Disclosure of Invention
In order to overcome the defects, the invention provides a method for determining the reactive compensation capacity of the power distribution network based on the random matrix theory, and the reactive compensation capacity of the power distribution network is determined through simple and convenient calculation.
The purpose of the invention is realized by adopting the following technical scheme:
a method for determining reactive compensation capacity of a power distribution network based on random matrix theory comprises the following steps:
(1) determining a node injection active time sequence matrix P, a node injection reactive time sequence matrix Q and a node voltage time sequence matrix V;
(2) performing normalization processing to construct a high-dimensional random matrix Y;
(3) defining a covariance matrix S of a high-dimensional random matrix, and acquiring a characteristic root of the covariance matrix;
(4) constructing a high-dimensional random matrix dY containing a node reactive compensation capacity time sequence matrix delta Q and a node voltage deviation time sequence matrix delta V, and defining a covariance matrix dS of the high-dimensional random matrix dY, and acquiring a characteristic root of the covariance matrix dS;
(5) calculating the ratio of the maximum eigenvalue of the covariance matrix S to the maximum eigenvalue of the matrix covariance matrix dS;
(6) and fitting the reactive compensation capacity of the power distribution network through a unitary linear function.
Preferably, the step (1) includes: acquiring historical data of a power distribution network, and injecting an active time sequence, a reactive time sequence and a node voltage time sequence into a node to generate a node injection active time sequence matrix P, a node injection reactive time sequence matrix Q and a node voltage time sequence matrix V;
both P, Q and V are M rows and N columns matrix; and N is the single-day data acquisition frequency, N is 24T, T is the data acquisition frequency of the measuring device per hour, and M is the number of the nodes of the power distribution network.
Further, the high-dimensional random matrix in the step (2) is constructed by taking 24 hours per day as a time window, and the specific steps include:
respectively carrying out normalization processing on P, Q, V before constructing the high-dimensional random matrix; the normalization of the Pjth column is performed according to equation (1):
wherein i is 1,2, …, N;
normalizing the active load of the ith row and the j column of the matrix P; p is a radical of
ijIs the element of ith row and j column of the matrix P;
the maximum load value of the jth column of the matrix P;
the j-th columns of the matrices Q and V are normalized by equations (2) and (3), respectively, as follows:
in formula (3), i is 1,2, …, N;
reactive load normalized for j columns and i rows of matrix Q, Q
ijIs the element of ith row and j column of the matrix Q;
the maximum load value in the jth column of the matrix Q,
normalized voltage, V, for ith row and j columns of matrix V
ijIs the element of the ith row and j column of the matrix V,
the maximum load value in the jth column of matrix V.
Further, let
The matrices obtained by performing normalization for P, Q and V, respectively;
selecting
As elements of the high-dimensional random matrix, the high-dimensional random matrix is constructed as follows:
expand Y as follows:
in the formula (5), Y is a matrix of 3M rows and N columns.
Preferably, the step (3) specifically includes: a covariance matrix S based on a large-dimensional stochastic matrix spectral analysis is defined by equation (6):
S=1/N*Y'*Y (6)
obtaining the characteristic root of the covariance matrix S through calculation:
SxS=λSxS, (7)
in the formula (7), Y' is an estimated value of a high-dimensional random matrix Y, xSIs an N-dimensional column vector; lambda [ alpha ]SIs the characteristic root of S;
obtaining lambda by solving a homogeneous system of linear equations of N unknownsSAnd recording the maximum characteristic root λmaxS。
Preferably, the step (4) specifically includes collecting historical data of the power distribution network, and injecting a time sequence of reactive compensation capacity and a node voltage deviation time sequence into the node to generate a time sequence matrix Δ Q of reactive compensation capacity and a time sequence matrix Δ V of node voltage deviation;
selecting delta Q and delta V as data sources of the high-dimensional random matrix, and constructing the high-dimensional random matrix by taking 24 hours a day as a time window;
both the delta Q and the delta V are matrixes of M rows and N columns; and N is the number of data acquisition per day, N is 24T, T is the number of data acquisition times of the measuring device per hour, and M is the number of nodes of the power distribution network.
Further, the constructing the high-dimensional random matrix may be preceded by: converting Δ V to a per unit value
And normalizing the delta Q by an expression (8), wherein the expression is as follows:
in formula (8), i is 1,2, …, N;
the normalized reactive compensation capacity of the ith row and j columns of the matrix delta Q is obtained; dq
ijIs the element of ith row and j column of the matrix delta Q;
the maximum load value of the jth column of the matrix P;
selecting
And
as the elements of the high-dimensional random matrix, the construction of the high-dimensional random matrix is completed as follows:
dY=[dQ;dV] (9)
expand dY as follows:
where dY is a matrix of 2M rows and N columns.
Further, in the step (4), defining a covariance matrix dS of the high-dimensional random matrix dY, and acquiring a feature root of the covariance matrix dS includes:
a covariance matrix dS based on a large-dimensional stochastic matrix spectral analysis is defined by equation (11):
dS=1/N*dY'*dY (11)
acquiring a characteristic root of the covariance matrix dS, wherein the expression is as follows:
dSxd=λdSxd, (12)
in the formula (12), xdIs an N-dimensional column vector; lambda [ alpha ]dSIs the characteristic root of dS;
obtaining lambda by solving a homogeneous system of linear equations of N unknownsdSAnd recording the maximum characteristic root λmaxdS。
Preferably, the step (5) includes calculating a ratio of the maximum eigenvalue of the covariance matrix S to the maximum eigenvalue of the matrix covariance matrix dS:
preferably, in the step (6), fitting the reactive compensation capacity of the power distribution network by using a unary linear function includes:
the expression of the reactive compensation capacity y of the power grid is as follows:
y=kx+b (14)
in the formula (14), b is a constant, and x is the sum of the active power of the distribution network.
Compared with the closest prior art, the invention has the following beneficial effects:
1. the method for determining the reactive compensation capacity of the power distribution network based on the random matrix theory introduces the high-dimensional random matrix theory into the reactive optimization analysis of the power distribution network, and provides a new analysis method for the reactive optimization of the power distribution network. Under the condition that the network topology structure is not changed, the method is not influenced by a network wiring mode, load diversity and load randomness, and therefore the calculation speed is improved.
2. Constructing a high-dimensional random matrix suitable for reactive power optimization of the power distribution network by using time sequence active power, time sequence reactive power and time sequence voltage acquired by the power distribution network in history, and calculating a characteristic value of a covariance matrix of the random matrix; constructing a target matrix by using historical time sequence reactive compensation capacity and voltage difference before and after time sequence compensation, and calculating a characteristic value of a covariance matrix of the target matrix; the ratio of the maximum eigenvalues of the two covariance matrices is used as the selection of the reactive compensation capacity, the calculation is simple, and the calculation result is accurate and effective.
The specific implementation mode is as follows:
the invention provides a method for determining the reactive compensation capacity of a power distribution network based on a random matrix theory, which comprises the steps of constructing a high-dimensional random matrix suitable for reactive optimization of the power distribution network by utilizing time sequence active power, reactive power and voltage collected by the power distribution network, analyzing a covariance matrix of the high-dimensional random matrix, and calculating the maximum characteristic root of the covariance matrix; and according to the result after the reactive compensation, constructing a high-dimensional random matrix of the reactive compensation capacity delta Q and the voltage deviation delta V, analyzing a covariance matrix of the high-dimensional random matrix, and calculating the maximum characteristic root of the covariance matrix. And calculating the ratio of the maximum characteristic root of the two-covariance matrix so as to find out the existing regularity.
As shown in fig. 1, the method specifically comprises the following steps:
(1) determining a node power injection time sequence matrix P, a node reactive power injection time sequence matrix Q and a node voltage time sequence matrix V;
the step (1) comprises the following steps: acquiring historical data of a power distribution network, and injecting an active time sequence, a reactive time sequence and a node voltage time sequence into a node to generate a node injection active time sequence matrix P, a node injection reactive time sequence matrix Q and a node voltage time sequence matrix V;
both P, Q and V are M rows and N columns matrix; and N is the single-day data acquisition frequency, N is 24T, T is the data acquisition frequency of the measuring device per hour, and M is the number of the nodes of the power distribution network.
(2) Performing normalization processing to construct a high-dimensional random matrix Y;
the high-dimensional random matrix in the step (2) is constructed by taking 24 hours per day as a time window, and the specific steps comprise:
respectively carrying out normalization processing on P, Q, V before constructing the high-dimensional random matrix; the normalization of the Pjth column is performed according to equation (1):
wherein i is 1,2, …, N;
normalizing the active load of the ith row and the j column of the matrix P; p is a radical of
ijIs the element of ith row and j column of the matrix P;
the maximum load value of the jth column of the matrix P;
the j-th columns of the matrices Q and V are normalized by equations (2) and (3), respectively, as follows:
in formula (3), i is 1,2, …, N;
reactive load normalized for ith row and j column of matrix Q,q
ijIs the element of ith row and j column of the matrix Q;
the maximum load value in the jth column of the matrix Q,
normalized voltage, V, for ith row and j columns of matrix V
ijIs the element of the ith row and j column of the matrix V,
the maximum load value in the jth column of matrix V.
Is provided with
The matrices obtained by performing normalization for P, Q and V, respectively;
selecting
As elements of the high-dimensional random matrix, the high-dimensional random matrix is constructed as follows:
expand Y as follows:
in the formula (5), Y is a matrix of 3M rows and N columns.
(3) Defining a covariance matrix S of a high-dimensional random matrix, and acquiring a characteristic root of the covariance matrix;
a covariance matrix S based on a large-dimensional stochastic matrix spectral analysis is defined by equation (6):
S=1/N*Y'*Y (6)
obtaining the characteristic root of the covariance matrix S through calculation:
SxS=λSxS, (7)
in the formula (7), Y' is an estimated value of a high-dimensional random matrix Y, xSIs an N-dimensional column vector; lambda [ alpha ]SIs the characteristic root of S;
obtaining lambda by solving a homogeneous system of linear equations of N unknownsSAnd recording the maximum characteristic root λmaxS。
(4) Constructing a high-dimensional random matrix dY containing a node reactive compensation capacity time sequence matrix delta Q and a node voltage deviation time sequence matrix delta V, and defining a covariance matrix dS of the high-dimensional random matrix dY, and acquiring a characteristic root of the covariance matrix dS;
the step (4) specifically comprises the steps of collecting historical data of the power distribution network, and injecting a time sequence of reactive compensation capacity and a node voltage deviation time sequence into nodes to generate a reactive compensation capacity time sequence matrix delta Q and a node voltage deviation time sequence matrix delta V;
selecting delta Q and delta V as data sources of the high-dimensional random matrix, and constructing the high-dimensional random matrix by taking 24 hours a day as a time window;
both the delta Q and the delta V are matrixes of M rows and N columns; and N is the number of data acquisition per day, N is 24T, T is the number of data acquisition times of the measuring device per hour, and M is the number of nodes of the power distribution network.
Before constructing the high-dimensional random matrix, converting the delta V into a per unit value
And normalizing the delta Q by an expression (8), wherein the expression is as follows:
in formula (8), i is 1,2, …, N;
the normalized reactive compensation capacity of the ith row and j columns of the matrix delta Q is obtained; dq
ijFor ith row and j columns of matrix DeltaQAn element;
the maximum load value of the jth column of the matrix P;
selecting
And
as the elements of the high-dimensional random matrix, the construction of the high-dimensional random matrix is completed as follows:
dY=[dQ;dV] (9)
expand dY as follows:
where dY is a matrix of 2M rows and N columns.
In the step (4), defining a covariance matrix dS of the high-dimensional random matrix dY, and obtaining a feature root of the covariance matrix dS includes:
a covariance matrix dS based on a large-dimensional stochastic matrix spectral analysis is defined by equation (11):
dS=1/N*dY'*dY (11)
acquiring a characteristic root of the covariance matrix dS, wherein the expression is as follows:
dSxd=λdSxd, (12)
in the formula (12), xdIs an N-dimensional column vector; lambda [ alpha ]dSIs the characteristic root of dS;
obtaining lambda by solving a homogeneous system of linear equations of N unknownsdSAnd recording the maximum characteristic root λmaxdS。
(5) Calculating the ratio of the maximum eigenvalue of the covariance matrix S to the maximum eigenvalue of the matrix covariance matrix dS;
(6) and fitting the reactive compensation capacity of the power distribution network through a unitary linear function. It includes:
the expression of the reactive compensation capacity y of the power grid is as follows:
y=kx+b (14)
in the formula (14), b is a constant, and x is the sum of the active power of the distribution network.
And selecting the sum of the active power of a time window in the historical data of the power distribution network and the corresponding reactive compensation capacity, and calculating the value b. And calculating reactive compensation capacity according to the values of k and b and the active power.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.