ABB PSPG-E7 MODAKOND More efficient and unit control Group May 8, 2014 Slide 1
OPTIMAX MODAKOND Challenge Conventional solution for frequency control (or to improve control performance for flexible plant operation): throttling the turbine control valves Major drawback: Throttling losses reduce plant efficiency How to activate available energy reserves in order to significantly reduce or completely eliminate throttling of the turbine control valves (TCV)? Requires a perfect coordination of such reserves in order to maintain stability of operation Group May 8, 2014 Slide 2
OPTIMAX MODAKOND Solution features Model based coordinated operation mode for boiler and turbine Feed forward strategy combined with decoupling of the closed-loop-control Integration of different actuators for economic provision of primary control like Condensate throttling Throttling extraction steam to HP preheaters Frequency control in boiler- or turbine- follow mode with initial control or position control of the turbine inlet valves For or fixed mode or combined /fixed mode Group May 8, 2014 Slide 3
Compliance with the Grid Code requirements Variant I: coordinated boiler following mode for operation remote dispatcher setpoint 90 setpoint fuel pls + + turbine valve position controller + model controller fuel controller feed-forward control boiler load setpoint k * f MW model + grid-frequency deviation feed-forward control turbine turbine load controller % 80 RH P EI 30 s P SG (boiler output load) G 10 min time P EI P Group May 8, 2014 Slide 4
Grid requirements for a fast grid-frequency support by fossil fired power plants (Grid Code in Europe) P P N 5 % 2 1 Load increase requirement for low grid load (3GW sudden loss, total grid load 150 GW) 5 seconds 30 Load increase requirement for high grid load (3GW sudden loss, total grid load 300 GW) time Group May 8, 2014 Slide 5
Individual calculation of the boiler steam storage capacities using measured data Measured responses for the boiler for a negative step of turbine load unit load 271 MW 168 MW live-steam flow utilized live-steam 987 kg 1483 kg position of the turbine inlet valves live-steam increase steam storage capacity steam storage time constant T S 6,7 bar 10,0 bar 147,0 kg/bar 148,3 kg/bar 72,8 s 112,0 s Group May 8, 2014 Slide 6
OPTIMAX MODAKOND Achieved results with MODAKOND at a 550 MW PP setpoint fuel flow setpoint fuel flow current boiler load load load utilized energy by MODAKOND restored energy for MODAKOND model boiler load setpoint generator load utilized energy by throttling restored energy for throttling simulated grid-frequency drop Group May 8, 2014 Slide 7
Efficiency gain by MODAKOND (ABB patent) Enhancement of overall efficiency owing to reduction in auxiliary load in comparison with an unit control system without a valve position controller in the modified range. Numerical example for a 700 MW unit: 6,000 hours per annum in modified operation with an average load of 88 %, 3 bar throttling error at the turbine inlet valves, 250 bar rated live steam, 23 MW power rating of the electrical feed water pumps MODAN leads to approx. 1.2 % less pump power consumption Result: Reduction in annual auxiliary load by 1,450 MWh Group May 8, 2014 Slide 8
Features of model-based unit control MODAKOND Full-coordination of boiler and turbine Applicable for power plants with fixed- or, which also may have district heating (additional extraction steam) Including the coordinated boiler and turbine following modes with/without throttle- control Application does not use the live-steam flow measurement Application runs on different HW/SW platforms (also on non-abb control systems) Primary frequency control fulfilling the Grid Code requirements without using the throttling reserve for unit load ramps Secondary and tertiary control support (remote dispatcher) Group May 8, 2014 Slide 9
Variants Group May 8, 2014 Slide 10
MODAKOND variant for existing units (only condensate stop without additional actuators) remote dispatcher setpoint p LS + turbine valve position controller unit setpoint k * f grid-frequency deviation model feed-forward control boiler MW model feed-forward control turbine + + controller fuel controller feed-forward control + turbine load controller RH G P P EI Coordinated boiler following mode for operation Group May 8, 2014 Slide 11 4 3 2 1
Efficiency increase up to 0.4% through MODAKOND (ABB-CONDSTOP: coordin. condensate & ext. steam stop) p LS + + + turbine valve position controller model controller fuel controller remote dispatcher setpoint feed-forward control boiler ABB-CONDSTOP load setpoint k * f feed-forward control MW model + grid-frequency deviation feed-forward control turbine turbine load controller 18 15 12 6 0 RH turbine valve throttling in % MODAN MODAKOND (ABB-CONDSTOP) 40 70 100 load in % G P P EI Coordinated boiler following operation mode 4 3 2 1 Group May 8, 2014 Slide 12
Ranking of the measures for primary frequency support using the existing plant equip., off-line simulation possible The fuel over-firing can be reduced by reducing the steam flow to the HP heater and condensate stop. 760 MWs throttling reserve HP heater A7 Condensate stop Time [s] The parallel operation of the condensate stop and HP-heater "throttling is reducing the necessary turbine throttling by 75% auf 760 MWs (without this countermeasures a throttling reserve of 3.100 MWs are necessary). Group May 8, 2014 Slide 13
Ranking of the measures for primary frequency support depending on the grid-frequency deviation 35 HP heater 30 25 condensate stop 20 power contributions [MW] 15 10 throttling of the turbine 5 0-250 -200-150 -100-50 0 50 100 150 200 250-5 -10-15 -20-25 -30-35 frequency deviation [mhz] Group May 8, 2014 Slide 14
OPTIMAX MODAKON Benefits Increase in economic efficiency by reducing the throttling of the turbine inlet valves Faster load ramps for increased flexibility Feasibility of primary and secondary frequency control Gentle operation of the main components with minimized control work Reduced minimum load for low load running Group May 8, 2014 Slide 15
Reference plants for MODAKOND (I) Power plant Nominal power (gross) Constant/ Fuel Boiler type Project status Remarks RDK 7 (Germany) Rostock (Germany) Schkopau (Germany) Westfalen unit C (Germany) 550 MW 550 MW 1 x 373 MW 1 x 391 MW 320 MW modified modified modified modified hard coal (oil) hard coal (oil) brown/ lignite coal (oil) hard coal (oil) Benson supercritical Benson supercritical Benson supercritical Benson completed 1985 completed 1995 completed 1996 Completed 1997 quick-acting condensate control valve and 3 rotary dampers: gland steam supply of the feedwater tank, bleed pipes for the LP heaters 3 & 4 (scope of supply: concept and basic design of the ABB-CONDSTOP) district heating (300 MWth), 3 quick-acting rotary dampers: gland steam supply of the feedwater tank, bleed pipes for the LP heaters 3 & 4 extraction steam and operation of a railway steam turbine (16 2/3 Hz, 110 MW), 2 quick-acting rotary dampers: gland steam supply of the feedwater tank, bleed pipe for the LP heaters 4 rehabilitation, unit with condensing turbine, 1 quick-acting rotary damper only for the gland steam supply of the feedwater tank Group May 8, 2014 Slide 17
Reference plants for MODAKOND (II) Power plant Nominal power (gross) Constant/ Fuel Boiler type Project status Remarks Staudinger 5 Germany Heyden Germany Zolling Germany 550 MW modified 920 MW modified 450 MW modified hard coal (oil) hard coal (oil) hard coal (oil) Benson supercritical Benson supercritical Benson 1999 completed 1999 completed 2001 (pre-study with site tests and simulation) district heating, ABB-Condstop with 3 quick-acting rotary dampers: gland steam supply of the feedwater tank, bleed pipes for the LP heaters 3 & 4. unit with condensing turbine, only condensate flow throttling cogeneration plant (district heating) only condensate flow throttling Weiher III Germany 703 MW natural hard coal (heavy oil) Benson 2002 unit with condensing turbine, only condensate flow throttling Group May 8, 2014 Slide 18