Why a Control System Alone Isn't Enough – What Really Matters in LV Grids

Exploring the requirements, differences, and challenges of modern control systems for distribution grids

Control systems, also known as SCADA systems, serve as the core system for monitoring and controlling electrical grids. They enable grid operators to determine the state of their infrastructure, identify malfunctions, execute switching operations, and ensure the safe operation of the system. In high- and medium-voltage operations, these systems are highly advanced and have been considered the industry standard for decades. 

In the low-voltage domain, however, the situation looks very different: Conventional control systems are rarely used. There are several reasons for this: Not only is there a lack of sensors to determine the state of the grid, but also of the technology needed for telecontrol. In addition, the load in low-voltage grids is evidently lower, diminishing the added value of monitoring them. When a mistake is made at the low-voltage level, the repercussions are much less serious than at higher voltage levels, as they affect fewer customers. All of that leads to grid operations largely relying on experience, manual processes or planning data. Only in recent years have there been initial approaches to digitally mapping low-voltage grids in all their complexity. This development has largely been driven by regulatory requirements like Section 14a of the German Energy Industry Act (EnWG), as well as the ongoing smart meter rollout and the expansion of decentralized generators. Next, find out why simply applying the existing SCADA approach to low-voltage use cases is not enough.

High Voltage vs. Low Voltage – Key Differences

Clearly, high and low voltage are different in a number of ways. With significantly differing technical, organizational and process conditions, the way the SCADA concept is applied to these voltage levels varies too:

Not all control systems are created equal

Control systems are the backbone of MV and HV grid operations. However, it's a mistake to assume that these systems can simply be applied to low-voltage use cases. Depending on the voltage level, the focus and the way these systems work, can vary drastically.

While conventional SCADA systems are designed for real-time control and monitoring of individual assets in medium- and high-voltage grids, low voltage is all about scale and quality: Thousands of secondary substations, highly fragmented grids and automated processes dominate the landscape. Manual monitoring is neither practical nor economical, and with the current staffing shortages, it's out of the question.

The fragmented data landscape also increases the complexity of an LV SCADA approach: Varying systems, inconsistent data formats, and missing measurements all make consistent grid operation a challenge. In addition, factors like decentralization and dynamic data can cause the grid state to change rapidly, as new PV systems, heat pumps or charging points keep affecting the infrastructure of the grid. The result: "Yet another control system" that only shows an additional voltage level is not a sustainable solution.

In the conventional understanding, the control system assumes the role of the system of record for data storage. This also means that, alongside the grid model used for planning, a second grid model is created. Given their highly dynamic nature and the large volumes of data in LV grids, a classic control system would barely provide any value. Instead, a new approach is necessary: A low-voltage control system should integrate and link data, e.g., from the GIS. This would keep it from being just another system of record and turn it into an end-to-end tool that creates transparency, and supports decision-making processes.

What does a modern LV control system need to do?

A low-voltage control system needs to offer more functionality than a conventional SCADA system. That does not necessarily mean that it needs to offer more features, but rather that it needs to meet different requirements than a regular SCADA system. With the increasing relevance of Section 14a of the German Energy Industry Act, the regulatory pressure to create operational control infrastructures and the integration of smart meters, one thing has become clear: The specific challenges of low voltage applications require new approaches. Instead, such a system needs to provide:

• A high degree of scalability: Distribution system operators usually operate grids that contain hundreds or even thousands of secondary substations. The sheer volume makes manual monitoring impossible.

• Automation & reliability: Especially in low-voltage grids, control processes need to be automated. Only in the case of critical anomalies should it be necessary for humans to get involved.

• Selective transparency: Some things are more important than others and relevant events must be easy to detect. That is why such systems need to be able to intelligently filter relevant events. This way, the user is not overwhelmed with a flood of information, but is not left in the dark either. 

• Platform thinking instead of silos: Planning, operation and control are becoming increasingly interconnected. In practice, that means, that, for instance, switching operations that are registered in the field on a tablet, need to be available and easy to understand in the control system. Creating such a closely interconnected structure for different grid operation user groups only works with an integrated platform solution.
• High data quality as a key factor: A reliable state estimation is the foundation for automated congestion management, control decisions, and grid security. This requires valid, continuously updated grid models that are able to calculate a reliable grid state. 

OT vs. IT – Quest for the Right Architecture

Another key issue is the hosting strategy: Classic SCADA systems are usually hosted in the OT (Operational Technology), making them deeply entrenched in the operational infrastructure of the grid operator. However, this approach hits its limits when applied to a low-voltage use case:

• IT solutions facilitate better process scaling, modern data processing and flexible integrations.
• Cloud approaches allow for decentralized, yet centrally orchestrated grid monitoring.

The challenge: Integrating into existing OT structures while still ensuring their security.

A good compromise might be a hybrid model, in which IT-based platforms are made secure, robust, and future-proof with OT integrations. The quick answer "Control system = OT" is not the whole story. Each distribution systems operator needs to make their own decision about what a good compromise between scalability and security looks like.  

It's not (just) about the tools – It's about how they work together 

A conventional low-voltage control system is not enough if it only adds yet another layer of visualization. The key lies in integrated processes. At envelio, we've already embraced this idea with our PlanOps approach: The central challenge in low-voltage grid operations is managing mass processes, which is nearly impossible without a high degree of automation. At the same time, grid operation cannot be viewed as an isolated issue: It is deeply interconnected with the planning process and has a direct influence on how measurement data is used. This can be illustrated by the common practice of having to carry out control measures first in order to prioritize planning measures. This is where PlanOps comes in. It's all about seamlessly integrating processes and consistently linking planning and operation:

• State estimation & grid insights for more transparency: Where are the bottlenecks today and where will they occur tomorrow? Using the Intelligent Grid Platform (IGP), grid operators can carry out criticality analyses to identify weak points in the grid at an early stage.These analyses can be based on smart meter data, feeder measurements and grid models.
• Congestion management in accordance with Section 14a of the German Energy Industry Act (EnWG): Congestions are automatically detected, evaluated and controlled. In this scope, they go through a non-discriminatory congestion resolution process, with sites accessed via the BDEW API.
• Harmonizing processes and ending regulatory ping-pong:   Congestions are often processed according to their source, differentiating between loads (Section 14a EnWG) and generators (Section 9 EEG). In reality, however, the boundaries often blur. An optimized, harmonized management of both processes is not only more efficient, but above all essential.
• Site operability checks & redispatch: Grid operation is more than just monitoring, it requires intelligent coordination.  That is why complex processes, such as the site operability check as defined Section 12 EnWG, can be run digitally: From the testing plan and control commands to coordinating all stakeholders.

Conclusion: This is not just another control system, but the next step in grid operations

The future of grid operations, especially in the low-voltage segment, requires more than just a new tool. In low-voltage grids, conventional control systems fall short, as the challenges of the energy transition, regulatory requirements, and the sheer number of secondary substations can no longer be managed with classic SCADA systems. Instead, what's needed is:

• Intelligent data integration
• A high degree of automation
• Systemic integrations instead of silo solutions
• Process-oriented work instead of a reactive approach

This is where envelio's IGP comes in: A platform approach that goes beyond visualizations and lets you take action. This creates transparency across voltage levels, reliable scaling even with a high number of substations, and automated mapping of processes that are required by regulations.