Managing Local Generation and EV Loads with DA and DERMS

The Challenge on Your Doorstep

Traditionally, distribution networks were simple, passive systems designed for one-way power flow from the transmission grid down to consumers. However, the rapid growth of Distributed Energy Resources (DERs) has turned this model on its head.

• Local Generation: Millions of rooftop solar panels can generate more power than a neighbourhood is consuming on a sunny day, causing power to flow "backwards" and potentially raising local voltage above safe limits.
• New Loads: The widespread adoption of Electric Vehicles (EVs) and heat pumps creates large, concentrated demands for power. If an entire street plugs in their EVs after work, it can overload local transformers and cables that were never designed for such a load.

Simply upgrading every cable and transformer is incredibly expensive and slow. Instead, network operators need to get smarter. This has driven the evolution of the traditional, passive Distribution Network Operator (DNO) into a more active Distribution System Operator (DSO).

To understand this shift and the tools required, let's start with a foundational reading.

Distribution Automation: The Grid's Reflexes

As the reading highlights, DSOs need new tools. The first layer of this new intelligence is Distribution Automation (DA). This isn't one single product, but a range of technologies that use sensors, communications, and processors to monitor and control the distribution grid automatically, improving reliability and efficiency.

One of the most common forms of DA is Fault Detection, Isolation, and Restoration (FDIR).

• Before DA: When a fault occurred (e.g., a tree branch falls on a power line), it would cause a blackout for a large area. Engineers would have to be sent out to manually find the fault and reconfigure switches to restore power, which could take hours.
• With FDIR: Smart sensors automatically detect the fault and its location. The system then automatically opens and closes switches to isolate the smallest possible section of the network and restore power to everyone else by re-routing it, often within a minute or two.

While FDIR is about reacting to faults, other automation systems are about proactively managing power flows. This is where Active Network Management (ANM), which we discussed in the last lesson, becomes crucial at the local level.

DERMS: The Brains of the Local Grid

While DA provides the automated reflexes, the Distributed Energy Resource Management System (DERMS) acts as the intelligent brain coordinating all the activity.

A DERMS is a software platform designed to manage and optimize the vast and growing number of DERs connected to the distribution network. Think of it as an air traffic control system for local energy resources.

To fully grasp what a DERMS does and how it differs from other concepts like Virtual Power Plants (VPPs), we'll turn to another excellent resource.

How DERMS Manages EVs and Solar in Practice

Let's consolidate what we've learned with concrete examples:

1. Managing EV Charging

• Problem: A housing estate with 50 homes gets a government grant for EV chargers. On the first cold evening, 40 residents arrive home between 5:30 and 6:00 pm and plug in their cars. The combined load is far greater than the local transformer was ever designed for, causing it to trip and blacking out the entire estate.
• DERMS Solution: The DSO uses a DERMS that communicates with the "smart" EV chargers.
  • The DERMS knows the thermal limit of the local transformer and cables.
  • As residents plug in, they tell the system when they need their car charged by (e.g., 7 am).
  • The DERMS creates an optimized charging schedule, staggering the charging throughout the night. It might charge 10 cars from 9 pm to 11 pm, another 10 from 11 pm to 1 am, and so on.
  • Result: All cars are fully charged by morning, but the peak load never exceeds the network's capacity. No expensive transformer upgrade is needed.

2. Managing Solar Generation

• Problem: It's a bright, sunny Sunday in May. Demand for power is low because people are out and about. However, the hundreds of rooftop solar panels in a suburb are generating at maximum capacity. This pushes so much power back into the local network that the voltage rises above the legal limit, which can damage appliances and force the solar inverters to disconnect for safety.
• DERMS Solution: The DERMS is constantly monitoring voltage levels across the distribution network.
  • As it detects the voltage rising towards the upper limit in a specific area, it sends signals to the smart inverters connected to the solar panels in that area.
  • It might instruct the inverters to momentarily reduce their power output by 10% or to absorb reactive power, which helps to pull the local voltage back down into the safe operating range.
  • Result: The grid remains stable, customers' equipment is safe, and the solar panels can continue to generate as much clean energy as the local network can safely handle.

DERMS vs. Virtual Power Plant (VPP)

You may have heard the term Virtual Power Plant (VPP) used in similar contexts. While related, they have a key difference.

• A VPP is primarily a commercial tool. It aggregates lots of individual DERs (like home batteries) and operates them as a single entity to sell services (like frequency response) into national electricity markets. It's not usually concerned with the physical location or local network impact of those assets.
• A DERMS is an engineering tool for the network operator. Its primary job is to maintain the physical integrity (voltage, thermal limits) of the local distribution grid. It is highly location-specific.

The two can work together. A VPP might tell a DERMS it wants to discharge 5,000 home batteries to sell power to the grid. The DERMS would then check if the local networks can handle that action and might adjust the instructions to prevent any local overloads.

Conclusion

In this lesson, we have seen how the humble distribution network is being transformed into a smart, active, and flexible system.

Key Takeaways:

• The rise of local generation (solar) and new loads (EVs) has created challenges like voltage issues and thermal overloads on the distribution grid.
• Distribution Automation uses technology like FDIR to automatically improve grid reliability.
• DERMS is the software "brain" that allows DSOs to actively manage these new resources. It uses real-time data and control signals to manage network constraints.
• By controlling smart EV chargers and solar inverters, a DERMS can prevent overloads and voltage problems, allowing more DERs to connect to the existing grid without requiring expensive and slow physical upgrades.

Preview of the next lesson:

We have now covered the key technological opportunities for improving the physical grid at both the transmission and distribution levels. In our next lesson, we will shift our focus to the commercial side of the industry. We will analyse how the digitalization of wholesale market platforms can improve liquidity, reduce barriers to entry for new players (like VPPs), and lower operational costs.