Power Supply Protection
DISCLAIMER: The content and information provided here is just recommendations and personal opinions. Do not take this infromation as fact, please do your own research or consult a professional.
Potential Power Issues:
Short Circuit: A common issue, a short is a electrical connection going where it is not suppose to. Sometimes it can only damage a controller or pixel, when a part of the circuit recieves a voltage level it should not have. A short accross the power supply power outputs(V+,common) is a 'dead-short', possibly damaging the power supply, while creating sparks and heat. A dead short will not always draw a lot of current, depending on the restistance of the short circuit. Possibly not tripping the power supplies internal over-load protection or fuses, this allows the cause of the short circuit to keep conducting and heat up. The result can be burning wire insulation, burning circuit boards, or a host of other issues.
Unconnected or Loose Connection: A loose connection can cause intermittent power issues, and if it were to come undone it could short to nearby contacts as well. A common issue is if the ground(common) wire comes undone from the power supply, the electrical system will try to find a ground(common) elsewhere. Possibly shorting through a data network such as the USB, DMX, or serial through other equipment such as transmitters and computers. Depending on the current, that will most likely damage or destroy the connected equipment.
Power Supply Internal Protection:
All power supplies will(or should) have very basic internal protections built into the power supply. These should not be relied upon in anyway for protection of the connected circuits. Protections may include short protection, over-load, under voltage. Typically depending on the quality of the supply these may not function as expected.
External Protection - Fuses:
https://www.littelfuse.com/about-us/education-center/fuses-vs-ptcs.aspx
https://hackaday.com/2018/01/29/the-engineering-case-for-fusing-your-led-strips/
Fuses: Most common solution, such as the tube cartridge and automotive blade fueses. Fuses can detect and protect against many types of power events, but not always expected way. Depends on many conditions and type of fuse, more than will be covered, so please research online. In regards to LEDs and pixels, a fuse can protect the system against dead shorts, but may not save the LEDs. Typically in LED systems the wires and connectors create resistance which reduces the amount of current that can flow during a short circuit. The reistance might be so high(and current low) that the fuse never blows. And instead overheats/burns/frys the cause of the short and surrounding components, such as strip PCB and LEDs.
Polyfuse or Resetable Fuses: An extremely complicated component, they have many specifications that all factor in to how and when it 'blows'. Really only suitable for low currents. They have some resistance, which can affect current and voltage drop, along with being temperature dependant, they may not function the same in different enviroments. Being resetable is handy, but power events that trip them should be very rare, and hopefully never happen. A lot of drawbacks and other issues, a regular fuse would probably be a better choice. Read up on them before considering using them in your project.