Energy Storage

You are currently browsing the archive for the Energy Storage category.

batteryMuch of our research within our lab has a focus on the low-voltage distribution network, the copper that runs through towns and cities across the UK and delivers energy into businesses and peoples homes. Along with other energy stakeholders talking about the use of energy storage, the distribution network operators (DNOs) are also considering how energy storage could be used to support the network at the street-level. DNOs are primarily concerned with keeping the lights on whilst avoiding exceeding operational constraints on voltage and current within their networks. If the volts vary, lights flicker; if the current gets too high, things start melting…

The impact that energy storage systems have on the voltage and current along a electricity feeder down a typical street is not immediately obvious and we have been running some simulations using an open source package OpenDSS to find out what might happen. In our relatively simple early tests, it appears that the location of the energy storage device has a big impact on the subsequent improvement of voltage and current along the feeder. For example, if you install a battery on a feeder and give it the simple instruction to charge in the middle of the night and discharge during the evening when everyone is at home cooking and watching TV with the lights on, then there is a pretty good chance you are going to reduce the peak energy that must be supplied from the grid to that feeder during that evening period –  it comes from the battery instead. Great. However, if what you are really worried about is whether the section of cable half-way down the feeder is going to fail because the houses connected just beyond that point have very high demand, then the battery ideally needs to go just beyond that point in the feeder… If you put it at the beginning of the feeder near the substation then you will reduce the power flow through the substation at peak time, but the same currents will still flow down the rest of the feeder to those houses with high demand and your high-risk section of cable will still see the same current and may fail.

Two things occur to me:

  1. In some contexts worrying about peak power through a LV substation, and increasing the associated headroom, is the right thing to do. However, from the point of view of the distribution network, and when primarily worried about voltage and current violations along a feeder, then (perhaps no surprise) it is important to think about the actual voltages and currents.
  2. The location of an energy storage system on a feeder, and in particular the location with respect to energy users with high demand or distributed generation, has a significant impact on the ability of that storage device to help the network.