CN106451518A - Method and system for determining DC field electrical main wiring of flexible DC power grid - Google Patents

Abstract

The present invention relates to a method and system for determining the electrical main wiring of a DC field in a flexible DC power grid, which includes the following steps: 1) performing reliability analysis on the alternative schemes for the electrical main wiring of the DC field of each converter station set in advance; 2) according to The cost level and quantity of each relevant equipment in the main wiring alternatives, and the economic analysis of the main wiring alternatives; 3) According to the structural characteristics, power distribution device layout, relay protection and control mode of the main wiring alternatives , to analyze the flexibility of the main wiring alternatives; 4) Determine the electrical main wiring scheme of the DC field of each converter station according to the reliability, economy and flexibility of the main wiring alternatives of each converter station; 5) According to The scheme of the electrical main wiring of the DC field of each converter station is obtained, and the scheme of the electrical main wiring of the DC field of the flexible DC grid is obtained. The present invention can comprehensively select the best main connection scheme through various factors, and can adapt to the rapid construction and development of the flexible direct current grid in the future.

Description

A method and system for determining the electrical main wiring of a DC field in a flexible DC grid

technical field

The invention relates to a method and a system for determining the electrical main wiring of a DC field in the field of power grids, in particular to a method and a system for determining the electrical main wiring of a DC field of a flexible DC grid.

Background technique

Flexible DC transmission uses voltage source converters, generally using fully controlled power electronic devices, which can independently and quickly control active power and reactive power. Based on the two basic characteristics of fully controlled devices (IGBT) and high-frequency modulation technology, flexible DC has the advantages of conventional DC, and also has the problems of reactive power compensation and commutation failure, independent control of active and reactive power, and power flow. It has technical advantages such as convenient and quick reversal and flexible operation mode change. At present, the flexible DC projects that have been put into production at home and abroad are basically relatively simple topological structures such as two-terminal chain or multi-terminal radial. They are not strictly DC power grids. There is currently no project for a flexible DC power grid with a typical network topology. practice.

According to the different DC fault clearing methods, there are two schemes for the flexible DC grid: half-bridge converter valves with DC circuit breakers (half-bridge scheme) and full-bridge converter valves with fast mechanical switches (full-bridge scheme). Among them, the full-bridge solution needs to block all converter stations during the fault clearing process, causing impact on the operation of the AC and DC power grids; in contrast, the half-bridge solution may not block or only block a few converter stations when clearing the DC fault. The flow station has little impact on the operation of the power grid, and can better adapt to the requirements of the operation and control of the complex DC power grid in the future. It is the development direction of the future DC power grid. DC circuit breakers have been used in power systems, but there are problems such as low voltage level and breaking capacity, and DC circuit breakers suitable for ±500kV voltage level are still in the development stage.

The DC field is one of the important components of the converter station. The DC field electrical main wiring design of the flexible DC transmission projects that have been put into production at home and abroad is relatively simple, and there is basically no relevant research on the selection of the DC field main wiring type, and simple wiring or single busbar wiring is usually used; the main reason is that the DC field equipment and the number of outlets are less, and because there is no high-voltage DC circuit breaker, the operation of the DC system is relatively simple. With the development and construction of the Global Energy Internet, the scale of the flexible DC grid will become larger and more complex, the number of outgoing lines and components of the converter station will continue to increase, and the operation mode of the flexible DC grid and the converter station will become more and more complicated. . Therefore, it is necessary to carry out special design and research on the selection of the electrical main wiring of the DC field of the flexible DC grid.

Contents of the invention

In view of the above problems, the purpose of the present invention is to provide a method and system for determining the electrical main wiring of the DC field of the flexible DC power grid, which can comprehensively select the best main wiring scheme based on various factors, and can adapt to the rapid construction of the flexible DC power grid in the future And development.

In order to achieve the above object, the present invention adopts the following technical solutions: a method for determining the electrical main wiring of the DC field of the flexible DC grid, which is characterized in that it includes the following steps: 1) according to the preset electrical main wiring of each converter station DC field The main wiring topology and the preset parameters of related equipment in the alternative scheme are used to analyze the reliability of the main wiring alternative scheme; 2) According to the cost level and quantity of each related equipment in the main wiring alternative scheme, calculate the main wiring alternative According to the initial project investment and annual cost of the scheme, the economy of the main wiring alternative scheme is obtained; 3) According to the structural characteristics, power distribution device layout, relay protection and control mode of the main wiring alternative scheme, the main wiring alternative scheme is carried out Flexibility analysis; 4) According to the reliability, economy and flexibility of the alternative schemes for the electrical main wiring of the DC field of each converter station, determine the scheme of the electrical main wiring of the DC field of each converter station; 5) According to the DC field of each converter station Based on the scheme of the main electrical wiring of the field, the scheme of the main electrical wiring of the DC field of the flexible DC grid is obtained.

Preferably, in the step 1), the alternatives for the electrical main wiring of the DC field of each converter station are set according to the functions of each converter station and the planning of the flexible DC grid.

Preferably, the alternatives for the electrical main wiring of the DC field of each converter station include single busbar wiring, double busbar wiring, angled wiring and 3/2 wiring.

Preferably, in the step 1), the specific steps for analyzing the reliability of the main wiring alternatives are as follows: carry out fault correlation analysis according to the structure of the main wiring alternatives, and obtain the common mode outage time of each equipment element; The reliability parameters of the relevant equipment in the main wiring alternative scheme are obtained to obtain the basic analysis results of the main wiring alternative scheme; sensitivity analysis is performed on the pre-selected equipment in the main wiring alternative scheme, and according to the sensitivity parameters of the selected equipment , to obtain the sensitivity analysis results of the main wiring alternatives; according to the basic analysis results and sensitivity analysis results of the main wiring alternatives, the reliability of the main wiring alternatives is obtained.

Preferably, the reliability parameters of each device include failure rate, average repair time, overhaul rate and overhaul time; the basic analysis results include system outage failure rate, average outage duration, availability rate, outage probability, and average outage time , frequency of outages, loss of electrical energy and annual operating costs.

Preferably, in the step 3), the flexibility of the main wiring alternative consists of operation flexibility, maintenance flexibility and expansion flexibility.

Preferably, the operational flexibility of the main wiring alternative is determined according to the flexibility of switching on and off of generators and loads during the scheduling operation of the main wiring alternative.

Preferably, the maintenance flexibility of the main wiring alternative is determined according to the impact on grid operation and power supply caused by the safety maintenance of outage circuit breakers, busbars and relay protection equipment of the main wiring alternative.

Preferably, the expansion flexibility of the main wiring alternative is determined according to the workload of the later expansion of the main wiring alternative and the impact on the system power supply.

A system for determining the electrical main wiring of a DC field in a flexible DC grid, characterized in that it includes a storage module, a reliability analysis module, an economical module, a flexibility analysis module, and a main wiring scheme module; the storage module is used to store pre- Alternative schemes for the electrical main wiring of the DC field of each converter station; the reliability analysis module is used to pre-set the main wiring topology and related equipment in the alternative schemes for the electrical main wiring of each converter station DC field. Set parameters to analyze the reliability of the main wiring alternatives. The economics module is used to obtain the economics of the main wiring alternatives according to the cost level and quantity of each device in the main wiring alternatives. The flexibility The analysis module is used to analyze the flexibility of the main wiring alternatives according to the structural characteristics, power distribution device layout, relay protection and control mode of the main wiring alternatives; The reliability, economy and flexibility of the wiring alternatives are determined, and the main electrical wiring scheme of the DC field of each converter station is determined, and the main electrical wiring of the DC field of the flexible DC grid is obtained according to the scheme of the main electrical wiring of the DC field of each converter station. scheme.

Because the present invention adopts the above technical scheme, it has the following advantages: 1. The present invention evaluates the reliability, economy and flexibility of the main wiring alternatives, and realizes the comprehensive evaluation of the electrical main wiring scheme of the DC field of the converter station, And it can evaluate the influence of different main wiring structures and various new equipment and other factors, adapting to the rapid construction and development of future flexible DC power grids. 2. The present invention evaluates the flexibility of the main wiring alternatives, so that the recommended electrical main wiring design has better coordination and adaptability. 3. The present invention is evaluated from the economical efficiency of the main wiring alternatives, which can meet the technical requirements in terms of operation and maintenance in the project commissioning year and prospect year.

Description of drawings

FIG. 1 is a single-line schematic diagram of the topological structure of the Zhangbei flexible DC power grid in this embodiment;

Fig. 2 is a schematic diagram of the electrical single-female wiring scheme of the DC field of Zhangbei Station in this embodiment;

Fig. 3 is a schematic diagram of the electrical double busbar wiring scheme of the DC field of Zhangbei Station in this embodiment;

Fig. 4 is a schematic diagram of the wiring scheme of the electrical angular line of the DC field of Zhangbei Station in this embodiment;

Fig. 5 is a schematic diagram of the electric 3/2 wiring scheme of the DC field of Zhangbei Station in this embodiment.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

The present invention provides a method for determining the electrical main wiring of a DC field in a flexible DC grid, the specific steps of which are as follows:

1) Perform reliability analysis on the main wiring alternatives according to the preset parameters of the main wiring topology in the electrical main wiring alternatives of the DC field of each converter station and the preset parameters of related equipment;

2) According to the cost level and quantity of each equipment in the main wiring alternative scheme, calculate the initial project investment and annual cost of the main wiring alternative scheme, and obtain the economic efficiency of the main wiring alternative scheme;

3) Analyze the flexibility of the main wiring alternatives according to the structural characteristics, power distribution device layout, relay protection and control mode of the main wiring alternatives;

4) According to the reliability, economy and flexibility of the main wiring alternatives of each converter station, determine the electrical main wiring scheme of the DC field of each converter station;

5) According to the scheme of the electrical main wiring of the DC field of each converter station, the scheme of the electrical main wiring of the DC field of the flexible DC grid is obtained.

In the above step 1), the alternative schemes for the electrical main wiring of the DC field of each converter station are set according to the functions of each converter station and the planning of the flexible DC grid.

In the above step 1), the specific steps for the reliability analysis of the main wiring alternatives are as follows:

(1.1) According to the structure of the main wiring alternative scheme, perform fault correlation analysis to obtain the common mode outage time of each equipment component;

(1.2) According to the reliability parameters such as the failure rate, average repair time, overhaul rate, and overhaul time of each equipment in the main wiring alternative scheme, the system power failure failure rate, average power outage duration, availability rate, and the main wiring alternative scheme are obtained. Basic analysis results such as power outage probability, average time of power outage, frequency of power outage, power loss, annual operating cost, etc.;

(1.3) Conduct sensitivity analysis on the pre-selected equipment in the main wiring alternative scheme, and obtain the sensitivity analysis results of the main wiring alternative scheme according to the sensitivity parameters of the pre-selected equipment;

(1.4) According to the basic analysis results and sensitivity analysis results of the main wiring alternatives, the reliability of the main wiring alternatives is obtained.

In the above step 3), the specific steps for the flexibility analysis of the main wiring alternatives are as follows:

(3.1) The flexibility of the main wiring alternatives consists of operational flexibility, maintenance flexibility and expansion flexibility;

(3.2) Determine the operational flexibility of the main wiring alternatives according to the flexibility of putting in and removing generators and loads during the scheduling operation of the main wiring alternatives;

(3.3) According to the impact on the operation and power supply of the power grid during the safety maintenance of the outage circuit breaker, busbar and relay protection equipment of the main wiring alternative, determine the maintenance flexibility of the main wiring alternative;

(3.4) Determine the expansion flexibility of the main wiring alternatives according to the workload of the later expansion of the main wiring alternatives and the impact on the system power supply;

(3.5) According to the operation flexibility, maintenance flexibility and expansion flexibility of the main wiring alternative scheme, the flexibility of the main wiring alternative scheme is obtained.

Based on the above method, the present invention also provides a system for determining the electrical main wiring of the DC field of the flexible DC grid, which includes a storage module, a reliability analysis module, an economics module, a flexibility analysis module and a main wiring scheme module.

The storage module is used to store the alternative schemes for the electrical main wiring of the DC field of each converter station set in advance;

The reliability analysis module is used to analyze the reliability of the main wiring alternatives according to the preset parameters of the main wiring topology in the DC field electrical main wiring alternatives of each converter station and the preset parameters of related equipment. The economical module It is used to obtain the economics of the main wiring alternatives according to the cost level and quantity of each equipment in the main wiring alternatives. The flexibility analysis module is used to obtain the main wiring alternatives according to the structural characteristics, power distribution device layout, and relay protection of the main wiring alternatives. Conduct a flexibility analysis of the main wiring alternatives and control methods.

The main wiring scheme module is used to determine the electrical main wiring scheme of the DC field of each converter station according to the reliability, economy and flexibility of the main wiring alternatives of each converter station, and to determine the electrical main wiring scheme of the DC field of each converter station. According to the scheme, the scheme of the electrical main wiring of the DC field of the flexible DC grid is obtained.

Embodiments, taking Zhangbei Station in the Zhangbei Flexible DC Grid as an example, the specific steps of the selection method for the electrical main wiring scheme of the DC field of Zhangbei Station are as follows:

1) As shown in Figure 1, the Zhangbei flexible DC power grid includes four converter stations, namely Zhangbei Station, Kangbao Station, Fengning Station and Beijing Station; among them, Zhangbei Station and Kangbao Station are the sending ends The new energy collection station, Fengning station is the energy storage regulation station, and Beijing station is the receiving station. The DC system of Zhangbei Station adopts a bipolar wiring structure, with a rated capacity of 3000MW. Each pole has 2 outlets, and 1 outlet each to Kangbao Station and Beijing Station; the voltage level of Zhangbei Flexible DC Grid is ±500kV, and the single busbar wiring is pre-set. , double busbar wiring, angled wiring and 3/2 wiring are four main wiring alternatives, as shown in Figure 2 to Figure 5 respectively;

2) The common mode outage time of the main wiring alternatives is shown in Table 1:

Table 1 Common mode outage time

device name Common Mode Downtime (h) DC bus 5 Isolation switch 14 Common Mode Isolation Switch 0.4 Common mode circuit breaker 0.5

The failure rate, average repair time, overhaul rate, overhaul time, equipment cost and other indicators of the main wiring alternatives are shown in Table 2;

Table 2 Equipment reliability parameters

According to the common-mode outage time and equipment reliability parameters, the basic analysis results such as power failure rate, average power outage duration, availability rate, power outage probability, power outage average time, power outage frequency, power loss and operation cost of the main wiring alternatives are obtained , as shown in Table 3; among them, the electricity price in the calculation is 0.5 yuan/kWh;

Table 3 Basic analysis results of each main electrical wiring of Zhangbei Converter Station

Since the 500kV DC circuit breaker is a newly developed equipment and there is no relevant operational statistical data, it is necessary to carry out a sensitivity analysis on the failure rate of the DC circuit breaker, and increase the failure rate of the DC circuit breaker by an order of magnitude. Increased to 0.061 times/set year; the sensitivity analysis results of the main wiring alternatives are obtained, as shown in Table 4;

Table 4 Sensitivity Analysis Results of Electrical Main Connections of Zhangbei Converter Station

According to the basic analysis results and sensitivity analysis results of the main wiring alternatives, the reliability results of the main wiring alternatives are obtained: 3/2 wiring > angled wiring > double busbar wiring > single busbar wiring; among them, the failure rate of DC circuit breakers fluctuates Does not affect reliability ordering of main wiring alternatives.

3) Calculate the initial investment cost of the main wiring alternatives. As shown in Table 5, the initial investment level of the single-bus wiring and angled wiring is the lowest, and the initial investment of the 3/2 wiring is the highest; among them, due to the high cost of the 500kV DC circuit breaker, About 150 million yuan/set, when calculating the initial investment of electrical main wiring, it is mainly the investment cost of circuit breakers;

Table 5 Initial investment cost of main wiring

The calculation results of the annual cost of the main wiring alternatives are shown in Table 6. The reliability evaluation results of the single-bus wiring and the double-bus wiring are relatively close; Carry out annual cost calculation and comparison with 3/2 wiring, among which, the economic service life of the project is 30 years, and the rate of return is 8%;

Table 6 Annual Costs of North Flexible DC Power Grid

According to the initial investment cost and annual cost of the project, the economic efficiency of the single-bus connection scheme is obtained.

4) The flexibility evaluation of the main wiring alternatives is carried out, as shown in Table 7. According to the comprehensive comparison of operation flexibility, maintenance flexibility and expansion flexibility, it is obtained that the flexibility of the double busbar and 3/2 wiring scheme is the best, and the single busbar The bus connection scheme is next, and the angle connection scheme is relatively poor.

Table 7 Flexibility Analysis of Electrical Main Wiring in Zhangbei Converter Station

5) According to the reliability, economy and flexibility of the main wiring alternatives, the electrical main wiring of the DC field of Zhangbei Station is determined to be a single-bus wiring scheme.

The above-mentioned embodiments are only used to illustrate the present invention, and the structure, size, location and shape of each component can be changed. On the basis of the technical solution of the present invention, all improvements to individual components according to the principles of the present invention and equivalent transformations shall not be excluded from the protection scope of the present invention.

Claims (10)

1. a kind of method determining flexible direct current electrical network DC fields electrical main connecting wire is it is characterised in that it comprises the following steps：

1) according to main electrical scheme topological structure and phase in each current conversion station DC fields electrical main connecting wire alternative pre-setting The parameter preset of pass equipment, carries out fail-safe analysis to main electrical scheme alternative；

2) the cost level according to relevant device each in main electrical scheme alternative and quantity, calculates the engineering of main electrical scheme alternative Initial cost and annual cost, obtain the economy of main electrical scheme alternative；

3) arranged according to the design feature of main electrical scheme alternative, power distribution equipment, relay protection and control mode, standby to main electrical scheme Scheme is selected to carry out Dexterity analysis；

4) according to the reliability of each current conversion station DC fields electrical main connecting wire alternative, economy and flexibility, determine each The scheme of current conversion station DC fields electrical main connecting wire；

5) scheme according to each current conversion station DC fields electrical main connecting wire, obtains flexible direct current electrical network DC fields electrical main connecting wire Scheme.

2. as claimed in claim 1 a kind of determine flexible direct current electrical network DC fields electrical main connecting wire method it is characterised in that： Described step 1) in, the alternative of each current conversion station DC fields electrical main connecting wire described be function according to each current conversion station and The setting of flexible direct current Electric Power Network Planning.

3. as claimed in claim 2 a kind of determine flexible direct current electrical network DC fields electrical main connecting wire method it is characterised in that： The alternative of each current conversion station DC fields electrical main connecting wire described include single bus scheme, double bus scheme, angle scheme and 3/2 wiring.

4. as claimed in claim 1 a kind of determine flexible direct current electrical network DC fields electrical main connecting wire method it is characterised in that： Described step 1) in, fail-safe analysis is carried out to main electrical scheme alternative and comprises the following steps that：

Structure according to main electrical scheme alternative carries out trouble correlation analytic, obtains the common mode idle time of each equipment component；

According to the dependability parameter of relevant device each in main electrical scheme alternative, obtain the fundamental analysis knot of main electrical scheme alternative Really；

Sensitivity analysis is carried out to previously selected equipment in main electrical scheme alternative, according to the responsive parameter of selected equipment, Obtain the sensitivity analysis result of main electrical scheme alternative；

Fundamental analysis result according to main electrical scheme alternative and sensitivity analysis result, obtain the reliability of main electrical scheme alternative Property.

5. as claimed in claim 4 a kind of determine flexible direct current electrical network DC fields electrical main connecting wire method it is characterised in that： The dependability parameter of described each equipment includes fault rate, mean repair time, maintenance rate and repair time；Described fundamental analysis knot Fruit include system blackout fault rate, System average interruption duration, availability, power failure probability, have a power failure average time, power failure frequency, Loss electric energy and annual operating cost.

6. as claimed in claim 1 a kind of determine flexible direct current electrical network DC fields electrical main connecting wire method it is characterised in that： Described step 3) in, the flexibility of main electrical scheme alternative is made up of operational flexibility, maintenance flexibility and enlarging flexibility.

7. as claimed in claim 6 a kind of determine flexible direct current electrical network DC fields electrical main connecting wire method it is characterised in that： According to main electrical scheme alternative in management and running, put into and excise the flexibility ratio of generator and load, determine that main electrical scheme is standby Select the operational flexibility of scheme.

8. as claimed in claim 6 a kind of determine flexible direct current electrical network DC fields electrical main connecting wire method it is characterised in that： During according to safety inspection being carried out to the stoppage in transit breaker of main electrical scheme alternative, bus and relay protection device, cause to electrical network The impact running and powering, determines the maintenance flexibility of main electrical scheme alternative.

9. as claimed in claim 6 a kind of determine flexible direct current electrical network DC fields electrical main connecting wire method it is characterised in that： Workload according to the enlarging of main electrical scheme alternative later stage and the impact to system power supply, determine the expansion of main electrical scheme alternative Build flexibility.

10. a kind of determine flexible direct current electrical network DC fields electrical main connecting wire system it is characterised in that：It include memory module, Fail-safe analysis module, economy module, Dexterity analysis module and Main Wire Connection Scheme module；Described memory module is used for storing The alternative of each current conversion station DC fields electrical main connecting wire pre-setting；Described fail-safe analysis module is used for according in advance The default ginseng of main electrical scheme topological structure and relevant device in each current conversion station DC fields electrical main connecting wire alternative of setting Number, carries out fail-safe analysis to the alternative of main electrical scheme, and described economy module is used for according to each in main electrical scheme alternative The cost level of equipment and quantity obtain the economy of main electrical scheme alternative, and described Dexterity analysis module is used for being connect according to master The design feature of line alternative, power distribution equipment arrangement, relay protection and control mode are carried out flexibly to main electrical scheme alternative Property analysis；Described Main Wire Connection Scheme module is used for according to the reliability of each converter substation scheme's alternative, economy and spirit Activity, determines the scheme of each current conversion station DC fields electrical main connecting wire, and according to each current conversion station DC fields electrical main connecting wire Scheme, obtains the scheme of flexible direct current electrical network DC fields electrical main connecting wire.