How do you sync power electronics with other electrical systems?

1 Synchronization basics

Synchronization means that two or more electrical systems operate at the same frequency, phase, and voltage. This is essential to avoid power quality issues, such as harmonics, flicker, voltage sag, and instability. Synchronization can be achieved by using a common reference signal, such as a grid voltage or a phase-locked loop (PLL), or by using a communication network, such as a wireless or wired protocol. The synchronization method depends on the type, configuration, and function of the power electronics and the other electrical systems.

2 Grid-tied power electronics

Grid-tied power electronics are connected to the utility grid and need to match its frequency, phase, and voltage. This is usually done by using a grid-synchronized inverter, which converts the direct current (DC) output of the power source, such as a solar panel or a battery, to an alternating current (AC) output that follows the grid waveform. The inverter uses a PLL to sense and track the grid voltage and adjust its output accordingly. The inverter also needs to comply with the grid codes and regulations, such as the maximum power point tracking (MPPT), the anti-islanding protection, and the fault ride-through capability.

3 Stand-alone power electronics

Stand-alone power electronics are not connected to the grid and need to generate their own AC output for the loads. This is usually done by using an oscillator-based inverter, which produces a sinusoidal waveform with a fixed or variable frequency, phase, and voltage. The inverter uses a feedback control system to regulate its output based on the load demand and the power source condition. The inverter also needs to coordinate with other stand-alone power electronics, such as parallel inverters or converters, to form a microgrid or a hybrid system.

4 Power electronics with transformers

Power electronics with transformers are used to step up or step down the voltage level of the AC output or input. This is usually done by using a transformer-based converter, which consists of a rectifier, a DC link, and an inverter. The converter can operate in different modes, such as buck, boost, or bidirectional, depending on the direction and magnitude of the power flow. The converter needs to sync its input and output with the transformer and the other electrical systems by using a control strategy, such as the pulse-width modulation (PWM), the space vector modulation (SVM), or the resonant converter.

5 Power electronics with generators

Power electronics with generators are used to interface the mechanical energy of the prime mover, such as a wind turbine or a diesel engine, with the electrical energy of the load or the grid. This is usually done by using a generator-based converter, which consists of a rectifier, a DC link, and an inverter. The converter can control the speed, torque, and power factor of the generator by using a vector control or a direct torque control. The converter also needs to sync its input and output with the generator and the other electrical systems by using a PLL, a communication network, or a droop control.

6 Power electronics with sensors

Power electronics with sensors are used to measure and monitor the electrical parameters, such as the current, voltage, frequency, and power, of the power electronics and the other electrical systems. This is usually done by using a sensor-based circuit, which consists of a transducer, a signal conditioner, and an analog-to-digital converter (ADC). The circuit can process and transmit the sensor data by using a filter, an amplifier, or a microcontroller. The circuit needs to sync its input and output with the power electronics and the other electrical systems by using a sampling rate, a resolution, or a calibration.

7 Here’s what else to consider

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