High penetration of renewable resources and the impact on power system stability. Dharshana Muthumuni

Transcription

1 High penetratin f renewable resurces and the impact n pwer system stability Dharshana Muthumuni

2 Outline Intrductin Discussin f case studies Suth Australia system event f September 2016 System Study integratin f up t 200 MW f wind t the Sri Lankan Grid

3 Intrductin Pwer systems are designed t ride thrugh credible system events such as faults, lad rejectin and generatr tripping. Due t diligent planning prcess invlved, majr disturbances that lead t wide spread pwer utages are rare. Hwever, majr event d ccur and n mst situatins, the such events are triggered by highly imprbable events.

4 Impact f Wind Generatin n System Inertia and Stability Exciter Synchrnus Generatr Gvernr/Turbine Netwrk SG Wind Generatr (T4)

5 Intrductin Mdern transmissin level wind and slar PV generatin are interfaced t the grid thrugh pwer electrnic cnverters. The characteristics are much different frm the cnventinal synchrnus machines. The kinetic energy assciated with rtating masses f cnventinal generating units act t prvide inertial supprt t the system. natural respnse f the machine and des nt depend n activatin f prtectin and cntrl functins. Pwer electrnic based wind and slar PV generatrs d nt prvide the same levels f inertia as the cnventinal generatrs. This can have a significant impact n system frequency stability when renewable penetratin in a regin becmes significant.

6 Example 1 Black System Suth Australia September 28, 2016

7 Event Descriptin

8 Event Descriptin

9 Suth Australia Generatin mix prir t event

10 Event Descriptin Extreme weather cnditins resulted in five system faults n the SA transmissin system in the 87 secnds between 16:16:46 and 16:18:13, with three transmissin lines ultimately brught dwn In respnse t these faults, and the resulting six vltage disturbances, there was a sustained reductin f 456 MW f wind generatin t the nrth f Adelaide. Increased flws n the Heywd Intercnnectr cunteracted this lss f lcal generatin by increasing flws frm Victria t SA This reductin in generatin and increase f imprts n the Intercnnectr resulted in the activatin f Heywd Intercnnectr s autmatic lss f synchrnism prtectin, leading t the tripping (discnnectin) f bth f the transmissin circuits f the Intercnnectr. As a result, apprximately 900 MW f supply frm Victria ver the Intercnnectr was immediately lst.

11 Event Descriptin This sudden and large deficit f supply caused the system frequency t cllapse mre quickly than the SA Under-Frequency Lad Shedding (UFLS) scheme was able t act. Withut any significant lad shedding, the large mismatch between the remaining generatin and cnnected lad led t the system frequency cllapse, and cnsequent Black System.

12 Fault ride thrugh requirements f wind farms All wind farms met the ride thrugh requirement fr the number f faults within the shrt duratin Hwever, an additinal prtectin that was nt knwn t system peratrs gt activated t trip sme f the wind farms (mre than 3-4 faults experienced within a pre defined shrt duratin)

13 Characteristics f Synchrnus Generatrs Exciter Gvernr/Turbine Netwrk SG The Synchrnus generatr respnse is determined by Machine electrical characteristics Exciter characteristics Gvernr / turbine Inertia f the rtating masses

14 Characteristics f Synchrnus Generatrs The inertial respnse immediately fllws the event Primary cntrl Sec Secndary minutes. The inertial respnse is due t the inertia f large synchrnus generatrs

15 Lessns Learned and Recmmendatins Generatin Mix and System Inertia: The system inertia n the SA side was nt sufficient t maintain the frequency drp (nce the Haywd intercnnectr tripped) and t make the under frequency lad shedding (UFLS) effective. Must run thermal generatin may have t be identified. Synchrnus cndensers may be investigated as a ptential slutin if the thermal generatin dispatch is expected t be lw under specific lad cnditins.

16 Lessns Learned and Recmmendatins Under Frequency Lad Shedding: The under frequency relays d nt start activating until the frequency drps t 49 Hz. The effectiveness f this scheme may have t be re-visited even if the SA side inertia is increased thrugh thermal generatin dispatch. UFLS shuld be the first line f defense. Special Prtectin Schemes: In ur pinin, special prtectin (SPS) shuld be cnsidered if UFLS des nt prvide the required system security. AEMO identify this in Sectin 3.6.

17 System Studies Mdel Validity

18 Reference BLACK SYSTEM SOUTH AUSTRALIA 28 SEPTEMBER Reprt by AEMO

19 Example 2 Integratin f 200 MW wind t a relatively small pwer netwrk

20 Integratin f 200 MW wind in Nrth West regin f Sri Lanka Studies t supprt the renewable energy Master Plan Technical Feasibility f integrating a significant amunt f renewable energy t a relatively small pwer netwrk. Lad flw studies Dynamic stability studies Wind farm fault ride thrugh studies

21 Operatin f the Sri Lankan System Event f September The event ccurred during a time when the system lad was unusually lw (800 MW) - A cal Generatin unit delivering apprximately 280 MW (33%) and absrbing 28 MVAr tripped due t a prtectin malfunctin. - The majr lad centre is arund the capital city.

22 Cmparisn f field data with simulatin results Event f September 2015 V (pu) Vltage cmparisins:220 kv Biyagama220 VOLT 2570 [BIYAG ] System Vltage: Recrded (Blue) and Simulatin (Green) V(pu) New Chilaw 220 VOLT 2815 [NCHILAW ] The simulatin mdel des nt capture the event accurately Lakvijaya220 VOLT 2810 [PUTTALAM-PS ] V (pu) Mdel predicts excellent vltage cntrl: V (pu) Kthmale220 VOLT 2220 [KOTMA ] Kelanitissa220 VOLT 2300 [KELAN ] Are tap changer actins adequately mdeled Are the remaining generatrs prviding the expected vltage supprt V (pu) Time(s)

23 Studies and Study Scenaris Lad flw studies Dynamic simulatin PSS/E dynamic stimulatins are perfrmed t identify vilatins f dynamic perfrmance criteria fr a set f selected disturbances. Study Scenaris Analyzed 2017 Hydr Maximum Day Peak (DH) 2017 Hydr Maximum Night Peak (DN) 2017 Thermal Maximum Day Peak (DT) 2017 Thermal Maximum Night Peak (NT) 2017 Off Peak (OP)

24 Results 400 Day Peak Maximum Hydr: 0 MW at Mannar Electrical pw er utput f unit 3 at Puttalam cal plant: Tripping f unit 1 at Puttalam cal plant Day Peak Maximum Hydr: 200 MW at Mannar P (MW) Time[s] Vltage at Mannar: Tripping f unit 1 at Puttalam cal plant 1.40 Day Peak Maximum Hydr: 100 MW at Mannar Day Peak Maximum Hydr: 150 MW at Mannar Day Peak Maximum Hydr: 200 MW at Mannar V[pu] Time[s]

25 System Data Mdel Uncertainties Bus Number BUS Name/Machine Id Base kv Mbase[MVA] Pmax[MW] H, Inertia 1300 KELAN-1 / KELAN-1/ KELAN-2 / KELAN-2 / KELAN-2 / KELAN-2 / KERAWALA_2 / KERAWALA_2 / KERAWALA_2 / KERAWALA_2 / KERAWALA_2 / HAMBA-2 / HAMBA-2 / SAMPOOR-1 / SAMPOOR-1 / PUTTA_G1 / PUTTA_G2 / PUTTA_G3 /

26 Cnclusins

27 Thank yu