To address the lack of a unified metric for heterogeneous reactive-power resources in weak renewable-energy grids and the absence of a voltage-security boundary when flexible resources are called for demand response, a coordinated configuration method is proposed. Transient voltage support, inertia contribution, and life-cycle cost are jointly considered. A multidimensional equivalent support-efficiency factor is first defined for a synchronous condenser (SC), grid-forming energy storage (GFMES), and a static var generator (SVG). The factor is then introduced as a virtual short-circuit-capacity weight to construct a generalized equivalent dynamic short-circuit ratio (GED-SCR). The sum of the corrected critical short-circuit ratio (CSCR) and a case-specific security margin is imposed as the strength constraint. Device locations and capacities are determined by a quantum genetic algorithm (QGA) and differential evolution (DE). A modified IEEE 33-bus equivalent system is employed to evaluate the configuration. The GED-SCR of the critical buses increases from approximately 1.1-1.6 to the range of 2.5-3.5; for Bus 25, the minimum voltage during the fault is significantly elevated, and the voltage recovery time is reduced to the millisecond scale.A security boundary for checking the available reactive-power capability of flexible demand-side resources before response activation is thereby provided;Demand-response scheduling itself is outside the scope of the configuration model.