Modeling of Reconnection of Decentralized Power Energy Sources Using EMTP ATP Ing. Dušan MEDVEĎ, PhD. Železná Ruda-Špičák, 25. May 2010 TECHNICAL UNIVERSITY OF KOŠICE FACULTY OF ELECTRIC ENGINEERING AND INFORMATICS Department of Electric Power Engineering

Contents Theoretical problems of reconnection of decentralized electric sources in power system Choosing of suitable model of power system for reconnection of decentralized sources Simulations of chosen electric sources in power system model in EMTP-ATP Conclusion

Problems of Reconnection of Decentralized Power Energy Sources to Distribution Grid Problems of reconnections of wind power plant: convention sources must be „on“ and prepared, in the case of wind power plants outage; dependence on actual meteorological situation; relatively small power of wind power plants; they are not possible to operate when the wind velocity is above 30 m/s or below 3 m/s. Problems of reconnections of solar power plants: convention sources must be „on“ and prepared, in the case of solar power plants outage; problems with the season variations of sunlight (in December is 7-times weaker than in July); difference between night and day is very significant Problems of reconnections of water power plants: they generate electric power only when the water flow is in allowable range;

Review of present possibilities of computer simulation of power system at our department MATLAB/SIMULINK EUROSTAG PSLF EMTP-ATP...

EMTP ATP (Electromagnetic Transient Program) Generally, there is possible to model the power system network of 250 nodes, 300 linear branches, 40 switchers, 50 sources,... Circuits can be assembled from various electric component of power system: Components with the lumped parameters R,L,C; Components with the mutual coupling (transformers, overhead lines,...); Morephase transmission lines with lumped or distributed parameters, that can be frequency-dependent; Nonlinear components R, L, C; Switchers with variable switching conditions, that are determined for simulation of protection relays, spark gaps, diodes, thyristors and other changes of net connection; Voltage and current sources of various frequencies. Besides of standard mathematical functions, there is possible to define also sources as function of time;

Model of three-phase synchronous engine with rotor, exciting winding, damping winding; Models of universal motor for simulation of three-phase induction motor, one-phase alternating motor and direct current motor; Components of controlling system and sense points. This program EMTP ATP is not only computational. Because of better representation of results and simplifying of inputting data, this program has spread with another sub- programs as follows: ATPDraw – graphical preprocessor; PCPLot, PlotXY, GTPPLot – graphical exporting of ATP; Programmer‘s File Editor (PFE) – text editor for creating and editing of output files; ATP Control Center – program that concentrate all controlling sub-programs into one general controlling window. EMTP ATP (Electromagnetic Transient Program)

Scheme of electric power network for simulations

Scheme of electric power network for simulations in EMTP-ATP

Parameters of power system Parameters setting of sources of power system

Parameters of power system Parameters setting of overhead lines of power system

Parameters of power system Parameters setting of transformers of power system

Sources reconnection There were reconnected various sources in different locations of power system First source was connected from the beginning of simulation, the second one was connected in 0,5 s and the third one in 1 s All parameters of components in power system were inserted as card data of given components Consequently, there were changed voltages and powers of connected sources The measured data (voltages, currents,...) were recorded and evaluated in various nodes of network The maximal possible connected power were calculated and tested with permitted difference of voltages (quality of voltages must agree with conditions of ± 2 % from nominal voltage in grid) The result were evaluated for phase L1 (A), because the loads were almost symmetrical

Simulation of reconnection of two sources with the same values and the maximal voltage of 326 V Sources reconnection

Voltage arising with sequential sources reconnecting Sources reconnection

Simulation of reconnection of two sources with the same values and the maximal voltage of 400 V Sources reconnection

Voltage deviation in the node, closest to third source Sources reconnection

Voltage deviation in the node, closest to the third source (detail) Sources reconnection

Simulation of reconnection of two sources with the same values and the maximal voltage of 385 V Sources reconnection

Simulation of reconnection of two sources with the various parameters and the maximal voltage of 391 V (2nd source) and 333 V (3rd source) Sources reconnection

Power of first source, when it operates alone (0-0,5 s), with the second one (0,5-1 s) and consequently with third one (1-2 s) Sources reconnection

Power of second source, when it operates with first one (0-0,5 s), and with the third one (1-2 s) Sources reconnection

Power of third source, when it operates with first and third one (1-2 s) Sources reconnection

Maximal voltages, that are possible to reach with the respecting of ± 2 % voltage variation in every node: Source 1: U m1 = V Source 2: U m2 = 391 V Source 3: U m3 = 333 V Maximal immediate power measured in the closest distances from the sources: Power of source 1 (single) = 2,2643 MW Power of sources = 3,5280 MW = 2,2541 MW + 1,2739 MW Power of sources = 3,5653 MW = 2,1458 MW + 1,2621 MW + 0,1574 MW Sources reconnection

Simulations of transient phenomena Complemented scheme for simulation of transient phenomena M1,M2,M3 – places of failure event; measuring places Simulated transient phenomena: short-circuits load (branch) disconnection phase interruption atmospheric overvoltage

Three-phase short circuit – overvoltage after short circuit elimination Voltage characteristics before short-circuit creation in location M1, during short circuit and after short circuit, measured in location M1

Three-phase short circuit – measured results Measured place Location M1Steady stateOvervoltage after shot-ciruit interuption Peak current during short-circuit Mutual distances [km]U [V] U [V] i p [A] M ,5 M24, ,5 M38, ,453 Measured place Location M2Steady stateOvervoltage after shot-ciruit interuption Peak current during short-circuit Mutual distances [km]U [V] U [V] i p [A] M1-4, ,5 M ,9 M34, ,373 Measured place Location M3 Steady stateOvervoltage after shot-ciruit interuption Peak current during short-circuit Mutual distances [km] U [V] U [V] i p [A] M17, ,3 M24, ,2 M ,8

Two-phase short circuit – overvoltage after short circuit elimination Voltage characteristics before short-circuit creation in location M1, during short circuit and after short circuit, measured in location M1

Two-phase short circuit – measured results Measured place Location M1Steady stateOvervoltage after shot-ciruit interuption Peak current during short-circuit Mutual distances [km]U [V] U [V] i p [A] M ,3 M24, ,08 M38, ,822 Measured place Location M2Steady stateOvervoltage after shot-ciruit interuption Peak current during short-circuit Mutual distances [km]U [V] U [V] i p [A] M1-4, ,6 M ,5 M34, ,975 Measured place Location M3Steady stateOvervoltage after shot-ciruit interuption Peak current during short-circuit Mutual distances [km]U [V] U [V] i p [A] M17, ,2 M24, M

One-phase short circuit – overvoltage after short circuit elimination Voltage characteristics before short-circuit creation in location M1, during short circuit and after short circuit, measured in location M1

One-phase short circuit – measured results Measured place Location M1Steady stateOvervoltage after shot-ciruit interuption Peak current during short-circuit Mutual distances [km]U [V] U [V] i p [A] M ,5 M24, ,81 M38, ,45 Measured place Location M2Steady stateOvervoltage after shot-ciruit interuption Peak current during short-circuit Mutual distances [km]U [V] U [V] i p [A] M1-4, ,7 M ,3 M34, ,43 Measured place Location M3Steady stateOvervoltage after shot-ciruit interuption Peak current during short-circuit Mutual distances [km]U [V] U [V] i p [A] M17, ,5 M24, ,2 M ,2

Phase interruption Voltage characteristics during phase interruption in location M1, measured in location M2

Voltage characteristics during phase interruption in location M1, measured in location M3 Phase interruption

Load disconnection Voltage characteristics after disconnection of branch AFA, measured in location M1

Current characteristics after disconnection of branch AFA, measured in location M1 Load disconnection

Atmospheric overvoltage During the direct lightning strike to overhead line pole (HV), it is considered line impedance Z 0 = Ω and lightning current of I = 20 kA, then the theoretical peak voltage magnitude of overvoltage wave is in the range 3-5 MV. HH

Atmospheric overvoltage Simulation of direct lightning strike to bus bar 22kV in location M1

Atmospheric overvoltage – measured results Measured place Location of failure M1Steady stateOvervoltage Mutual distances [km] U [V] U [MV] M ,304 M24, ,96 M38, ,83 Location of failure M2 M1-4, ,65 M ,01 M34, ,28 Location of failure M3 M17, ,28 M24, ,23 M ,43

Conclusion using of EMTP-ATP it is possible to relatively quickly consider connectivity of new power source (voltage change, short-circuit ratio, overvoltage,...); there were confirmed theoretical assumptions that the most important points with the highest quantity change are the closest branches to connection node, i.e.: - the highest increasing of voltage magnitude is in the node of source connection, - the highest increasing of short-circuit current is in the node of source connection, if there were connected 3 sources, the voltage in the power system was increased to permitted maximum voltage, and then it is possible to connect another load to the grid without significant complications, the similar procedure can be used for various small power systems

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