WO2016141683A1

WO2016141683A1 - Implementation method for energy internet absorbing large-scale distributed power supply

Info

Publication number: WO2016141683A1
Application number: PCT/CN2015/087811
Authority: WO
Inventors: 赵珊珊; 宋晓辉; 孟晓丽; 盛万兴
Original assignee: 中国电力科学研究院; 国家电网公司
Priority date: 2015-03-10
Filing date: 2015-08-21
Publication date: 2016-09-15
Also published as: CN104659780A; CN104659780B

Abstract

An implementation method for an energy Internet absorbing a large-scale distributed power supply. The method comprises: firstly, according to a network structure and load characteristics of a closed-loop operating power distribution network and the grid-connection situation of distributed power supplies, selecting key nodes of which energy requires optimal distribution from the power distribution network; and then optimally configuring a double-level regulation and control connection line among the selected key nodes, and reasonably configuring an electrical isolation device in the closed-loop operating power distribution network, so as to configure local protection by taking the electrical isolation device as a boundary node. By means of the method, the problems of reasonable flow and optimal configuration of energy in a complex closed-loop operating power distribution network containing large-scale distributed power supplies can be effectively solved; and flexible scheduling, scheduling as required and optimal scheduling of energy can be realized on the premise of meeting the requirements of system security and reliability, so that a cost-effective solution is provided for an energy Internet at a level of constructing a power distribution network.

Description

Implementation method of energy internet suitable for eliminating large-scale distributed power sources

Technical field:

The invention relates to the technical field of distribution networks, and more particularly to an implementation method of an energy internet suitable for consuming large-scale distributed power sources.

Background technique:

The traditional distribution network mostly adopts the "closed loop design, open loop operation" mode, and the current trend shows a natural distribution according to the characteristics of the power grid topology. However, with the increasing demand for large-scale distributed power grid integration and higher power supply reliability, the future distribution network will gradually develop into an energy Internet with renewable, distributed, interconnected and intelligent features to achieve wide-area Flexible scheduling, on-demand scheduling and optimized scheduling of energy in the range to meet the safe and reliable access of large-scale distributed power sources and wide-area energy sharing, ensuring high power supply reliability and good power quality and economic benefits.

Comparing the new requirements and new features of the above-mentioned distribution network, the existing grid structure and implementation have the following problems: On the one hand, the existing grid structure does not have the function of reasonable flow of energy and optimized distribution, and cannot achieve wide-area scope. Flexible scheduling of energy, on-demand scheduling and optimized scheduling; on the other hand, after the existing grid closed-loop operation or a large number of distributed power sources are connected to the grid, the short-circuit current is too large, and the relay protection and safety automatic devices cannot meet the system safety and reliability requirements.

Since the structure and implementation of the existing power grid cannot meet the new requirements and new features of the future distribution network, it is necessary to propose an energy Internet implementation method to solve the following two problems: 1) to realize the reasonable energy in the distribution network Flow and optimized distribution; 2) meet the requirements of system safety and reliability.

At present, there are two main technical solutions for solving the problem of reasonable adjustment and distribution of energy in the distribution network:

(1) Set up communication lines between different regional power grids, such as the “petal” communication lines in the “Plum Blossom” distribution network in Singapore, so as to achieve interconnection between regional power grids and improve system power supply reliability. However, it still has the following shortcomings: on the one hand, the regional power grids are only interconnected by simple tie lines, the current trend is still naturally distributed, and it cannot be adjusted in both directions, on-demand adjustment and fast and flexible adjustment; on the other hand, due to regional memory In some nodes where energy cannot be reasonably flowed and distributed, flexible scheduling, on-demand scheduling, and optimal scheduling of energy within the area cannot be achieved.

(2) Install a flexible AC transmission (FACTS) device on the original transmission line to solve the problem of unreasonable distribution of local power flow in the transmission network. However, since the network structure has not changed, the FACTS device can only affect the local power flow distribution, and cannot solve the problem of flexible scheduling, on-demand scheduling, and global optimization scheduling in the wide-area range.

In addition, for the closed-loop operation of the grid or the excessive short-circuit current after a large number of distributed power sources are connected to the grid, the common current limiting measure is to install a current-limiting reactor, but the electrical distance of the line is also increased while reducing the short-circuit current. , generating a large voltage drop, reducing the quality of power, and the relay protection method in the existing distribution network is also difficult to meet the safety of the system. Reliability requirements.

Summary of the invention:

The object of the present invention is to provide an energy Internet implementation method suitable for consuming large-scale distributed power sources, and to solve the problem of reasonable energy flow and optimal distribution in a complex distribution network with closed-loop operation of a large-scale distributed power source. Flexible scheduling, on-demand scheduling, and optimal scheduling of energy are achieved under the requirements of system security and reliability.

To achieve the above object, the present invention is implemented by the following technical solution: an implementation method of an energy Internet suitable for consuming a large-scale distributed power source, which is a complex distribution network with closed-loop operation of a large-scale distributed power source. , the method includes:

According to the network structure, load characteristics and distributed power grid connection situation of the closed-loop operation distribution network, the key nodes in the distribution network whose energy needs to be optimally allocated are selected;

Optimize the configuration of dual-level control tie lines between selected key nodes to achieve rapid and flexible regulation of power flow and optimal energy allocation;

The electrical isolation device is arranged in the closed-loop operation distribution network to realize the limitation of the short-circuit current and the isolation of the fault in the closed-loop operation distribution network;

The in-situ protection is configured with the electrical isolation device as a boundary node to realize regional fault diagnosis, isolation and automatic recovery.

The present invention provides an implementation method of an energy Internet suitable for consuming a large-scale distributed power source. The key nodes that need to be optimally allocated for the energy include: a grid connection point of a distributed power source or a public connection point of a user system, and a network appears in the network. A node with an overload phenomenon, a primary load or secondary load node requiring high power supply reliability, a weak voltage node in the network, or a node with an overvoltage phenomenon. Through the selection of key nodes, it can solve the problem that the energy supply in the closed-loop operation distribution network can not reasonably distribute the power supply capacity.

The invention provides an implementation method of an energy internet suitable for consuming a large-scale distributed power source, wherein the optimally configured dual-level control tie line comprises: optimizing the planning method according to the principle of optimal energy allocation and economic efficiency of investment operation Deploy a dedicated flexible power flow control link between two or more key nodes in the power supply area where energy energy is required to be actively scheduled, or between two or more key nodes in the power supply area where the energy needs to be naturally balanced. A simple dedicated tie line is built to form a double-layered control tie line structure. In the complex distribution network with closed-loop operation of large-scale distributed power supply, the double-layered control tie line structure can solve the problem of rational energy flow and optimal distribution, and realize flexible scheduling and on-demand energy in a wide area. Scheduling and optimizing scheduling.

The invention provides an energy internet implementation method suitable for consuming large-scale distributed power sources, and obtains the special flexible power flow control connection line through optimization calculation according to the optimal power flow control requirements and the principle of investment operation economy. Installation location and capacity of the flexible power distribution unit D-FACTS.

The invention provides an energy internet implementation method suitable for absorbing a large-scale distributed power supply, and the flexible power distribution device D-FACTS on the dedicated flexible power flow control contact line selects a unified power flow controller UPFC or a static synchronous compensator STATCOM Or static synchronous series compensator SSSC or thyristor controllable series compensator TCSC. Two-way adjustment, on-demand adjustment and controllable adjustment of the power flow can be realized by the D-FACTS device.

The present invention provides an implementation method of an energy Internet suitable for consuming a large-scale distributed power source. The process of determining the installation location of the electrical isolation device includes:

Load weighting calculation, wherein the weighting coefficient of the load is determined according to the importance of the load, the weighting coefficient of the primary load is the largest, the secondary load is second, and the weighting coefficient of the tertiary load is the smallest;

Dividing a section of the closed-loop operating line according to the principle of load balancing;

Verify that the electrical distance between the segments meets the requirements for protection sensitivity. If not, re-divide the segment so that the electrical distance meets the requirements for protection sensitivity;

An electrical isolation device is installed at the segmentation point of the segment. Through the process, fault isolation and short-circuit current limitation of different sections can be realized, which facilitates the cooperation of multi-level protection, ensures good voltage quality, and can achieve lightning protection and anti-interference effects.

The invention provides an implementation method of an energy internet suitable for consuming a large-scale distributed power source. The configuration principle of the electrical isolation device is that the short-circuit current that may flow through each node in the power supply circuit should meet the maximum short-circuit current level of the system. Requirements; can achieve reliable and effective fault isolation in the system; can meet the needs of system security protection.

The present invention provides an implementation method of an energy Internet suitable for consuming a large-scale distributed power source, the electrical isolation device comprising an isolation transformer or a power electronic converter device.

The invention provides an energy internet implementation method suitable for consuming a large-scale distributed power source, and the isolation transformer form comprises an unloaded voltage regulator or an on-load voltage regulator or an isolation transformer with high impedance or secondary winding split or The voltage and short circuit current conditions of the electrical system are selected from a combination of two or more of the isolated transformer forms. If the voltage of the power distribution system cannot meet the requirements, an on-load voltage regulating isolating transformer can be used to ensure good voltage quality. Otherwise, a no-load voltage regulating isolating transformer can be used; if the system short-circuit current cannot meet the requirements, high impedance can be used and twice The isolation transformer of the winding split reduces the short-circuit current; if the system voltage and the short-circuit current cannot meet the requirements, an isolation transformer with on-load voltage regulation and high-impedance splitting can be used.

The invention provides an implementation method of an energy internet suitable for consuming a large-scale distributed power source, and the electrical isolation device is selected according to an equivalent impedance parameter, an installation capacity parameter and a quantity parameter.

The invention provides an implementation method of an energy internet suitable for consuming a large-scale distributed power source. The configuration principle of the equivalent impedance parameter, the installation capacity and the quantity of the electrical isolation device is: satisfying each line segment on the power supply circuit The requirements of electrical isolation, the short-circuit currents that may pass through each node in the power supply loop meet the requirements of the maximum short-circuit current level of the power system and ensure the economy and investment in the whole life cycle under the premise of ensuring the safe and reliable operation of the power system. rationality.

The present invention provides an implementation method of an energy Internet suitable for consuming large-scale distributed power sources. The specific type of local protection configured by using the electrical isolation device as a boundary node may be determined according to the specific situation of the distribution network, and may be Select longitudinal differential protection or current quick-break protection or over-current protection or overload protection or single-phase ground protection. In addition, the main supply line for closed-loop operation should also be equipped with longitudinal differential protection, and the downstream radial branch line can be protected by three-stage current protection. Through the relay protection described, reliable multi-level protection coordination and regional fault diagnosis, isolation and automatic recovery are realized.

Compared with the closest prior art, the present invention provides the following technical effects:

1. The technical solution provided by the invention realizes the active regulation and natural balance of energy in the energy internet through the optimization method of the double-layer regulation connection line, and allows the two-way regulation of the power flow, the adjustment on demand and the rapid and flexible adjustment, and the power flow control effect is remarkable and reliable. Effectively solve the problem of reasonable energy flow and optimal allocation in complex distribution network with closed-loop operation of large-scale distributed power supply, thereby realizing flexible energy scheduling, on-demand scheduling and optimal scheduling for building a distribution network level. Energy Internet provides a cost-effective solution;

2. The technical solution provided by the invention can well meet the requirements of system safety and reliability, because it can effectively limit the short-circuit current in the complex distribution network fault with closed-loop operation of large-scale distributed power supply, and ensure good performance. The power supply quality can also realize the diagnosis, isolation and automatic recovery of regional faults through reliable multi-level protection, and at the same time achieve lightning protection and anti-interference effects;

3. The technical solution provided by the invention is simple and effective, and is convenient for operation and maintenance as well as popularization and application;

4. The technical solution provided by the present invention can not only fully mobilize and utilize various distributed resources in the distribution network, but also improve the capability of the distribution network to receive distributed power, and provide a secure access for large-scale distributed power supply. A cost-effective solution, and can improve asset utilization, maximize the power supply capacity of the grid, and greatly improve the economics of grid operation under the premise of ensuring power quality and reliability.

DRAWINGS

1 is a general flow chart of an implementation method of an energy Internet suitable for consuming a large-scale distributed power supply according to the present invention;

2 is a schematic structural diagram of a double-layer control tie line provided by the present invention;

3 is a schematic structural diagram of an implementation method of an energy Internet suitable for a large-scale distributed power supply applied to a hand-held single ring network according to the present invention;

FIG. 4 is a schematic structural diagram of an implementation method of an energy Internet suitable for consuming a large-scale distributed power supply applied to a three-power handle ring network according to the present invention.

detailed description

The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

The overall flow chart of an implementation method of an energy Internet suitable for consuming large-scale distributed power sources is shown in FIG. 1 , which is a complex distribution network with closed-loop operation of large-scale distributed power sources. The specific implementation is as follows:

1. According to the network structure, load characteristics and distributed power grid connection situation of the closed-loop operation distribution network, select the key nodes in the distribution network where the energy needs to be optimally allocated.

Due to the existence of some nodes in the closed-loop operating distribution network with large-scale distributed power, the energy cannot be reasonably flowed and distributed, which severely limits the power supply capacity of the complex distribution network in closed-loop operation, so they are selected as the key to configuring the dedicated tie line. node.

The key nodes in the distribution network that need to be optimized for energy distribution mainly include the following nodes: 1) the connection point of the distributed power supply or the common connection point of the user system; 2) the heavy load nodes in the network that cannot continuously meet the power demand for a long time or often appear The node with overload phenomenon; 3) the important load node with high requirements on power supply reliability, generally the primary load or secondary load node; 4) the weak node in the system, such as the system does not meet the voltage stability margin requirement Or nodes that often have overvoltages; 5) other important nodes of the network that need to be optimized for allocation of energy, such as network nodes that cannot meet the energy allocation requirements in the optimization calculation.

The rational selection of key nodes is the basis for cost-effective allocation of dedicated tie lines, which can promote the rational distribution of power flow and the optimal allocation of energy.

2. Optimize the configuration of the dual-level control tie line between the selected key nodes to realize the rapid and flexible regulation of the power flow and the optimal allocation of energy. The structure of the double-layer control tie line is established as shown in Figure 2:

1 According to the principle of optimal energy allocation and economic efficiency of investment operation, through the optimization planning method, a special flexible power flow control contact line is established between two or more key nodes in the power supply area or between areas where energy active scheduling is required;

2 According to the principle of optimal power flow control and the economics of investment operation, the optimization algorithm is used to calculate the installation position and capacity of the D-FACTS on the dedicated flexible power flow control link;

3 According to the principle of optimal energy allocation and economic efficiency of investment operation, through the optimization planning method, a simple special contact line is established between two or more key nodes in the power supply area or between the areas where energy natural balance is needed;

4 Configure reasonable line protection for the dual-level control tie line.

In steps 1 and 3, an effective flexible power flow control tie line can be established between two or more key nodes in an important power supply area or between the two areas through the optimization planning method to realize active energy dispatching in the general power supply area or between areas. A simple dedicated tie line between two or more key nodes creates a natural balance of energy. Among them, the basic principles of the optimization planning method are: to ensure the rapid and flexible regulation of the current; to ensure the reasonable flow of energy and optimize the distribution; to ensure the economical and investment rationality of the dedicated communication line in the whole life cycle.

The basic requirement of the optimization calculation in step 2 is: under the premise of ensuring rapid and flexible control of the power flow, the economics of the D-FACTS device in the whole life cycle should be met as much as possible; and the D-FACTS device is selected under the condition of the static characteristics of the voltage. The smallest installation plan and control strategy.

The dual-level regulatory tie line includes dedicated flexible power flow control tie lines and simple dedicated tie lines. The dedicated flexible power flow control tie line refers to a dedicated contact line for installing a flexible power distribution (D-FACTS) device in order to achieve rapid and flexible regulation of the power flow. Among them, D-FACTS devices include unified power flow controller (UPFC), static synchronous compensator (STATCOM), static synchronous series compensator (SSSC), thyristor controllable series compensator (TCSC), static var compensator (SVC), etc. . If the UPFC device is installed on the dedicated contact line, it is called a dedicated flexible power flow control link line containing UPFC, and so on, a dedicated flexible power flow control contact line with different flexible power distribution devices can be obtained. A simple dedicated tie line refers to a dedicated line set up to achieve communication between different nodes, in which no D-FACTS device is installed on the line. It is a concept that is opposed to a dedicated flexible power flow regulation tie line.

Therefore, in the complex distribution network with closed-loop operation of large-scale distributed power supply, the structure of the two-level control tie line is formed by optimizing the configuration of the dedicated flexible power flow control contact line and the simple dedicated tie line, and the rational flow and optimization of energy are solved. The problem of allocation enables flexible scheduling, on-demand scheduling, and optimized scheduling of energy across a wide area.

3. Reasonably configure the electrical isolation device in the closed-loop operation distribution network to realize the short-circuit current limitation and fault isolation in the closed-loop distribution network, including the following steps:

1 According to the principle of load balancing and satisfying the sensitivity of protection, the closed-loop running line is reasonably divided into sections to determine the installation position of the electrical isolation device;

2 select the specific type of electrical isolation device configured in the system;

3 Determine the specific parameters of the electrical isolation device configured in the system.

The general principle of the configuration of the electrical isolation device: the short-circuit current that may flow through each node in the power supply circuit should meet the requirements of the maximum short-circuit current level of the system; it can realize reliable and effective fault isolation in the system; it can meet the needs of system security protection.

The method for determining the installation position of the electrical isolation device in step 1: 1) load weighting calculation; 2) according to the load The principle of balance is to divide the section of the closed-loop running line reasonably; 3) whether the electrical distance between the sections meets the requirements of protection sensitivity, and if not, re-divide the section so that the electrical distance meets the requirements of protection sensitivity; Installing an electrical isolation device at the segmentation point of the segment. Among them, the weighting coefficient of the load is determined according to the importance of the load. The weighting coefficient of the primary load is the largest, the secondary load is the second, and the weighting coefficient of the tertiary load is the smallest.

In step 2, the electrical isolation device may be an electrical isolation device such as an isolation transformer or a power electronic converter. Among them, the isolation transformer can adopt the following basic forms: an isolation transformer with no load regulation, an isolation transformer with load regulation, a high-impedance isolation transformer, and an isolation transformer with secondary winding split. It is also possible to select a combination of two or more of the isolated transformer forms depending on the voltage of the power distribution system and the short-circuit current. If the voltage of the power distribution system cannot meet the requirements, an on-load voltage regulating isolating transformer can be used to ensure good voltage quality. Otherwise, a no-load voltage regulating isolating transformer can be used; if the system short-circuit current cannot meet the requirements, high impedance can be used and twice The isolation transformer of the winding split reduces the short-circuit current; if the system voltage and the short-circuit current cannot meet the requirements, an isolation transformer with on-load voltage regulation and high-impedance splitting can be used. If the maximum short-circuit current of the node in the power supply circuit is still unable to meet the requirements of the system's allowable short-circuit current level after proper configuration of the electrical isolation device, a current-limiting reactor can be installed to reduce the short-circuit current, for example, in the following two forms: 1) A current limiting reactor and an isolation transformer with on-load voltage regulation; 2) a current limiting reactor and two isolation transformers, at least one of the two transformers has an isolation transformer with load regulation. This can achieve the purpose of limiting the short-circuit current while ensuring good power quality.

The parameter selection of the electrical isolation device in step 3 mainly considers equivalent impedance, installation capacity and quantity.

In order to effectively limit the short-circuit current in the fault of the distribution network with closed-loop operation of a large-scale distributed power supply, the equivalent impedance of the electrical isolation device can be determined according to the maximum short-circuit current that may flow through the circuit in the maximum operating mode of the system, specifically The following formula determines:

Where: I _d —— short-circuit current synthesis current of short-circuit point; m——ratio of combined current and positive-sequence current; X ^* _{Σ ——synthetic} impedance standard value other than equivalent impedance of electrical isolation device; X ^* _Iso - the standard value of the equivalent impedance of the electrical isolation device; S _B - the reference capacity; U _B - the reference voltage; I _{max_heat} - the thermal stable current allowed by the device; i _ch - the inrush current during the short circuit; _Ch - impact coefficient; I _{max_dyna} - the dynamic steady current allowed by the device.

If the impedance of the electrical isolation device itself does not meet the requirements of equation (1), it may be considered to install a current limiting reactor in the vicinity of the electrical isolation device.

The principle of installation capacity and quantity of electrical isolation devices: meet the requirements of electrical isolation of each line segment on the power supply circuit; the short-circuit current that may flow through each node in the power supply circuit should meet the maximum short-circuit current of the system. Flat requirements; under the premise of ensuring the safe and reliable operation of the system, the economics and investment rationality within the whole life cycle should be met as much as possible.

If the electrical isolation device selects an isolation transformer, the configuration of the isolation transformer specifically includes the selection of the isolation transformer, the number of installations, and the location selection.

The selection of the isolation transformer can be considered from the aspects of capacity and equivalent impedance. The capacity of the isolation transformer should be determined according to the maximum capacity that the circuit needs to deliver. It should consider not only the current maximum load, but also the load development in the next 5 to 10 years. The equivalent impedance of the isolation transformer can be determined by referring to equation (1).

The method of determining the number and position of the isolation transformers can be determined by referring to the above-described method of determining the number and location of the electrical isolation devices.

4. Configure the local protection with the electrical isolation device as the boundary node to realize the diagnosis, isolation and automatic recovery of the regional fault.

The specific type of local protection can be determined according to the specific conditions of the distribution network, such as longitudinal differential protection, current quick-break protection, over-current protection, overload protection, single-phase grounding protection, etc.

In addition, the main supply line for closed-loop operation should also be equipped with longitudinal differential protection, and the downstream radial branch line can be protected by three-stage current protection.

Example 1:

The following is an example of a hand-held single ring network, and the technical solution of the present invention is as follows:

A hand-in-hand single-loop network consists of three feeders of “two vertical and one horizontal”. Busbar I and busbar II can be different busbars of different substations or the same substation, or the same busbar of the same substation, each feeder is divided into two. Sections, numbered L ₁ , L ₂ , ..., L ₆ , nodes a and b are the grid-connected points of the distributed power source, and nodes c and d are heavy-duty nodes that cannot continuously meet the power demand for a long time. The schematic diagram of the implementation method of the energy Internet for applying the large-scale distributed power supply to the hand-held single ring network is shown in FIG. 3 . Among them, L ₇ is a special flexible power flow control link line containing UPFC, and L ₈ is a simple dedicated tie line, which constitutes the structure of the double-layer control tie line. One end of the UPFC device on L ₇ is connected to the system in parallel through a transformer, and the other end is connected in series through another transformer. The electrical isolation device adopts an isolation transformer with on-load voltage regulation and high impedance and secondary winding splitting. The six isolation transformers are numbered T ₁ , T ₅ , T ₇ , T ₁₀ , T ₁₃ , T ₁₄ . The technical solution of the present invention includes the following implementation steps:

(1) According to the network structure, load characteristics and distributed power grid connection situation of the hand-in-hand single-ring network, select the grid-connected points (nodes a and b) of the distributed power source and the heavy-duty nodes (nodes) that cannot meet the power demand for a long time. c, d) As a key node for optimal allocation of energy.

(2) Using the method of optimization planning of the distribution network, between two key nodes a and d in the important power supply area Establish a dedicated flexible power flow control contact line to achieve active energy dispatch.

(3) The UPFC device is installed on the dedicated flexible power flow control contact line. One end of the UPFC is connected to the system through the transformer in parallel, and the other end is connected to the system through another transformer. The UPFC device is selected under the condition of considering the static characteristics of the voltage. The smallest installation plan and control strategy.

(4) Using the method of distribution network optimization planning, a simple special tie line is established between two key nodes b and c in the general power supply area to achieve the natural balance of energy, thereby forming a structure of double-layer regulation tie line. .

(5) Select the longitudinal differential protection as the main protection of the double-layer regulation tie line. The longitudinal differential protection uses dual-channel fiber current differential protection and has channel detection function.

(6) According to the principle of load balancing and satisfying the sensitivity of protection, the hand-in-hand single-ring network is reasonably divided into sections to determine the installation position of the electrical isolation device, wherein the electrical isolation device adopts on-load voltage regulation and high impedance and isolation of the secondary winding split. transformer.

(7) Determine the specific parameters of the isolation transformer configured in the system. The capacity of the isolation transformer is determined according to the maximum capacity that the circuit needs to deliver. The equivalent impedance and quantity of the isolation transformer are determined according to the maximum short-circuit current that may flow through the circuit in the maximum operating mode of the system. For details, refer to equation (1).

(8) The in-situ protection is configured with the isolation transformer as the boundary node, including longitudinal differential protection, overcurrent protection, overload protection and single-phase grounding protection. In addition, the main supply line of the closed-loop operation is configured with longitudinal differential protection, and the downstream radial branch line uses three-stage current protection. The longitudinal differential protection uses dual-channel fiber current differential protection and has channel detection.

Example 2:

The following is an example of a three-power handle ring network, and the technical solution of the present invention is as follows:

A three-power handle ring network consists of four feeders of “three vertical and one horizontal”. The busbars I, II and III can be different busbars of different substations or the same substation, or the same busbar of the same substation, each feeder is divided into two. Sections, numbered L ₁ , L ₂ , ..., L ₈ , nodes a and c are heavy-duty nodes that cannot sustain power demand for a long time, and node b is a grid-connected point of distributed power. The schematic diagram of the implementation method of the energy Internet for applying the large-scale distributed power supply to the three-power handle ring network is shown in FIG. 4 . Among them, L ₉ is a special flexible power flow control link line containing UPFC, and L ₁₀ is a simple dedicated tie line, which constitutes the structure of the double-layer control tie line. One end of the UPFC device on L ₉ is connected in parallel to the system through a transformer, and the other end is connected in series through another transformer. The electrical isolation device adopts an isolation transformer with on-load voltage regulation and high-impedance splitting. The eight isolation transformers are numbered T ₁ , T ₄ , T ₅ , T ₆ , T ₁₀ , T ₁₁ , T ₁₃ , T ₁₄ . The technical solution of the present invention includes the following implementation steps:

(1) According to the network structure, load characteristics and distributed power supply of the three power supply handle ring network, select the distribution The grid-connected point of the power supply (node b) and the heavy-duty nodes (nodes a and c) that cannot sustain the power demand for a long time are the key nodes for the optimal allocation of energy.

(2) Using the method of distribution network optimization planning, a dedicated flexible power flow control tie line is established between two key nodes a and b in the important power supply area to realize active energy dispatching.

(6) According to the principle of load balancing and satisfying the protection sensitivity, the three power supply handle ring network is reasonably divided into sections to determine the installation position of the electrical isolation device, wherein the electrical isolation device adopts on-load voltage regulation and high impedance and the secondary winding is split. Isolation transformer.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to be limiting, and those skilled in the art should understand that the specific embodiments of the present invention may be modified or equivalently replaced. It is intended that any modifications or equivalents of the present invention are intended to be included within the scope of the appended claims.

Claims

An implementation method of an energy Internet suitable for consuming a large-scale distributed power source, which is a complex distribution network with closed-loop operation of a large-scale distributed power source, characterized in that: the method comprises:

According to the network structure, load characteristics and distributed power grid connection situation of the closed-loop operation distribution network, the key nodes in the distribution network whose energy needs to be optimally allocated are selected;

Optimize the configuration of dual-level control tie lines between selected key nodes;

Configuring an electrical isolation device in a closed loop operating distribution network;

The in-situ protection is configured with the electrical isolation device as a boundary node.
The method for implementing an energy Internet suitable for dissipating a large-scale distributed power source according to claim 1, wherein the key nodes for which the energy needs to be optimally allocated include: a grid-connected point of a distributed power source or a user system. Public connection points, nodes with overload phenomena in the network, primary load or secondary load nodes requiring high power supply reliability, weak voltage nodes in the network, or nodes with overvoltage phenomena.
The method for implementing an energy Internet suitable for consuming a large-scale distributed power source according to claim 1, wherein the optimally configured dual-level control tie line comprises: optimal energy allocation and investment operation The principle of economy is to build a dedicated flexible power flow control link between two or more key nodes in the power supply area or between the areas that need to achieve active energy dispatch through the optimization planning method, in the power supply area or area where energy natural balance is needed. A simple dedicated tie line is established between two or more key nodes to form a double-layered control tie line structure.
The method for implementing an energy Internet suitable for consuming a large-scale distributed power source according to claim 3, characterized in that: the special flexibility is obtained through optimization calculation according to the principle of optimal power flow control and economics of investment operation The installation location and capacity of the flexible power distribution unit D-FACTS on the power flow control link.
The method for implementing an energy Internet suitable for dissipating a large-scale distributed power source according to claim 4, wherein the flexible power distribution device D-FACTS on the dedicated flexible power flow control contact line selects unified power flow control UPFC or static synchronous compensator STATCOM or static synchronous series compensator SSSC or thyristor controllable series compensator TCSC.
The method for implementing an energy Internet suitable for consuming a large-scale distributed power source according to claim 1, wherein the process of determining the installation location of the electrical isolation device comprises:

Load weighting calculation;

Dividing a section of the closed-loop operating line according to the principle of load balancing;

Verify that the electrical distance between the segments meets the requirements for protection sensitivity. If not, re-divide the segment so that the electrical distance meets the requirements for protection sensitivity;

An electrical isolation device is installed at the segmentation point of the segment.
A method for implementing an energy Internet suitable for consuming a large-scale distributed power source according to claim 1 or 6, wherein the electrical isolation device comprises an isolation transformer or a power electronic converter.
The method for implementing an energy Internet suitable for dissipating a large-scale distributed power source according to claim 7, wherein the isolation transformer form comprises no-load voltage regulation or on-load voltage regulation or high impedance or secondary The isolation transformer of the winding splitting may select a combination of two or more of the isolated transformer forms according to the voltage and short-circuit current conditions of the power distribution system.
The method for implementing an energy Internet suitable for consuming a large-scale distributed power source according to claim 1 or 6, wherein the electrical isolation device is selected according to an equivalent impedance parameter, an installation capacity parameter, and a quantity parameter. .
The method for implementing an energy Internet suitable for consuming a large-scale distributed power source according to claim 9, wherein the configuration principle of the equivalent impedance parameter, the installation capacity and the quantity of the electrical isolation device is: The requirements for electrical isolation of each line segment on the power supply loop and the possible short-circuit current flowing through each node in the power supply loop satisfy the requirements of the maximum short-circuit current level of the power system and ensure that the power system is safe and reliable. Economics and investment rationality over the life cycle.