(2) DG annual equivalent investment cost

$$\mathbf{C}\_{i} = \frac{r(\mathbf{1} + r)^{n\_{y}}}{(\mathbf{1} + r)^{n\_{y}} - \mathbf{1}\_{i \in \mathcal{N}\_{\rm DG}}} \sum\_{i \in \mathcal{N}\_{\rm DG}} (c\_{i} \mathbf{S}[i]) \tag{13}$$

where *r* is the discount rate; *n<sup>y</sup>* is the DG payback period; *c<sup>i</sup>* is the investment cost of installing DG at the *i*-th node, 10,000 yuan; and *S*[*i*] is the number of DG installations at the *i*-th candidate node.

(3) System network loss cost

$$\mathsf{C}\_{\text{loss}} = c\_{\text{loss}} \sum\_{t=1}^{8760} \sum\_{i \in T} I\_i^2(t) r\_i \tag{14}$$

where *closs* is the unit network loss; *I<sup>i</sup>* is the current on the *i*-th line, kA; and *r<sup>i</sup>* is the resistance of the *i*-th line, Ω.

(4) MT fuel cost

$$\mathcal{C}\_f = \mathcal{c}\_f \sum\_{t=1}^{8760} \sum\_{i \in \mathcal{N}\_{mt}} E\_{mt,i}(t) \tag{15}$$

where *c <sup>f</sup>* is the unit fuel cost per hour, 10,000 yuan/(MW·h); and *E*mt,*i*(*t*) is the MT power generation connected to the *i*-th node at time *t*, MW·h.

(5) Pollution compensation cost

$$\mathcal{C}\_{\varepsilon} = K\_{\text{mt}} \sum\_{i \in \mathcal{N}\_{\text{mt}}} E\_{\text{mt},i} (V\_{\text{CO}\_2} + R\_{\text{CO}\_2}) \ast 10^{-4} \tag{16}$$

where *K*mt is the emission intensity of greenhouse gas produced by a unit MT, kg/(MW·h); *V*CO<sup>2</sup> is the environmental protection value, yuan/kg; and *R*CO<sup>2</sup> is a fine for the MT to emit greenhouse gases, yuan/kg.

(6) Environmental protection subsidy fee

$$\mathcal{C}\_{p} = \sum\_{t=1}^{8760} \left( \sum\_{i \in \mathcal{N}\_{p\overline{v}}} c\_{p\overline{v}} E\_{p\overline{v},i}(t) + \sum\_{i \in \mathcal{N}\_{\overline{w}\overline{g}}} c\_{\overline{w}g} E\_{\overline{w}g,i}(t) \right) \tag{17}$$

where *c*pv and *c*wg are respectively PV and WG environmental subsidies for unit power generation, 10,000 yuan/(MW·h); *E*pv,*i*(*t*) and *E*wg,*i*(*t*) are respectively the PV and WG power generations connected to the *i*-th node at time *t*, MW·h.
