# Evolutionary Game Analysis of Power Generation Groups Considering Energy Price Fluctuation
## 3 Analysis of Power Generation Cost under Primary Energy Price Fluctuation
### Gas-Fired Power Generation Cost Analysis  
The power generation cost of gas-fired power generation needs to first consider its transportation costs and tax rates from the CIF/ex-factory price of natural gas to calculate the arrival price of natural gas; then calculate the variable cost of gas-fired power generation; finally, calculate its marginal cost of gas-fired power generation. It includes the following steps:  
First, the arrival price of natural gas is obtained from the CIF/ex-factory price of natural gas, as shown in the following Equation (16):  
\[\lambda_{facgas}=\lambda_{gas}(1-T_{gas})+TR_{gas}(1-T_{tregas}) \tag{16}\]  
In the formula: \(\lambda_{facgas}\) is the arrival price of natural gas; \(\lambda_{gas}\) is the CIF/ex-factory price of natural gas; \(T_{gas}\) is the natural gas tax rate; \(TR_{gas}\) is the natural gas transportation cost; \(T_{tregas}\) is the natural gas transportation tax rate. Then the variable cost of gas-fired power generation can be obtained from the arrival price of natural gas, as shown in the following Equation (17):  
\[C^{VAR}_{gas}=\lambda_{facgas}\sigma_{gas}(1+T_{gaslec})/(1-\eta_{gafaclec}) \tag{17}\]  
In the formula: \(C^{VAR}_{gas}\) is the variable cost of gas-fired power generation; \(\sigma_{gas}\) is the gas power consumption; \(\eta_{gafaclec}\) is the power consumption rate of gas-fired power plants; \(T_{gaslec}\) is the gas-fired power generation tax rate. Finally, the marginal cost of gas-fired power generation can be obtained from the variable cost of gas-fired power generation, as shown in the following Equation (18):  
\[C_{gas}=C_{gas}^{VAR}+C_{gas}^{Const}(1+\eta_{gafacelec}) \tag{18}\]  
In the formula: \(C_{gas}\) is the marginal cost of gas-fired power generation; \(C_{gas}^{Const}\) is the fixed cost of gas-fired power generation. Therefore, the influence of energy price on power generation cost can be calculated by Formula (13)-(18). The following will further analyze the bidding game behavior and evolution trend of gas and coal-fired power generation groups under the influence of supply-demand relationship changes and cost fluctuations. Analysis of the Bidding Game of Power Generation Groups under the Fluctuation of Primary Energy Price  
The fluctuation of primary energy prices, thermal coal prices, and natural gas prices determine the power generation cost of the two groups of power generators, thus affecting their bidding strategies and causing the entire market to evolve to different game equilibrium points. In addition, the supply and demand situation will also have a significant impact on the bidding strategy of the power generation group. First, it is assumed that the single-unit power generation capacity, power generation cost, and the number of power generation groups of coal-fired power generation groups are \(Q_{coal,i}\), \(C_{coal}\) and \(m\) respectively, the gas-fired power generation group is assumed to be \(Q_{gas,i}\), \(C_{gas}\) and \(n\) respectively. Then the power generation capacity participating in the market competition is \(Q_{SP}=\sum\limits_{i=1}^{m}Q_{coal,i}+\sum\limits_{i=1}^{n}Q_{gas,i}\), and the total demand for the electricity market is \(Q_{DM}\). In addition, let the cost bidding coefficient of coal-fired power generation groups be \(\mu_{coal}\) the strategic bidding coefficient \(v_{coal}\). Similarly, let the cost bidding coefficient of gas-fired power generation groups be \(\mu_{gas}\) the strategic bidding coefficient is \(v_{gas}\), and assume \(\mu_{coal}=\mu_{gas}\)\(v_{coal}=v_{gas}\).