A New Load Shedding System for Industrial Loads in the Italian Power System

Transcription

1 . A New Load Shedding System for Industrial Loads in the Italian Power System Giorgio Giannuzzi Grid Division 7th International Workshop on Electric Power Control Centers Ortisei, 28 Maggio 2003 giannuzzi.giorgio@grtn.it

2 Typical power flow. SVIZZERA AUSTRIA FRANCIA Milano Venezia SLOVENIA Torino Firenze FRANCIA (Corsica) Roma Napoli Cagliari GRECIA Palermo

3 Feared phenomena Fast phenomena AUTOMATIC LOAD SHEDDING (<1 sec) Pole slipping due to transient instability Distance protection false trip due to stable oscillation Several distance protection trips (chain reaction) due to instable oscillations Slow phenomena MANUAL LOAD SHEDDING Voltage instability Distance protections trips due to overcharge (max power or max current) 52 % of peak load underfrequency relays 24 % of peak load manual/automatic load shedding

4 IC & on field verifications: CESI role To verify that Interruptible Customers meet requirements MAIN REQUIREMENTS to be a final user, so that the responsibility of the consequences of shedding can be directly attributed to the customer; to be users powered by the high voltage network; to have a shedding power above a certain limit; to select and document loads relating to the assigned bands, as an Interruptible Customer can shed loads both in real time and upon notice; to guarantee a continuous service of the apparatus, and of the router connected to it; to guarantee there are no timers, by-pass circuits, relays, PLCs (Programmable Logic Controller) between the apparatus and the interruptible load; to realise a blocking circuit upon re-closure by, and to present suitable presettings to assure the redundancy of the opening commands received; to guarantee security for people, equipment and productive processes, releasing from any civil and criminal responsibility as regards damages to things or people due to load shedding.

5 Interruptible Customers CR ACC ST CNC NCC RETE DI COMUNICAZIONE FRAME RELAY COMMUNICATION INTERFACE (ROUTER) REDOUNDANT DOPPIO COMMUNICATION CANALE DI COMUNICAZIONE CHANNEL (PROVIDER TELEFONICO) T E R M MORSETTIERA sigillata I N A L S T R I P SLOW PHENOMENA DEFERRED IC (operating time < 15 ) CONVERTORE (POTENZA LOAD ISTANTANEA POWER CONVERTER ASSORBITA) CARICO LOAD INTERROMPIBILE VT TV TA CT POSIZIONE LOAD INTERRUTTORE SWITCH POSITION DEL CARICO LOAD COMANDO SHEDDING DI DISTACCO COMMAND FAST PHENOMENA REAL TIME IC CR ACC (direct CB opening < 200 ms) CNC NCC RETE DI COMUNICAZIONE FRAME RELAY ROUTER (ROUTER) REDOUNDANT COMMUNICATION CHANNEL DOPPIO CANALE DI COMUNICAZIONE (PROVIDER TELEFONICO) T E R M I MORSETTIERA sigillata N A L S T R I P CONVERTORE (POTENZA LOAD ISTANTANEA POWER CONVERTER ASSORBITA) CONFIRMATION REDUCTION REQUEST LOAD CARICO LOAD INTERROMPIBILE VT TV TA CT LOCAL LOAD SHEDDING SYSTEM

6 Communication & Overall Architecture ACC CAGLIARI ACC VENEZIA ACC PALERMO FRAME RELAY WAN ACC FIRENZE ACC TORINO ACC MILANO NCC ROMA PROTOCOLS ACC NAPOLI IEC on TCP MANUAL/AUTOMATIC LS IEC M on UDP VERY FAST AUTOMATIC LS

7 Automatic IC load shedding Protection tripping Concentrator Load shedding multicast event generators (Sentinels) Central system Load shedding Load shedding Load shedding Load rejection command Load shedding (Fingers) Start communication Subscription to the group address Armed by the Center to interesting events (by bitstring) In absence of the Center, default arming

8 Multicast benefits Each subscribe itself only to interest events Periodically the Center arms s basing on DSA calculations (by CESI) The Center transfers by bitstring the event address Every information it is available to everyone on the network Optimization of traffic with IGMP Project status DSA: prototype finetuning and testing in progress Automatic multicast load shedding (available only by manual configuration) Multicast diffusion: all the ICs; next step: to be available on all the Italian load shedding system (distribution and transmission plants)

9 MMI quick, simple and efficient shedding of interruptible loads in real time; coordinated and flexible shedding management between Control Rooms; separate management of the different types of shedding; interfacing of the new load shedding system with national network s control system; allows data exchange with Energy Management Systems;

10 Other systems interfaces IMC SERVERS IMC CLIENTS EMS/SCADA SYSTEM NCC FRAME RELAY WAN ACC IMC CLIENTS BILLING & SETTLEMENT INTERFACE (*.XML FILES) LOAD SHEDDING DURATION SHEDDED LOADS LIST POWER SHEDDED AND UNSUPPLIED ENERGY POWER DEVIATION FROM CONTRACTUAL DUTIES LOCAL LOAD SHEDDING UNAVAILABILITY Intranet interface (via WEB server)