It is well known that the replacement of traditional lamps by low energy lamps is saving significant energy and there introduction is even mandatory in some countries. The better heat management by isolating walls and windows is another effective way of saving energy.
But on top of that control systems to manage the use of electrical energy for lighting or blinds or climate control offers a large additional potential of efficient consumption of electrical energy.
Today consumption and generation are mostly decoupled. Utilities make estimates on the future demand based on historical data and experience, which works reasonably well. More intermittent power generation in the energy mix will bring new challenges.
Consumers just use the electrical energy without knowing about issues like peak demand and reserve capacity.
If consumption patterns could be available to the utilities closer to the actual need and if challenges in supply could be communicated to the consumers a common effort to efficient energy use could help to save energy and reduce CO2 emissions.
One way of facilitating this dialog is the tariff for electricity which needs to be different for peak and off-peak consumption. So the consumer can get a response to his demand of electricity and can decide in real time whether he wants to consume for the actual price per kWh or whether he can wait with his consumption.
Demand response is the name of the game.
When the tariff for electrical energy is the main instrument for demand response a real time market is required at which supply and demand can meet to fix the prices.
Platforms are required to enable this market and new functions beyond the traditional utility-consumer interaction will develop.
It is quite obvious that a consumer will not be able to directly react in real time to demand responses but a high degree of automation is necessary to make this system effective.
The traditional grid was designed to use centralized power generation, resulting in power flowing in one direction. Due to the lack of proliferation of large scale storage and in order to preserve stability the system has to be operated in such a fashion that generation follows load. This operating paradigm I heavily dependent on historical experience. The interconnection of new producers is time consuming and slightly anti-competitive. BUT FOR THE MOST PART THE SYSTEM BEHAVED IN A PREDICATBLE FASHION
What we are noticing now is that the market is asking for both centralized and distributed power generation; in addition in order to be kind to the environment we the market wants a lot of renewable energy sources, which for some of these are intermittent presenting us with an operational challenge. Due to the emergence and market pull for of small-scale distributed energy resources we have a situation where a traditional consumer can also now become a producer at select periods. This paradigm shift leads to multi-directional flows on the grid making it difficult to protect and control the power system and its elements using our old paradigm. Also technology means are emerging where load can be partially adapted to match the production.
In short operation of this evolved grid will be predominantly based on real-time data, in order to better manage the random behavior found in this grid.
Smart Grid with demand response requires buildings that are much smarter than
existing buildings
buildings (smart-homes) will be able to produce energy (renewables)
buildings (smart-homes) will share information about power consumption,
(future) power demand and energy production with the smart-grid
buildings (smart-homes) will react and interact with smart grids
via flexible demand tariffs
buildings (smart-homes) will be able to safe energy costs and reducing CO2 by
using new flexible tariffs
buildings (smart-homes) will be able to switch on/off and or delay energy consumption in the building
buildings (smart-homes) will be able to give the user a clear indication and transparency of current and future energy consumption and tariffs
TFT display: Thin Film Transistor display
RSS-feeds (various interpretations exists):
- Rich Site Summary (in RSS-Version 0.9x)
- RDF Site Summary (in RSS-Version 0.9 und 1.0)
- Really Simple Syndication (in RSS 2.0)
Minute-to-minute HEMS decisions include scheduling and shifting of electrical power usage
Consumption of electric appliances
Charging/discharging of energy storage devices
Power generation
Power exchanges with distribution system operator
Appropriate methods for sequential decision making under uncertainty:
Rule-based
Stochastic Dynamic Programming
Model-base Predictive Control
In this type of system, the short-circuit current value on the direct current side is almost always limited, so overcurrent protections are not required. The disconnect and operating devices on the direct current side must be class DC21 according to the classification of standard IEC EN 60947-3. Under current law, up to 20 kWp galvanic separation is not compulsory between the direct current side and the grid. In the case of inverters without a low frequency transformer, and in any case when the inverter is not for construction intended to block direct current earth faults in the electrical system, the protection against indirect contacts on the alternating current side must be achieved using class B circuit breakers.
Depending on the designer’s choices, these plants can be built using a single central inverter or plant power can be divided over multiple inverters. Protection against overcurrents becomes compulsory when the cable capacity is below 1.25 the short circuit current is calculated as (n-1) x Isc where:
Isc is the short-circuit current of the individual string
- n is the number of strings in parallel on the direct current side. In fact, in the event of a short-circuit, the fault is powered by all of the strings that operate correctly. Under current regulations for plants with rated output greater than 20 kWp, electrical separation is required between the direct current side and the grid. For systems connected to the grid on medium voltage, this separation is provided by a LV/MV transformer.
Optimized standard modules for each stage of the plant process and a complete capability in design, engineering, erection, installation and commissioning - this is what differentiates ABB’s solution from the alternatives. The benefits are proven - maximum power produced at each moment of the day, fewer power losses at each stage of the process, and higher revenues. Each ABB module and the ABB products it contains are engineered for the requirements of PV solar applications. These compact, pre-tested 1 MW units are easy to install, easy to integrate and highly scalable. As a result, delivery and project completion times are reduced.
