xml-schema-validator
This repository is a wrapper for https://github.com/openscd/xmlvalidate.js which is using libxml2 under the hood. It si running the worker, so your browser must support this feature.
Although this function can theoretically validate any XML it has been test with SCL files as defined by the IEC 61850-6. I would love to have additional test contributed to proof that other XML schemas are supported as well.