3. What is Ripple Control???
• What is RC, Is it PLC?
– Yes, it is a power line communication. The RC is a
communication method used extensively by electrical
distributors to turn on and off loads such as off-peak hot water
systems and street lighting. This works by superimposing a
coded control signal on to the normal 50Hz voltage waveform.
This allows for one way communication with loads without
additional communication infrastructure.
• Why we use RC even if we have Smart metering communication?
– Still at some location LC system is based on RC and they have
not rolled out to 3G or RF communications.
– RCR provide greater control of poles and wire over 3G & RF.
– Ripple control switching via RC is a much faster LC system than
can be supplied by 3G comms, very important in an emergency
LC system. There will probably be other reasons that customers
want to continue with Ripple control.
4. Grid Sensing???
• What is mean by grid sensing? And why it is used?
– Grid sensing is a integration of wireless/wired networks with
grid computing concepts to enable real time sensor data
collection and sharing computational and storage resources
for sensor data processing & management
– It is used for monitoring, control, measurement and fault
diagnosis in various domain in grid network. Like
» Economical solution for monitoring the behaviour of
renewable energy resources.
» Effective & prominent solution for consumer in home
automation to decide the time of use and rates of
energy usages.
» Real time monitoring of overhead transmission lines,
underground cable network, substations and
distribution transformers to prevent power failures due
to equipment breakdown or malicious attacks.
5. Load Management through Ripple
• Directly through dynamic control of supply to appliances, mainly
hot water cylinders. This “peak control” shifts the heating load to
occur just after the peak. Aim to turn cylinders off for short periods
only, to prevent any noticeable effects on customers' hot water
supply. Then turn the cylinders back on when network demand
reduces.
• Directly through fixed time control of supply to appliances, mainly
hot water cylinders and night store heaters, by switching them on
during off-peak night periods only. This “fixed time control”
permanently shifts load away from the day time periods when
peaks occur.
• Indirectly through pricing incentives that reward retailers'
customers who lower the amount of electricity they consume
during our high priced peak period. Provide ripple signals to tell
customers that it's a peak period so that they can reduce their load
and reduce their charges – this arrangement is more useful for
larger business connections with special half-hour interval metering
that records the reduced loading level during the peak period.
6. Load Management Continue…
• For customers that want a near-continuous supply for their water
heater (and don’t want regular peak control or night rate options),
we have emergency control channels that operate only during an
emergency that threatens supply.
Examples:
• P1: Off during peaks and emergencies. For peaks, aim to limit control to no more than 4 hours in any 8 hour period (and no
more than 8 hours per day). Generally off for up to 250 hours per year during the coldest winter weekday mornings and
evenings.
• P1 (Business): Off during peaks and emergencies. For peaks, aim to limit control to no more than 2 hours in any 5 hour
period (and no more than 6 hours per day).
• E1 (Residential): Left on continuously except during capacity emergencies. Expect less than 2 events per year, lasting up to 2
hours (longer in extreme circumstances).
• E1 (Business): As above, but given priority for restoration of supply.
7. Generation & Measurement of Ripple
• There are two technologies currently in use for generating the
injected signals
– Motor Generator Set: An electric motor is used to spin a
generator which supplies the desired injection frequency. A
contactor is used to apply the injection signal to the network via
tuning coils and an isolation transformer as appropriate.
– Static Frequency Converter: Electronics are used to generate the
injection signals which are again applied to the network via an
isolation transformer and tuning coils.
• Where these injected signals are applied???
– In urban areas, the signal is generally applied at 11kV, while in
more rural areas, may be at 22kV, 33kV or 66kV.
• What frequency range & amplitude is used???
– Frequency varies from 100Hz to 1600Hz having bandwidth
5Hz~40Hz with maximum amplitude of 0.3%~4% of operating
voltage.
8. Measurement continue….
• There are various methods of encoding the signal which is
superimposed on to the normal voltage waveforms
1. Decabit 2. Semagyr
3. Pulsadis 4. Ricontic B
• Decabit : The Decabit system comprises of a start pulse plus 10
coded pulses. Each Decabit injection comprises of 5 asserted pulses
and 5 non-asserted pulses. A receiving relay turns on if it receives
the 5 asserted pulses corresponding to its programmed channel.
The relay turns off if it receives the inverse of the on code. Each
injection lasts 600 ms.
• The Semagyr, Pulsadis & Ricontic B differ in maximum number of pulses in each telegram, the
pulse width & abort pulse support.
9. Impact of Ripple
• Under normal operating conditions, there is little impact on
equipment due to
– Ripple Signal Attenuation
– Ripple Signal Amplification
• Ripple Signal Attenuation :
– Cause : If signal losses in the network are too high or if the
injection level at the signal source is too low, the magnitude of
the signal when it reaches the receiving relay may not be
sufficient for the relay to operate.
– Impact: The main impact of receiving relays not operating is that
the load which is controlled by the relay will not turn on or off
as appropriate. This is a particular problem for relays which
control off-peak hot water systems.
10. Impact of Ripple
If the receiving relay does not turn on the water heater as
appropriate, the water will not heat and the customer will be
left with the inconvenience of cold water. Conversely if loads
that are meant to be turned off stay on, it can adversely affect
network loading levels and defeats the purpose of the
injection control system.
• Ripple Signal Amplification:
– Cause: The main mechanism for signal amplification is network
resonance. Under certain conditions, the impedance of the
network is such that there is resonance at the approximate
frequency of the injected signal.
– Impact: High ripple signals include flickering of dimmed lights or
touch lamp, Audible noise through speakers as well as devices
with laminated motors such as ceiling fan. Also can cause
“racing clock” phenomenon due to multiple zero crossing on
voltage waveforms.
11. Resolution….
• Mitigation of ripple signals which are at inappropriate levels is not
straightforward as signal levels are not homogenous across
networks and will change with network development and addition
or loss of load.
– For signal levels which are too low, the injection level is
generally increased at the source. Two main methods are used
for mitigation of signal levels which are too high. These are
changes to the network in order to change the network
resonant frequency and filters.
