Cortexo case study: Emergency Load Shedding Event

Emergency Load Shedding in Action: Evnex and Cortexo Test Flexible EV Charging

A simulated emergency test between Evnex and Cortexo has shown how smart EV charging could give New Zealand another way to respond when the electricity system is under pressure.

The emergency event was simulated. It was generated via FlexViz’s Transpower connection point, replicating how an emergency signal from Transpower’s FlexPoint platform would appear. Cortexo and Transpower previously tested this connection through the FlexTalk project.

FlexViz is connected to multiple flexibility service providers. When an event occurs, it can relay a notice to participating providers whose flexible assets are relevant to the affected part of the electricity network. 

In this case, Evnex temporarily reduced charging load across participating chargers in its New Zealand network. The response occurred over a few seconds before full-speed charging resumed a few minutes later.

This was a controlled test, not a live emergency activation by Transpower. But it demonstrated a real capability: an end-to-end signal can move from Transpower’s platform through FlexViz to a connected flexibility provider, triggering a measured demand response.

A controlled response at scale

Evnex is a Christchurch-based smart EV charging provider with chargers operating across New Zealand and Australia.

Evnex is connected to FlexViz, where its available charging flexibility can be made visible. FlexViz is also connected to Transpower’s FlexPoint platform, allowing a grid-event signal to be relayed to participating flexibility service providers.

In this test, that signal was passed to Evnex, which reduced charging demand across participating chargers in its network.

The result was a visible drop in load of around 3MW across roughly 1,000 chargers.

The significance is not simply the number of chargers involved. It is that a large, distributed fleet of EV chargers received one signal and responded in a coordinated way.

Cortexo’s Managing Director, Terry Paddy says, “It shows that we’re not just talking about what flexibility can do. We actually did it.”

This is the next step beyond visibility. FlexViz helps show where flexibility exists. This test showed that connected flexibility can also respond when needed.

Why security of supply matters

On 9 May 2024, Transpower warned of a risk that there would not be enough generation and reserve offers to meet demand during the following morning peak. The situation was managed through increased generation, industrial demand response and public efforts to reduce electricity use, avoiding a grid emergency.

The event showed that reducing demand can help when the system is tight. It also relied on people seeing a message, understanding the request and changing their behaviour at short notice.

Connected flexibility gives the system another option. Instead of relying only on public conservation appeals, agreed technologies can respond to a signal in a managed way.

A connected pathway between Transpower, FlexViz and flexibility service providers could give the system a more coordinated way to communicate with participating flexible assets, alongside public conservation appeals and other security-of-supply measures.

Flexible demand is one tool in the toolbox

Demand flexibility does not replace new generation, storage, operating reserves or network investment. It adds another practical option when supply is constrained or demand is high.

Terry notes, “This is one of the tools in the toolbox.”

Smart EV charging is one source of flexible demand. Others include hot-water ripple control, home and commercial batteries, building heating and cooling, refrigeration, pumping and selected industrial processes.

Not every asset will suit every event. Some loads cannot be interrupted, while others can only shift for a short period. But when flexible assets are connected and coordinated, their combined capability can become meaningful.

What Evnex and Cortexo tested

The test simulated the end-to-end pathway that could be used during a grid emergency:

1. A simulated event signal was generated at the Transpower connection point inside FlexViz, as if it had been received from Transpower’s FlexPoint platform.
2. FlexViz relayed the event to Evnex as a connected flexibility service provider.
3. Evnex temporarily reduced charging demand across participating chargers.
4. The resulting load response was visible through FlexViz.
5. Charging returned to normal shortly afterwards.

The event was simulated. The integration pathway was real.

It did not represent a live emergency activation by Transpower or create a new market arrangement. Commercial agreements, customer settings and participation rules still need to be in place before flexibility can be called on at scale.

But the technical capability is now clear.

A distributed and connected charging fleet can receive a signal, reduce demand and resume normal charging in a coordinated way.

What the test proved

The Evnex and Cortexo test demonstrated several important things.

First, distributed EV charging can respond at scale. The chargers involved were not located in a single building or controlled by a single physical switch. They were spread across a connected fleet.

Second, demand can be shifted rather than simply removed. In many cases, EV charging does not need to happen at one precise moment. A short delay can reduce pressure during a critical period while still allowing drivers to charge.

Third, the response can be measured. This matters because networks, Transpower and future market participants need confidence in what flexibility is available, where it is located and how it may respond.

The test moves the discussion beyond theory.

It gives the sector a practical example of a flexibility supplier responding to a signal through a shared platform.

What this means for New Zealand

New Zealand’s electricity system is changing. EVs, batteries, solar, smart heating and electrified industry will all increase demand.

They can also become part of the response.

Flexible demand gives the system more options during tight supply conditions, national peak-demand events and local network constraints. It can help shift electricity use away from the moments when it is most needed, while making better use of available generation and infrastructure.

The opportunity is not limited to emergency events. It is about building a system that can respond more effectively as electricity demand grows and becomes more variable.

Everyday value beyond emergencies

The emergency use case is the most visible. The everyday value may be even greater.

For consumers, smart charging and other flexible technologies can shift electricity use without requiring constant manual action. 

For businesses, controllable assets may help manage peak demand while creating future opportunities to participate in flexibility programmes.

For flexibility suppliers, connected assets can become visible capacity that networks and other users can assess.

For EDBs and Transpower, flexibility can help manage local constraints, understand available demand response and inform investment decisions.

The point is not to replace infrastructure. It is to give the system more choices before infrastructure is the only answer.

The next step: connect more flexibility

The Evnex test showed that flexible EV charging can respond to a signal quickly and in a coordinated way.

The next step is to connect more flexible assets, make their capability visible and establish the commercial arrangements that enable networks and system operators to use them.

As Terry says, “The more people we get on FlexViz, the more capability we can offer to Transpower.”

The technology is already here. The task now is to make more of that flexibility visible, trusted and ready to use.

For EDBs and Transpower

See the flexibility available through FlexViz and discuss how it could support local constraints, peak demand and events affecting security of supply.

For flexibility suppliers

Connect EV charging, batteries, smart buildings or controllable load to FlexViz, making available flexibility visible to networks and future market participants.

Terry Paddy
Managing Director, Cortexo Limited