 
            Phase Locked Loop PLL - Identification of the Instantaneous grid angle
4 Enrollments Level : AdvancedRelevance
Phase-Locked Loops (PLL) are control systems that synchronize an output signal's phase and frequency with those of an input signal. PLLs are widely used in communications, signal processing, and power electronics and are versatile and essential components in modern electronic systems, enabling precise control of frequency and phase in a wide range of applications from communications to power systems.
Abstract
This section covers the Phase Locked Loop (PLL) and its in identifying the instantaneous grid angle θ. It explains the purpose of a PLL, detailing its input and output quantities and how it integrates into the overall system. The discussion includes both three-phase and single-phase implementations, providing insight into their applications and benefits. An outlook section offers perspectives on future advancements and potential developments in PLL technology.
Learning Outcomes
Students
- have a clear understanding of the functionality and the purpose of a PLL 
- can implement PLL structures in simulations 
- can implement PLL structures as code 
in order to
- be enabled to apply PLL routines for grid connected applications 
- design and test single- and three-phase grid-voltage detections 
- to be enabled for step-by-step implementation including debugging steps 
Prior Knowledge
1. Inverter Leg Operation, Controller Interaction and Protection Features
2. H-Bride Operation
3. Basics on three-level converters
Keywords
- Frequency Synthesis
- Phase Detector
- Digital PLL DPLL
- Synchronization
Elements
1. About this Building Block
About this Building Block
2. Exercises
Exercises
3. Simulations
Simulations
4. Self-assessments
Self Assessment
Suggested Building Block
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                          Inverter Leg Operation, Controller Interaction and Protection Features5 EnrollmentsThis segment focuses on inverter leg operation, exploring topology, current behavior, and both transient and steady-state responses. Key topics include voltage transfer ratio, inductor current control, and synchronous sampling. It also examines the influence of digital controllers, highlighting control parameter settings. Essential protection features covered are Over Current Protection (OCP), Over Voltage Protection (OVP), and Over Temperature Protection (OTP). 
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                          H-Bridge Converter as single-phase, grid-coupled DC AC Converter6 EnrollmentsThis section focuses on the H-Bridge converter, a versatile topology used as a single-phase, grid-coupled DC/AC converter. Also known as an H4 or Full Bridge, this configuration includes two inverter legs and supports four-quadrant operation. Initially, it is explored as a DC/DC converter with various modulation possibilities. As a DC-AC converter, the same topology is applied with a focus on slowly modulating a sinusoidal waveform, accounting for ripple at twice the mains frequency. 
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                          Three-Phase DC AC Converter - Topologies and Tasks in PV and Wind Energy Systems, Modulation with Orthogonal Signals5 EnrollmentsThis section examines three-phase DC/AC converter topologies and their in photovoltaic and wind energy systems, focusing on modulation with orthogonal signals. It discusses applications of three-phase converters without filter capacitance linked to the DC-link, commonly used in wind energy. PWM modulation techniques are explored in depth. The section also analyzes three-phase converters with filter capacitance connected to the DC-link, typically used in PV systems, highlighting key differences. Additionally, it looks into alternative three-phase topologies. 
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                          Filter Inductor Current Control of Three-Phase Converters6 EnrollmentsThis section addresses filter inductor current control in three-phase converters, utilizing the rotary reference frame and Park Transformation to manage dq components. It tackles the challenge of controlling AC variables and selecting appropriate controllers, highlighting how the Park Transformation facilitates the control loop closure and simplifies regulating DC components. Special attention is given to handling the zero-system and the use of the reference system θ in transformations. The section explores an alternative regulatory approach and discusses determining the magnitude of the 150Hz zero system in PV converters. 
