documentclass[11pt, a4paper]{book}

usepackage{amsmath}
usepackage{amssymb, amsfonts}

usepackage{makecell}
usepackage{multirow}


newlength{arraycolsepdefaultl}
setlength{arraycolsepdefaultl}{2.12mm}
newcommand{arraycolsepdefault}{ setlength{arraycolsep}{arraycolsepdefaultl} }
arraycolsepdefault

newcommand {arraystretchdefaultl} {1.3}
newcommand{arraystretchdefault}{ renewcommand {arraystretch} {arraystretchdefaultl} }
arraystretchdefault


usepackage{bm}

begin{document}

begin{equation}
setlength{arraycolsep}{1.06mm}
left[
    begin{array}{c}
        V_{1}
        \
        vdots
        \
        V_{k}
        \
        vdots
        \
        V_{p}
        \
        vdots
        \ Xhline{0.25mm}
        0
    end{array}
right]
%
=
%
renewcommand{arraystretch}{1.7}
left[
    begin{array}{c >{medspace}c !{vrule width 0.25mm}>{medspace}c}
        multirow{5}{=}{centering LARGE $bm{Z}_{orig}$} & &  multirow{5}{=}{centering $col. thinspace k - col. thinspace p$}
        \
        & &
        \
        & &
        \
        & &
        \
        & &
        \
        Xhline{0.25mm}
        row. thinspace k - row. thinspace p & & Z_{th, thinspace kp} + Z_{b}
    end{array}
right]
arraystretchdefault
left[
    begin{array}{c}
        I_{1}
        \
        vdots
        \
        I_{k}
        \
        vdots
        \
        I_{p}
        \
        vdots
        \
        Xhline{0.25mm}
        I_{q}
    end{array}
right]
arraycolsepdefault
end{equation}

end{document}