Resilient Electric Vehicle Charging

Decarbonisation of the economy will drive a transformation of the GB power system beyond that already caused by the growth in renewable energy.

By around 2040:

  • Peak demand is forecast to increase by 50% in all Future Energy Scenarios (FES’)
  • Demand for energy will at least double over the same time period in three out of four scenarios.

Much of this new demand will come from “smart loads”, controlled by software systems, whose behaviour will be very different to traditional system demand. Just as inverter-connected generation has brought new challenges for grid operation, the presence of these new types of smart load will introduce system risks that have not been seen before.

Phase 1 of Project REV has explored what these risks might be for one rapidly growing group of technologies, Electric Vehicle Charging (EVC) and Vehicle-to-Grid generation (V2G).

Six ways in which Electric Vehicle chargers present a risk to grid security

1. Step: Too many chargers switching on or off at the same moment

  • Time of use tariff step (real or accidental)
  • Failure of fault ride-through
  • Software error (EV vendor, OSR aggregator, etc..)
  • Malicious actors

2. Ramp: Too many chargers switching on or off within a few minute

  • Software-controlled load pick-up
  • Cascade tripping for high or low volts
  • “Panic charging”

3. Oscillations: A group of chargers switching on and off

  • Control system interactions
  • Malicious actors

4, Degraded stability: Increases risk of post-fault collapse

  • Constant Power loads will impact voltage, transient and oscillatory stability of the system
  • V2G lacks inertia and PSS

5. Demand control: Defences are eroded

  • Constant Power loads will not respond to voltage reduction
  • V2G will offset LFDD operation

6. Restoration: Erratic behaviour after restart will hinder the process of restoration

  • Load return depends on restart of hardware, software and communication systems
  • Risk of tripping on high or low volts during restoration
  • Risk of transformer overloads.

Key points

Mass adoption of EVs will bring a range of new system operability challenges for grid operators, not just the increase in energy demand. Urgent action is needed on regulation, system and market design to successfully mitigate risk from EV charging and V2G, and to unlock their benefits.

Common-mode behaviour reducing load diversity

The 2021 Future Energy Scenarios’ envisage between 12 and 26 million EVs in service in 2035. With typical 7kW domestic chargers, just 2% of these chargers switching on at the same time would generate a load step of between 1.7 and 3.6 GW, significantly more severe than the August 2019 loss of supply incident2.

Smart charging control systems could cause such synchronised action by responding to Time-of-Use tariffs, by accident or through malicious intent.

Randomisation helps soften load steps, but the volume of price-driven demand could still result in rapid multi-GW ramps.

Design for customer needs, not grid requirements

 The focus of EV charging / V2G technology design is customer needs and cost; it will do “just enough” to meet grid-related regulations such as fault ride­ through and high/low voltage withstand. Present regulations were not designed for a zero-carbon future so will need revision.

Charging speed is maximised by constant power I current operation, with no load response to voltage or frequency excursions. This will negatively impact system stability.

Dependence on an interconnected software ecosystem

Smart charging depends on multiple software systems running on multiple hardware platforms from multiple vendors connected by multiple communication systems.

This complexity creates the risk of conflicting controls and unforeseen behaviour under normal and abnormal conditions (loss of comms or restoration after loss of power), and a high risk of cyber compromise.

An urgent decarbonisation agenda

It is vital that regulations are updated quickly to manage these risks while giving the industry time for implementation so that we avoid the need for a significant retrospective program (such as ALoMCP3);

NGESO should consider whether ToU tariffs, in the present half-hour market, will be viable when up to half of system demand is price-responsive.

Exploiting the full capability of smart EV charging Demand Side Response (DSR) flexibility and V2G can support decarbonization targets, reducing operating costs and enhancing system resilience.

  • We need to prepare now for the increase in demand in the 2030s from the forecast moss adoption of EVs and  other low carbon technologies.
  • Mass adoption of EVs will bring a range of new system operability challenges for grid operators, not just the increase in energy demand.

Read the Report

Resilient Electric Vehicle Charging

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Project REV: The Impact of Electric Vehicle Charging on Grid Stability | Launch Event with Sygensys

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The impact of Electric Vehicle charging on grid short term frequency and voltage stability, and cascade fault prevention and recovery.


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