How change headless codepage?

Hi everyone. I’ve been using LibreOffice headless for Liferay Portal(using soffice -headless -accept=“socket,host=,port=8100;urp;” -nofirststartwizard) for converting documents(doc,docx,xls and etc.) to html. From LibreOffice >4.4 to 5.1 it works fine. I edited LibreOffice 5\share\registry\main.xcd string from to 76 and utf-8 works fine. But in version it does not work. Files after libreoffice becoming with cp1251(Russian windows default codepage) and looks like this Is this bug? How can i change libreoffice use utf-8 permanently?