Selecting and sizing transformer and AC cable for PV system's safe and reliable operation

Abstract

Summary Single phase loss (SPL) and nuisance tripping are common causes of disrupting the safe and reliable operation of utility interactive photovoltaic (PV) systems. A missed SPL may degrade and damage equipment as well as put utility repair crew in danger. Similarly, nuisance tripping may result in generation and revenue loss. Hence, it is critical for PV systems to detect SPL and take corrective actions (in the form of anti‐islanding) while minimizing erroneous tripping. However, PV systems can miss SPL and trip erroneously if not properly designed by carefully considering the transformer and alternating current (AC) cable from the inverter to the point of common coupling (PCC). To solve this issue, this paper proposes a design procedure to select and size transformer and AC cable for successful detection of SPL while ensuring minimum nuisance tripping of PV systems. The outlined design procedure is validated through MATLAB/Simulink simulations and field tests of 30‐ and 220‐kW utility interactive PV systems. Results show that the outlined procedure can successful detect SPL and minimize nuisance tripping, ie, improving safety and increasing revenue.

Optimization Method for the Internal Distribution Network of a Photovoltaic Plant Using Genetic Algorithm

“…The correct sizing of cables is of paramount importance to guarantee the correct operation and safety of the system for years. The proposed sizing follows national regulations in Brazil NBR 5410 and international regulations IEC 60364-5-52 [24][25]. Formula 1 shows the correct current correction of a base project [24][25].…”

“…The proposed sizing follows national regulations in Brazil NBR 5410 and international regulations IEC 60364-5-52 [24][25]. Formula 1 shows the correct current correction of a base project [24][25].…”

“…After correcting the rated current, the cable manufacturer must be chosen and its respective rated conductor current informed by the manufacturer respecting the installation method must be greater than the corrected project current, according to Formula 2. [24][25] 𝐼𝑏 = 𝐼𝑝 /(𝑘1 * 𝑘2 * 𝑘3)…”

“…Where: The voltage drop in a cable must be calculated to ensure compliance with technical standards, and it is also one of the criteria that the cable must meet to ensure the safety of the entire system [25][26]. Formula 3 and 4 show how to calculate the voltage drop of a conductor and the percentage voltage drop should never exceed 5% [25][26].…”