documentclass[11pt, a4paper]{book}
usepackage{makecell}
usepackage{amsmath}
usepackage{amssymb, amsfonts}
usepackage{graphicx}
usepackage{float}
usepackage{tabularx}
usepackage{booktabs}
usepackage{adjustbox}

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

usepackage[showframe = true]{geometry}

begin{document}

    begin{equation}
    left[
        begin{array}{c}
        V_{i} \ midrule[0.25mm]
        0
        end{array}
    right]
    %
    =
    %
    left[
        begin{array}{c c!{vrule width 0.25mm} c c}
        & Z_{orig} &  & col. medspace k - col. medspace p \ Xcline{1-4}{0.25mm}
        & row. medspace k - row. medspace p & & Z_{th,kp}+Z_{b}\
        end{array}
    right]
    %
    left[
        begin{array}{c}
        I_{i} \ midrule[0.25mm]
        I_{q}
        end{array}
    right]
end{equation}


begin{adjustbox}{width=1textwidth, center}

    begin{minipage}{1textwidth}
    %
        begin{equation}
        %
                %
                renewcommand{arraystretch}{1.1}
                left[
                    begin{array}{c}
                        V_{1} \
                        vdots \
                        V_{l} \
                        vdots \
                        V_{k} \
                        vdots \
                        V_{p} \
                        vdots \
                        vdots \ midrule[0.25mm]
                        0 \
                    end{array}
                right]
                =
                renewcommand{arraystretch}{1.1}
                left[
                    begin{array}{c c c c c c c c c !{vrule width 0.25mm}c}
                        & & & & & Z_{1k} & dotsm & Z_{1p} & dotsm & Z_{1k} - Z_{1p} \
                        & & scalebox{1}{$Z_{orig}$} &  & & vdots & & vdots &  & vdots \
                        & & & & & Z_{lk} & dotsm & Z_{lp} & dotsm & Z_{lk} - Z_{lp} \
                        & & &  & & vdots & & vdots &  & vdots \
                        Z_{k1} & dotsm & dotsm & Z_{km} & dotsm & Z_{kk} & dotsm & Z_{kp} & dotsm & Z_{kk} - Z_{kp} \
                        vdots & & & vdots & & vdots & & vdots &  & vdots \
                        Z_{p1} & dotsm & dotsm & Z_{pm} & dotsm & Z_{pk} & dotsm & Z_{pp} & dotsm & Z_{pk} - Z_{pp} \
                        vdots & & & vdots & & vdots & & vdots &  & vdots \
                        vdots & & & vdots & & vdots & & vdots &  & vdots \ Xcline{1-10}{0.25mm}
                        Z_{k1} - Z_{p1} & dotsm & dotsm & Z_{km} - Z_{pm} & dotsm & Z_{kk} - Z_{pk} & dotsm & Z_{kp} - Z_{pp} & dotsm & Z_{th, kp} + Z_{b} \
                    end{array}
                    right]
                    left[
                    begin{array}{c}
                        V_{1} \
                        vdots \
                        V_{l} \
                        vdots \
                        V_{k} \
                        vdots \
                        V_{p} \
                        vdots \
                        vdots \ midrule[0.25mm]
                        0 \
                    end{array}
                    right]
                %
                arraystretchdefault
        %
        end{equation}
    %
    end{minipage}

end{adjustbox}




end{document}