Optimal operation control method of air-source heat pump and gas-fired heater combined heating system

An optimal operation control method of the air-source heat pump and gas-fired heater combined heating system, including the following steps:

• step 1. constructing a mathematical model of the air-source heat pump and gas-fired heater combined heating system, and calculating hourly operation performance of the combined heating system;
• wherein the mathematical model includes a heating and energy consumption model for an air-source heat pump unit and a heating and energy consumption model for a gas-fired heater unit;
• step 2. determining a comprehensive evaluation index system of the combined heating system, including primary evaluation indexes and secondary evaluation indexes, and constructing a secondary evaluation index calculation model;
• wherein 3 primary evaluation indexes are provided, including energy conservation, environmental protection and economical efficiency, and 4 secondary evaluation indexes are provided, including a comprehensive energy efficiency ratio (EER) and a clean energy utilization rate, η, that are subordinate to the energy conservation index, a CO2 emission TCO2 that is subordinate to the environment protection index, and operation cost Cr that is subordinate to the economical efficiency index;
• a calculation formula of the EER of the combined heating system is as follows:
• EER
• =
• Q
• p
• +
• Q
• b
• W
• p
• /
• β
• e
• +
• V
• g
• ·
• H
• i
• a calculation formula of the clean energy utilization rate, η, of the combined heating system is as follows:
• η
• =
• Q
• p
• Q
• p
• +
• Q
• b
• a calculation formula of the CO2 emission, TCO2, of the combined heating system is as follows:
• TCO2=Tb+Tp, Tb=Vg×ab, Tp=Wp×ap;
• a calculation formula of the operation cost, Cr, of the combined heating system is as follows:
• Cr=Wp×Pe/(3.6×106)+Vg×Pg
• where Wp is the power consumption of the air-source heat pump unit;
• βe is the power generation efficiency of a gas-fired device;
• TCO2 is the CO2 emission of the combined heating system;
• Tb is the CO2 emission of the gas-fired heater unit;
• Tp is the CO2 emission of the air-source heat pump unit;
• ab is a conversion coefficient of the gas consumption to the carbon dioxide emission of the gas-fired heater for heating;
• αp is a conversion coefficient of the power generation capacity to the carbon dioxide emission;
• Cr is the operation cost;
• Pe is an electricity price;
• and Pg is a fired gas price;
• Qp is heating capacity of the air-source heat pump unit;
• Qb is heating capacity of the gas-fired heater unit;
• Vg is the gas consumption per second of the gas-fired heater unit;
• Hi is a calorific value of fired gas fed into the gas-fired heater for heating;
• step 3. constructing an index determination matrix through an analytic hierarchy process based on the evaluation index system of the combined heating system, carrying out normalization and consistency check, and determining respective weights of the primary evaluation indexes and the secondary evaluation indexes;
• step 4. normalizing the secondary evaluation indexes of the combined heating system, and respectively calculating membership functions of the EER, the clean energy utilization rate, the carbon dioxide emission and the operation cost;
• step 5. a comprehensive objective function calculation model is constructed based on the membership functions of the secondary evaluation indexes, with a calculation formula as follows:
• ƒ=w1(w11׃1(EER)+w12׃2(η))+w2׃3 (TCO2)+w3׃4 (Cr), where w1, w2, and w3 denote the weights of the primary evaluation indexes:
• the energy conservation, the environmental protection and the economical efficiency, respectively;
• and w11 and w12 denote the weights of the secondary evaluation indexes:
• the EER and the clean energy utilization rate, respectively;
• step 6. implementing floor radiant heating at a heating terminal form of the combined heating system, constructing a heating parameter prediction model based on characteristics of the heating terminal form, and performing calculation in a constant flow control method to obtain an actual operation water supply temperature tg, an actual operation return water temperature th and a heating load Q at different outdoor temperatures;
• and
• step 7. determining whether the operation of an air-source heat pump alone can meet the requirement of the heating load at the current outdoor temperature in real time by taking the priority of meeting the heating requirement as a principle;
• if the air-source heat pump cannot meet the requirement, respectively calculating a comprehensive objective function in a combined operation mode of the air-source heat pump and a gas-fired heater for heating and a comprehensive objective function in an operation mode of the gas-fired heater for heating alone, whichever the comprehensive objective function is greater;
• and if the air-source heat pump can meet the requirement of the heating load, calculating a comprehensive objective function in an operation mode of the air-source heat pump alone and the comprehensive objective function in the operation mode of the gas-fired heater for heating alone, respectively, whichever the comprehensive objective function is greater, and based on the operation mode with the greater comprehensive objective function, obtaining an operation control strategy of the air-source heat pump and gas-fired heater combined heating system wherein the operation control strategy is employed to control and operate the air-source heat pump and gas-fired heater.