presentazione luce sul blackout inglese

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Page 1: Presentazione Luce Sul Blackout Inglese
Page 2: Presentazione Luce Sul Blackout Inglese

The production of Italian power stations, isn’t enough to cover energy needs of nation; therefore is bought from foreign

countries the necessary to cover entirely the request. This is possible because Italian electric grid is interconnected with

European electric grid.

Page 3: Presentazione Luce Sul Blackout Inglese

Interconnection between Italian and European grid

Page 4: Presentazione Luce Sul Blackout Inglese

In the night of 28° of September in 2003, the fall of a tree on Airolo – Mettlen line, seemingly little important fact, has caused a concatenation of events which have carried to the interruption between electric energy supplies coming

from France and travelling through Swiss, and Italian electric system.

Previous events to blackoutPrevious events to blackout

Page 5: Presentazione Luce Sul Blackout Inglese
Page 6: Presentazione Luce Sul Blackout Inglese

3.25:25 Airolo-Mettlen(740 MW). Canton Ticino is

separated from Swiss electric grid.

3.25:33 Soverzene-Lienz (309 MW).

3.25:33 Rondissone-Albertville (841+682 MW): Separation of I

and F

3.25:28 Avise-Riddes

(281 MW) e Riddes-

Valpelline (299 MW)

3.25:33 Le Broc Carros-

Camporosso (248 MW)

3.25:32 Albertville-La

Coche (F). Rapid Voltage instability.

3.25:34 Redipuglia-Divaccia (646 MW): Italy is connected

only trough a 132 KV asynchronous mode

connection.

3.26:30 Separation completed.

Page 7: Presentazione Luce Sul Blackout Inglese

The disengagement from European grid, The inadequacy about the modification of

exchange program required by Helvetic operator,

The fact about Italian operator who didn’t dispose of necessary coordination of defence plan’s instruments,

has determined an imbalance between power required and power generated, with consequent total interruption of energy supply to other users.

Page 8: Presentazione Luce Sul Blackout Inglese

The project tends to reproduce and simulate the trend of some electrical quantities, with particular attention for

frequency, which are present in Italian grid in the immediately following instants to the complete

seperation from the remainder of Europe.

Page 9: Presentazione Luce Sul Blackout Inglese

For that reason a mathematic model, that groups various components of system, has been made.

In this model have been studied precisely in sequence:

- The regulator of generation group

- The single machine in primary regulation

- All Italian grid

Finally mathematic model has been analyzed with application software called “Matlab”.

Page 10: Presentazione Luce Sul Blackout Inglese

The machine group formed by a turbine coupled with an alternator, allows to transform primary energy,

normally thermic or water, into electric energy.

Generation of electric energyGeneration of electric energy

Page 11: Presentazione Luce Sul Blackout Inglese
Page 12: Presentazione Luce Sul Blackout Inglese

The fundamental quantity analyzed by our system is the frequency, linked to rotation speed of generator by relation: P x n = 60 x f.

50 Hz is the nominal value of frequency for European grid. This condition happens when the tractor pair (dependenting by the amount of fluid introduced in the turbine) equalizes resistant pair (dependenting by the request of load factor).

Any action which modifies the previous condition, involves a transient condition, at which term must be restored stable condition.

The problem usually resolves modifying the amount of

fluid introduced in the turbine.

Page 13: Presentazione Luce Sul Blackout Inglese

The regulator is a device that makes varying, when there is a transient condition, motor fluid discharge at the turbine, with the purpose of restoring nominal speed (primary regulation).

The regulatorThe regulator

Page 14: Presentazione Luce Sul Blackout Inglese
Page 15: Presentazione Luce Sul Blackout Inglese
Page 16: Presentazione Luce Sul Blackout Inglese

The regulator was analized with a feedbacked sistem.

- (block integrator). K1 bounds the variation of volume of fluid with the consequent variation of frequency .

The block of feedback K2 that carryover to the knot of comparison the information of the variation of the course of the fluid

The knot C that confronts the relevant variation of frequency Df* with the information of the block of feedback

Page 17: Presentazione Luce Sul Blackout Inglese

the previous diagram is easily convertible in the more schematic block:

T1 is the constant of time of the regulator equal to the relation 1/ (K1 x K2 ) :

-Thermoelecrtic stations 10 s

-Hydroelectric stations 6 s

G1 bounds to the statism S (sensibility to the variations of frequency), to the power generated and to the nominal frequency from the connection G1 = Pg / (S X fn). Real values for the statism are:

5-8% for thermoelectric stations

-2-5% for hydroelectric stations

Since retains the power generated Pg proportional only to the opening of the distributor of fluid of the turbine is valid the equivalence: Dpg*=DA* .

Page 18: Presentazione Luce Sul Blackout Inglese

A group of generation is characterized from an own indolence that influences on the times of reply to the regulation in case of a disruption.

The couple engine in fact should provide to the resistant couple and to the couple of indolence definable from the connection Cj = J X / dt).

Machines of high power, and consequent enormous masses rotating will have considerable indolence and therefore more high than times of reply machine of smaller power.

Page 19: Presentazione Luce Sul Blackout Inglese

What previously said is summarized in the following diagram to blocks:

The start time is given from the relation (J) / C0; a reliable value for turbines to vapor is of about 8

seconds .

The moderate power in entrance (Dpr) is bound to the variation of relativ frequency (Df*) of the

current produced from the group .

The moderate power in entrance (Dpr) is bound to the variation of relativ frequency (Df*) of the

current produced from the group .

Page 20: Presentazione Luce Sul Blackout Inglese

All the elements analyzed up to here, translate in the following flow diagram:

The relative term DQ0* that can be positive or negative, means the load factor variation that starts primary regulation. The negative sign of DQ0* signifies a load factor increase that causes a negative value of Df; but a positive sign of Df agrees with a load factor reduction and a consequent frequency increase.

The term G2 of feedback block, that is favourable to the operation stability of the system, means the self – controlling energy of the load factor.

Page 21: Presentazione Luce Sul Blackout Inglese

The following figure means principle diagram of a primary regulation of a grid, from which we started for schematize the real Italian electric grid:

•The kind of blocks [-G / (1+sT) ] means the regulators present in a grid.

•In the adder knot B the powers (corrector), defined by regulators, converge. The result will be the total regulating power.

•In knot C, the power of regulators and the power normally generated converge; out of the knot the total power generated appears in that moment.

• In knot D the total power generated, the load factor power variation and the self – regulating energy (not considered in this experience) converge. The result is the remaining regulating power DP*rR.

•The block [ 1/ ( 1+Tae s ) ]. Tae is the equivalent starting time (subsequently defined better), that means the middle value of inertia of all generation groups implicated.

Schematization of the complete grid

Page 22: Presentazione Luce Sul Blackout Inglese

Initial considerations:

All the powers involved have been linked to energy imported from foreign countries at the beginning of Blackout, that is equal 6700MW. That determines the presence of “multiplying” blocks shown in the flow diagram with the mark “rel”:

In some cases “multiplying” blocks don’t appear explicitly in the total flow diagram, because they are inserted in blocks corresponding subsets (for example the block of the disengagement of “non – regulating” generators).

The power plants have been divided into two groups: regulating power plants that partecipate to primary regulation, and non – regulating power plants. Non – regulanting power plants only enter in the system because they generate power, but don’t regulate it.

The regulating power of a power plant isn’t infinity, but it is limited to a maximum value. For that reason special limiter blocks have been created.

The disengagement, whether of a power plant or a load factor, will be effected, in order of precision of simulation, in function of time or frequency value.

The decision, based on our data, has been taken case for case. Different decisions determine blocks with different specification functions.

Analysis of total model of Italian electric grid

Page 23: Presentazione Luce Sul Blackout Inglese

Starting from the considerations effected and from a series of specific data it has been possible completing the principle model of a grid in primary regulation. That facilitated the “schematization” of all Italian electric grid

and parts of model built (reported in the next page), have been included in subsets with the purpose of

make him easily comprehensible.

Page 24: Presentazione Luce Sul Blackout Inglese

Modello complessivo

Page 25: Presentazione Luce Sul Blackout Inglese

•Subsystem “primary regulation.” The regulators of the plants of great power (all thermoelectric) are singularly indicate, while those of the plants of small importance are gathered in an only block denominated “eq.regolanti.” The value of G1 has been calculated: -using the data known of the generated powers, -in operation of the general power for the “eq.regolanti”, -considering a statism of 0,08. The constant of time of the regulators worth 10 sec for the thermoelectric plants and 6.2 secs for the “eq. Regolanti” (because of the presence also of hydroelectric groups).

Section of generation

Page 26: Presentazione Luce Sul Blackout Inglese

Section of generation

Blocks of separation of primary regulators. They exclude the primary regulators according to a temporal sequence deduced by the indications of the “Chart Plants.” The block is not present for the governing equivalent because the evident not possibility to exclude it contemporarily.

Page 27: Presentazione Luce Sul Blackout Inglese

Limit control block of governing energy They limit the value of governing energy in operation of the characteristics of the plant to which are referred. The block doesn't appear for “montalto-trino-livorno” because considered useless because of the sudden separation from the service of these groups.

Section of generation

Page 28: Presentazione Luce Sul Blackout Inglese

Subsystem “separation governing generators.” The subsystem effects the sum of the generated powers from the groups in primary regulation. The exit from the service of a plant determines the total separation of the same one (normally generated + regulated power).

Section of generation

Page 29: Presentazione Luce Sul Blackout Inglese

Subsystem “separation of not governing generators and MT.”

The block is of complex composition in fact are present: Generators of medium tension MT that are excluded according to a temporal sequence (for the first two separations) and in according to the value of the frequency (for the remainder). -the not governing power plants are present nominally in the case of remarkable power while they are gathered in two blocks those of small importance. Their separation happens according to a temporal sequence.

Section of generation

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Page 31: Presentazione Luce Sul Blackout Inglese

Complex of the load

Import It represents the lack of energy deriving from abroad equal to 6700 MW (voice others of the chart Importation) that has determined the beginning of the Blackout. The block, rather than to be considered of generation and therefore agent like a separation, is represented like a load that to the instant t = 2 sec comes to burden on the net electric Italian working in “island.”

Block “increase load for increase tension” The block is comparable to an increase of load because of the increase of net’s tension in the transitory .

Page 32: Presentazione Luce Sul Blackout Inglese

Complex of the load

The separation of the hydroelectric plants of pumping, that exploit energy nighttime surplus with the purpose to bring water in the basin, it makes part of strategies put in action to oppose the onset of a blackout. In our simulation we have excluded some pumping central in operation of the time, others in according to the value of the frequency.

Detachment of pumping central in operation of the time. Condition has been divided in two blocks whose gone out by the service happens in

succession.

Page 33: Presentazione Luce Sul Blackout Inglese

Complex of the loadDetachment of

pumping central in operation of the frequency. The exclusion of some pumping central has happened comparing the frequency of net to the value of reference for the separation. This has been possible because we are in possession of precise data.

Page 34: Presentazione Luce Sul Blackout Inglese

Complex of the load

Subsystem “separation loads uses “. The loads of use have been divided on 11 steps for a general value of 4000 MW detachable to time according to the values suggested by the plan of defense. Naturally they have been excluded for first the less important uses.

Page 35: Presentazione Luce Sul Blackout Inglese

Equivalent inertia Equivalent inertia:

The block represents the equivalent middle inertia of all the groups of generation understood also those not governing. The Tae is an average's result weighed between the constants of time of the thermo-electrical plants and hydroelectric present in the net, also keeping account of the respective generated power. The simple calculation brought here:

(PThydro x Taehydro + PTthermo x Taethermo) / PT = 9.7 sec underlines that the Tae assumes a value very near to 10 sec like it was in the expectations seen the extremely remarkable contribution of the power from thermo-electrical plants in comparison to the hydroelectric .

Page 36: Presentazione Luce Sul Blackout Inglese

The result of the simulation is the course of the frequency during the transitory determined by the Blackout.

The value of the frequency is deduced from the study of the block under brought.

 

The oscilloscopes inserted in the general scheme visualize the course of some important parameters for the system (visualized in the following graphs).

Page 37: Presentazione Luce Sul Blackout Inglese

Generated total power (available). The curve always has negative value to underline the fact that is always a deficit of production. When the inclination is void events of separation of load or plant are not verified. The negative variations correspond to a separation of plant, the evident positive variations in the first part of the graph are due to the intervention of the regulation.

Separation of the loads.The negative steps correspond to real separations of load, those positive to consequent increases for example to the increase of the value of the tension.

Page 38: Presentazione Luce Sul Blackout Inglese

Governing total power. The evident increase of power in the first part of the graph is due to the intervention of the regulation that has always decreased its effects because of the sequential separations of the governing central in the prosecution of the transitory.

Separation of the governing centrals. The logic of the block scheme put positive sign to the separation of a corresponded governing plant. This premised, to every step it corresponds the exit from the service of a single plant.

Page 39: Presentazione Luce Sul Blackout Inglese

The graph has only the purpose to point out that the power managed by a regulator can not assume endless values but it is limited to a maximum value select in operation of the characteristics of the single plants.

Page 40: Presentazione Luce Sul Blackout Inglese

The graph represents the course of the frequency in operation of the time. They are to underline: - a first time interval 2-39 sec. in which it has a rapid fall corresponding to 1 Hz/sec, caused from the initial deficit and from a series of separations of plants. - a second time interval 40-130 sec. Characterized by a leveling of the curve (in reduction of the frequency) as a result of separations of load.

Page 41: Presentazione Luce Sul Blackout Inglese

46,0

46,5

47,0

47,5

48,0

48,5

49,0

49,5

50,0

50,5

03:2

5:30

03:2

5:40

03:2

5:50

03:2

6:00

03:2

6:10

03:2

6:20

03:2

6:30

03:2

6:40

03:2

6:50

03:2

7:00

03:2

7:10

03:2

7:20

03:2

7:30

03:2

7:40

03:2

7:50

03:2

8:00

Time

f [H

z]

-0,5

-0,4

-0,3

-0,2

-0,1

0,0

0,1

df/

dt

[Hz/

s]

Monfalcone=-327MWEntracque+S.Massenza+S.Fiorano+Presenzano=2159

Montalto+Trino+Livorno=-677MWBargi+Roncovalgrande+Anapo=1157

Edolo=538

La Spezia=-622 MW

P.Tolle=-496 MW

TVDN=-502 MW

P.Tolle=-400 MW Trino=-105 MW

Trino=-105 MW

ISAB=-180 MW

In the upper graph is brought the real course of the recorded frequency in the station of Musignano (blue line) and of his derived (red line). They are present besides the indications of the times of separation of the greatest production’s central , that have determined the onset of the blackout.

Page 42: Presentazione Luce Sul Blackout Inglese

The comparison of the course of the resultant frequency from our simulation with that real, recorded in the station of Musignano underlines the substantial correctness of the built model and the goodness of the choices of separation effected.

The model besides lends for ulterior studies and simulations that have the tendency to verify the possibility to avoid analogous events coordinating in different way the varied interventions and the strategies of defense.