Stage 0 summary. Foundations

Electricity is the flow of electrons through a conductor, and voltage is the push that makes them flow. Conductors such as copper and aluminium carry the flow, insulators such as rubber and plastic contain it. Generation creates the push. Most power stations spin a magnet inside coils of wire, whether steam from gas, coal, or a nuclear reaction drives the turbine or the wind pushes the blades directly, while solar panels use sunlight to knock electrons loose inside semiconductors with no spinning parts at all. Once the electrons are moving on the network they are all the same, whatever the source. What differs between sources is reliability, start-up speed, and carbon, not the electricity they make.

Transmission is the motorway. It carries power across the country at 275,000 or 400,000 volts because the energy lost as heat grows with the square of the current, so delivering the same power at double the voltage halves the current and cuts the loss to a quarter. Distribution is the local road system. The voltage steps down through substations and their transformers, to 132,000 volts at a grid supply point, 33,000 volts on the primary network, 11,000 volts on the secondary network, and 230 volts at the wall socket.

Different organisations run different parts of the chain. Separate transmission owners own and maintain the high-voltage wires. The National Energy System Operator, NESO, which replaced National Grid ESO in 2024, owns none of it but operates the system, keeping the amount generated matched to the amount used moment by moment. In England, Scotland, and Wales, 14 licensed distribution network operators manage the local networks, each responsible for a geographical area. The company this course follows, London Grid Distribution, is a fictional DNO managing Greater London's network.

Grid electricity is alternating current. It reverses direction 50 times a second, and every generator on the network spins in step with that 50 hertz rhythm. Frequency is the grid's heartbeat. At every moment the total generated must match the total used, and when a station trips or demand spikes the frequency starts to drift. If it falls too far, automatic protection systems disconnect parts of the network. That is load shedding, a deliberate, controlled sacrifice of some customers to save the rest of the system from a total blackout.

The stage's opening case shows the stakes. Just before 5pm on Friday 9 August 2019, a lightning strike hit a transmission circuit in Cambridgeshire, and within seconds the gas-fired power station at Little Barford and the Hornsea One offshore wind farm disconnected. Neither loss alone would have caused a major problem, but together they took out more power than the backup systems could replace quickly enough. Frequency dropped sharply, protection acted, and over one million homes and businesses lost power. Trains stopped mid-journey, hospitals switched to emergency generators, and Newcastle Airport closed temporarily.

The official investigation found the protection systems had worked as designed. The gap was coordination. Generators, the transmission operator, and the distribution networks each had their own protection rules, and those rules did not work together fast enough to contain the problem. Different companies own different parts of the system, with different computer systems, data formats, and decision processes, so the blackout is an information, communication, and organisational problem as much as an engineering one. That is why a course about architecture starts here.

London Grid Distribution is invented for this course, and deliberately so. It is modelled on a mid-sized DNO responsible for the electricity distribution network across Greater London, managing roughly 36,000 kilometres of underground cables and 77 primary substations, serving approximately 2.3 million homes and businesses, and employing around 4,000 people. No real company's internal details, commercial information, or staff are used, so when the course says the control room does something, that is a teaching scenario, not a claim about a real operator.

Its core job is keeping electricity flowing safely and reliably, 24 hours a day, 365 days a year. That unpacks into monitoring the network from a control room that must know about a fault within seconds, fixing faults that in London usually sit underground and are slower to reach than overhead lines, connecting new customers, maintaining and replacing equipment before it fails, and planning years ahead for changing demand. The people carrying that work range from control room operators, the air traffic controllers of the network, to field engineers, connections engineers, data analysts, IT and operational technology teams, and the regulation and compliance staff who answer to Ofgem.

Five systems carry the work. SCADA is the heart monitor, collecting real-time readings from the network and sending commands back to remote equipment. DMS is the satnav, modelling switching options and helping operators reroute power during a fault. GIS is the map, the single source of truth for where every cable, substation, and connection point physically sits. OMS is the fault tracker, following each outage from the first customer call through to restoration. ERP is the business backbone for finance, procurement, HR, payroll, and asset management. They were built or bought at different times, by different teams, from different vendors, and getting them to share data reliably is one of the hardest problems the company faces.

Distribution was built as a one-way system, from large generators through the network to consumers, and that model is breaking down. Clean Power 2030, the government commitment to decarbonise the electricity system by 2030, brings far more wind and solar and far less gas, and renewables are less predictable, which makes balancing harder. Rooftop solar pushes surplus power back into a network whose equipment, protection systems, and monitoring tools all assumed one-way flow. And the electrification of heat and transport sharply raises demand, where a single fast charger for an electric vehicle can draw as much power as an entire house.

The connections queue makes the pressure concrete. By late 2024, over 700 gigawatts of projects were waiting to connect to a system whose peak demand is roughly 50 gigawatts, a queue more than fourteen times the size of the system it was trying to join, and many queued projects were speculative placeholders blocking genuine ones. NESO launched a connections reform programme to redesign the queue from scratch, and for every distribution company that reform means changed business processes, updated computer systems, retrained staff, and renegotiated agreements, all at once.

The correction the module insists on is that more cables and substations are part of the answer but not all of it. The transition also needs smarter monitoring for two-way flow, processes that handle thousands of small connection requests instead of a few large ones, data systems that share information in real time, and new skills across the workforce. It is a transformation of the entire organisation, not just the network, and cross-cutting change of exactly that kind is what enterprise architecture exists to coordinate.

When teams each buy the best tool for their own job and nobody checks how the tools connect, the failures are predictable. Islands of information that only manual spreadsheet work can bridge. Duplicated spend on capabilities the company only needed once. Decisions made on incomplete data, or delayed for weeks while someone assembles a report by hand. Change that grows slower and riskier because nobody knows what depends on what. And for a regulated company, trouble with Ofgem when it cannot produce accurate figures for network condition or for customer interruptions and customer minutes lost, the measures the regulator uses to reward and penalise distribution operators.

The running scenario makes it concrete. Over three years, five London Grid departments each bought a good system, a customer portal, a monitoring upgrade, a condition-monitoring platform, an analytics tool, and a replacement ERP, spending over eight million pounds in total. When the new chief executive asked how many customers are affected by the ten worst-performing circuits and what the investment plan is to fix them, the answer took six weeks, because the data sat in five systems that could not share it and that used different codes for the same substations. The problem was not the systems. Nobody had asked how they would work together before buying them.

Architecture is the discipline that asks that question early. Not hundreds of diagrams, but a light set of agreed decisions and four checks a change should clear before it goes live. Is the cross-domain scope agreed, is the source of truth confirmed, is the integration contract agreed up front, and is the decision logged so an audit can trace it later. Applied to a whole organisation this becomes enterprise architecture, which looks at business, data and information, applications, and technology together, and Stage 1 introduces that discipline properly through TOGAF.

London Grid Distribution exists so the course can explore realistic scenarios without pretending to know the inside of any actual organisation. The primers give it everything the later stages need. A physical network of roughly 36,000 kilometres of underground cable and 77 primary substations serving about 2.3 million homes and businesses. A working day of monitoring, fault repair, connections, maintenance, and forward planning carried by around 4,000 people. Five named systems that struggle to share data. And a first failure, the eight million pounds spent on five systems that could not answer the chief executive's question, which the rest of the course keeps returning to and answering properly.

Hold the shape of what comes next. Stage 1 introduces enterprise architecture and TOGAF with London Grid as the company whose transformation the course follows. Its executive team then commissions a transformation programme, its business processes are analysed and redesigned, its data flows and system landscape get a target state, its infrastructure and cyber security posture are assessed, it builds a migration roadmap, it establishes an Architecture Board, and the capstone reviews the whole architecture. Every concept from here on lands as a London Grid scenario before it is applied more broadly.