Understanding Electrical Systems

🔄 Is your secondary voltage always stable — even when your grid isn’t? Let’s talk about the real-time hero inside your transformer… ⚡ On-Load Tap Changers (OLTCs) They adjust the transformer’s turns ratio under load to keep output voltage steady — and yes, they do it live and smoothly. 👀 But how does it really work? With calculations? At different input voltages? Let’s break it down visually👇 🎯 GIF Breakdown: OLTC Action in Real-Time ✅ Why OLTC? Grid voltages fluctuate. Loads vary. But your supply must stay steady. OLTC ensures just that — without shutdown. ✅ What happens when voltage drops? 🔹 Input = 31.5kV instead of 33kV 🔹 Output drops to ~10.5kV 🔹 OLTC taps down by -4 steps (1.25% each) 🔹 Output = ~11.02kV restored 🔧 Live voltage correction in action ✅ What about overvoltage? 🔹 Input = 34.6kV 🔹 Output rises to ~11.55kV 🔹 OLTC taps up by +4 🔹 Output brought back to ~11.01kV 🧯 No surge. No stress on equipment. 🎓 Engineers, if you work with transformers, grid-connected systems or voltage control — this is a fundamental you must master. 💬 What’s your experience with OLTC maintenance, failures, or control strategies? ♻️ Repost to share with your network if you find this helpful. 🔗 Follow Ashish Shorma Dipta for posts like this. #PowerSystem #TransformerProtection #OLTC #VoltageRegulation #ElectricalEngineering #TapChanger

We are almost certainly Sleepwalking into a System-Wide Blackout? Last Monday, the Iberian grid collapsed in 3.5 seconds. Not minutes—seconds. At 12:33, a disturbance in southwestern Spain quickly cascaded. France disconnected, renewables dropped off, and soon after, so did rotating generation. A total blackout engulfed Spain and Portugal. Why? Because 79% of their 28.4GW generation was solar and wind—sources that supply zero grid inertia. What is Inertia, and Why Should You Care? Inertia is the silent stabiliser of every electrical grid. Thermal generators—gas, coal, and nuclear—supply it through heavy spinning turbines. When something disturbs the grid, that kinetic energy resists sudden frequency swings, buying operators precious seconds to act. Renewables don’t provide that buffer. They disconnect immediately when frequency wobbles beyond limits. No resistance. No time to correct. Just… blackout. The UK Is Headed the Same Way • 66% of UK generation (as of this Tuesday) had no inertia—solar, wind, and DC imports. • Dinorwig, our backbone pumped-storage stabiliser, is offline for repairs with no return date. • We’re retiring our gas and nuclear base. • And we’re doing this while increasing asynchronous renewables. Let’s be clear: the UK grid has never suffered a total blackout. Not even in WWII. But how long can we keep that record? Grid Engineers: You’re Not Alone At Johnson & Phillips, we work on the front line of power quality and grid stability. We test. We analyse. We reinforce. Whether it’s inertia substitution, stabilisation through PFC systems, or consulting on resilient interconnection strategies—we’re here to help design and defend a resilient, responsive power system. What Now? Inertia used to be a given. Now it’s a luxury. As we race toward a renewable future, we can’t ignore the engineering truths: No inertia means no forgiveness. No Volume…. Let’s start making inertia part of every system design, every policy conversation, every operational plan. #PowerQuality | #GridStability | #EnergyTransition | #JohnsonAndPhillips | #InertiaMatters | #ElectricalResilience | #UKGrid | #Renewables

This image represents the “Duck Curve,” a common visualization of electricity system load over the course of a day, highlighting the challenges of integrating renewable energy into the grid. Here’s a detailed explanation: 1. System Load (Y-axis): The graph shows the electricity demand in megawatts (MW) over time. 2. Time of Day (X-axis): The curve spans a 24-hour period, starting at 6 AM and ending at 9 PM. 3. Historical and Forecasted Trends: • The colored solid lines represent actual system loads for different years (2020 to 2023). • The dashed lines show forecasts for 2024 and 2025. 4. Duck Shape: • The “belly” of the duck (midday dip) reflects low electricity demand during peak solar generation (12 PM–3 PM), as solar panels supply a significant portion of energy. • The “neck” (steep rise after 3 PM) highlights the rapid increase in demand when solar generation decreases and other sources must ramp up quickly to meet the evening demand. 5. Grid Stability Challenge: • The shaded area near the bottom indicates “potential for grid instability,” occurring during the lowest load times. This happens because traditional power plants might struggle to reduce their output quickly enough to accommodate the surge in solar power. 6. Key Observations: • The midday dip grows deeper over the years due to increased solar generation. • The evening ramp (neck) becomes steeper, emphasizing the need for flexible power sources (like battery storage or fast-ramping plants) to balance the grid. Conclusion: The Duck Curve illustrates the need for grid modernization, storage solutions, and demand-side management to handle the variability of renewable energy sources like solar power.

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.

There are several types of grounding systems in electrical networks, and each system differs from the other based on the way it is connected and used. The most prominent of these types are: 1. Direct Grounding (TN System): The system is connected directly to the ground without any resistors or transformers. There are sub-types of this system depending on how the elements are connected, such as: TN-S: Where the Neutral line and the Earth line are separated along the network. TN-C: Where the neutral and grounding lines are combined into one wire, it is known as PEN. TN-C-S: This system combines the two previous methods, where the partner is involved in one part of the system and separated in another part. 2. Indirect earthing (TT system): In this system, the grounding line is completely separate from the electrical supply network, and can be grounded elsewhere (usually by the user rather than by the regulator). Choose this simple and less expensive system, usually in small homes and small buildings. 3. Insulated grounding or resistance grounding (IT System): This system depends on connecting the phase line with a small resistance to the ground, or not connecting it to the ground completely, so that in this case the grounding is isolated or the current is limited. This system is used in locations that require special protection against loss of power, such as hospitals and industrial sites with sensitive equipment. 4. Resistance Grounding: In this system, a medium or large resistance is added between the neutral point and the ground. This system helps reduce current during ground faults and is used in industries that require additional protection against ground faults to reduce their impact on the network and equipment. The difference between the systems: The TN system is more common in cities and modern facilities because it provides high protection and quick response to faults. The TT system is suitable for rural or remote locations where it is difficult to provide a central earthing system. The IT system is best used in environments where frequent power outages due to grounding faults cannot be tolerated. Each grounding system has its advantages and disadvantages, and choosing the most appropriate system depends on the type of building, the type of devices used, and security requirements.

Neutral and Earthing are two essential concepts in electrical systems, often confused with each other. Here's a clear explanation of the differences: #Neutral:- 1. A current-carrying conductor connected to the star point of a 3-phase system. 2. Carries the unbalanced current in a 3-phase system. 3. Provides a return path for the current. 4. Connected to the neutral busbar. 5. Typically represented by the letter 'N'. #Earthing (Grounding):- 1. A safety measure to protect against electrical shock. 2. Connects the electrical system to the earth. 3. Provides a safe path for fault currents to flow to the earth. 4. Helps to: - Reduce voltage rise during faults. - Prevent electrical shock. - Protect equipment from damage. 5. Typically represented by the symbol. # Key differences:- 1. Purpose: - Neutral: Carries current, provides return path. - Earthing: Safety, protects against electrical shock. 2. Connection: - Neutral: Connected to the star point, neutral busbar. - Earthing: Connected directly to the earth. 3. Current flow: - Neutral: Carries unbalanced current. - Earthing: Carries fault currents to the earth. 4. Voltage: - Neutral: Has voltage potential. - Earthing: At zero voltage potential (earth potential). # Why both are necessary:- 1. Neutral ensures proper current flow and balance in 3-phase systems. 2. Earthing provides safety and protects against electrical shock. *Types of Earthing:- 1. System Earthing (e.g., TN-S, TN-C-S). 2. Equipment Earthing (e.g., grounding of metal enclosures). 3. Functional Earthing (e.g., grounding of communication systems). # Standards and regulations:- 1. IEC 60364 (Electrical installations of buildings). 2. IEEE 80 (Guide for safety in AC substation grounding). 3. NEC (National Electric Code). 4. Local regulations and standards.

Last week, a visit to a power plant left me questioning the very foundation of my physics knowledge. The engineer explained, “We pump water from a lower reservoir to a higher one, then release the stored water to generate electricity.” Isn’t this a blatant violation of the first and second laws of thermodynamics? Conservation of energy? The inevitability of entropy? How could the output energy ever exceed the input energy? Surely, energy must dissipate due to friction and inefficiencies—basic thermodynamics, right? To simplify: imagine starting with 10 apples but somehow ending up with 12 apples. Sounds impossible, doesn’t it? Here’s the twist: Power can't be generated when measured in Joules per second, but it can when measured in ₹! Let’s revisit the apple analogy. Suppose you could buy 20 apples for the cost of 10 during a sale. Even if a few apples spoil, you’re still left with more than you started with—say, 12 apples. This is essentially what’s happening at the Purulia Pumped Storage Project (PPSP). It’s less a power plant and more a colossal battery for storing energy. The primary goal of PPSP is to flatten the demand curve. It "buys" cheap electricity during off-peak hours to pump water to the higher reservoir. When demand spikes and electricity prices soar, it releases the water to generate electricity and meet peak demand. So, while it doesn’t generate energy or violate law of thermodynaimcs, it certainly generate value by smartly balancing supply and demand. A clever engineering solution, isn’t it? Pic: Bengal Darshan - Purulia Pumped Storage Project

🔋 Why Grid Frequency Matters – and How Inertia Keeps the Lights On Did you know that the stability of our entire power grid depends on keeping frequency within ±0.1 Hz of its target value (50 Hz or 60 Hz worldwide)? If it drifts ±0.5 Hz outside the norm, grids enter emergency mode, risking blackouts. A more extreme deviation? It could lead to a full system failure—costing economies millions and endangering lives. At the heart of frequency stability is inertia—the kinetic energy stored in the spinning turbines of synchronous generators. This “rotating mass” acts like a shock absorber, slowing down frequency changes when sudden disruptions occur (like losing a 1 GW power plant). 🛁 Imagine it like a bathtub: The tap = power generation (flowing in) The drain = consumption (flowing out) The water level = frequency The size of the tub = inertia As long as inflow and outflow are equal, the water level (frequency) stays stable. But if the flow changes? The level moves. And the bigger the tub (more inertia), the slower and smaller the change. ⚡️ As we transition to renewables (which often lack inherent inertia), maintaining frequency stability becomes even more challenging, and innovative solutions are needed to “artificially” replicate inertia in modern grids. 👉 What role do you see for battery storage, synthetic inertia, or demand response in solving this challenge? Let’s talk about the future of grid stability. #Energy #PowerSystems #GridFrequency #Inertia #Renewables #Electricity #SmartGrid #EnergyTransition #PowerQuality

Cyberattacks could exploit home solar panels to disrupt power grids - New Scientist The growth of domestic solar installations opens the possibility of hackers targeting their smart inverter devices as a way to cause widespread power-system failures Power grids around the world are increasingly under threat from cyberattacks because of the vulnerabilities of home solar installations. As distributed energy resources like rooftop solar become more prevalent, grids are increasingly reliant on smart inverters, which manage connections to local power networks. “While these technologies offer many benefits, they also introduce new operational and cybersecurity challenges,” says Sid Chau at CSIRO, an Australian government research agency. Smart inverters convert the direct current produced by solar panels into the alternating current needed to power appliances. They also optimise energy storage and enable remote monitoring via the internet. These web connections mean they pose a threat not just to home solar systems, but also to the wider power-generation network, Chau and his colleagues warn. The team identified multiple ways that smart inverters could be hacked, including exploitation of the security flaws in the physical hardware and software of smart inverters. Malicious actors could trick users into granting excessive permissions for apps connected to the inverter or work with manufacturers to embed malicious code into the hardware. Chau and his colleagues only modelled the threat from inverters in Australia, where around a third of homes have rooftop solar. But the situation is similar for power grids throughout parts of the world where private solar systems are becoming more common. While any attack would require careful orchestration and planning, the researchers found that, if vulnerabilities align, relatively few solar smart inverters would need to be hacked to cause disruption. Once the smart inverter has been compromised, hackers can then mount coordinated attacks on the broader power grid, according to the researchers. #cybersecurity #solarpanels #smartinverter #IoT #OT

🔌 Grid-forming (GFM) inverters gained significant interest because of their potential to enhance grid stability and reliability, particularly as the limitations of grid-following converters became clear. However, the GFM converter faces substantial challenges in current limiting during fault conditions. The core challenge is protecting the inverter hardware from thermal damage due to excessive output currents. The ideal current limiter must act swiftly and accurately to curtail overcurrent; however, engaging the current limiter alters the entire control architecture. This typically leads to different dynamic output behaviours that may introduce small-signal instability or excessive output voltage and current harmonics.   ⚡ Current limiting methods for GFM inverters can be categorised into direct and indirect approaches. The current limiters are highlighted in red colours in the figure. Direct current limiters aim to curtail the inverter output current by manipulating the current-reference control signals or directly controlling the semiconductor switch signals. For instance, the current-reference saturation limiter dynamically scales the current-reference signal based on the maximum allowable current, ensuring that the output current does not exceed predefined limits. The other option is the switch-level current limiting method, which directly modulates the switching signals fed to the bridge. This method achieves the fastest response as it bypasses the other control loops. However, the unavoidable consequence of bypassing the control loops is the sacrifice of power quality and even controller stability, which leads to integrator windups in the hierarchical control loops.   ⚡ Indirect current limiters, on the other hand, work by manipulating voltage-reference and power-reference signals in the inverter controls. These approaches can be slower than direct methods but avoid the windup issues associated with them. For example, voltage-based current limiting reduces the voltage reference in response to overcurrent conditions, effectively limiting the output current while maintaining control over the voltage and current phasors. This method can enhance transient stability during faults but may also lead to challenges in frequency stability and post-fault recovery. The last group of limiters that has been explored are hybrid solutions that combine the strengths of both direct and indirect methods, aiming to improve reliability and stability during current-limited operations. One of the promising approaches is combining a VI current limiter and a current-reference saturation limiter. First, the saturation limiter kicks in and limits the current to Imax. After the initial phase of fault passes, the VI current limiter takes over because the threshold current for the VI current limiter is set lower than Imax. #gridforming #microgrids #powerelectronics #battery #energystorage #gridmodernization #cleanenergy #renewables