The present disclosure relates to an intra-day rolling scheduling method for an integrated heat and electricity system, belongs to the field of operation and control technologies for a power grid with a plurality of energy forms.
The multi-energy system may include a plurality of energy flow subsystems. The energy may refer to such as electricity, heat, cold, gas, or transportation. The multi-energy system has considerable benefits, such as reducing energy consumption, improving overall energy efficiency, and reducing total energy costs, but improves the control complex.
The integrated heat and electricity system is one of the multi-energy systems. The integrated heat and electricity system may include a power grid and a heating network, in which coupling components such as combined heat and power units, heat pumps, and circulating pumps may couple the power grid and the heating network. However, there coupling components bring about new requirements on operation and control on the integrated heat and electricity system, such as the intra-day rolling scheduling on the integrated heat and electricity system needs to consider these coupling components comprehensively.
The intra-day rolling scheduling method for the integrated heat and electricity system, provided by the present disclosure, may include the following: establishing an objective function for scheduling of the integrated heat and electricity system, the objective function aiming to make operating costs of the integrated heat and electricity system to be a minimum, the integrated heat and electricity system comprising combined heat and power units, thermal power units, heat pumps, and circulating pump; establishing constraints for a steady-state safe operation of the integrated heat and electricity system; and solving the objective function based on the constraints by an interior point method, to obtain an active power and a heating power of each combined heat and power unit, an active power of each thermal power unit, a heating power of each heat pump, and an active power consumed by each circulating pump, as an intra-day rolling scheduling scheme of the integrated heat and electricity system.
The integrated heat and electricity system is shown in
The intra-day rolling scheduling method for the integrated heat and electricity system, provided by the present disclosure, may include: establishing (110) an objective function for scheduling of the integrated heat and electricity system, the objective function aiming to make operating costs of the integrated heat and electricity system to be a minimum, the integrated heat and electricity system comprising combined heat and power units, thermal power units, heat pumps, and circulating pump; establishing (120) constraints for a steady-state safe operation of the integrated heat and electricity system; and solving (130) the objective function based on the constraints by an interior point method, to obtain an active power and a heating power of each combined heat and power unit, an active power of each thermal power unit, a heating power of each heat pump, and an active power consumed by each circulating pump, as an intra-day rolling scheduling scheme of the integrated heat and electricity system.
In detail, the intra-day rolling scheduling method for the integrated heat and electricity system, provided by the present disclosure, may include the following steps.
(1) An objective function for optimal scheduling of the integrated heat and electricity system may be established by a formula of:
where, pb,t represents an active power of a bth combined heat and power unit in the integrated heat and electricity system at a tth scheduling period, qb,t represents a heating power of the bth combined heat and power unit in the integrated heat and electricity system at the tth scheduling period, N represents a number of combined heat and power units in the integrated heat and electricity system, F(Pb,t,qb,t) represents a running cost of the bth combined heat and power unit in the integrated heat and electricity system at the tth scheduling period, px,t represents an active power of an xth thermal power unit in the integrated heat and electricity system at the tth scheduling period, NTU represents a number of thermal power units in a power grid in the integrated heat and electricity system, FTU(px,t) represents a running cost of the xth thermal power unit in the power grid in the integrated heat and electricity system, Δt represents an interval between two neighboring scheduling periods, and a value of Δt is 15 minutes.
(2) Equality constraints for a steady-state safe operation of the power grid and the heating network in the integrated heat and electricity system may be set, which may include the following.
(2-1) A power flow constraint of the power grid in the integrated heat and electricity system is denoted by formulas of:
where, Pi,t represents an injected active power of a ith node of the power grid in the integrated heat and electricity system at the tth scheduling period, i,t represents an injected reactive power of the ith node of the power grid in the integrated heat and electricity system at the tth scheduling period, θi,t represents a voltage phase angle of the ith node at the tth scheduling period, θj,t represents a voltage phase angle of the jth node at the tth scheduling period, Ui,t represents a voltage amplitude of the ith node at the tth scheduling period, Uj,t represents a voltage amplitude of the jth node at the tth scheduling period, Gij represents a real part of an element at ith cow and jth column in a node admittance matrix Y of the power grid, Bij represents an imaginary part of the element at ith cow and jth column in the node admittance matrix Y of the power grid, the node admittance matrix Y of the power grid is obtained from an energy management system of the integrated heat and electricity system, and n represents a number of nodes of the power grid.
(2-2) A pipe pressure loss constraint of the heating network in the integrated heat and electricity system is denoted by a formula of:
ΔHl,t=Slml,t|ml,t|, t=1,2, . . . ,16,
where, ΔHl,t represents a pressure loss of a lth pipe of the heating network in the integrated heat and electricity system at the tth scheduling period, Sl represents a resistance characteristic coefficient, a range of Sl is 10 Pa/(kg/s)2≤Sl≤500 Pa/(kg/s)2, and ml,t represents a mass flow rate of the lth pipe at the tth scheduling period.
(2-3) A hydraulic characteristic constraint of a circulating pump of the heating network in the integrated heat and electricity system is denoted by a formula of:
H
P,t
=H
0
−S
p
m
p,t
2
t=1,2, . . . ,16,
where, HP,t represents a head of delivery of the circulating pump at the tth scheduling period, H0 represents a static head of delivery of the circulating pump, Sp represents a resistance coefficient of the circulating pump, H0 and Sp are obtained from a factory manual of the circulating pump, and mP,t represents a mass flow rate that flowing through the circulating pump at the tth scheduling period.
(2-4) A pipe heating loss constraint of the heating network in the integrated heat and electricity system is denoted by a formula of:
where, Te,l,t represents a tail-end temperature of the lth pipe of the heating network at the tth scheduling period, Th,l,t represents a head-end temperature of the lth pipe at the tth scheduling period, Ta,l,t represents an ambient temperature of the lth pipe at the tth scheduling period, ml,t represents the mass flow rate of the lth pipe at the tth scheduling period, L1 represents a length of the lth pipe, Cp represents a specific heat capacity of water, a value of the specific heat capacity is 4182 Joules/(kg·° C.), λ represents a heat transfer coefficient per unit length of the pipe, λ is obtained from the energy management system of the integrated heat and electricity system, and e represents a natural logarithm.
(2-5) A temperature constraint of a junction node of a plurality of pipes of the heating network in the integrated heat and electricity system is denoted by a formula of:
where, ml,t represents the mass flow rate of the lth pipe at the tth scheduling period, Te,l,t represents the tail-end temperature of the lth pipe of the heating network at the tth scheduling period, Th,l,t represents the head-end temperature of the lth pipe at the tth scheduling period, Snout represents a set of all pipe numbers flowing out of a nth node of the heating network, Snin represents a set of all pipe numbers flowing into the nth node of the heating network, and j,n,t represents a heating power of the nth node of the heating network at the tth scheduling period.
(2-6) A coupling constraint between the power grid and the heating network coupled by combined heat and power units in the integrated heat and electricity system is denoted by formulas of:
p
b,t=Σk−1NK
where, pb,t represents the active power of the bth combined heat and power unit at the tth scheduling period, qb,t represents the heating power of the bth combined heat and power unit at the tth scheduling period, (Pbk,bk) represents the kth vertex of an approximate convex polygon in a running feasible region of the bth combined heat and power unit, αb,tk represents a kth combination coefficient of the bth combined heat and power unit at the tth scheduling period, Σk−1NK
(2-7) A coupling constraint between the power grid and the heating network coupled by a circulating pump in the integrated heat and electricity system is denoted by a formula of:
where, PP,t represents an active power consumed by the circulating pump at the tth scheduling period, g represents an acceleration of gravity, ηP represents an efficiency of the circulating pump, a value of ηP ranges from 0 to 1, mP,t represents the mass flow rate that flowing through the circulating pump at the tth scheduling period, and HP,t represents the head of delivery of the circulating pump at the tth scheduling period.
(2-8) A coupling constraint between the power grid and the heating network coupled by a heat pump in the integrated heat and electricity system is denoted by a formula of:
P
hp,t
=C
hp
hp,t
,t=1,2, . . . ,16,
where, hp,t represents a heating power emitted by the heat pump in the integrated heat and electricity system at the tth scheduling period, php,t represents an electric power consumed by the heat pump at the tth scheduling period, Chp represents a heat generation efficiency of the heat pump, and Chp is obtained from a factory manual of the heat pump.
(3) Inequality constraints for a steady-state safe operation of the power grid and a heating network in the integrated heat and electricity system may be set, which may include the following.
(3-1) The voltage amplitude Ui,t of the ith node of the power grid in the integrated heat and electricity system at the tth scheduling period is between a set upper and lower limits Ui, Ūi of safe operating voltage of the power grid, in which, Ui is 0.95 times a rated voltage of the ith node, and Ūi is 1.05 times the rated voltage of the ith node, i.e.:
U
i
≤U
i,t
≤Ū
i
,t=1,2, . . . ,16.
(3-2) A transmission capacity Sl,t of a lth branch of the power grid in the integrated heat and electricity system at the tth scheduling period is less than or equal to a set maximum value
S
l,t
≤
l
, t=1,2, . . . ,16.
(3-3) Ramp constraints of active powers of combined heat and power units of the power grid of the integrated heat and electricity system are denoted by a formula of:
−Δpbdown·Δt≤pb,t−pb,t−1≤Δpbup·Δt,t=1,2, . . . ,16,
where, Δpbup represents an upward ramp rate of the active power of the bth combined heat and power unit, Δpbdown represents a downward ramp rate of the active power of the bth combined heat and power unit, Δpbup and Δpbdown are obtained from a factory instruction of the combined heat and power unit, Δt represents the interval between two neighboring scheduling periods, pb,t represents the active power of the bth combined heat and power unit at the tth scheduling period, and pb,t−1 represents the active power of the bth combined heat and power unit at the (t−1)th scheduling period.
(3-4) Ramp constraints of heating powers of combined heat and power units of the power grid of the integrated heat and electricity system are denoted by a formula of:
−Δqddown·Δt≤qb,t−qb,t−1≤Δqbup·Δt,t=1, 2, . . . ,16,
where, Δqbup represents an upward ramp rate of the heating power of the bth combined heat and power unit,Δqbdown represents a downward ramp rate of the heating power of the bth combined heat and power unit, Δqbup and Δqbdown are obtained from a factory instruction of the combined heat and power unit, Δt represents the interval between two neighboring scheduling periods, qb,t represents the heating power of the bth combined heat and power unit at the tth scheduling period, and qb,t−1 represents the heating power of the bth combined heat and power unit at the (t−1)th scheduling period.
(3-5) Ramp constraints of active powers of thermal power units of the power grid of the integrated heat and electricity system are denoted by a formula of:
Δ−p
x
down
·Δt≤p
x,t
−p
x,t−1
≤Δp
x
up
·Δt,t=1,2, . . . ,16,
where, Δpxup represents an upward ramp rate of the active power of the xth thermal power unit, Δpxdown represents a downward ramp rate of the active power of the xth thermal power unit, Δpxup and Δp,xdown are obtained from a factory instruction of the thermal power unit, Δt represents the interval between two neighboring scheduling periods, px,t represents the active power of the xth thermal power unit at the tth scheduling period, and px,t−1 represents the active power of the xth thermal power unit at the (t−1)th scheduling period.
(3-6) The active power pb,t of the bth combined heat and power unit at the tth scheduling period is between a set upper and lower limits
P
b
≤P
b,t
≤
b
,t=1,2, . . . ,16 .
(3-7) The heating power qb,t of the bth combined heat and power unit at the tth scheduling period is between a set upper and lower limits
p
b
≤p
b,t
≤
b
,t=1,2, . . . ,16.
(3-8) The active power px,t of the xth thermal power unit at the tth scheduling period is between a set upper and lower limits px, and
p
x
≤p
x,t
≤
x
,t=1,2, . . . ,16.
(3-9) The mass flow rate ml,t of the lth pipe at the tth scheduling period is less than or equal to an upper limit
T≤T
i,t
≤
(3-10) A return water temperature Ti,t of an ith heat exchange station in the heating network at the tth scheduling period is between a set upper and lower limits T and
T≤T
i,j
(4) Using an interior point method, the equation in the above step (1) is used as the objective function, and all equations in the above step (2) and step (3) are used as the constraints, to solve to obtain the active power and the heating power of each combined heat and power unit, the active power of each thermal power unit, the heating power of each heat pump, and the active power consumed by each circulating pump, as the intra-day rolling scheduling scheme of the integrated heat and electricity system, realizing the intra-day rolling scheduling of the integrated heat and electricity system.
The intra-day rolling scheduling method for the integrated heat and electricity system, proposed by the present disclosure, has the characteristics and effects as follows. The method considers the mutual influence of the integrated heat and electricity system and realizes the intra-day rolling scheduling method for the integrated heat and electricity system. This method can continuously modify the current intra-day rolling scheduling plan to obtain a more accurate intra-day rolling scheduling scheme. Compared with independent optimization analysis of the power grid and the heating system, it may get a better scheduling scheme (lower total operating cost), and improve scheduling flexibility. The method can be applied to the formulation of the intra-day rolling scheduling method for the integrated heat and electricity system, which is beneficial to improving the energy efficiency of the integrated heat and electricity system and reducing operating costs.
Number | Date | Country | Kind |
---|---|---|---|
201710989015.9 | Oct 2017 | CN | national |
This is a continuation of International Application No. PCT/CN2017/114465 filed Dec. 4, 2017, which claims priority to Chinese Patent Application No. 201710989015.9, filed Oct. 22, 2017, the entire disclosures of which are incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
Parent | PCT/CN2017/114465 | Dec 2017 | US |
Child | 16842566 | US |