Technical Article

Voltage and Current Measurement Technology for PV Energy Management Systems

September 02, 2021 by

To increase the efficiency of solar power energy, the voltage of the DC power line is upgraded from DC1000V to DC1500V. The increased power generation voltage is certainly attractive, but the insulation rating of the entire PV system should be increased and the equipment involved should also be able to operate at higher voltages.

This situation raises the need for high-precision voltage and current sensors for DC1500V power lines. J&D designed a voltage sensor to provide high insulation technology that can withstand 1500V, enabling high precision using Ultra Precision Zero-Driftv Op Amps.

1. DC 1500V high accuracy voltage sensor; IDVT-series. Hybrid design using reinforced isolation amplifier technology and Ultra Precision Zero-Driftv Op Amps

The temperature of the Solar power plant usually rises to 40˚ in the summer day. In addition, the temperature inside the Distribution board can reach 100 degrees in the worst case. Therefore, the voltage sensor must maintain accuracy even at these high temperatures. J&D's voltage sensor was developed with high voltage isolation reinforced amplifier technology. Voltage Sensors – IDVT series begins with an internal High voltage resistor network. This network measures DC Voltage by directly contacting both the Positive High Voltage (+HT) and the Negative High Voltage (-HT). This Voltage signal is transmitted to the secondary side of the sensor through an insulated Reinforced transformer that isolates the Primary High Voltage from the Secondary Low Voltage. The resulting signal is then converted through an auto-zeroing techniques amplifier into either Voltage signal. Therefore, the circuit converts a primary Voltage into a secondary Voltage that is proportional to the input.

The reinforced isolation amplifier technology and the hybrid design using Ultra Precision Zero-Driftv Op Amps not only maintain high accuracy at high temperatures, but also achieve accuracy with 5V to 30V free wide range voltage. When you refer to figure 1-1 you can find that the Voltage sensor can provide high precision despite the high temperature.

Features:

(1) Power consumption : 5V

(2) Input voltage : DC1500V

(3) Output voltage : ± 0.5V

(4) Accuracy : 0.5%

(5) Ambient Operating temperature : -40˚ to +105˚ (Reference Figure 1-1)

Figure 1: Temperature accuracy data

2. High-insulation and High-accuracy current sensor JPS-H Series for DC1500V power line monitoring. Temperature Reinforced Amplifier Technology

J&D, the first in the world, has developed a product designed with high insulation so that it can be used stably in the DC 1500V line. JPS-H is a sensor that develops input voltage from 600V to 1500V and is a product that has obtained PD2 certification and CATIII 1500V certification of IEC-61010-1. JPS-H series begins with an internal Insulation distance design split core technology network. This network is measured using two hall elements and a permalloy core based on advanced open loop technology and resulting signal is then converted through an auto-zeroing techniques amplifier into either Voltage signal. A split-core sensor that can be easily installed on a cable and designed by hybridizing Hall element twin technology and Ultra Precision Zero-Driftv Op Amps is designed to maintain high precision even at high temperatures. This can solve problems of high operating temperatures because it is installed where solar power is maximized for the best energy capture performance due to the feature of the PV system. 0.5% accuracy can be achieved even with a low power consumption which is 5V to 30V free wide voltage. Also, figure 1-2 shows High accuracy of current measurement is possible even at high temperature.

Features:

(1) Power consumption : 5V

(2) Rated current : DC 400A

(3) Output voltage: ± 0.5V

(4) Accuracy : 0.5%

(5) Ambient Operating temperature : -40˚ to +105˚ (Reference Figure 1-2)

Figure 2. IDVT, JPS product image and schematic diagram

3. J&D's options. CTid technology and UI

Increasing demand for green energy is one of the driving forces behind the adoption of PV DC1500V power. In addition, as the amount of energy supplied from renewable energy such as PV power increases, power lines must be measured in high quality efficiency and critical power protection is always important for abnormal situations, from solar panels to PV inverter systems. Solar panels commonly use a PV Inverter that works with the DC-DC converter to connect the generated power to the grid. However, a common problem of power electronics is the generation and emission of harmonic currents, which dramatically reduce the quality of the injected current. To identify this issue, it is very important to measure the power quality and efficiency by measuring the voltage and current of the DC 1500V line. In addition, one of the main considerations is to ensure system reliability and safety under all environmental conditions and temperatures when converting primary voltage and current from DC to AC.

J&D Electronics plans to launch J&D's voltage and current sensor and eGauge meters that can be used for DC1500V power lines all over the world. J&D's voltage and current sensors can optionally built-in eGauge's CTid technology. If you use the voltage sensor IDVT series and the current sensor JPS-H series which built-in CTid technology together with a gateway AC/DC energy meter using eGauge's CTid technology, you can operate a solar power plant with stable power.