Optimal scheduling method for electricity-heat multi-energy flow system based on heat supply phasor model

An optimal scheduling method for an electricity-heat multi-energy flow system based on a heat supply phasor model, comprising:

• step 1:
• converting a load power of a heat supply system in the electricity-heat multi-energy flow system into a phasor form as:
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• a superscript HI, represents a heat load identifier, {dot over (Q)}i,kΩHL represents a heat consumption power phasor when a frequency of an ith heat load in the heat supply system is kΩ, qiHI,τw represents a load power of the ith heat load in the heat supply system at a scheduling moment τw, Ω represents a fundamental wave frequency of a phasor, K represents an order of the fundamental wave frequency of the phasor, a value of K is equal to a number of scheduling moments and KΩ=24 hours, and Δτ represents a scheduling time interval;
• step 2:
• setting constraint conditions of the heat supply system in the electricity-heat multi-energy flow system in the phasor form, comprising:
• step 2-1:
• a constraint equation of a heat loss of a heat supply network pipe of the heat supply system in the phasor form being:
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• where, BH represents a set of numbers of pipes of the heat supply system, {dot over (T)}s,b,kΩ represents a temperature phasor at a head end when a frequency of a bth pipe in the heat supply system is kΩ, {dot over (T)}e,b,kΩ represents a temperature phasor at a tail end when a frequency of the bth pipe in the heat supply system is kΩ, tam represents an ambient temperature of the heat supply system, mb represents a flow of the bth pipe, Lb represents a length of the bth pipe, Cw represents a specific heat capacity of water, a value of the specific heat capacity is 4182 joule/(kilogram-degree centigrade), λb represents a heat transfer coefficient per unit length of the bth pipe, and λb is obtained from an energy management system of the electricity-heat coupled multi-energy flow system;
• step 2-2:
• a constraint equation of a temperature of a multi-pipe junction of the heat supply system in the phasor form being:
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• where, a superscript HS represents an identifier of a heat source in the heat supply system, {dot over (Q)}i,kΩHS represents a heat supply power phasor when a frequency of an ith heat source in the heat supply system is kΩ, {dot over (T)}e,b,kΩ represents a temperature phasor at a tail end when a frequency of a bth pipe in the heat supply system is kΩ, Cw represents a specific heat capacity of water, the value of the specific heat capacity is 4182 joule/(kilogram-degree centigrade), mb represents a flow of the bth pipe, {dot over (Q)}i,kΩHL represents a heat consumption power phasor when a frequency of an ith heat load in the heat supply system is kΩ, {dot over (T)}n,kΩ represents a temperature phasor when a frequency of an nth node in the heat supply system is kΩ, SnHS represents a set of numbers of heat source nodes of the heat supply system, SnHL represents a set of numbers of heat load nodes of the heat supply system, SnH,in represents a set of numbers of pipes when a node at a tail end is the nth node in the heat supply system, and SnH,out represents a set of numbers of pipes when a node at a head end is the nth node in the heat supply system;
• step 2-3:
• a constraint equation of a temperature at a head end of the pipe of the heat supply system in the phasor form being:
• {dot over (T)}s,b,kΩ={dot over (T)}n,kΩ,∀b∈SnH,out,n∈NH,k=0, . . . ,K,
• where, {dot over (T)}s,b,kΩ represents a temperature phasor at a head end when a frequency of a bth pipe in the heat supply system is kΩ, {dot over (T)}u,kΩ represents a temperature phasor when a frequency of a nth node in the heat supply system is kΩ, SnH,out represents a set of numbers of pipes when a node at a head end is the nth node in the heat supply system, and NH represents a set of numbers of nodes of the heat supply system;
• step 2-4:
• a constraint equation of a heat source phasor of the heat supply system with a Fourier inverse transform being:
• qiHS,τw=Re(Σk=0K{dot over (Q)}i,kΩHSejkΩτw),∀i∈IHS,w=1, . . . ,K,
• where, a superscript HS represents an identifier of a heat source in the heat supply system qiHS,τw represents a heat supply power of an ith heat source in the heat supply system at a scheduling moment τw, a function Re(●) represents taking a real part of a complex number, {dot over (Q)}i,kΩHS represents a heat supply power phasor when a frequency of the ith heat source in the heat supply system is kΩ, and IHS represents a set of numbers of heat sources of the heat supply system;
• step 2-5:
• a constraint equation of temperature historical data of a node of the heat supply system being:
• tn,hisτw,his=Re(Σk=0K{dot over (T)}n,kΩejkΩτw,his),∀n∈NH,w=−K+1, . . . ,0,
• where, tn,hisτw represents a node temperature of an nth node in the heat supply system at a historical scheduling moment τw,his, a function Re(●) represents taking a real part of a complex number, {dot over (T)}n,kΩ represents a temperature phasor when a frequency of a nth node in the heat supply system is kΩ, and NH represents a set of numbers of nodes of the heat supply system;
• step 2-6:
• a constraint equation of a limit of the temperature of the node of the heat supply system being:
• tn≤Re(Σk=0K{dot over (T)}n,kΩejkΩτw)≤tn,∀n∈NH,w=1, . . . ,K,
• where, tn represents a lower temperature limit of an nth node in the heat supply system, tn represents a upper temperature limit of the nth node in the heat supply system, a function Re(●) represents taking a real part of a complex number, {dot over (T)}n,kΩ represents a temperature phasor when a frequency of the nth node in the heat supply system is kΩ, and NH represents a set of numbers of nodes of the heat supply system;
• step 2-7:
• constraint equations of a combined heat and power unit in the heat supply system being:
• piES,τw=Σκ,iNKiξκ,iτwPκ,i,∀i∈ICHP,w=1, . . . ,K,
• qiHS,τw=Σκ,iNKiξκ,iτwQκ,i,∀i∈ICHP,w=1, . . . ,K,
• Σκ=1NKiξκ,iτwQκ,i,∀i∈ICHP,w=1, . . . ,K,
• ξκ,iτw≥0,∀κ=1, . . . ,NKi,i∈ICHP,w=1, . . . ,K,
• where, a superscript ES represents a power supply identifier, piES,τw represents a power generation of an ith combined heat and power unit in the heat supply system at a scheduling moment τw, qiHS,τw represents a heat supply power of the ith combined heat and power unit in the heat supply system at the scheduling moment τw, Pκ,i represents an abscissa of a κth vertex of an approximate polygon of an running feasible domain of the ith combined heat and power unit, Qκ,i represents an ordinate of the κth vertex of an approximate polygon of the running feasible domain of the ith combined heat and power unit, ξκ,iτw represents a κth combined coefficient of the ith combined heat and power unit at the scheduling moment τw, NKi represents a number of vertexes of the approximate polygon of the running feasible domain of the ith combined heat and power unit, the approximate polygon of the running feasible domain of the combined heat and power unit is obtained from a factory specification of the combined heat and power unit, and ICHP represents a set of numbers of combined heat and power units in the heat supply system;
• step 3:
• setting constraint conditions of a power system in the electricity-heat multi-energy flow system, comprising:
• step 3-1:
• constraint equations of a direct current power flow of the power system being:
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• where, a superscript ES represents a power supply identifier, piES,τw represents a power generation of an ith generator unit in the power system at a scheduling moment τw, pnELτw represents an electrical load power of an nth node in the heat supply system at a scheduling moment τw, IES represents a set of numbers of generator units of the power system, NE represents a set of numbers of nodes of the power system, Fb represents an upper limit of a power of a bth line in the power system, Φb,n represents a transfer distribution factor between the nth node and the bth line in the power system, SnES represents a set of generator units on the nth node in the power system, and BE represents a set of lines in the power system;
• step 3-2:
• a constraint equation of the generator unit in the power system being:
• pi≤piES,τw≤pi,∀i∈ITU,w=1, . . . ,K,
• where, a superscriptTU represents an identifier of anther generator unit except the combined heat and power unit in the power system, pi represents a lower power limit of an ith generator unit in the power system, pi represents an upper power limit of the ith generator unit in the power system, piES,τw represents a power of the ith generator unit in the power system at a scheduling moment τw, and ITU represents a set of numbers of the generator units of the power system;
• step 4:
• establishing an objective function for optimal scheduling the electricity-heat multi-energy flow system, wherein the objective function is:
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• where, ciCHP,τw represents an operation cost of an ith combined heat and power unit in the heat supply system at a scheduling moment τw, ciTU,τw represents an operation cost of an ith generator unit in the power system at the scheduling moment τw, ICHP represents a set of numbers of combined heat and power units in the heat supply system, ITU represents a set of numbers of generator units in the power system, and specific expressions of ciCHP,τw and ciTU,τw are:
• ciCHP,τw=a0,i+a1,ipiES,τw+a2,iqiHS,τw+a3,i(piES,τw)2+a4,i(qiHS,τw)2+a5,ipiES,τwqiHS,τw,∀i∈ICHP,
• ciTU,τw=a0,i+a1,ipiES,τw+a3,i(piES,τw)2,∀i∈ITU,
• where, a0,i, a1,i, a2,i, a3,i, a4,i, and a5,i represents cost factors of an ith combined heat and power unit/generator unit, a0,i, a1,i, a2,i, a3,i, a4,i, and a5,i are obtained from the energy management system of the electricity-heat coupled multi-energy flow system, piES,τw represents a power generation of the ith combined heat and power unit or generator unit at a scheduling moment τw, and qiHS,τw represents a heat supply power of the ith combined heat and power unit at the scheduling moment τw;
• step 5:
• solving, by using an interior point method, an optimization model consisting of the objective function in step 4 and the constraint conditions in step 2 and step 3, obtaining the power generation of the generator unit, the power generation and the heat supply power of the combined heat and power unit in the electricity-heat multi-energy flow system as optimal scheduling parameters of the electricity-heat multi-energy flow system, to achieve the optimized scheduling of the electricity-heat multi-energy flow system based on the heat supply phasor model, and
• generating power by the generator unit in the power system in the electricity-heat multi-energy flow system based on the power generation of the generator unit obtained in step 5, and generating power and supplying heat by the combined heat and power unit in the heat supply system in the electricity-heat multi-energy flow system based on the power generation and the heat supply power of the combined heat and power unit obtained in step 5.