# Evaluation of the Reactive Power Support Capability and Associated Technical Costs of Photovoltaic Farms’ Operation

^{1}

^{2}

^{*}

^{†}

## Abstract

**:**

## 1. Introduction

## 2. PV Farm Models

#### 2.1. Single-Stage PV Farm Model

#### 2.2. Two-Stage PV Farm Model

## 3. Methodology

#### 3.1. Flowcharts

#### 3.2. PV System Losses

#### 3.3. Technical Costs

## 4. Operation without Reactive Power Support

#### 4.1. Single-Stage PV Farm Losses without Reactive Power Support

#### 4.2. Two-Stage PV Farm Losses without Reactive Power Support

## 5. Operation with Reactive Power Support

#### 5.1. Reactive Power Support Capability Area

#### 5.2. PV Farm Losses with Reactive Power Support

#### 5.3. Technical Cost for Reactive Power Support

#### 5.4. Reactive Power Support Economics

## 6. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

- SolarPower Europe. Global Market Outlook for Solar Power 2015–2019; Technical Report; Euoropean Photovoltaic Industry Association: Bruxelles, Belgium, 2015. [Google Scholar]
- Quitmann, E.; Erdmann, E. Power system needs—How grid codes should look ahead. IET Renew. Power Gener.
**2014**, 9, 3–9. [Google Scholar] [CrossRef] - Industrial Standards Committee. IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems; IEEE Standard 1547; Institute of Electrical and Electronics Engineers: New York, NY, USA, 2003. [Google Scholar]
- European Standard. Voltage Characteristics of Public Distribution Systems; EN Standard 50160; EN: Bruxelles, Belgium, 2004. [Google Scholar]
- Technischen Richtlinie Erzeugungsanlagen am Mittelspannungsnetz. Richtlinie für Anschluss und Parallelbetrieb von Erzeugungsanlagen am Mittelspannungsnetz. Available online: http://www.megamonheim.de/assets/bdew_rl_ea-am-ms-netz_juni_2008_end.pdf (accessed on 12 June 2018).
- Gil, J.B.; San Román, T.G.; Rios, J.A.; Martin, P.S. Reactive power pricing: A conceptual framework for remuneration and charging procedures. IEEE Trans. Power Syst.
**2000**, 15, 483–489. [Google Scholar] - Thomas, R.J.; Mount, T.D.; Schuler, R.; Schulze, W.; Zimmerman, R.; Alvarado, F.; Lesieutre, B.C.; Overholt, P.N.; Eto, J.H. Efficient and reliable reactive-power supply and consumption: Insights from an integrated program of engineering and economic research. Electr. J.
**2008**, 21, 70–81. [Google Scholar] [CrossRef] - Chattopadhyay, D.; Chakrabarti, B.B.; Read, E.G. A spot pricing mechanism for voltage stability. Int. J. Electr. Power Energy Syst.
**2003**, 25, 725–734. [Google Scholar] [CrossRef] - Amjady, N.; Rabiee, A.; Shayanfar, H. Pay-as-bid based reactive power market. Energy Convers. Manag.
**2010**, 51, 376–381. [Google Scholar] [CrossRef] - Hinz, F.; Moest, D. Techno-economic Evaluation of 110 kV Grid Reactive Power Support for the Transmission Grid. IEEE Trans. Power Syst.
**2018**. [Google Scholar] [CrossRef] - Gabash, A.; Li, P. Active-reactive optimal power flow in distribution networks with embedded generation and battery storage. IEEE Trans. Power Syst.
**2012**, 27, 2026–2035. [Google Scholar] [CrossRef] - Varma, R.K.; Khadkikar, V.; Seethapathy, R. Nighttime application of PV solar farm as STATCOM to regulate grid voltage. IEEE Trans. Energy Convers.
**2009**, 24, 983–985. [Google Scholar] [CrossRef] - Varma, R.K.; Rahman, S.A.; Mahendra, A.; Seethapathy, R.; Vanderheide, T. Novel nighttime application of PV solar farms as STATCOM (PV-STATCOM). In Proceedings of the IEEE Power and Energy Society General Meeting, San Diego, CA, USA, 22–26 July 2012; pp. 1–8. [Google Scholar]
- Varma, R.K.; Das, B.; Axente, I.; Vanderheide, T. Optimal 24-hr utilization of a PV solar system as STATCOM (PV-STATCOM) in a distribution network. In Proceedings of the IEEE Power and Energy Society General Meeting, San Diego, CA, USA, 24–29 July 2011; pp. 1–8. [Google Scholar]
- Varma, R.K.; Rahman, S.A.; Vanderheide, T. New control of PV solar farm as STATCOM (PV-STATCOM) for increasing grid power transmission limits during night and day. IEEE Trans. Power Deliv.
**2015**, 30, 755–763. [Google Scholar] [CrossRef] - Mulolani, F.; Armstrong, M.; Zahawi, B. Modeling and simulation of a grid-connected photovoltaic converter with reactive power compensation. In Proceedings of the 9th International Symposium on Communication Systems, Networks & Digital Signal Processing (CSNDSP), Manchester, UK, 23–25 July 2014; pp. 888–893. [Google Scholar]
- Romero-Cadaval, E.; Francois, B.; Malinowski, M.; Zhong, Q.C. Grid-connected photovoltaic plants: An alternative energy source, replacing conventional sources. IEEE Ind. Electron. Mag.
**2015**, 9, 18–32. [Google Scholar] [CrossRef] - Albuquerque, F.L.; Moraes, A.J.; Guimarães, G.C.; Sanhueza, S.M.; Vaz, A.R. Photovoltaic solar system connected to the electric power grid operating as active power generator and reactive power compensator. Sol. Energy
**2010**, 84, 1310–1317. [Google Scholar] [CrossRef] - Samadi, A.; Ghandhari, M.; Söder, L. Reactive power dynamic assessment of a PV system in a distribution grid. Energy Procedia
**2012**, 20, 98–107. [Google Scholar] [CrossRef] - Blaabjerg, F.; Teodorescu, R.; Liserre, M.; Timbus, A.V. Overview of control and grid synchronization for distributed power generation systems. IEEE Trans. Ind. Electron.
**2006**, 53, 1398–1409. [Google Scholar] [CrossRef] - Gabash, A.; Li, P. Active-reactive optimal power flow for low-voltage networks with photovoltaic distributed generation. In Proceedings of the 2012 IEEE International Energy Conference and Exhibition (ENERGYCON), Florence, Italy, 9–12 September 2012; pp. 381–386. [Google Scholar]
- Ullah, N.R.; Bhattacharya, K.; Thiringer, T. Wind farms as reactive power ancillary service providers—Technical and economic issues. IEEE Trans. Energy Convers.
**2009**, 24, 661–672. [Google Scholar] [CrossRef] - Jung, S.; Jang, G. A Loss Minimization Method on a reactive power supply process for Wind Farm. IEEE Trans. Power Syst.
**2017**, 32, 3060–3068. [Google Scholar] [CrossRef] - Zhang, B.; Hu, W.; Hou, P.; Tan, J.; Soltani, M.; Chen, Z. Review of Reactive Power Dispatch Strategies for Loss Minimization in a DFIG-based Wind Farm. Energies
**2017**, 10, 856. [Google Scholar] [CrossRef] - Gabash, A.; Li, P. Evaluation of reactive power capability by optimal control of wind-vanadium redox battery stations in electricity market. Renew. Energy Power Qual. J.
**2011**, 1–6. [Google Scholar] [CrossRef] - Gabash, A.; Li, P. On variable reverse power flow—Part I: Active-Reactive optimal power flow with reactive power of wind stations. Energies
**2016**, 9, 121. [Google Scholar] [CrossRef] - Gabash, A.; Li, P. On variable reverse power flow—Part II: An electricity market model considering wind station size and location. Energies
**2016**, 9, 235. [Google Scholar] [CrossRef] - Lourenço, L.F.N. Technical Cost of Operating a PV Installation as a STATCOM during Nightime. Master’s Thesis, Universidade de São Paulo, São Paulo, Brazil, 2017. [Google Scholar]
- Lourenço, L.F.N.; Salles, M.B.C.; Monaro, R.M.; Quéval, L. Technical Cost of Operating a Photovoltaic Installation as a STATCOM at Nighttime. IEEE Trans. Sustain Energy
**2018**. [Google Scholar] [CrossRef] - Lourenço, L.F.N.; Salles, M.B.C.; Monaro, R.M.; Quéval, L. Technical cost of PV-STATCOM applications. In Proceedings of the 2017 IEEE 6th International Conference on Renewable Energy Research and Applications (ICRERA), San Diego, CA, USA, 5–8 November 2017; pp. 534–538. [Google Scholar]
- Blaabjerg, F.; Chen, Z.; Kjaer, S.B. Power electronics as efficient interface in dispersed power generation systems. IEEE Trans. Power Electron.
**2004**, 19, 1184–1194. [Google Scholar] [CrossRef] - Kouro, S.; Leon, J.I.; Vinnikov, D.; Franquelo, L.G. Grid-connected photovoltaic systems: An overview of recent research and emerging PV converter technology. IEEE Ind. Electron. Mag.
**2015**, 9, 47–61. [Google Scholar] [CrossRef] - Yazdani, A.; Di Fazio, A.R.; Ghoddami, H.; Russo, M.; Kazerani, M.; Jatskevich, J.; Strunz, K.; Leva, S.; Martinez, J.A. Modeling guidelines and a benchmark for power system simulation studies of three-phase single-stage photovoltaic systems. IEEE Trans. Power Deliv.
**2011**, 26, 1247–1264. [Google Scholar] [CrossRef] - De Brito, M.A.; Sampaio, L.P.; Luigi, G.; e Melo, G.A.; Canesin, C.A. Comparative analysis of MPPT techniques for PV applications. In Proceedings of the 2011 International Conference on Clean Electrical Power (ICCEP), Ischia, Italy, 14–16 June 2011; pp. 99–104. [Google Scholar]
- Huang, L.; Qiu, D.; Xie, F.; Chen, Y.; Zhang, B. Modeling and Stability Analysis of a Single-Phase Two-Stage Grid-Connected Photovoltaic System. Energies
**2017**, 10, 2176. [Google Scholar] [CrossRef] - Blaabjerg, F.; Jaeger, U.; Munk-Nielsen, S. Power losses in PWM-VSI inverter using NPT or PT IGBT devices. IEEE Trans. Power Electron.
**1995**, 10, 358–367. [Google Scholar] [CrossRef] - Hansen, A.D.; Michalke, G. Modelling and control of variable-speed multi-pole permanent magnet synchronous generator wind turbine. Wind Energy
**2008**, 11, 537–554. [Google Scholar] [CrossRef] - Liserre, M.; Blaabjerg, F.; Dell’Aquila, A. Step-by-step design procedure for a grid-connected three-phase PWM voltage source converter. Int. J. Electron.
**2004**, 91, 445–460. [Google Scholar] [CrossRef] - Fronius International GmbH Solar Energy Division. Sizing the Maximum DC Voltage of PV Systems; Fronius International GmbH Solar Energy Division: Wels, Austria, 2015. [Google Scholar]
- Martinez, J.A.; Mork, B.A. Transformer modeling for low-and mid-frequency transients—A review. IEEE Trans. Power Deliv.
**2005**, 20, 1625–1632. [Google Scholar] [CrossRef] - Blaabjerg, F.; Pedersen, J.K.; Sigurjonsson, S.; Elkjaer, A. An extended model of power losses in hard-switched IGBT-inverters. In Proceedings of the Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting (IAS’96), San Diego, CA, USA, 6–10 October 1996; Volume 3, pp. 1454–1463. [Google Scholar]
- Rajapakse, A.; Gole, A.; Wilson, P. Electromagnetic transients simulation models for accurate representation of switching losses and thermal performance in power electronic systems. IEEE Trans. Power Deliv.
**2005**, 20, 319–327. [Google Scholar] - Wong, C. EMTP modeling of IGBT dynamic performance for power dissipation estimation. IEEE Trans. Ind. Appl.
**1997**, 33, 64–71. [Google Scholar] [CrossRef] - Drofenik, U.; Kolar, J.W. A general scheme for calculating switching-and conduction-losses of power semiconductors in numerical circuit simulations of power electronic systems. In Proceedings of the 2005 International Power Electronics Conference (IPEC 9205), Niigata, Japan, 4–8 April 2005; pp. 4–8. [Google Scholar]
- Munk-Nielsen, S.; Tutelea, L.N.; Jaeger, U. Simulation with ideal switch models combined with measured loss data provides a good estimate of power loss. In Proceedings of the Conference Record of the IEEE Industry Applications Conference, Rome, Italy, 8–12 October 2000; Volume 5, pp. 2915–2922. [Google Scholar]
- Cole, S. Steady-State and Dynamic Modelling of VSC HVDC Systems for Power System Simulation. Ph.D. Thesis, Katholieke Universiteit Leuven, Leuven, Belgium, 2010. [Google Scholar]
- Haghighat, H.; Kennedy, S. A model for reactive power pricing and dispatch of distributed generation. In Proceedings of the IEEE Power and Energy Society General Meeting, Providence, RI, USA, 25–29 July 2010; pp. 1–10. [Google Scholar]
- Tarifas de Energia de Otimização e de Serviços Ancilares para 2018 (Optimization and Ancillary Services Tariffs for 2018). Available online: http://www.aneel.gov.br/sala-de-imprensa-exibicao-2/-/asset_publisher/zXQREz8EVlZ6/content/fixadas-as-tarifas-de-energia-de-otimizacao-e-de-servicos-ancilares-para-2018/656877?inheritRedirect=false (accessed on 7 June 2018).

**Figure 8.**Single-stage PV farm losses per component, without reactive power support. The losses without reactive power support are approximately linear as a function of the irradiance.

**Figure 9.**Two-stage PV farm losses per component for various ${v}_{dc}$, without reactive power support. (

**a**) At 720 V; (

**b**) at 750 V; (

**c**) at 800 V. The losses without reactive power support are approximately linear as a function of the irradiance.

**Figure 13.**Two-stage PV farm losses per component at 500 W/m${}^{2}$ for various ${v}_{dc}$, with reactive power support. (

**a**) At 720 V; (

**b**) at 750 V; (

**c**) at 800 V. The losses with reactive power support are approximately a quadratic function of the reactive power reference value.

**Figure 14.**Single-stage PV farm losses per component at 500 W/m${}^{2}$, with reactive power support. The losses with reactive power support are approximately a quadratic function of the reactive power reference value.

**Figure 15.**Technical costs of providing reactive power support at 500 W/m${}^{2}$ for both PV farms, as a percentage of the rated power. Despite losses from two-stage PV farms being higher, the technical costs are similar for both topologies.

**Figure 16.**Reactive support capability areas with associated technical costs: (

**a**) Single-stage; (

**b**) Two-stage at 720 V; (

**c**) Two-stage at 750 V; (

**d**) Two-stage at 800 V. At 1000 W/m${}^{2}$, there is no reactive power capability since full converter capacity is being used to inject active power.

**Figure 17.**Hourly average solar irradiance data and reactive power dispatch for estimation of the reactive power support revenue. The base value considered for the solar irradiance is 1000 W/m${}^{2}$ and for reactive power is 850 kVAr.

**Figure 18.**Technical costs for the test systems following the reactive power dispatch and daily irradiation cycle presented in Figure 17.

Parameter | Value | Unit | Parameter | Value | Unit | Parameter | Value | Unit |
---|---|---|---|---|---|---|---|---|

Rated power | 850 | kW | ${v}_{\Delta}$ | 380 | V | ${R}_{f}$ | 0.5 | $\mathsf{\Omega}$ |

${v}_{pv}$ @1000 W/m${}^{2}$ | 798 | V | f | 50 | Hz | ${L}_{f}$ | 397.8 | $\mathsf{\mu}$H |

C | 87.8 | mF | ${r}_{r}$ | 1 | m$\mathsf{\Omega}$ | ${C}_{f}$ | 0.64 | $\mathsf{\mu}$F |

${L}_{r}$ | 54.1 | $\mathsf{\mu}$H | ||||||

Component | Reference | Series modules | Parallel modules | Total | ||||

PV module | Kyocera Solar KD205GX-LP | 30 | 138 | 4.140 | ||||

DC/AC converter | ABB 5SNA1600N170100 IGBT | 1 | 2 | 12 |

Parameter | Value | Unit | Parameter | Value | Unit | Parameter | Value | Unit |
---|---|---|---|---|---|---|---|---|

Rated power | 850 | kW | ${v}_{\Delta}$ | 380 | V | f | 50 | Hz |

${v}_{pv}$ @ 1000 W/m${}^{2}$ | 691 | V | ${r}_{DC}$ | 1 | m$\mathsf{\Omega}$ | ${R}_{f}$ | 0.5 | $\mathsf{\Omega}$ |

C, ${C}_{pv}$ | 87.8 | mF | ${L}_{DC}$ | 5.0 | mH | ${L}_{f}$ | 397.8 | $\mathsf{\mu}$H |

${r}_{r}$ | 1 | m$\mathsf{\Omega}$ | ${L}_{r}$ | 54.1 | $\mathsf{\mu}$H | ${C}_{f}$ | 0.64 | $\mathsf{\mu}$F |

Component | Reference | Series modules | Parallel modules | Total | ||||

PV module | Kyocera Solar KD205GX-LP | 26 | 159 | 4.134 | ||||

DC/DC converter | ABB 5SNA1600N170100IGBT | 1 | 1 | 1 | ||||

DC/AC converter | ABB 5SNA1600N170100IGBT | 1 | 2 | 12 |

**Table 3.**Reactive power support economic feasibility evaluation. Revenue, expenses and profit are expressed in BRL.

Test System | Reactive Power (MVArh) | Technical Costs (MWh) | Revenue | Expenses | Profit |
---|---|---|---|---|---|

Single-stage | 8.59 | 0.046 | 59.06 | 46.53 | 12.16 |

Two-stage @720V | 8.59 | 0.045 | 59.06 | 45.57 | 13.12 |

Two-stage @750V | 8.59 | 0.047 | 59.06 | 47.18 | 11.51 |

Two-stage @800V | 8.59 | 0.049 | 59.06 | 48.93 | 9.75 |

© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Lourenço, L.F.N.; Monaro, R.M.; Salles, M.B.C.; Cardoso, J.R.; Quéval, L. Evaluation of the Reactive Power Support Capability and Associated Technical Costs of Photovoltaic Farms’ Operation. *Energies* **2018**, *11*, 1567.
https://doi.org/10.3390/en11061567

**AMA Style**

Lourenço LFN, Monaro RM, Salles MBC, Cardoso JR, Quéval L. Evaluation of the Reactive Power Support Capability and Associated Technical Costs of Photovoltaic Farms’ Operation. *Energies*. 2018; 11(6):1567.
https://doi.org/10.3390/en11061567

**Chicago/Turabian Style**

Lourenço, Luís F. N., Renato M. Monaro, Maurício B. C. Salles, José R. Cardoso, and Loïc Quéval. 2018. "Evaluation of the Reactive Power Support Capability and Associated Technical Costs of Photovoltaic Farms’ Operation" *Energies* 11, no. 6: 1567.
https://doi.org/10.3390/en11061567