Smart substations

A substation is integral part of a power system and form important links between the generating station, transmission systems, distribution systems and the load points. Substations transform voltage from high to low, or the reverse using transformer. Electric power may flow through several substations between the generating plant and the consumer, and the voltage may be changed in several steps.

A: Primary power lines' side

B: Secondary power lines' side

 

1. Primary power lines	2. Ground wire	3. Overhead lines
4. Potential Transformer	5. Disconnect switch	6. Circuit breaker
7. Current transformer	8. Lightning arrester	9. Main transformer
10. Control building	11. Security fence	12. Secondary power lines

 

The number of distributed energy resources and new appliances with power electronics in the distribution grid rapidly grows. This leads to power quality deterioration and power flow fluctuations. A smart MV-station (33/11 or 6.6 kV) / LV-station (11 or 6.6 kV/ 400 V) has been designed known as smart substation to manage voltage fluctuation,   maintaining power quality and reliability. Intelligent components of smart substation increase the immunity against power quality problems, such as harmonics, voltage dips, voltage swell, flicker. Additional features of the Smart MV/LV-station are:

• Remote monitoring of sensors and power equipments(Power x-mer, CTs, PTs, CBs, etc.).
• An electric storage system, consisting of a battery and a bi-directional inverter (ESI)
• Step less control of the voltage level on the LV bus bar, performed by a smart transformer
• Bidirectional communication between home appliances and the smart substation, using a home automation system.
• Perform “expert system” analysis
• Inform engineers or dispatchers about possible incipient problems
• Supply “operational and non-operational” data to control center for analysis of power system condition.

 

Smart substation enables a significant reduction in harmonic voltages and resonances (70%), as well as a reduction of the peak load by 30%. It also improves the reliability of the power supply. This is achieved through a combination of features, including overload prevention, prioritised energy supply and the coordination of supply from local energy storage and distributed generation.

 

A smart substation able to remotely monitor the status of the Transformers by transmitting data to a smart grid monitoring center server through a DTU or RTU directly.

Functions of the Smart Substation

• Effective gearing of demand and supply despite the great diversity of local grids.
• Reliable & efficient handling of decentralised energy generators in order to facilitate an affordable and sustainable energy supply in the future.
• Autonomous operation during calamities, through deployment of electric storage and decentralised generation.

 

Management of current quality through full control of power peaks from intermittent and stochastic generators.