits The question is no longer whether probabilistic real-time capacity forecasting will be adopted — but who will be ready in time.

𝗨𝗻𝗹𝗼𝗰𝗸𝗶𝗻𝗴 𝗘𝘅𝗶𝘀𝘁𝗶𝗻𝗴 𝗚𝗿𝗶𝗱 𝗖𝗮𝗽𝗮𝗰𝗶𝘁𝘆 𝗪𝗶𝘁𝗵 𝗗𝘆𝗻𝗮𝗺𝗶𝗰 𝗟𝗶𝗻𝗲 𝗥𝗮𝘁𝗶𝗻𝗴 Dynamic line rating is one of those rare grid tools that creates value even when it does not increase capacity. Sometimes it uncovers spare headroom on existing lines and reduces congestion. Sometimes it shows operators were overestimating wind cooling and running closer to the edge than they realized. Both outcomes matter. Full article linked in comments. The core point is simple. Dynamic line rating replaces conservative static assumptions with measurements and forecasts of what a line can actually carry under real weather conditions. It addresses thermal limits. Static ratings assume hot air, little wind, and strong sun. That keeps lines safe, but it also means the rating often reflects weather that is rare across the full corridor. When air is cooler or wind is stronger, conductors shed heat faster and can safely carry more current. That can mean 5% to 15% more usable capacity. The public case studies are strong. Austrian operator APG reported peak capacity increases of about 10% on monitored lines, with congestion savings around €12 million per year and payback well under two years. In Texas, Oncor found that a 5% increase in transfer capability could relieve about 60% of congestion, while 10% nearly eliminated it. Terna in Italy reported dynamic ratings above seasonal static ratings most of the time. There is an important caveat. A lot of the early gain often comes from ambient adjusted ratings, where operators stop assuming worst case weather year round and use actual conditions. Once that is in place, the extra value from conductor sensors and better forecasting is smaller, but still worthwhile on heavily constrained lines or in difficult terrain. And sometimes the answer is not more capacity. BC Hydro found that vegetation and sheltered terrain reduced wind cooling below planning assumptions. Dynamic measurement showed less headroom than expected. That was not a failure. It was the point. Dynamic line rating is not magic. If the real bottleneck is transformers, breakers, or voltage stability, it solves nothing. But where conductor thermal limits are binding, it is one of the fastest ways to get more value from existing infrastructure. The broader lesson is that grids are becoming information-driven physical systems. Better measurements and forecasts let operators run closer to real limits instead of imagined ones. Sometimes that unlocks millions in savings. Sometimes it prevents dangerous overconfidence. Either way, that is a better grid.

The grid is moving away from a 100-year old paradigm where controllable centralised supply is adjusted to meet uncontrollable demand, to one where controllable demand is adjusted to meet increasingly uncontrollable and decentralised supply. Data centres have huge UPS and backup generators. The issue is whether they can avail of these for interruptible load/demand response, bearing in mind their very stringent operational requirements. The grid is the backbone of decarbonisation. There is no transition without transmission. "Singapore's demand for electricity is also expected to grow with the increase in businesses and facilities that rely on large and steady supplies of electricity, such as data centres and EVs. "Grid management will become more complex with these new load profiles", he added. To address this, EMA will explore a demand-side flexibility roadmap aimed at allowing the grid to tap "underutilised" distributed energy resources such as battery energy storage systems and backup generators. This means that such resources, which keep energy on standby when they are not being used, could be relied on for Singapore's power needs on a "near-continuous basis". The authority said in a statement: "These resources are typically maintained on standby, placing them in a state of readiness that enables activation with short notice. "Their capability to sustain load curtailment over extended periods suggests they could be well-positioned to provide ancillary services alongside their primary operational role." Together, distributed energy resources and electricity users or facilities that require a continuous and high load of power can be a "potentially dependable and scalable means of contributing to system reserves", EMA said. EMA will be publishing a tender to explore the feasibility and design of a programme that can incentivise relevant parties to contribute to power grid reliability continuously, it said. As part of this roadmap, EMA will also enhance its interruptible load programme, which is targeted at business consumers. The scheme allows eligible participants to be compensated for being on standby and to reduce their electricity demand when the grid faces tight supply constraints. The authority plans to provide greater certainty to these participants during contingencies by reducing interruptible load activation period to 30 minutes. Implementation details have yet to be finalised." EMA said the current pool of interruptible load resources was "opportunistic", as participants only reduce their load when schedules allow. These participants, who are mainly factories or production lines, cannot offer capacity consistently or for prolonged periods as they need to keep their own core operations running." https://lnkd.in/gh9U7Sp5

[When EDRA Power Plant Went Offline: A Real Lesson in Grid Stability] Last week, the EDRA power plant experienced a sudden shutdown event. Within seconds, the national grid frequency started to drop rapidly, triggering alarms across multiple substations. What actually happened? In any power system, the balance between generation and demand is fundamental. Pgen=Pload+Ploss When the ERDA plant tripped, the equation became unbalanced. Pgen < Pload This means the total generation was not enough to supply the demand and losses. As a result, the system frequency (f) began to fall. Frequency is directly proportional to the speed of rotating generators: f = n(rpm) × (p/120) where p is the number of poles and n is the rotor speed in revolutions per minute (rpm). When more load is drawn from the grid than generated power, the kinetic energy stored in the generator rotors temporarily compensates for the deficit, causing the rotors to slow down. As n decreases, frequency also decreases. If this continues, under frequency relays start to operate. Selected loads are disconnected to reduce total demand. This process is known as load shedding. To restore the system, additional generation or spinning reserves are dispatched to increase Pgen until balance is achieved again. At this point, frequency rises back towards its nominal value of 50 Hz, and stability is regained. This incident demonstrates the core principle of grid operation: Stability is achieved when generation and load are perfectly balanced in real time. For engineers, events like this are valuable lessons that connect theory to real-world operation. They highlight the importance of automatic control systems, frequency monitoring, and coordinated response between power plants and grid operators. Fuad Latip #PowerSystem #GridStability #FrequencyControl #EnergyEngineering #ERDA #EngineeringInsights https://lnkd.in/gAwaXX6Q