	US 12,136,816 B2
	Online voltage control method for coordinating multi-type reactive power resources using reactive voltage operation characteristics of power grids
Bin Wang, Beijing (CN); Guannan Wang, Beijing (CN); Wenchuan Wu, Beijing (CN); Haitao Liu, Beijing (CN); Hongbin Sun, Beijing (CN); Jun Zhang, Beijing (CN); Qinglai Guo, Beijing (CN); Qi Wang, Beijing (CN); and Ziang Liu, Beijing (CN)
Assigned to DEPARTMENT OF ELECTRICAL ENGINEERING, TSINGHUA UNIVERSITY, Beijing (CN); and STATE GRID JIBEI ELECTRIC POWER COMPANY LIMITED, Beijing (CN)
Filed by DEPARTMENT OF ELECTRICAL ENGINEERING, TSINGHUA UNIVERSITY, Beijing (CN); and STATE GRID JIBEI ELECTRIC POWER COMPANY LIMITED, Beijing (CN)
Filed on May 19, 2022, as Appl. No. 17/748,535.
Claims priority of application No. 202110550498.9 (CN), filed on May 20, 2021.
Prior Publication US 2022/0385072 A1, Dec. 1, 2022
Int. Cl. G05B 19/042 (2006.01); H02J 3/18 (2006.01); H02J 3/38 (2006.01)

CPC H02J 3/18 (2013.01) [G05B 19/042 (2013.01); H02J 3/381 (2013.01); G05B 2219/25357 (2013.01); G05B 2219/2639 (2013.01); H02J 2203/10 (2020.01); H02J 2203/20 (2020.01); H02J 2300/20 (2020.01)]

1 Claim

1. An online voltage control method for coordinating multi-type reactive power resources, comprising steps:

(1) establishing a variable set Ω of a base-state operation point model of a power system, wherein

Ω={V_n,V_n^slack^_up,V_n^slack^_down,V_n,V_i^G,Q_ij^b,Q_i^G,Q_n,Q_n^cp,Q_n^un,Q_n^ld,N_unit^cp,N_unit^rc,μ_unit,B_i^cp,B_j^rc,t_i^adj_up,t_i^adj_down}

where, V_nis a voltage after adjustment of a node n, V_n^slack_upand V_n^slack_downrespectively are an up slack variable and a down slack variable of the voltage after adjustment of the node n, V_nis an adjustment voltage value after slack of the node n, V_i^Gis a voltage of a generator i, Q_ij^bis reactive power flowing into a branch b with ports being nodes i and j from the port being the node i, Q_i^Gis reactive power of the generator i, Q_nis reactive power of the node n, Q_n^cpis reactive power supplied by a reactive power compensator connected to the node n, Q_n^unis reactive power supplied by a generator connected to the node n, Q_n^ldis reactive power absorbed by a load connected to the node n, N_unit^cpis a number of capacitance compensators in a state of being put in operation under a controller unit, N_unit^rcis a number of inductance compensators in a state of being put in operation under the controller unit, μ_unitis a binary variable of the controller unit, B_i^cpis a Boolean variable of a capacitance compensator i to indicate the capacitance compensator numbered with i whether changes its operation state, B_j^rcis a Boolean variable of an inductance compensator j to indicate the inductance compensator numbered with j whether changes its operation state, t_j^adj_upis an upwards adjusted tap position of a transformer i, and t_i^adj_downis a downwards adjusted tap position of the transformer i;

(2) establishing a linearized equation of reactive power of branch, comprising:

for each the branch b, calculating a Jacobi matrix of reactive power of the branch to obtain the following values:

where, i and j are node numbers respectively corresponding to two ports of the branch b,

is a partial derivative of reactive power of the branch b flowing out from the port node j relative to a voltage V_iafter adjustment of the port node i,

is a partial derivative of the reactive power of the branch b flowing out from the port node j relative to a voltage V_jafter adjustment of the port node j,

is a partial derivative of reactive power of the branch b flowing out from the port node i relative to the voltage V_iafter adjustment of the port node i,

is a partial derivative of the reactive power of the branch b flowing out from the port node i relative to the voltage V_jafter adjustment of the port node j,

is a partial derivative of the reactive power of the branch b flowing out from the port node j relative to a tap position t of a transformer connected to the branch b, and

is a partial derivative of the reactive power of the branch b flowing out from the port node i relative to the tap position t of the transformer connected to the branch b;

an expression of the linearized equation of reactive power of the branch b is as follows:

where, Q_ij^bis the reactive power flowing into the branch b from the port node i, Q_ij0^bis an initial reactive power flowing into the branch b from the port node i, V_i0is an original voltage of the node i, V_j0is an original voltage of the node j, t is a tap position after adjustment of the transformer connected to the branch b, and t₀is an original tap position of the transformer connected to the branch b;

(3) establishing an online voltage control model of multi-type reactive power resources, wherein the online voltage control model comprises an objective function and constraint conditions, specifically comprising the following steps:

(3-1) establishing an expression of the objective function of the online voltage control model as follows:

minC_total,

wherein

minC_total,

wherein,

C_total=Σ(Q_n^cp,op·C_n^cp,op)+Σ(Q_n^un,adj_up·C_n^un,adj_up+Q_n^un,adj_down·C_n^un,adj_down)+Σ(t_i^adj_up+t_i^adj_down)·C_i^t,adj+Σ(V_n^slack_up^²+V_n^slack_down^²)·C_p,

where, C_totalis a sum of a total cost and a penalty term of regulation, Q_n^cp,opis a 0-1 variable of the reactive power compensator connected to the node n whether is put in operation, C_n^cp,opis a cost of the reactive power compensator connected to the node n in operation, Q_n^un,adj_upis an amount of upward adjustment of output reactive power of the generator connected to node n, C_n^un,adj_upis a cost of upward adjustment of output reactive power of the generator connected to node n, Q_n^un,adj_downis an amount of downward adjustment of output reactive power of the generator connected to node n, C_n^un,adj_downis a cost of downward adjustment of output reactive power of the generator connected to node n, C_i^t,adjis a cost per unit tap position of adjustment of the transformer i, Σ(V_n^slack_up^²+V_n^slack_down^²)·C_pis the penalty term, and C_pis a penalty coefficient of slack variable;

(3-2) establishing the constraint conditions as follows:

(3-2-1) generator reactive power constraints:

when the QC is adjustable, there is a constraint condition:

Q_i^G_min≤Q_i^G≤Q_i^G_max, ∀_i∈I^G,

where, Q_i^G_minis a lower limit of the reactive power of the generator i, Q_i^G_maxis an upper limit of the reactive power of the generator i, and IG is a collection of generators;

when the Q_i^Gis non-adjustable and the generator i is a PQ node whose real power P and reactive power Q are specified, there is a constraint condition: Q_i^G=Q_i0^G;

when the Q_i^Gis non-adjustable and the generator i is a PV node whose real power P and a voltage magnitude V are specified, there is a constraint condition: V_i^G=V_i0^G,

where, Q_i0^Gand V_i0^Grespectively are original reactive power and an original voltage of the generator i;

(3-2-2) reactive power compensator constraints:

N_unit^cp=N_unit^cp0+Σ_i∈I_₀B_i^cp−Σ_i∈I_₁B_i^cp,

where, the controller is a minimum control unit of a group of reactive power compensators, the group of reactive power compensators comprise capacitance compensators and inductance compensators, I₀is a capacitance compensator set in exit state under the controller unit, I₁is a capacitance compensator set in the state of being put in operation under the controller unit, N_unit^cp0is a number of the capacitance compensators in the state of being put in operation under the controller unit at an initial stage;

N_unit^rc=N_unit^rc0+Σ_j∈J_₀B_j^rc−Σ_j∈J_₁B_j^rc,

where, J₀is an inductance compensator set in exit state under the controller unit, J₁is an inductance compensator set in the state of being put in operation under the controller unit, N_unit^rc0is a number of the inductance compensators in the state of being put in operation under the controller unit at the initial stage;

using a big-M method to establish a constraint as follows:

where, N_sum^unitis a number of all the reactive power compensators under the controller unit;

(3-2-3) slack contained nodal voltage constraints:

when a voltage on the node n has upper and lower limit constraints, there is a constraint condition:

V_n^min≤V_n≤V_n^max,

when the voltage on the node n has an objective voltage value, there is a constraint condition:

V_n=V_n^obj,

where, V_n^minis an allowable minimum value of the voltage on the node n, V_n^maxis an allowable maximum value of the voltage on the node n, and V_n^objis the objective voltage value of the node n;

(3-2-4) transformer tap position constraints:

when a tap of the transformer i is adjustable, there is a constraint condition:

where, t_i^minis a minimum value of the tap position of the transformer i, t_i^maxis a maximum value of the tap position of the transformer i, and to is an original value of the tap position of the transformer i;

(3-2-5) a nodal reactive power balance constraint:

Q_n=ΣQ_n^cp+ΣQ_n^un−ΣQ_n^ld−Σ_jQ_nj^b=0,

where, ΣQ_n^cpis a sum of reactive power flowing in the node n from all the reactive power compensators connected to the node n, ΣQ_n^unis a sum of reactive power flowing in the node n from all generators connected to the node n, ΣQ_n^ldis a sum of reactive power of flowing from the node n into all loads connected to the node n, Σ_jQ_nj^bis a sum of reactive power of flowing from the node n into all branches each with the node n as its port, and Q_nj^bis calculated by the linearized equation of reactive power of branch established in the step (2);

(4) solving the online voltage control model of multi-type reactive power resources established in the step (3) to obtain optimal values of respective optimization variables contained in the variable set Ω;

wherein the method further comprises the following steps:

performing the voltage control on the power system based on the obtained optimal values of respective optimization variables contained in the variable set Ω, which comprises: adjusting the voltage and the reactive power of the node n to the respective optimal values, adjusting the voltage and the reactive power of the generator i to the respective optimal values, adjusting the reactive power supplied by the reactive power compensator connected to the node n to the respective optimal value, adjusting the reactive power supplied by the generator i connected to the node n to the respective optimal value, adjusting the reactive power absorbed by the load connected to the node n to the respective optimal value, adjusting the number of the capacitance compensators in the state of being put in operation under the controller unit to the respective optimal value, adjusting the number of the inductance compensators in the state of being put in operation under the controller unit to the respective optimal value, and adjusting the upwards adjusted tap position and the downwards adjusted tap position of the transformer i to the respective optimal values.