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The three-phase primary control block generates the reference magnitudes (peak value) of the active and reactive components of current for the three-phase wave reference component to control the inverter's active and reactive power output. The primary active power control loop can generate the reference magnitude of the active power current component either in open loop condition, through a DC link voltage controller, or through an AC side closed-loop power control loop. Similarly, the primary reactive power control loop may generate the reference magnitude of the reactive power current component in open-loop conditions or through an AC-side closed-loop reactive power control loop. The input reference values for power quantities can be set directly to the desired value or they may be generated from the Secondary Control component.
Mask and Parameters
The configuration mask of the Primary Control block contains the following tabs:
Configuration
Controller
Rate Limiter
Configuration Tab
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Name | Description | Unit |
|---|---|---|
Primary Active Power Control Method | Select the primary active power control method of the inverter system: Open Loop, DC-Link, or Closed-Loop. | - |
Primary Reactive Power Control Method | Select the primary reactive power control method of the inverter system: Open Loop or Closed Loop. | - |
Current Limit | The maximum limit for the peak value of the inverter output current | pu |
Initial active power | Input initial active power | pu |
Initial reactive power | Input initial reactive power | pu |
Controller Tab
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Name | Description | Unit |
|---|---|---|
Proportional Gain | Proportional gain of the DC Link/active power/reactive power voltage PI controller. | - |
Integral Gain | Integral gain of the DC Link/active power/ reactive power voltage PI controller | - |
Rate Limiter Tab
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Name | Description | Unit |
|---|---|---|
Enable Rate Limiters | Select to apply rate limiters on DC-Link voltage, real, and reactive power commands | |
Maximum Increase Rate for Active Power/Reactive Power/DC Link Voltage Reference | Limits the output active power and/or reactive power and/or DC Link voltage to the desired maximum increase rate. | pu/s |
Maximum Decrease Rate for Active Power/Reactive Power/DC Link Voltage Reference | Limits the output active power and/or reactive power and/or DC Link voltage to the desired maximum decrease rate. | pu/s |
Inputs, Outputs and Signals Available for Monitoring
Inputs
Name | Description | Unit |
|---|---|---|
Pr | The reference value of active power (unavailable when DC Link Control mode is activated) | pu |
P | Active power measurement (available when the Primary Active Power Control Method is set to AC Side (Closed Loop).) | pu |
Qr | The reference value of reactive power | pu |
Q | Reactive Power measurement (available when Primary Reactive Power Control Method is set to AC Side (Closed Loop)) | pu |
Vdcr | DC-link voltage reference (available when the Primary Active Power Control Method is set to DC Link.) | V |
Vdc | DC-link voltage measurement (available when the Primary Active Power Control Method is set to DC Link.) | V |
Vrms | Average of the RMS value of the three-phase grid voltages | pu |
Prd | Active Power reference of the DC link (available when the Primary Active Power Control Method is set to DC Link.) | |
Disable | Signal that controls the output of the primary control block. When Disable = 1, the outputs are forced to 0 | - |
Reset | The signal used to reset the controller(s). When Reset = 1, the controller is reset | - |
VRTm | Voltage ride-through input to enable momentary cessation (when VTRm = 2, the power reference is set to zero internally) | - |
Outputs
Name | Description | Unit |
|---|---|---|
Ip | Peak value of the single-phase current component representing the real power (3x1 vector with identical values) | pu |
Iq | Peak value of the single-phase current component representing the reactive power (3x1 vector with identical values) | pu |
Description
The following figure represents the schematic diagram of the inside of the primary control block:
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The active and reactive current component signals are passed through the rate limiters to limit their rate of increase/decrease for active power reference/reactive power reference/ DC link voltage reference.
Limitations
The Primary Control block is intended to be used with balanced three-phase systems.
References
T. Krein, J. Bentsman, R. M. Bass and B. L. Lesieutre, “On the Use of Averaging for the Analysis of Power Electronics Systems,” IEEE Transactions on Power Electronics, vol. 5, pp. 182–190, Apr 1990.
Timbus, M. Liserre, R. Teodorescu, P. Rodriguez and F. Blaabjerg, “Evaluation of Current Controllers for Distributed Power Generation Systems,” IEEE Transactions on Power Electronics, vol. 24, no. 3, pp. 654–664, Mar 2009.
IEEE Std. 1547-2003, IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems, 2003.
A. Ninad and L. A. C. Lopes, “A Low Power Utility Interactive Inverter for Residential PV generation with Small DC Link Capacitor,” in Proceeding of 3rd Canadian Solar Building Conference, Fredericton, Canada, pp. 28-36, Augt 2008.
Bower and M. Ropp, “Evaluation of Islanding Detection Methods for Utility-Interactive Inverters in Photovoltaic Systems” SANDIA Report SAND2002-3591, Albuquerque, NM: Sandia National Labs, Nov 2002.
Ye, A. Kolwalkar, Y. Zhang, P. Du and R. Walling, “Evaluation of Anti-islanding Schemes Based on Non-detection Zone Concept,” IEEE Transactions on Power Electronics, vol. 19, no. 5, pp. 1171–1176, Sep 2004.
Ropp, M. Begovic and A. Rohatgi, “Analysis and Performance Assessment of the Active Frequency Drift Method of Islanding Prevention,” IEEE Transaction on Energy Conversion, vol. 14, no. 3, pp. 810–816, Sep1999.
A. C. Lopes and H. Sun, “Performance Assessment of Active Frequency Drifting Islanding Detection Methods,” IEEE Transactions on Energy Conversion, vol. 21, no. 1, pp. 171–180, Mar 2006 .
Ye, R. Walling, L. Garces, R. Zhou, L. Li and T. Wang, “Study and Development of Anti-Islanding Control for Grid-Connected Inverters,” Report NREL/SR-560-36243, Golden, CO: National Renewable Energy Laboratory, May 2004.
Yafaoui, B. Wu, and S. Kouro, “Improved Active Frequency Drift Anti-islanding Detection Method for Grid Connected Photovoltaic Systems,” IEEE Transactions on Power Electronics, vol. 27, no. 5, pp. 2367-2375, May 2012.
Stevens, R. Bonn, J. Ginn, S. Gonzalez and G. Kern, “Development and Testing of an Approach to Anti-Islanding in Utility-Interconnected Photovoltaic Systems,” Sandia National Laboratories, Tech. Rep. SAND2000-1939, Aug 2000.
Mulhausen, J. Schaefer, M. Mynam, A. Guzman and M. Donolo, “Anti-Islanding Today, Successful Islanding in the Future,” in 63rd Annual Conference for Protective Relay Engineers, pp. 1–8, Mar 2010.
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