Measurement inside renewable-energy power conversion
Photovoltaic inverters, wind converters and stationary battery systems all depend on controlled energy conversion between DC and AC domains. At each conversion stage, current and voltage feedback supports regulation, protection, grid compliance and system supervision. Galvanic isolation is often structural because power stages operate at high or floating potentials relative to the low-voltage control electronics.
From PV strings to the grid
String current
DC current measurement supports production monitoring and fault detection at string or MPPT level.
DC-link voltage
Continuous isolated voltage supervision protects the conversion stage against overvoltage and maintains control stability.
Inverter / AC output current
Current feedback controls the injected current and supports overcurrent and grid-fault protection.
Grid voltage
Voltage measurement supports grid-code functions and anti-islanding logic.
Utility-scale PV systems can operate at DC voltages up to around 1,500 V, while compact string inverters often favour PCB-mounted sensing because internal space is limited.
Generator → converter → DC link → grid
Wind turbines use current feedback on the generator side for torque and speed control, DC-link voltage supervision between converter bridges, and grid-side current measurement for active/reactive power control. Medium-voltage supervision at the point of connection supports grid-code functions such as Low Voltage Ride-Through (LVRT).
Nacelle and tower-base electronics must tolerate long-duration vibration, thermal cycling and, in offshore systems, corrosive saline environments.
Bidirectional sensing in BESS architectures
Battery current
Bidirectional current measurement feeds charge/discharge protection and contributes to State-of-Charge estimation by coulomb counting.
DC-bus voltage
Voltage supervision supports system protection and PCS operating-point optimisation.
AC-side current
Measured at the PCS output to control power exchange with the grid or local load.
Grid voltage
Used to supervise supply quality in grid-connected, backup and microgrid operating modes.
Offset stability and thermal drift are particularly important in battery-current measurement because small errors accumulate over time in coulomb-counting based SOC estimation.
Reference framework
| Reference | Domain | Measurement relevance |
|---|---|---|
| IEC 62109-1/-2 | PV inverter safety | Isolation monitoring and shutdown functions |
| IEC 61400-21 | Wind power quality | Accuracy of grid-side measurements |
| IEC 61869 series | Instrument measurement | Accuracy classes for metering and protection |
| IEC 62619 | Stationary lithium-ion batteries | Fault detection within the battery-system measurement chain |
| IEC 60068 series | Environmental testing | Mechanical and climatic qualification |
| Grid codes | Grid connection | LVRT and voltage-monitoring requirements |
The sensor is only one part of the measurement chain
Response-time budget
Protection performance depends on sensor delay, ADC conversion and controller processing together.
EMC-aware wiring
Strong switching dv/dt and di/dt around IGBTs or MOSFETs require disciplined shielding, grounding and routing.
ADC full-scale matching
Sensor rating should use the controller's dynamic range efficiently while retaining headroom for transients.
Anti-alias filtering
Low-pass filtering must balance switching-noise attenuation with control-loop and protection response.
Different renewable segments weight the same criteria differently.
| Criterion | Solar PV | Wind | BESS |
|---|---|---|---|
| DC current capability | Essential | Mainly within DC link | Essential |
| Bidirectionality | Usually not dominant | Partial | Essential |
| Offset stability | Important | Moderate | Critical for SOC |
| Response / bandwidth | Moderate | High for grid response | High for protection |
| Environment | Temperature, high DC voltage | Vibration, corrosion, thermal cycling | Temperature, fault-current withstand |
In practice, one installation often combines several sensor technologies because no single approach gives the optimum balance of isolation, accuracy, bandwidth, cost and integration at every measurement point.
Translate the measurement requirement into the right sensing architecture.
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