Optimal power flow calculation method of power distribution network considering output characteristics of distributed power supply

Abstract

The invention provides an optimal power flow calculation method of a power distribution network considering output characteristics of distributed power supplies. The optimal power flow calculation method specifically comprises the following steps: S1, acquiring initial network parameters of the power distribution network and access position information of each distributed power supply; s2, dividing each power supply into a plurality of node networks according to the communication time of the power supply; s3, analyzing a topological structure of each node network, and performing load flow calculation of the node networks according to the topological structures; s4, regarding the node network as an independent node with input and output, and simplifying the topological structure of the power distribution network; and S5, on the basis of a set period, carrying out load flow calculation on the simplified power distribution network topological structure by adopting a Newton-Raphson algorithm, and adjusting the internal operation state of the node network on the basis of an operation result. According to the invention, the power supply in the power distribution network is divided into the node networks, the topological structure of the power distribution network is simplified, and the operation rate of the power distribution network is improved while the accuracy is ensured based on the distributed operation processing node networks.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to an optimal power flow calculation method for a distribution network taking into account output characteristics of distributed power sources. Background Art

[0002] Power flow calculation is to calculate the distribution of active power, reactive power and voltage in the power grid under the given power system network topology, component parameters and power generation and load parameters. Power flow calculation is a very important analytical calculation in the power system, which is used to study various problems raised in system planning and operation.

[0003] Distributed power technology is based on new technologies such as automatic control systems, advanced material technologies, and flexible manufacturing processes. It has the advantages of low pollution emissions, flexibility, convenience, high reliability, and high efficiency. As an effective supplement to traditional power supply methods, it is increasingly used in distribution networks, which has a revolutionary impact on traditional power system technology and economy, and will play an increasingly important role in the power system. However, the distributed power distribution network has the characteristics of short transmission lines, many line branches, and low voltage levels, which are quite different from the traditional distribution network. It will affect the node voltage, power quality, power reliability, system relay protection, etc. in the distribution network, resulting in the original power flow calculation method cannot be well applied to the distribution network containing distributed power sources, and cannot accurately analyze the distribution network containing distributed power sources. Summary of the invention

[0004] In order to solve the technical problem that the existing power flow calculation method in the prior art cannot accurately analyze the distribution network including distributed power sources, the optimal power flow calculation method of the distribution network considering the output characteristics of distributed power sources proposed in the present invention specifically includes the following steps:

[0005] S1. Obtain the initial network parameters of the distribution network and the access location information of each distributed power source, and model each distributed power source;

[0006] S2, identifying each power source in the distribution network, and dividing each power source into multiple node networks according to the communication time of the power source;

[0007] S3, analyzing the topological structure of each node network, performing power flow calculation of the node network according to the topological structure, and setting the initial value of the node network;

[0008] S4, treat the node network as an independent node with input and output, set the input and output constraints of the node network, and simplify the topological structure of the distribution network;

[0009] S5. Based on the set cycle, the Newton-Raphson algorithm is used to perform power flow calculation on the simplified distribution network topology, and the operating state inside the node network is adjusted based on the calculation results.

[0010] Furthermore, in S1, the initial network parameters of the distribution network include network topology, line impedance, loads of each node, and specific access points of each distributed power source, and the distributed power sources include wind turbines, photovoltaic generators and micro gas generators.

[0011] Furthermore, in S2, the power source includes a thermal power generating set, a wind power generating set, a photovoltaic generating set and a micro gas generating set, and each power source is provided with an intelligent computing device.

[0012] Furthermore, in S2, the specific process of dividing each power supply into multiple node networks according to the communication time of the power supply is based on the network topology of the distribution network, sending test signals between adjacent power supplies, calculating the transmission time of the test signals, forming multiple tentative node networks according to the transmission time, and integrating the multiple tentative node networks to obtain the final node network.

[0013] Furthermore, the specific process of forming multiple temporary node networks based on transmission time is to construct multiple temporary node networks with each power supply as a central unit, the number of temporary node networks is the same as the number of power supplies, and the power supply whose transmission time with the central unit of the temporary node network is less than the time threshold is added to the corresponding temporary node network.

[0014] Furthermore, the specific process of integrating multiple temporary node networks is to divide the temporary node networks into multiple groups according to whether there are overlapping power sources, and within each group, arrange the temporary node networks from large to small according to the number of power sources in the temporary node network to form an integration sequence, and integrate the temporary node networks based on the integration sequence, and add the node loads connected to the power sources in the temporary node network to the temporary node network to form a final node network.

[0015] Furthermore, the specific steps of performing the tentative node network integration based on the integration sequence are as follows:

[0016] S21, the number of node networks in the integration sequence is tentatively set to n, and the current integration node i is initialized to 1;

[0017] S22, obtaining all power sources in the i-th tentative node network in the integration sequence as target power sources, and determining whether the target power source exists in the (i+1)-th tentative node network to the n-th tentative node network in the integration sequence, and if so, deleting the target power source from the corresponding tentative node network;

[0018] S23, determine whether i is less than (n-1), if i is less than (n-1), so that i=i+1, return to S22, otherwise, end the tentative node network integration.

[0019] Furthermore, in S3, if the node network is a radial network, a forward-backward algorithm is used to calculate the power flow; if the node network is a ring network, a Newton-Raphson algorithm is used to calculate the power flow.

[0020] Furthermore, in S4, the specific process of setting the input and output constraints of the node network is to obtain the historical operating data of the uncontrollable power supply in the node network, and set the input and output constraints of the node network in combination with the operating parameters of other power supplies. The uncontrollable power supply is a wind turbine and a photovoltaic generator.

[0021] Furthermore, in S5, the Newton-Raphson algorithm is used to perform power flow calculations on the simplified distribution network topology to determine the operating parameters of the independent nodes corresponding to the node network. The node network obtains real-time data of the power supply through a computing array composed of intelligent computing devices configured by the power supply, and performs calculations to determine whether the calculated operating parameters can be achieved. If they can be obtained, the operating state of the power supply is adjusted. If they cannot be obtained, the current operating state of the power supply is not adjusted, and the input and output constraints of the node network are adjusted based on the real-time data of the power supply, so that the distribution network performs the next power flow calculation based on the updated input and output constraints of each node network.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The power sources in the distribution network are divided into node networks, the topology of the distribution network is simplified, and the node network is processed based on distributed computing, which improves the computing speed of the distribution network while ensuring accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of the optimal power flow calculation method of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0026] like Figure 1 As shown, the optimal power flow calculation method for the distribution network considering the output characteristics of distributed power sources proposed by the present invention specifically includes the following steps:

[0027] S1. Obtain the initial network parameters of the distribution network and the access location information of each distributed power source, and model each distributed power source. The initial network parameters of the distribution network include network topology, line impedance, load of each node, and specific access point of each distributed power source. Distributed power sources include wind turbines, photovoltaic generators, and micro gas generators.

[0028] The power model of a wind turbine generator set is as follows:

[0029]

[0030] Where P W is the active power of wind power generation, N W is the number of wind turbines in the wind farm, P WG is the actual output active power of the wind turbine, Q W is the reactive power of wind power generation, θ W is the wind turbine power factor angle of the wind farm.

[0031] The power model of the photovoltaic generator set is as follows:

[0032]

[0033] Where, P PV is the active power of photovoltaic power generation, γ is the solar radiation intensity, A is the total area of ​​the solar cell array, μ is the overall photoelectric conversion efficiency, Q PV is the reactive power of photovoltaic power generation, θ PV is the power factor angle of photovoltaic power generation.

[0034] S2. Identify each power source in the distribution network, and divide each power source into multiple node networks according to the communication time of the power source. The power sources include thermal power generators, wind power generators, photovoltaic power generators and micro gas generators, and each power source is provided with an intelligent computing device. The specific process of dividing each power source into multiple node networks according to the communication time of the power source is based on the network topology of the distribution network, sending test signals between adjacent power sources, calculating the transmission time of the test signals, forming multiple tentative node networks according to the transmission time, and integrating the multiple tentative node networks to obtain the final node network. The specific process of forming multiple tentative node networks according to the transmission time is to construct multiple tentative node networks with each power source as the central unit, the number of tentative node networks is the same as the number of power sources, and the power source whose transmission time with the central unit of the tentative node network is less than the time threshold is added to the corresponding tentative node network. The specific process of integrating multiple tentative node networks is to divide the tentative node networks into multiple groups according to whether there are overlapping power sources. Within each group, arrange the tentative node networks from large to small according to the number of power sources in the tentative node networks to form an integration sequence. Based on the integration sequence, the tentative node networks are integrated, and the node loads connected to the power sources in the tentative node networks are added to the tentative node networks to form the final node network. The specific steps for integrating tentative node networks based on the integration sequence are as follows:

[0035] S21, the number of node networks in the integration sequence is tentatively set to n, and the current integration node i is initialized to 1;

[0036] S22, obtaining all power sources in the i-th tentative node network in the integration sequence as target power sources, and determining whether the target power source exists in the (i+1)-th tentative node network to the n-th tentative node network in the integration sequence, and if so, deleting the target power source from the corresponding tentative node network;

[0037] S23, determine whether i is less than (n-1), if i is less than (n-1), so that i=i+1, return to S22, otherwise, end the tentative node network integration.

[0038] S3. Analyze the topological structure of each node network, perform power flow calculation of the node network according to the topological structure, and set the initial value of the node network. Specifically, if the node network is a radial network, the forward-backward algorithm is used for power flow calculation. If the node is a ring network, the Newton-Raphson algorithm is used for power flow calculation. The intelligent computing devices set in the power supply of the node network form a computing array to perform power flow calculation.

[0039] S4. Treat the node network as an independent node with input and output, set the input and output constraints of the node network, and simplify the topological structure of the distribution network. The specific process of setting the input and output constraints of the node network is to obtain the historical operation data of the uncontrollable power supply in the node network, combine the operation parameters of other power supplies, and set the input and output constraints of the node network. The uncontrollable power supply is a wind turbine and a photovoltaic generator.

[0040] S5. Based on a set period (e.g., 30 minutes), the Newton-Raphson algorithm is used to perform flow calculations on the simplified distribution network topology, and the operating state inside the node network is adjusted based on the calculation results. Specifically, the Newton-Raphson algorithm is used to perform flow calculations on the simplified distribution network topology to determine the operating parameters of the independent nodes corresponding to the node network. The node network obtains the real-time data of the power supply through the operation array composed of the intelligent computing devices configured by the power supply, performs calculations, and determines whether the calculated operating parameters can be achieved. If they can be obtained, the operating state of the power supply is adjusted. If they cannot be obtained, the current operating state of the power supply is not adjusted. The input and output constraints of the node network are adjusted based on the real-time data of the power supply, so that the distribution network performs the next flow calculation based on the updated input and output constraints of each node network.

[0041] The above disclosure is only the preferred embodiment of the present invention, and certainly cannot be used to limit the scope of the present invention. It should be pointed out that for those skilled in the art, any equivalent changes made to the scheme of the present invention without departing from the design structure and principle of the present invention are considered to be within the protection scope of the present invention.

Claims

1. A method for calculating the optimal power flow of a distribution network considering the output characteristics of distributed power sources, characterized in that ,The optimal power flow calculation method specifically includes the following steps: S1. Obtain the initial network parameters of the distribution network and the access location information of each distributed power source, and model each distributed power source; S2, identifying each power source in the distribution network, and dividing each power source into multiple node networks according to the communication time of the power source; S3, analyzing the topological structure of each node network, performing power flow calculation of the node network according to the topological structure, and setting the initial value of the node network; S4, treat the node network as an independent node with input and output, set the input and output constraints of the node network, and simplify the topological structure of the distribution network; S5. Based on the set cycle, the Newton-Raphson algorithm is used to perform power flow calculation on the simplified distribution network topology, and the operating state inside the node network is adjusted based on the calculation results.

2. The optimal power flow calculation method according to claim 1, characterized in that: In S1, the initial network parameters of the distribution network include network topology, line impedance, loads of each node, and specific access points of each distributed power source, and the distributed power source includes a wind turbine generator set, a photovoltaic generator set and a micro gas generator set.

3. The optimal power flow calculation method according to claim 1, characterized in that: In S2, the power sources include thermal power generating sets, wind power generating sets, photovoltaic generating sets and micro gas generating sets, and each power source is provided with an intelligent computing device.

4. The optimal power flow calculation method according to claim 3, characterized in that: In S2, the specific process of dividing each power supply into multiple node networks according to the communication time of the power supply is based on the network topology of the distribution network, sending test signals between adjacent power supplies, calculating the transmission time of the test signals, forming multiple tentative node networks according to the transmission time, and integrating the multiple tentative node networks to obtain the final node network.

5. The optimal power flow calculation method according to claim 4, characterized in that: The specific process of forming multiple temporary node networks according to the transmission time is to construct multiple temporary node networks with each power supply as the central unit, the number of temporary node networks is the same as the number of power supplies, and the power supply whose transmission time with the central unit of the temporary node network is less than the time threshold is added to the corresponding temporary node network.

6. The optimal power flow calculation method according to claim 4, characterized in that: The specific process of integrating multiple temporary node networks is to divide the temporary node networks into multiple groups according to whether there are overlapping power sources. Within each group, the temporary node networks are arranged from large to small according to the number of power sources in the temporary node network to form an integration sequence. The temporary node networks are integrated based on the integration sequence, and the node loads connected to the power sources in the temporary node network are added to the temporary node network to form a final node network.

7. The optimal power flow calculation method according to claim 6, characterized in that: The specific steps of performing provisional node network integration based on the integration sequence are as follows: S21, the number of node networks in the integration sequence is tentatively set to n, and the current integration node i is initialized to 1; S22, obtaining all power sources in the i-th tentative node network in the integration sequence as target power sources, and determining whether the target power source exists in the (i+1)-th tentative node network to the n-th tentative node network in the integration sequence, and if so, deleting the target power source from the corresponding tentative node network; S23, determine whether i is less than (n-1), if i is less than (n-1), so that i=i+1, return to S22, otherwise, end the tentative node network integration.

8. The optimal power flow calculation method according to claim 1, characterized in that: In S3, if the node network is a radial network, the forward-backward algorithm is used to calculate the power flow; if the node network is a ring network, the Newton-Raphson algorithm is used to calculate the power flow.

9. The optimal power flow calculation method according to claim 3, characterized in that: In S4, the specific process of setting the input and output constraints of the node network is to obtain the historical operating data of the uncontrollable power supply in the node network, and set the input and output constraints of the node network in combination with the operating parameters of other power supplies. The uncontrollable power supply is a wind turbine and a photovoltaic generator.

10. The optimal power flow calculation method according to claim 3, characterized in that: In S5, the Newton-Raphson algorithm is used to perform power flow calculations on the simplified distribution network topology to determine the operating parameters of the independent nodes corresponding to the node network. The node network obtains the real-time data of the power supply through a computing array composed of intelligent computing devices configured by the power supply, and performs calculations to determine whether the calculated operating parameters can be achieved. If they can be obtained, the operating state of the power supply is adjusted. If they cannot be obtained, the current operating state of the power supply is not adjusted. The input and output constraints of the node network are adjusted based on the real-time data of the power supply, so that the distribution network performs the next power flow calculation based on the updated input and output constraints of each node network.

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