CN-114884064-B - Ship alternating current-direct current hybrid power system probability power flow calculation method based on field opening method

CN114884064BCN 114884064 BCN114884064 BCN 114884064BCN-114884064-B

Abstract

The invention relates to a ship alternating current-direct current hybrid power system probability power flow calculation method based on a field opening method, which is formed by combining field openings in a quality engineering with alternating current-direct current hybrid power flow calculation, so that the calculation frequency can be further reduced, the calculation efficiency can be improved, the states of all nodes in the system can be mastered by ship alternating current-direct current hybrid power flow calculation, the power distribution can be further carried out, the economy of the system can be improved, the method is not limited to a fixed network structure, and the method has wide applicability and good ductility and can be suitable for different types of ships and even land vehicles.

Inventors

HUANG YUQING
ZHANG YUANWEI
WANG LE
NI FENGYAN
LU XIAOLEI

Assignees

中国船舶重工集团公司第七0四研究所

Dates

Publication Date: 20260512
Application Date: 20220505

Claims (6)

1. A method for calculating the probability power flow of a ship AC/DC hybrid power system based on a field method is characterized in that, 1) Determining a topological structure of a ship alternating current-direct current hybrid power system; 2) Establishing mathematical models of cables, converters and DC converters in the system, and forming mathematical modules of all nodes of an AC/DC hybrid power system together with a traditional AC system model; 3) Establishing a field method orthogonal matrix Tian Koufa orthogonal matrix for determining an experiment mode and times according to an uncertain variable and a level value corresponding to the uncertain variable in a ship alternating-current/direct-current hybrid power system; 4) Determining bus type and power flow calculation convergence conditions according to the topological structure of the ship alternating current-direct current hybrid power system in the step 1), and determining an alternating current-direct current hybrid power flow calculation initial value; 5) Calculating a node admittance matrix according to each node mathematical module of the alternating-current and direct-current hybrid power system; 6) Calculating parameters of each node of the direct current network, namely solving voltage offset, power offset and current offset of each node in the direct current system by using a power flow calculation method, and calculating the ending values of voltage, power and current of each node after iteration; 7) Calculating parameters of each node of the alternating current network, namely solving the ending values of the voltage, the power and the current of each node of the alternating current system by using a tide calculation method; 8) The voltage amplitude and the corresponding phase angle of the system node form a Jacobian matrix, whether the Jacobian matrix needs to be corrected or not is judged, if the Jacobian matrix does not need to be corrected, the next step is carried out; 9) Judging whether the current calculation convergence condition is satisfied, judging whether all experiments of the field orthogonal experiment table are completed, and if so, outputting statistical values of voltage, power and current.
2. The method for calculating the probability power flow of the ship alternating current-direct current hybrid power system based on the field method according to claim 1 is characterized in that the field method orthogonal matrix in the step 3) has the orthogonal principle that the number of the level values of each variable appears in each column is the same, all experimental groups of the level values of each variable appear in each two columns, and all experimental groups of the level values of each variable appear in any two columns have the same frequency.
3. The method for calculating the probability power flow of the alternating current-direct current hybrid power system of the ship based on the field method according to claim 2, wherein the uncertain variable in the alternating current-direct current hybrid power system of the ship is the load of the electric propulsion system, and the load power values of the electric propulsion system corresponding to two points are selected from the load cumulative distribution probability of the electric propulsion system to serve as the two level values of the field method.
4. The method for calculating the probability power flow of the alternating current-direct current hybrid power system of the ship based on the field method according to claim 1, wherein the power flow expression of the direct current system of the i-th node in the power flow calculation method in the step 6) is: Wherein j is a system node associated with a node i, P Gi is active power generated by a generator of the node i, P Li is active power absorbed by a load of the node i, Q Gi is reactive power generated by the generator of the node i, Q Li is reactive power absorbed by the load of the node i, U i is node i voltage, theta ij is a phase difference between voltages of the node i and the node j, G ij 、B ij is conductance and susceptance between the node i and the node j, k is a direct current node on a branch where the node i is located, and U dk 、I dk 、φ k is direct current voltage and current output by a current converter corresponding to the direct current node k and a power factor phase angle of the current converter; The correction equation is obtained according to the Taylor expansion formula, the Jacobian matrix element value is obtained, the power and current offset is obtained, the new power and current value is calculated, and the voltage offset and the new voltage value are obtained.
5. The method for calculating the probability power flow of the ac/dc hybrid power system of the ship based on the field method according to claim 1, wherein the ac system power flow expression of the i-th node in the power flow calculation method in step 7) is as follows: Wherein j is a system node associated with a node i, P Gi is active power generated by a generator of the node i, P Li is active power absorbed by a load of the node i, Q Gi is reactive power generated by the generator of the node i, Q Li is reactive power absorbed by the load of the node i, U i is voltage of the node i, theta ij is phase difference of voltages between the node i and the node j, and G ij 、B ij is conductance and susceptance between the node i and the node j; the correction equation is obtained according to the Taylor expansion formula, the Jacobian matrix element value is solved, the power and current offset is solved, and the new power and current value is calculated.
6. The method for calculating the probability power flow of the alternating current-direct current hybrid power system of the ship based on the field method according to claim 1, wherein the step 8) is characterized in that in the iterative calculation process, whether the alternating current-direct current hybrid power flow calculation termination condition is met is judged by using the iterative ending value, and the calculation process is the back-pushing process of the step 5).

Description

Ship alternating current-direct current hybrid power system probability power flow calculation method based on field opening method Technical Field The invention relates to an electric power system operation and ship technology, in particular to a ship alternating current-direct current hybrid electric power system probability load flow calculation method based on a field method. Background Compared with an alternating current system, the direct current system in the ship power system has the advantages of simplifying power generation equipment, reducing system level and equipment redundancy, effectively saving materials, reducing fuel loss and the like. The ship power system adopting direct current does not need reactive compensation, and is beneficial to limiting and managing fault current, thereby improving the controllability of tide. With the new generation of the power electronic converter, the original alternating current equipment is interconnected with a large number of direct current devices, and the alternating current and direct current systems of the ship power system are mutually stored to form a ship alternating current and direct current hybrid power system. The operation of the ship AC/DC hybrid power system is highly random and uncertain under the influence of ship navigation and complex sea conditions, and the safe and stable operation of the ship is seriously influenced. In order to describe the uncertainty in the ship operation process more accurately, the alternating current-direct current mixed probability power flow calculation is an effective tool for evaluating the operation uncertainty and the safety stability of a ship power system. However, there is no probability flow calculation method for a ship ac/dc hybrid power system. The probability power flow method is to use statistical knowledge to consider uncertainty factors in power flow calculation, establish a multi-element nonlinear equation and use different methods to solve and calculate. At present, the statistical probability power flow calculation method can be roughly classified into an analog method, an approximation method and an analysis method. The simulation method has accurate results, large calculated amount and low efficiency. In view of accuracy advantages, a Monte Carlo simulation method is generally selected as a reference method to measure the accuracy of other methods. The approximation method uses the distribution characteristics of the input variables, considers the correlation among the input variables, can be subdivided into a point estimation method, a moment estimation method and a state transformation, and the calculation efficiency can be further mined. The analysis method is usually a semi-invariant method and a sequence operation method, and has high calculation speed, but complex calculation process. Disclosure of Invention In order to improve the calculation efficiency of the alternating current and direct current mixed probability power flow of the ship and save the calculation cost, the probability power flow calculation method of the alternating current and direct current mixed power system of the ship based on the field method is provided, the characteristics of each component in the system are fully excavated, and the accuracy and the reliability of the calculation result are ensured through reasonable mathematical modeling and optimization calculation. The technical scheme of the invention is that a ship alternating current-direct current hybrid power system probability power flow calculation method based on a field method, 1) Determining a topological structure of a ship alternating current-direct current hybrid power system; 2) Establishing mathematical models of cables, converters and DC converters in the system, and forming mathematical modules of all nodes of an AC/DC hybrid power system together with a traditional AC system model; 3) Establishing a field method orthogonal matrix Tian Koufa orthogonal matrix for determining an experiment mode and times according to an uncertain variable and a level value corresponding to the uncertain variable in a ship alternating-current/direct-current hybrid power system; 4) Determining bus type and power flow calculation convergence conditions according to the topological structure of the ship alternating current-direct current hybrid power system in the step 1), and determining an alternating current-direct current hybrid power flow calculation initial value; 5) Calculating a node admittance matrix according to each node mathematical module of the alternating-current and direct-current hybrid power system; 6) Calculating parameters of each node of the direct current network, namely solving voltage offset, power offset and current offset of each node in the direct current system by using a power flow calculation method, and calculating the ending values of voltage, power and current of each node after iteration; 7) Calculating parameters of each node