Inside REGIDESO: How Burundi's National Power Grid Actually Works

A Quick Context: What is REGIDESO?

REGIDESO — the Régie de Production et de Distribution d'Eau et d'Électricité du Burundi — is the state-owned company managing both water supply and electricity across Burundi. Founded in 1962 during the Belgian colonial administration, it is headquartered in Bujumbura on Avenue de la Révolution.

The company operates under a Director General and five major divisions: Human Resources, Commercial, Administrative & Financial, Water, and Electricity. The Electricity division itself splits into Exploitation, Equipment, Production, and Maintenance. My internship took place across all these branches, supervised by the Head of Maintenance, Françoise N.

Burundi runs almost exclusively on renewable energy. The country has 8 to 10 hydroelectric power plants for a total installed capacity of over 178 MW, representing roughly 80% of total energy production. The biggest plants are Jiji (32.5 MW), Mulembwe (17 MW), Rwegura (18 MW), Kabu 16 (20 MW), and Ruzibazi (15 MW). Two thermal plants of 5 MW and 30 MW are currently out of service. A few solar installations also inject into the grid, notably at Mubuga in Gitega province.

Step 1 — Generation: Inside the Ruzibazi Plant

The first major visit of the internship was to the Ruzibazi hydroelectric plant, located near Rumonge on the southern coast of Burundi. Construction began in 2018 by JWHC (Sinohydro) and was completed in 2022. With three 5 MW alternators, Ruzibazi serves as a base-load plant for the Burundian grid.

In practice, the plant only runs two of its three alternators to preserve the river's ecological balance, and those alternators operate at roughly 80% of their rated power to extend equipment lifespan. At noon, during a medium-consumption period, both units were producing 4.7 MW each.

Three Zones to Understand Any Hydro Plant

The plant is divided into three distinct zones:

• Upper building: The reservoir and the manual valve control room. Personnel maintain a permanent presence here. The spherical valve — the master on/off switch of the whole installation — sits just after the penstock. Normal operating conditions require a flow of 1.64 m³/s and a pressure of 3.55–3.6 MPa upstream and downstream of the valve.
• Lower building: The main control room, the penstock inlet, auxiliary power supplies, UPS systems, and the alternators themselves. Everything in the plant is ultimately controlled from here.
• Transformer zone: A classic outdoor substation with a 6.3/110 kV transformer for transmission towards Bujumbura and a three-winding 6.3/110/30 kV transformer to feed nearby zones directly in 30 kV — avoiding waste and preventing overload.

What Made This Visit Technically Interesting

The speed governor was the most remarkable piece of automation on site. Controlling the rotation speed of the alternator — which is directly tied to grid frequency — it does not simply run a closed-loop PID on a hydraulic system. It must also anticipate the actions of other plants on the grid. If the network is at 49.7 Hz, this plant cannot act as if it were the only one responsible for bringing frequency back to 50 Hz. Other plants are simultaneously adjusting their output, so the proportional action here is deliberately scaled down.

Redundancy was everywhere. Two 6.3 kV busbars split between the alternators, two excitation transformers, two communication protocols running in parallel (IEC 104 over TCP/IP for SCADA and IEC 60870-5-101 for legacy telecom), plus DC battery banks backing up auxiliaries for at least 24 hours. For pressure measurement at the spherical valve alone: an industrial piezoresistive transmitter in 4–20 mA, a second sensor using a different technology, and an analogue pressure gauge on the wall. Industrial systems require you to manage information from multiple sources, sometimes old and new simultaneously.

Step 2 — National Dispatching: The Brain of the Grid

If the hydroelectric plants are the heart of Burundi's grid, the national dispatching centre — known internally as RN1, located in the Kamenge neighbourhood of Bujumbura — is its brain. From the outside it looks like another substation. Inside, it is the most technically advanced site in the entire network.

The dispatching centre is split into several areas: the outdoor substation, an administrative wing, a relay room, and the main control room. Every substation and power plant in the country sends its data here.

How the Control Room Works Day-to-Day

Operators monitor the state of the entire national grid through the SCADA system, running on Zenon software. Every switch, breaker, and measurement point in the connected substations can be seen and operated from here. If a substation plans maintenance, it must notify the control room first, which will check whether any load redistribution is needed.

Grid stability is maintained within tight bounds: voltage must stay in the [105–120] kV range on the 110 kV network, and frequency must stay in [49.5–50.5] Hz. A deviation outside these limits triggers a general trip. To prevent that from happening, the dispatching centre manages a procedure called délestage — load shedding.

Load Shedding and the Ring Network

Load shedding works by frequency. If production falls short of demand, the grid frequency drops — 49.8, 49.7 Hz and further. Rather than letting it reach the trip threshold, pre-defined load stages are activated: certain feeders are disconnected, cutting power to specific neighbourhoods in rotation until production and demand are balanced again.

The 30 kV ring network (bouclage) is the other key tool. Substations are interconnected in a closed loop. When a fault occurs or a line goes down for maintenance, power can be re-routed through the ring so most customers see no interruption — or at worst, a very brief one. In a total blackout, it is from here that restoration starts: plants are brought online one at a time, matched against incrementally increasing loads, using automatic synchronoscopes.

One note on the grid's future: the dispatching centre is technically ready to evolve. But it currently lacks reactive power compensation equipment (no capacitor banks), and only a handful of sites are fully connected to SCADA. Most substations still rely on circuit-carrier telecom and phone calls to coordinate.

Step 3 — HV/MV Substations: The Distribution Nodes

The second week was dedicated to visiting Bujumbura's six main distribution substations: Poste Nord, Poste Sud (Kanyosha), Poste Ozone (Kiriri), Poste SNEL (industrial zone), Poste RN1 (Kamenge), and Poste Rubirizi. Their placement is deliberately circular around the capital to balance loads, distribute feeders evenly, and form the physical nodes of the ring network.

The Standard Anatomy of a Substation

Every substation follows a recognizable logic from incoming line to outgoing feeder:

1. HV line arrival — aerial or mixed aerial/underground, with ceramic, glass, or polymer insulators and lightning rods covering a 500 m to 1 km radius.
2. Disconnector — provides visible galvanic isolation so maintenance work can be done safely on the isolated side. Always operated without load.
3. HV outdoor circuit breaker — the protection upstream of the power transformer. Uses SF6 gas; its pressure level must be monitored regularly. Always operated under load.
4. Power transformer — the central element, typically above 10 MVA apparent power. Configurations seen on site include 110/30 kV, 30/6.6 kV, 30/0.4 kV, and 6.3/110 kV. Some are three-winding units.
5. MV busbar — the copper bar on the secondary side of the transformer where all outgoing feeder cables connect.
6. Indoor circuit breaker cells — one per feeder, vacuum type (no SF6). Each cell carries sensors for active, reactive, and apparent power, plus voltage and current per phase. When a fault occurs, the cell also attempts to indicate its location — though in practice this indication is often unreliable, and operators note readings from the screen by hand in a paper logbook.
7. Auxiliaries — surge arresters, circuit-carrier communication units, current and voltage transformers, an auxiliary transformer, rectifiers, and battery banks for backup power to all low-voltage control circuits.

Three Substations Worth a Closer Look

Poste SNEL is the only entry point for 70 kV lines in the country, coming from the DRC. It technically belongs to the DRC's national utility (SNEL) but has been maintained by REGIDESO due to the geopolitical situation at the time of writing. Some cells date from 1958 and are no longer functional. During my visit, an accident had brought down HV line poles, the protection relays had tripped the breakers on both sides, and the power flow was reversed — the transformers that normally step voltage down were being fed from the secondary side by Burundian production.

Poste Ozone has two power transformers fed from two different sources: Mugere hydroelectric plant on one 30/6.6 kV busbar and the RN1 dispatching centre on another. A closed-loop coupling connects them via a busbar tie disconnector, so both sources are always simultaneously active. The tie disconnector can be opened to isolate either source if one develops a fault.

Poste Nord serves the industrial zone and the international airport — both high-priority loads during load shedding. On the day I arrived, a circuit breaker had failed. The team improvised a temporary fix: a breaker assigned to a secondary feeder was re-deployed to protect a critical infrastructure circuit. The risk was real — a fault on the secondary feeder would now also cut the priority load. The circuits were theoretically mounted in parallel with disconnectors to isolate any fault, but the temporary constraint made the standard procedure harder to execute immediately. What I observed was less the technical solution and more the engineering judgment required to manage it: knowing the exact load on each circuit, assessing the acceptable risk window, and communicating clearly with the dispatching centre.

Interlude — The Transformer Workshop

The first week of the internship took place not in a substation but in the transformer repair workshop, located near the main garage in the industrial zone. This is where damaged distribution transformers from across the network are brought, diagnosed, and rebuilt.

The workflow for a single transformer — say, a 160 kVA 30/0.4 kV unit — goes through four stages before it goes back into service:

1. Continuity test — using a Megger MIT515, measure continuity across every winding. If more than two windings are faulty, the unit is set aside. If only one MV/LV pair is faulty, assess whether the winding can be physically repaired or replaced from a donor unit with compatible characteristics.
2. Insulation test — still with the Megger, measure insulation resistance between each phase and earth (at 5 kV), and between the MV and LV sides. A reading above 400 MΩ is preferred; the typical healthy value is around 1400 MΩ. If values are too low, remove the core and put it in the oven at 100°C (removing all plastic components first). Then re-test.
3. Oil regeneration — circulate the existing oil (combined with fresh stock from the workshop) through the regenerator machine in a closed loop for several hours to restore its dielectric properties.
4. Turns ratio test — feed 0.4 kV into the primary and verify that the measured secondary voltage is consistent and equal across all three phases.

The whole process can take up to two days per transformer. The workshop technicians do this work with limited tooling: lifting is done entirely by hand, there is no in-house access to 30 kV for a more accurate turns ratio test, and the Megger itself was overdue for replacement. The workshop could process significantly more units with better equipment and more space.

Step 4 — MV/LV Lines: Getting Power to the Neighbourhoods

The third week moved to the field with the Equipment/Works division, responsible for building and extending the distribution network. Burundi has committed to electrifying 1,520 localities by 2040, and this team is at the sharp end of that target.

How a New Line Gets Built

Before a single pole is planted, a topographic survey maps everything: existing infrastructure, the route of the new line, the locations of future earthing points. That document becomes the reference for the whole project team.

Poles can be wood, concrete, or metal. Wood is still dominant in Burundi, but new extensions increasingly use concrete or steel. In MV lines there are three pole types: alignment poles (straight sections, spaced 100 m apart), angle poles (direction changes, require reinforced stays), and dead-end/anchor poles (every 8 to 10 poles, and at the end of a section — these are also where distribution transformers are mounted).

For BT pre-assembled cable, the standard cross-sections are 3×35, 3×50, or 3×70 mm² for phase conductors plus a 54.6 mm² neutral (sized large both for mechanical tension support and to handle unbalance and harmonic return currents — per NF C 33-209) and a 16 mm² street-lighting conductor.

The insulator chain on each pole consists of an eyelet, two or three discs (two for sub-10 kV, three for sub-30 kV lines), a ball-socket fitting, and a clamp (anchor, dead-end, angle, or suspension type depending on the pole). Earthing points must appear every 400 m with a resistance of 5–10 Ω.

Pulling a BT Line in the Field

I followed a BT line extension in the northern district of Bujumbura: an existing wooden pole section being extended with new concrete poles. All material was on site. The process runs in four steps:

1. Unroll the pre-assembled cable on the ground along its future path, with about ten extra metres for sag.
2. Install pulleys on all poles except the first (where an anchor clamp goes instead). Climb concrete poles with a ladder, wooden poles with climbing irons and a body belt.
3. Thread the rope through all the pulleys and pull the cable tight — tension judged entirely by the experienced operator's eye.
4. Fix the cable at the far end with an anchor clamp, and connect it to the existing BT cable at the first pole using an insulation-piercing connector that ensures electrical contact without stripping insulation.

Five to six technicians and one engineer for a single 100-metre section, a full working day. It works, but it is not fast.

Step 5 — Underground Cable Fault Detection

During week four, a fault appeared in an MV cable supplying a priority zone of the capital. The ring network kept the area supplied through a backup path, but the overloaded backup line had to be relieved quickly, so the faulted cable needed to be repaired.

The standard procedure: protection relays identify the faulted section and trip only the breakers bracketing it. The relay data gives an approximate fault location on the cable. A Megger fault-location vehicle drives to the site, pinpoints the exact location using time-domain reflectometry, then the team opens the breakers on both sides, earths the cable, and digs.

The repair itself is a splice: cut the damaged section, insert a short replacement length, join the two ends with crimp sleeves and heat-shrink insulation.

In practice, that day, the relay location data was imprecise and the Megger vehicle was temporarily unavailable for maintenance. The fallback: teams split up across the suspected stretch, applied test voltages, listened for the discharge arc, and dug wherever there was a suspicion. Cut the section, bridge the gap with a temporary conductor, test. If it did not work, repeat. Each temporary splice is a potential future fault point. This kind of improvisation is not a failure of the team — they are experienced and resourceful — but it is a symptom of maintenance being overwhelmingly corrective rather than predictive.

Step 6 — The Last Mile: Getting Power to the Customer

In Bujumbura, each neighbourhood has a distribution transformer and a BT panel at its base. Every subscriber has their own meter, rechargeable by mobile payment or at a point of sale. The connection from the pole to the meter is handled by a separate electrical contractor, and REGIDESO verifies it after the fact.

For industrial customers, the process is different: the company submits its project to REGIDESO, which conducts a feasibility study and dimensioning exercise — circuit breaker cells, step-down transformer, MV feeder specification — as described in the context of Poste Nord.

One critical gap exists here: when a new residential subscriber is connected, there is no systematic verification of phase balance. The electrician connects to whichever phase is most accessible on the pole. Over time, this accumulates into severe phase unbalance at the transformer level. This is one of the main causes of premature transformer failure — and it is the subject of the companion article on load balancing solutions.

What I Took Away

Six weeks inside REGIDESO gave me a ground-level view of what running a national utility looks like when resources are tight, the grid is expanding fast, and the infrastructure ranges from 1958 circuit breakers to a modern SCADA control room.

The technical depth is real. The engineers I worked alongside understand their systems thoroughly and solve genuinely complex problems with limited tools. What struck me most was not the equipment gaps but the maintenance culture gap — the distance between what corrective maintenance requires in daily firefighting and what predictive maintenance could free up in engineering capacity and equipment life.

Burundi has ambitious electrification targets for 2040. Whether those targets translate into a stable, reliable grid will depend less on whether new equipment gets installed and more on whether the organisation builds the processes and technical culture to maintain it. The hardware is necessary but not sufficient. That observation shaped the direction of the technical project I developed in parallel — three concrete solutions to the phase unbalance problem, modelled and costed from a field perspective.