Power system fundamentals Flashcards
What is system frequency? And on what level should it be maintained?
- A universal indicator of imbalance between electricity supply and demand.
- The system needs to be maintained close to its nominal value, normally 50 Hz. The variations are often not more than 0.06 Hz.
How is the current power system designed? What are future challenges?
- Current system: supply follows demand, energy mix is based predominantly on fossil fuels
- Future challenges: integration of renewable energy sources, while ensuring the reliability of the power system.
What is the power system evolution? Name three levels of control.
- Manual control of electricity power systems
- Multi-area interconnected power systems
- Power system control in deregulated environments
How does the manual control of electricity power systems work?
- Primary regulation through generator droop control.
- Manual dispatch of generation units.
How does the multi-area interconnected power systems work?
- power frequency control based on area control error (ACE) calculations
- ACE should be 0, the TSO should manage this
- Economic dispatch of generation units
How does the power system control in deregulated environments work?
- Market-based operations for participation in load frequency control (LFC)
- The TSO calculates the ACE for a given control area and communicates change of set-points (so called delta signals)
- In the case that frequency deviations and/or deviations of inter-area exchanges occur, bids for regulating capacity are called and the TSO sends the delta signal to the associated Balancing Service Providers
Why are power systems interconnected? (2 reasons, 1 challenge)
- to maintain the required supply and demand balance
- interconnected tie lines provide operational flexibility and improve market integration
- the implementation of new interconnections and the expansion of congested tie-lines involve difficult political decisions
Interconnection tie-lines provide operational flexibility and improved market integration. What are the three flexibility options?
1) Exchange of reserve power
2) Avoid curtailment of (renewable) power generation surplus
3) Reduce power generation costs by selecting power plants with the lowest marginal costs across neighbouring systems.
Which two thing are required to maintain the required supply and demand balance
- Availability of adequate amount of generation
- Adequate interconnection capacity for power transfer
Why leads the implementation of new interconnections and the expansion of congested tie-lines to difficult political decisions? (give 4)
1) High investment cost
2) economic and technical risks
3) extensive planning
4) legislation procedures
What are the three types of electricity markets?
1) Long term markets
2) Spot markets
3) Ancillary services markets
What kind of long term markets are there? (give 2)
1) Forward markets, over-the-counter (OTC) financial markets
2) futures exchanges that trade standardized futures contracts
Give two types of sport markets
1) Day-ahead spot market
2) intra-day spot market
What are ancillary services? (give short definition)
Ancillary Services support the transmission of energy from resources to loads, while maintaining a reliable operation of the Power System. Operating reserves (incl. balancing), reactive power and voltage control, congestion management, system restart etc.
What do you know about the competition within electricity markets?
- Since the electricity market liberalization process was initiated in the EU in 1996 (Directive 96/92/EC which was repealed by Directive 2003/54/EC), many Member States have pioneered the creation of competitive markets.
- Not all segments of the electricity business are market capable, i.e. the distribution and transmission of electrical power involve natural monopolies where competition cannot work due to large investment costs and dominant economies of scale.
- The wholesale trade of electricity is a segment for which a market can exist.
