Ancillary Service (on a commercial basis)
vertical-integrated unbundled market - liberal
flexibility
active power
reactive power
voltage angle, syst. frequency
voltage module
produce Q, |U| rise;
consume/ absorb Q, |U| drops
security of system operation
Transmission Load Relief (TLR)
Power Transfer Distribution Factors (PTDF)
Pareto
voltage stability
+- 10%
ISO, TSO/ DSO
Exercise topics
transmission line currents
frequency fluctuation
synchronism
bilateral agreement
pool market mechanism
energy reserve
black-start capability
Congestion management
Frequency control
primary control/ local
secondary control/ load following / centralised & coordinated
droop control
Nash equilibrium
ch2- optimal single power plant generation w/
constraints
service quantity, spot price, power dispatch profile, cost & revenue, marginal cost, operation cost &profit,
ch3- Plant operation w/ optional contracts
ch4-optimal dispatch for two plants
pool market trade, spot price, CfD,
biding strategies:
pareto optimum, nash equilibrium
ch5- Transmission Load Relief (TLR)
unconstrained/ constrained eco dispatch, LMP
review contract types
review biding strategies: pareto optimum, nash equilibrium with payoff table
practice!
review LMP, TLP,
redispatch to control power flows in grids
rotor angle stability
congestion at line/ transformer occurs when current exceeds its thermal limits
cascading outage on the devices may occur until complete blackout
loads increase suddenly, freq drops due to the taken kinetic energy from sync gen. rotors
speed governors of generators run against
to recover the reference freq
facilities
reactive compensation devices, transformers(tap-changing& phase shift), Flexi AC Transmission Systems (FACTS), grid topology changes
HOWEVER, it can not help to control the freq. due to load variations!
provision through market
dedicated to preventive or curative issues
prevent freq. collapse
Gen. w/ AVR or PSS
(contribution) AVR: sync. torque; PSS: damping torque
unique buyer: ISO, GenCos & interruptible loads are sellers
long-term contracts
Thermal units: hydro- diesel/ gas turbine gens. w/ limited contribution to the flexibility of volt/ freq stability
short-term contracts
spinning reserve (gens. in)
Cold energy reserve (gen. out)
Service Charges
balancing market
service charge for the users (if any)
transmission services