Millions of Controllable Devices

Learning objectives

By the end of this lesson you should be able to:

Understand why the number of controllable devices connected to electricity networks is rapidly increasing.
Recognise how distributed energy resources differ from traditional generators.
Appreciate the scale of coordination required in modern electricity systems.
Understand why communication and automation are becoming essential.
Recognise the opportunities and challenges created by millions of controllable devices.
Understand why operating the electricity system is increasingly a distributed coordination problem.

Introduction

For most of the twentieth century, electricity systems were controlled by adjusting a relatively small number of large generators.

If demand increased, additional power stations were instructed to generate more electricity.

If demand decreased, generators reduced their output.

Although electricity systems were physically large, the number of controllable assets was relatively small.

Today, that picture is changing dramatically.

Electric vehicles, heat pumps, batteries, rooftop solar systems and smart appliances are creating millions of controllable devices connected throughout electricity networks.

Operating the electricity system is no longer simply about controlling large generators—it is increasingly about coordinating millions of distributed resources.

What is a controllable device?

A controllable device is any piece of equipment whose electricity consumption or production can be adjusted.

Examples include:

battery energy storage systems,
electric vehicle chargers,
heat pumps,
electric water heaters,
air conditioning systems,
commercial refrigeration,
industrial processes,
rooftop solar inverters.

Some devices consume electricity.

Some generate electricity.

Some can do both.

Many can adjust their behaviour automatically.

From hundreds to millions

Traditional electricity systems were designed around relatively few controllable assets.

For example:

large power stations,
major substations,
transmission equipment.

Modern electricity systems may eventually include millions of controllable devices connected to distribution networks.

Each individual device may be relatively small.

Collectively, however, they represent a very significant proportion of the electricity system.

Small devices become large resources

A single electric vehicle has only a modest impact on the electricity system.

However, millions of electric vehicles charging simultaneously could represent many gigawatts of electricity demand.

Similarly:

one home battery stores relatively little energy,
one heat pump consumes relatively little power,
one smart appliance shifts only a small amount of demand.

Taken together, millions of these devices become major system resources.

The electricity system is therefore becoming increasingly decentralised in both generation and control.

Every device has choices

Unlike many traditional electrical loads, modern devices often have flexibility in how they operate.

For example, an electric vehicle may decide:

whether to charge now,
later this evening,
overnight,
or tomorrow morning.

A battery may choose whether to:

charge,
discharge,
remain idle.

A heat pump may decide whether to:

heat immediately,
pre-heat a building,
temporarily reduce consumption.

Each device therefore makes operational decisions within its own physical constraints.

Independent decisions

An important characteristic of distributed energy resources is that they are owned by many different people and organisations.

Each participant may have different objectives.

For example:

A homeowner may wish to minimise electricity bills.

A business may prioritise maintaining production.

A battery operator may seek commercial revenues.

A network operator may wish to avoid local congestion.

These objectives do not always align perfectly.

Coordinating many independent participants therefore becomes a significant systems engineering challenge.

Coordination at scale

The electricity system must continuously balance supply and demand.

Historically, this balance was maintained by controlling relatively few generators.

Increasingly, balancing may involve coordinating:

millions of electric vehicles,
millions of heat pumps,
millions of batteries,
millions of smart appliances,
distributed renewable generation.

The scale of coordination has increased by several orders of magnitude.

Why automation becomes essential

It would clearly be impossible for human operators to manually control millions of individual devices.

Instead, modern electricity systems increasingly rely upon automation.

Devices can respond automatically to:

prices,
control signals,
local measurements,
customer preferences,
contractual arrangements.

Automation allows decisions to be made far more quickly than would be possible through manual operation.

Communication becomes infrastructure

Historically, electricity infrastructure consisted primarily of physical assets such as:

generators,
transformers,
cables,
substations.

Increasingly, communications infrastructure is becoming just as important.

Devices require the ability to:

receive information,
transmit measurements,
communicate operating status,
coordinate actions.

Modern electricity systems therefore combine physical infrastructure with digital communications.

The value of flexibility

Millions of controllable devices provide significant flexibility.

For example:

Electric vehicles may delay charging until renewable generation is abundant.

Home batteries may store excess solar generation during the day.

Commercial buildings may reduce electricity consumption during periods of network congestion.

This flexibility can improve:

renewable energy utilisation,
network efficiency,
system reliability,
consumer choice.

Properly coordinated, distributed flexibility becomes an important system resource.

Complexity grows rapidly

Although each individual device is relatively simple, the overall system becomes increasingly complex.

Consider a neighbourhood containing:

500 homes,
300 electric vehicles,
250 rooftop solar systems,
200 batteries,
400 heat pumps.

Each device may have:

different operating schedules,
different customer preferences,
different technical capabilities,
different communication links.

The number of possible interactions becomes extremely large.

This makes coordination considerably more challenging than operating a traditional electricity system.

From engineering to cyber-physical systems

The electricity system is therefore evolving from a purely physical network into a cyber-physical system.

The physical layer includes:

generators,
cables,
transformers,
batteries,
electric vehicles.

The digital layer includes:

communications,
software,
optimisation,
control algorithms,
forecasting,
automation.

Both layers must work together to operate the electricity system safely and efficiently.

Opportunities

Millions of controllable devices create many opportunities.

These include:

greater flexibility,
improved renewable integration,
reduced operating costs,
increased consumer participation,
better utilisation of existing infrastructure,
new electricity services.

Distributed resources can contribute to system operation in ways that were previously impossible.

Challenges

At the same time, coordinating millions of devices introduces new challenges.

These include:

communications,
cybersecurity,
interoperability,
scalability,
local network constraints,
maintaining system stability,
ensuring fairness between participants.

Successfully addressing these challenges is becoming one of the defining problems of modern electricity systems.

A shift in thinking

Perhaps the most important change is conceptual.

Traditional electricity systems were largely concerned with controlling generation.

Modern electricity systems increasingly involve coordinating behaviour across millions of distributed resources.

The objective is no longer simply deciding which power stations should operate.

It is increasingly about orchestrating countless small decisions across the electricity network while maintaining overall system security.

A key insight

Modern electricity systems are rapidly evolving from networks containing hundreds of controllable assets to systems containing millions.

Although each individual device is relatively small, together they represent a substantial source of generation, storage and flexible demand.

Coordinating these distributed resources safely and efficiently requires new approaches to communication, automation and system operation.

Key takeaways

Millions of controllable devices are being connected to electricity networks.
Distributed energy resources include batteries, electric vehicles, heat pumps and smart appliances.
Individually small devices become significant system resources when considered collectively.
Automation is essential for coordinating large numbers of distributed devices.
Modern electricity systems increasingly depend upon digital communications as well as physical infrastructure.
Distributed flexibility creates significant opportunities for improving system efficiency and reliability.
Coordinating millions of independent participants is becoming one of the central challenges of electricity system operation.

Looking ahead

Coordinating millions of devices requires one essential ingredient: visibility.

Before operators can manage distributed resources effectively, they must understand what is happening throughout the electricity network.

In the next lesson, we examine the low-voltage observability problem, and explore why much of today's electricity system remains surprisingly difficult to observe in real time.