Electrical Engineering Power Systems

Something VERY cool just happened in California and… it could be the future of energy.   On July 29, just as the sun was setting, California’s electric grid was reaching peak demand.   However, instead of ramping up fossil fuel resources, the California Independent System Operator (CAISO) and local utilities decided to lean on a network of thousands of home batteries.   More than 100,000 residential battery systems (made up primarily by Sunrun and Tesla customers) delivered about 535 megawatts of power to California’s grid right as demand peaked, visibly reducing net load (as shown in the graphic).   Now, this may not seem like a lot but 535 megawatts is enough to power more than half of the city of San Francisco and that can make all the difference when a grid is under stress.   This is what’s called a Virtual Power Plant or VPP. It’s a network of distributed energy resources that grid operators can call on in an emergency to provide greater resilience to our energy systems. Homeowners are compensated for the dispatch, grid operators are given another tool for reliability, and ratepayers are saved from instability. It’s a win-win-win.   Now, this was just a test to prepare for other need-based dispatches during heat waves in August and September. But it’ historic.   As homeowners add more solar and storage resources, the impact of these dispatch events will become even more profound and even more necessary. This was the second time this summer that VPPs have been dispatched in California and I expect to see even more as this technology improves.   Shout out to Sunrun, Tesla, and all companies who participated. Keep up the great work.

April 6th: A bright spring day in Germany, one that perfectly illustrates the need for battery storage systems. Like so many other sunny days, PV generation in Germany covered a large portion of the electricity demand for several hours in the middle of the day, thanks to the cloudless sky and millions of solar modules. But there is a darker side to the sunshine. Large amounts of daytime solar can overload the grid and cause severe electricity price fluctuations: on April 6th, intraday electricity prices dropped to -200€/MWh at their lowest point. In cases where more electricity is generated from solar energy than the grid can handle, grid operators regularly require solar installations to curtail their production. This means that energy that could otherwise be made available to consumers cannot be used. And when the sun goes down, most of the demand must quickly be met with flexible sources. This adds an extra layer of complexity: deciding which conventional power plants can be shut down during the day and switched on again in the evening is a careful balancing act. This is precisely the situation where battery energy storage systems (BESS) can bridge the gap, with several advantages: - By storing part of the solar energy at peak generation times and dispatching it later, BESS can help shift the curve to more closely align with evening demand. - Better management of volatile generation from renewables also helps keep prices stable. - Provided they are close to the overproducing solar systems, BESS contribute to grid stability by helping balance supply and demand. Of course, there is no one-size-fits-all technology. A secure and flexible energy system needs a diverse mix. But batteries are playing an increasing role, especially as they become more and more affordable. We at RWE are harnessing the benefits: we have 1.2 GW of installed BESS capacity worldwide, of which nine systems totalling 364 MW of capacity operate in Germany alone. We’re scaling fast, with new large-scale projects recently commissioned in Germany and the Netherlands. And we have just decided to build a BESS facility in Hamm with an installed capacity of 600 megawatts. So, let’s continue to make the most of those sunny days — by creating the right framework conditions to build up affordable and flexible support.

Virtual Power Plants (VPPs) have been around for a long time as a concept. After China has seen a rise in their use will the US be next? By digitally aggregating thousands—often millions—of flexible assets like heat pumps, EV chargers, batteries, smart thermostats, and commercial HVAC, VPPs deliver reliable capacity, balancing, and ancillary services at a fraction of the cost and carbon of traditional peaker plants, without compromising comfort or productivity. As electrification accelerates and variable renewables scale, grid stress is rising, and building new firm capacity is expensive and slow; unlocking demand-side flexibility is faster, cleaner, and more scalable. The enabling technologies exist today—smart, standards-based controls—and policy is beginning to catch up. Priority actions are clear: pay-for-performance markets that let flexibility compete fairly with supply-side resources, interoperability through open standards to reduce costs and avoid lock-in, and consumer-first participation models with simple enrollment, strong privacy by default, and equitable access, particularly for low-income customers.

Arc flash is a dangerous electrical event that occurs when an electric current travels through the air between conductors or from a conductor to ground, typically due to a fault or short circuit. The result is a sudden release of energy in the form of intense heat, light, and pressure. 🔥 What Causes an Arc Flash? Arc flashes can result from several factors: Equipment failure (e.g., breaker or switchgear failure) Human error (e.g., improper maintenance or accidental contact with energized parts) Dust, corrosion, or moisture buildup Loose or deteriorated connections Dropped tools or conductive objects 🏗 Where It Happens in a Substation Arc flashes can occur in: Switchgear Circuit breakers Transformers Busbars Cable terminations Any location with live, high-voltage components 🛡 How to Prevent Arc Flash in Substations 1. Perform Arc Flash Risk Assessments. 2. Proper PPE: Ensure personnel wear appropriate arc-rated clothing and face shields. 3. Engineering Controls: Arc-resistant switchgear Remote racking/switching systems Current-limiting devices 4. Maintenance and Inspection: Keep equipment clean and in good condition Follow strict lockout/tagout procedures 5. Training and Awareness: Train staff in electrical safety and emergency respons.

🔴 The Spanish power system collapsed within seconds following a double contingency in its interconnection lines with France. First, a 400 kV line disconnected, and less than a second later, a second line also failed, suddenly isolating Spain while it was exporting 5 GW of power. The frequency rose abruptly, triggering the automatic disconnection of approximately 10 GW of renewable generation, programmed to shut down when exceeding 50.2 Hz. This led to a sudden energy shortfall, a sharp frequency drop, and within just nine seconds, a total system blackout. 🪕 The causes of the incident are attributed to low rotational inertia (only about 10 GW of synchronous generation online), identically configured renewable protections that reacted simultaneously, reserves that were inadequate for such a high share of renewables, and an under-dimensioned interconnection with France. Could this have been avoided? Several measures could help prevent similar situations in the future, such as requiring synthetic inertia in large power plants, reinforcing the interconnection with France, and establishing a fast frequency response market, among others. 💡 In this context, Battery Energy Storage Systems (BESS) are more essential than ever. These systems can provide synthetic inertia, ultra-fast frequency response, and backup power in critical situations—capabilities that today’s renewable-dominated system cannot ensure on its own. By reacting in milliseconds, BESS help stabilize the grid during sudden frequency deviations, preventing massive disconnections and buying time for other reserves to activate. Their strategic deployment, combined with appropriate regulation, would make these systems a cornerstone of a more secure and resilient future power system. ... ✋️Please note that this post was written based on the information published on or before its release. Root cause analysis is still ongoing and updates will be released with the outcomes of the investigation. The goal is to show the features that can be provided by BESS within the wide portfolio of solutions applicable in these cases. All inisghts are highly welcome and appreciated in order to enrich our collective understanding. ... 📸 Reid Gardner Battery Energy Storage System (Nevada, USA) A real-world example of how BESS ensures grid stability by delivering synthetic inertia and fast frequency response—essential in a renewable-heavy energy mix.

Why are European power prices so high? Both wholesale and final prices are higher in Europe then elsewhere • E.g., wholesale prices are 70% in Germany than in Texas The reason for higher wholesale prices is *not* marginal pricing (the “merit order”) • All other power markets power markets apply the same price logic of price formation, including Texas The true reasons are simple: gas and carbon • Gas is more expensive in Europe  • We price carbon, America does not • These two commodity prices easily explain the entire wholesale price gap The wholesale prices is only part of the picture – what also matters: • Grid costs recovered through grid tariff • Subsidies recovered from taxpayers How policy choices have inflated power system costs • Large investment in expensive power generation (small-scale solar, biogas, offshore wind) • Delayed and expensive grid expansion (underground cables) • Barriers to smart electricity consumption (delayed and expensive smart meters, harmful subsidies) • Lack of locational prices (resulting in curtailment and grid congestion costs) • Decommissioning existing assets before end of lifetime (coal, nuclear) • Self-consumption (solar & batteries in homes, fossil plants in industry), driving up the cost for everyone else There has been reasons for this • People want to have solar panels on their rooftop, they don’t like to see transmission towers, and they are scared of nuclear, etc. • But nevertheless: these choices have driven up the costs of the power system 👉 Looking forward: what can be done Not an option: inventing a new “pricing rule” • Replace marginal pricing (“getting rid of the merit order”) with something else will create chaos, not lower prices Pathway 1: scale back on climate ambition • Lower the carbon price & reduce renewables targets • This will bring down power prices … • … at the cost of higher emissions and more climate change Pathway 2: do things better • Focus on low-cost investment options: large solar farms not small rooftop, overhead lines not underground cables, fossil gas rather not hydrogen, solar not biogas, utility-scale not small batteries, etc. • Improve market design: prices should reflect marginal costs (split bidding zones, grid tariff reform, dynamic pricing, digitalization, production-independent CfDs, etc.)

“DOE expects a surge in annual DER additions from 2025 to 2030, including 20 GW to 90 GW of demand capacity from EV charging infrastructure and 300 GWh to 540 GWh of storage capacity from EV batteries. It expects smart thermostats, smart water heaters and non-residential DER will contribute an additional 5 GW to 6 GW of flexible demand annually, distributed solar and fuel-based generators will add 20 GW to 35 GW a year and up to 24 GWh of capacity a year from stationary batteries. “Rather than viewing the massive adoption of EV and other DERs just as load to serve, utilities and regional grid operators can view this as an opportunity to increase the flexibility of the grid and more efficiently use existing resources and infrastructure,” DOE said. Buying peaking capacity from a VPP made of residential smart thermostats, smart water heaters, home managed EV charging, and behind-the-meter batteries can be 40% lower net cost to a utility than buying capacity from a utility-scale battery and 60% lower than from a gas peaker plant, DOE said, citing a May report by The Brattle Group.” #VirtualPowerPlants

The ocean has always been a powerful force of nature—endless, untamed, and constant. Today, innovators are finding ways to harness that very force to fuel a more sustainable future.Eco Wave Power’s system is a fascinating leap in this direction. Unlike offshore floating technologies, their design anchors wave energy converters to coastal and man-made structures (like breakwaters and piers) making it easier to integrate, maintain, and scale.Wave energy remains one of the least tapped renewable sources, yet it has immense potential—covering global electricity demand many times over if harnessed effectively. What excites me about solutions like Eco Wave Power is not just the technology, but the simplicity of design and the foresight of integration into existing infrastructure. Renewables need diversity—solar, wind, hydro, offshore—and wave energy could become the next big piece of the puzzle. With climate change intensifying, we need more than promises; we need practical, scalable solutions that work with nature, not against it. #CleanEnergy #OceanEnergy #WavePower #Sustainability #Innovation #ClimateAction #EnergyTransition #RenewableEnergy

Everyone’s Worried About Insufficient FFR. But What Happens When The Problem Is Too Much…Voltage? As we transition to high inverter-based resources, frequency stability dominates headlines. Yet one of the most disruptive, and silent, threats to modern grids is overvoltage, especially in systems with high solar PV penetration. Voltage instability develops faster and more quietly than frequency instability. While frequency deviations are system-wide and trigger alarms, voltage issues are often more localised and can escalate rapidly, sometimes before system-wide alarms are triggered. What’s happening under the hood? ➤ Most grid-following inverters can exchange reactive power, but without proper headroom, settings, or coordination, they often fail to provide dynamic voltage support during disturbances. ➤ Under light load, long transmission lines behave like capacitors, injecting charging current (the Ferranti effect). ➤ When synchronous generators trip, the system loses critical reactive power sinks, weakening its ability to absorb excess vars. The Result? Rising voltages trigger protection relays, sometimes before frequency deviations begin. Clean Energy ≠ Stable Grid Overvoltage isn’t new, but phasing out synchronous machines (coal, gas, etc.) also removes inertia, voltage damping, and fault ride-through capability. Even if solar isn’t the root cause, the grid may lack the tools to mitigate minor disturbances before they cascade. The key question isn’t just what trips, it’s what stays online that determines whether a voltage cascade unfolds. What do we need now? ● Grid-forming inverters with reserved reactive power headroom and robust voltage control. ● Synchronous condensers for dynamic VAR absorption and system strength. ● FACTS devices (STATCOMs, SVCs) for fast, localised voltage regulation. Updated grid codes addressing overvoltage risks in high-VRE, low-demand scenarios. The gap may lie not in capability, but in implementation strategy, grid code enforcement, and system coordination. Case Study: When Inverters Don’t Trip In the modelling below, I forced a DFIG-based grid-following inverter to remain connected beyond its overvoltage threshold, emulating a scenario where, under low system strength, protection systems respond too slowly to isolate the fault. Rather than tripping offline as expected, the inverter stayed online: → Reactive power surged, → Active power spiked, and → Voltage oscillations spread across the system. This is one of the hidden fragilities of passive inverter behaviour, clean on paper, but unstable in practice when protection systems delay or inverters fail to disengage. The result? Small disturbances can escalate rapidly, turning a local issue into a system-wide event. Have you encountered overvoltage challenges in your grid? How is your region or market adapting its tools and standards to manage this risk? #PowerSystemStability #GridResilience #GridForming #GridCode #VoltageStability #IBR #FFR

⚡️ LCOE vs. System-LCOE: Why understanding the full picture matters! As part of Norway’s efforts to promote smart, sustainable energy solutions abroad, we often highlight how competitive solar, wind, and offshore technologies have become. The progress is real, costs have dropped, and renewables are at the heart of the global energy transition. But when planning large-scale investments or national energy strategies, headline figures alone aren’t enough. For real impact, we must understand the difference between LCOE and System-LCOE and why this distinction matters for delivering reliable, low-emission power 24/7. 📉 LCOE. A valuable, but limited metric LCOE (Levelized Cost of Electricity) is a well-established measure of production cost per MWh over a plant’s lifetime. It’s an essential benchmark and the reason why solar, wind, and offshore wind are now increasingly preferred in many markets. However, LCOE only tells us what it costs to produce electricity, not what it takes to deliver it when and where it’s needed. That’s where System-LCOE becomes critical. 🧩 What System-LCOE adds to the conversation System-LCOE reflects the broader cost of integrating energy into a functioning power system. This includes: - Backup capacity (e.g., hydropower, gas peakers) - Storage (batteries, hydrogen, thermal, etc.) - Grid upgrades and interconnection - Curtailment losses and balancing services This doesn’t make renewables "too expensive", but reminds us that energy systems need more than generation alone. The Norwegian perspective: our flexibility is a strength Norway is in a unique position. A flexible hydropower system provides natural balancing for intermittent energy sources, such as wind. That makes it easier and cheaper to integrate renewables at scale, a goal many other countries are actively pursuing, for instance, through battery deployment or hydrogen-based storage. This means Norwegian companies, technologies, and experience in system integration and flexibility are more relevant than ever. ⚠️ Why this nuance matters Comparing LCOE from solar in Spain with baseload gas in Southeast Asia doesn’t tell the whole story. System integration matters, and System-LCOE can often be 1.5–3 times higher than LCOE, depending on geography, grid structure, and generation mix. Norwegian companies must be prepared to address this complexity when advising or exporting and show how smart design and flexible technology can manage these costs. ✅ Bottom line To support our partners in making sound energy decisions, we must: - Go beyond LCOE when discussing costs - Highlight Norway’s strength in system-level thinking - Recognise that renewables are essential, and so is integration 📣 Next time you see that solar or wind is “the cheapest,” ask: Is that just the generation cost or the full cost of reliable energy delivery, including the cost of infrastructure? Is that the full answer, or is it still blowin’ in the wind 👍