active and reactive power control praveen jain 19 september 2014
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Active and Reactive Power Control
Praveen Jain
19 September 2014
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Reactive power
June 2014Sparq Confidential
Voltage and current are not in-phase Reactive Power for the same voltage and current amplitude (constant Apparent Power), less active (real) power is allowed to be transferred.
Most of the loads (such as motors) draw current not in phase with the voltage (large reactive power) Since reactive power generation does not require any source of energy, traditionally capacitor banks and recently smart converters even with no source of energy can produce the required reactive power locally to free up some real power transfer capacity on the transmission and distribution systems.
Definition and Static Compensation
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New Requirements for Reactive and Active Power Control
July 2014Sparq Confidential
Dynamic active power compensation proportional to the frequency deviation helps the grid frequency becomes stable because of the way all the generators are controlled.
It can be shown that negative reactive power generation can locally cause a small grid voltage sag. Dynamic reactive power compensation depending on grid voltage deviation can stabilize the grid voltage.
During the fault new standards require smart dynamic reactive power support from the smart inverters to help the grid voltage stabilize faster. This is called Fault Ride Through (FRT).
Dynamic Compensations
Instantaneous Power control (Ultra-fast Reactive power
control)
New control block diagram which controls the instantaneous power directly instead of active and reactive power independently. This improves the dynamic response of the system and improves stability of the systemWhen there are several microinverters in the grid.
Instantaneous power feedbackNo current feedback
Instantaneous power referenceNew control strucutre
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Experimental Results for different active and reactive power levels: case 1: P= low,
Q = low
Steady state condition for early in the morning or late in the afternoon with no reactive power
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Case 2: P= low, Q = medium
Steady state condition for early in the morning or late in the afternoon with 100Var reactive power
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Case 3: P= low, Q = High
Steady state condition for early in the morning or late in the afternoon with 300Var reactive power
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Case 4: P= High, Q = Low
Steady state condition for full sun and low Reactive power
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Case 5: P= High, Q = High
Steady state condition for full sun 300Var Reactive power
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Case 6: Ppv= zero, Q= low
Steady state condition for night operation with 30Var Reactive power
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Case 7: Ppv= zero, Q= medium
Steady state condition for night operation with 150Var Reactive power
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Case 8: Ppv= zero, Q= High
Steady state condition for night operation with 300Var Reactive power
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Case 9: Ppv= jump, Q= zero
Transient response for input power jump with no reactive power
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Case 10: Ppv= jump, Q= High
Transient response for input power jump while injecting 200Var reactive power
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Case 11: Ppv= zero, Q= jump
Transient response for reactive power jump with zero active power
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Case 12: Ppv= High, Q= jump
Transient response for reactive power jump when injecting 100W active power
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Case 13: Ppv= zero, Q=jump inductive to
capacitive
Transient response for reactive power jump from inductive to capacitive at night
Qref jump
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Case 14: Ppv= high, Q=jump indutive to capacitive
Transient response for reactive power jump from inductive to capacitive when injecting 100W active power
Qref jump