CN108683209B - A method and device for evaluating the grid-connected capability of a distributed power source - Google Patents

Abstract

The invention provides a distributed power supply grid-connected capability evaluation method and a distributed power supply grid-connected capability evaluation device, wherein equipment parameters, a topological structure, operation data and initial power of an energy storage device of a power distribution network after grid connection of a distributed power supply are firstly obtained, then a plurality of operation scenes are determined according to the operation data, and load flow calculation is carried out on the power distribution network after grid connection of the distributed power supply according to the equipment parameters, the topological structure and the initial power of the energy storage device of the power distribution network, so that load flow calculation results under each operation scene are obtained; and finally, evaluating the grid-connected capability of the distributed power supply according to the load flow calculation result in each operation scene. According to the distributed power supply grid-connected capability evaluation method, the power of the energy storage device is considered, the distributed power supply grid-connected capability evaluation under the participation of the energy storage device is further realized, the accuracy of the evaluation result is improved, the real accepting capability of the power distribution network to the distributed power supply can be correctly reflected, and the development requirement of the energy storage device in the power distribution in the future is met.

Description

A method and device for evaluating the grid-connected capability of a distributed power source

technical field

The invention relates to the field of grid-connected analysis of new energy power generation technologies, in particular to a method and device for evaluating the grid-connected capability of a distributed power source.

Background technique

At present, with the advancement of low-carbon and green energy strategies and the implementation of a new round of power system reform supporting policies, the application value of energy storage has been recognized by the market, especially the user-side energy storage continues to maintain high growth. According to statistics, from 2000 to 2016, the cumulative installed capacity of the energy storage system applied to the user side was 107.9MW (excluding pumped storage and thermal storage projects), accounting for 57% of the total installed capacity. From the second half of 2015 to the present, the newly planned installed capacity of energy storage is about 740MW, of which the proportion installed on the user side accounts for 54% of the total planned. With the continuous increase of energy storage in the distribution network, it has a huge impact on the absorbing capacity of the distributed power generation. In the prior art, when evaluating the grid-connected capacity of the distributed power generation, only the safety of the distributed power generation itself is considered. For the influence of stable operation, the assessment indicators such as voltage and load fluctuation are used as limiting factors. The calculation results are biased and cannot correctly reflect the true acceptance capacity of the distribution network for distributed power generation.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned deficiencies in the prior art that the evaluation results are biased because the power of the energy storage device is not considered and cannot correctly reflect the real acceptance capability of the distributed power supply by the distribution network, the present invention provides a grid-connected capability of the distributed power supply. The evaluation method and device first obtain the equipment parameters, topology structure, operation data and the initial power of the energy storage device of the distribution network after the distributed power supply is connected to the grid, and then determine a plurality of operation scenarios according to the operation data, and according to the equipment of the distribution network The parameters, topology structure and initial power of the energy storage device are used to calculate the power flow of the distribution network after the distributed power supply is connected to the grid, and the power flow calculation results in each operating scenario are obtained. The power of the energy storage device is considered, the accuracy of the evaluation results is improved, and it can correctly reflect the real capacity of the distribution network to accept the distributed power.

In order to realize the above-mentioned purpose of the invention, the present invention adopts the following technical solutions:

In one aspect, the present invention provides a method for evaluating the grid-connected capability of a distributed power source, including:

Obtain the equipment parameters, topology, operation data and initial power of the energy storage device of the distribution network after the distributed generation is connected to the grid;

Determine multiple operating scenarios according to the operating data, and perform power flow calculation on the distribution network after the distributed power supply is connected to the grid according to the equipment parameters of the distribution network, the topology structure and the initial power of the energy storage device, and obtain the power flow calculation under each operating scenario. Result; the power flow calculation result includes the use capacity of the transformer, the use capacity of the line, the node voltage and the node voltage fluctuation;

According to the power flow calculation results in each operating scenario, the grid-connected capability of the distributed power generation is evaluated.

The equipment parameters include transformer parameters and line parameters;

The operation data includes load operation data and distributed power supply operation data;

The initial power of the energy storage device includes the initial active power of the energy storage device and the initial reactive power of the energy storage device.

The operation scenarios include a large load and small power generation scenario, a large load fluctuation power generation scenario, a small load large power generation scenario, and a small load fluctuation power generation scenario.

The power flow calculation is performed on the power distribution network after the distributed power supply is connected to the grid according to the equipment parameters of the power distribution network, the topology structure and the initial power of the energy storage device, and the power flow calculation results in each operation scenario are obtained, including:

According to the equipment parameters, topology structure of the distribution network, the initial power of the energy storage device, and the time sequence matching between the load curve and the output curve of the distributed power supply, the power system simulation software is used to analyze the power distribution after the distributed power supply is connected to the grid. The network performs power flow calculation, and obtains the power flow calculation results in each operating scenario.

The evaluation of the grid-connected capability of the distributed power source according to the power flow calculation results in each operating scenario includes:

Determine whether the use capacity of the transformer and the use capacity of the line meet the corresponding constraints at the same time, if so, go to the next step, otherwise reduce the preset installed capacity of the distributed power supply;

Determine whether the node voltage and the node voltage fluctuation amount do not exceed the standard. If yes, go to the next step. Otherwise, determine whether the energy storage device satisfies the corresponding constraint conditions. If the energy storage device meets the corresponding constraint conditions, determine the actual value of the energy storage device power and The actual value of the state of charge, otherwise the preset installed capacity of the distributed power supply is reduced;

Determine whether the capacity of the transformer, the use flow of the line, the node voltage or the fluctuation of the node voltage are equal to their respective limits. If so, output the final installed capacity of the distributed power supply, and evaluate the acceptance capacity of the distribution network after the distributed power supply is connected to the grid. , otherwise increase the preset installed capacity of distributed power.

The constraints corresponding to the operating capacity of the transformer are as follows:

S _T < S _{T amount}

Among them, S _T represents the operating capacity of the transformer, and the _{amount of S T} represents the rated capacity of the transformer;

The constraints corresponding to the usage capacity of the lines are as follows:

S _L < S _{L amount}

Among them, _SL represents the use capacity of the line, and _SL represents the rated capacity of the line.

The judging whether the node voltage and the node voltage fluctuation amount do not exceed the standard, including:

且

节点电压及节点电压波动量都不超标，其中V_k表示节点k的电压，

和

分别表示节点k的电压下限值和上限值；dV_k表示节点k的电压波动量，

表示节点k的电压波动限值。if satisfied

and

The node voltage and the node voltage fluctuation are not exceeding the standard, where V _k represents the voltage of node k,

and

respectively represent the lower limit and upper limit of the voltage of node k; dV _k represents the voltage fluctuation of node k,

Represents the voltage fluctuation limit at node k.

The constraints corresponding to the energy storage device are as follows:

S _SOCmin ≤S _SOC0 ≤S _SOCmax

Among them, P _E0 represents the active power of the energy storage device, Q _E0 represents the reactive power _{of the energy storage device, P represents the rated power of} the energy storage device; S _SOC0 represents the initial value of the state of charge of the energy storage device, S _SOCmin and S _SOCmax represents the lower limit value and the upper limit value of the state of charge of the energy storage device, respectively.

The determining of the actual value of power and the actual value of the state of charge of the energy storage device includes:

Determine the actual value of the active power, the actual value of the reactive power and the actual value of the state of charge of the energy storage device as follows:

Among them, PE represents the actual value of the active power of the energy storage device, ω _c represents the cut-off frequency of the filter in the energy storage device, P _k represents the active power of node _k , s represents the Laplace operator, and h represents the power adjustment coefficient , S _SOC represents the actual value of the state of charge of the energy storage device, and Δt represents the sampling time interval of the operating data.

The evaluation of the acceptance capacity of the distribution network after the grid-connected distributed generation includes:

Calculate the grid-connected benefits of distributed power sources as follows:

C=(c _p +c _b )E _s +(c _g +c _b )E _p

Among them, C represents the grid-connected income of the distributed power generation, Es represents the self-consumption electricity of the distributed power supply, _Ep represents the on-grid electricity, _cp represents the electricity price, _{c g represents} the on-grid price, and c _b represents the electricity subsidy price;

It is judged whether _{C≥C set} is satisfied. If yes, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is good; otherwise, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is poor.

The evaluation of the acceptance capacity of the distribution network after the grid-connected distributed generation includes:

The average power supply availability rate of the distribution network after the distributed power grid is connected to the grid is calculated as follows:

Among them, ASAI represents the average power supply availability rate of the distribution network after the distributed generation is connected to the grid, N _k represents the number of users of node k, and U _k represents the annual average power outage time of node k, and its unit is hour/year;

Determine whether ASAI≥ASAI _set is satisfied. If yes, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is good, otherwise the acceptance capacity of the distribution network after the distributed generation is connected to the grid is poor, where ASAI _set represents the average power supply availability threshold.

On the other hand, the present invention provides a distributed power grid-connected capability evaluation device, comprising:

The acquisition module is used to acquire the equipment parameters, topology structure, operation data and the initial power of the energy storage device of the distribution network after the distributed power supply is connected to the grid;

The power flow calculation module is used to determine multiple operation scenarios according to the operation data, and perform power flow calculation on the distribution network after the distributed power grid is connected according to the equipment parameters of the distribution network, the topology structure and the initial power of the energy storage device. The power flow calculation result in the operation scenario; the power flow calculation result includes the used capacity of the transformer, the used capacity of the line, the node voltage and the node voltage fluctuation;

The evaluation module is used to evaluate the grid-connected capability of the distributed power generation according to the power flow calculation results in various operating scenarios.

The equipment parameters obtained by the obtaining module include transformer parameters and line parameters;

The operation data includes load operation data and distributed power supply operation data;

The initial power of the energy storage device includes the initial active power of the energy storage device and the initial reactive power of the energy storage device.

The power flow calculation module includes a determination unit, and the operation scenarios determined by the determination unit include a large load and small power generation scenario, a large load fluctuation power generation scenario, a small load large power generation scenario, and a small load fluctuation power generation scenario.

The power flow calculation module includes a power flow calculation unit, and the power flow calculation unit is specifically used for:

According to the equipment parameters, topology structure of the distribution network, the initial power of the energy storage device, and the time sequence matching between the load curve and the output curve of the distributed power supply, the power system simulation software is used to analyze the power distribution after the distributed power supply is connected to the grid. The network performs power flow calculation, and obtains the power flow calculation results in each operating scenario.

The evaluation module includes:

The first judgment unit is used for judging whether the use capacity of the transformer and the use capacity of the line meet the corresponding constraint conditions at the same time, if so, go to the next step, otherwise reduce the preset installed capacity of the distributed power source;

The second judging unit is used to judge whether the node voltage and the node voltage fluctuation amount are not exceeding the standard, if so, go to the next step, otherwise judge whether the energy storage device satisfies the corresponding constraint conditions, if the energy storage device satisfies the corresponding constraint conditions, determine the storage device The actual value of the power and the actual value of the state of charge of the energy device, otherwise the preset installed capacity of the distributed power supply is reduced;

The third judging unit is used to judge whether the use capacity of the transformer, the use flow of the line, the node voltage or the node voltage fluctuation amount are equal to their respective limits, if so, output the final installed capacity of the distributed power supply, and evaluate the grid connection of the distributed power supply The receiving capacity of the distribution network, otherwise, the preset installed capacity of the distributed power supply will be increased.

The constraints corresponding to the operating capacity of the transformer are as follows:

S _T < S _{T amount}

Among them, S _T represents the operating capacity of the transformer, and the _{amount of S T} represents the rated capacity of the transformer;

The constraints corresponding to the usage capacity of the lines are as follows:

S _L < S _{L amount}

Among them, _SL represents the use capacity of the line, and _SL represents the rated capacity of the line.

The second judgment unit is specifically used for:

且

节点电压及节点电压波动量都不超标，其中V_k表示节点k的电压，

和

分别表示节点k的电压下限值和上限值；dV_k表示节点k的电压波动量，

表示节点k的电压波动限值。if satisfied

and

The node voltage and the node voltage fluctuation are not exceeding the standard, where V _k represents the voltage of node k,

and

respectively represent the lower limit and upper limit of the voltage of node k; dV _k represents the voltage fluctuation of node k,

Indicates the voltage fluctuation limit at node k.

The constraints corresponding to the energy storage device are as follows:

S _SOCmin ≤S _SOC0 ≤S _SOCmax

Among them, P _E0 represents the active power of the energy storage device, Q _E0 represents the reactive power _{of the energy storage device, P represents the rated power of} the energy storage device; S _SOC0 represents the initial value of the state of charge of the energy storage device, S _SOCmin and S _SOCmax represents the lower limit value and the upper limit value of the state of charge of the energy storage device, respectively.

The second judgment module is specifically used for:

Determine the actual value of the active power, the actual value of the reactive power and the actual value of the state of charge of the energy storage device as follows:

Among them, PE represents the actual value of the active power of the energy storage device, ω _c represents the cut-off frequency of the filter in the energy storage device, P _k represents the active power of node _k , s represents the Laplace operator, and h represents the power adjustment coefficient , S _SOC represents the actual value of the state of charge of the energy storage device, and Δt represents the sampling time interval of the operating data.

The third judgment unit is specifically used for:

Calculate the grid-connected benefits of distributed power sources as follows:

C=(c _p +c _b )E _s +(c _g +c _b )E _p

Among them, C represents the grid-connected income of the distributed power generation, Es represents the self-consumption electricity of the distributed power supply, _Ep represents the on-grid electricity, _cp represents the electricity price, _{c g represents} the on-grid price, and c _b represents the electricity subsidy price;

It is judged whether _{C≥C set} is satisfied. If yes, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is good; otherwise, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is poor.

The third judgment unit is specifically used for:

The average power supply availability rate of the distribution network after the distributed power grid is connected to the grid is calculated as follows:

Among them, ASAI represents the average power supply availability rate of the distribution network after the distributed generation is connected to the grid, N _k represents the number of users of node k, and U _k represents the annual average power outage time of node k, and its unit is hour/year;

Determine whether ASAI≥ASAI _set is satisfied. If yes, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is good, otherwise the acceptance capacity of the distribution network after the distributed generation is connected to the grid is poor, where ASAI _set represents the average power supply availability threshold.

Compared with the closest prior art, the technical solution provided by the present invention has the following beneficial effects:

In the method for evaluating the grid-connection capability of the distributed power supply provided by the present invention, the equipment parameters, topology structure, operation data and initial power of the energy storage device of the distribution network after the distributed power supply is connected to the grid are first obtained, and then a plurality of operation data are determined according to the operation data. According to the equipment parameters of the distribution network, the topology structure and the initial power of the energy storage device, the power flow calculation is carried out on the distribution network after the distributed power grid is connected to the grid, and the power flow calculation results under each operating scenario are obtained. Finally, according to each operating scenario The power flow calculation results below evaluate the grid-connected capability of the distributed power generation, taking into account the power of the energy storage device, which improves the accuracy of the evaluation results, and can correctly reflect the distribution network's real capacity to accept the distributed power generation;

The device for evaluating the grid-connected capability of the distributed power supply provided by the present invention includes an acquisition module, a power flow calculation module and an evaluation module. The acquisition module is used to acquire the equipment parameters, topology structure, operation data and energy storage device of the distribution network after the distributed power supply is connected to the grid. The power flow calculation module is used to determine multiple operating scenarios according to the operating data, and perform power flow calculation on the distribution network after the distributed power generation is connected to the grid according to the equipment parameters, topology structure and initial power of the energy storage device of the distribution network. , to obtain the power flow calculation results in each operating scenario; the power flow calculation results include the use capacity of the transformer, the use capacity of the line, the node voltage and the node voltage fluctuation; the evaluation module is used for the distributed power generation according to the power flow calculation results in each operating scenario. The power of the energy storage device is considered, the accuracy of the evaluation results is improved, and it can correctly reflect the real capacity of the distribution network to accept the distributed power;

The technical solution provided by the present invention takes the power of the energy storage device into consideration, thereby realizing the grid-connected capability evaluation of the distributed power source with the participation of the energy storage device, and adapting to the development needs of the energy storage device in power distribution in the future;

The technical solution provided by the present invention considers the use capacity of the transformer, the use capacity of the line, the node voltage, the node voltage fluctuation, and the respective constraints of the power and state of charge of the energy storage device, and from the aspects of economy and reliability. The grid-connected capability of distributed power generation is evaluated, and the evaluation is more comprehensive.

Description of drawings

1 is a flowchart of a method for evaluating the grid-connected capability of a distributed power source in an embodiment of the present invention;

2 is a schematic diagram of a distribution network model including distributed photovoltaics and energy storage devices in an embodiment of the present invention;

3 is a schematic diagram of a load operation scenario formed by load operation data in an embodiment of the present invention;

4 is a schematic diagram of a photovoltaic operation scene formed by photovoltaic operation data in an embodiment of the present invention.

Detailed ways

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

An embodiment of the present invention provides a method for evaluating the grid-connected capability of a distributed power source. The specific flowchart is shown in FIG. 1 , and the specific process is as follows:

S101: Obtain the equipment parameters, topology structure, operation data and initial power of the energy storage device of the distribution network after the distributed power source is connected to the grid;

S102: Determine multiple operation scenarios according to the operation data, and perform power flow calculation on the distribution network after the grid-connected distributed power supply according to the equipment parameters, topology structure and initial power of the energy storage device of the distribution network, and obtain the power flow under each operation scenario. Power flow calculation results, including the use capacity of the transformer, the use capacity of the line, the node voltage and the node voltage fluctuation;

S103: Evaluate the grid-connection capability of the distributed power source according to the power flow calculation results in each operation scenario.

In the above S101, the distribution network model including distributed photovoltaic and energy storage devices is shown in Figure 2. In Figure 2, nodes 1 to 17 are all connected to loads, and node 9, node 10, and node 13 to node 17 are all connected to the load. Photovoltaic, node 11 and node 12 have photovoltaic and energy storage devices, and the capacity of both energy storage devices is 180kW/220kWh. Obtain the equipment parameters, topology, operation data and initial power of the energy storage device of the distribution network after the distributed power supply is connected to the grid from Figure 2. The equipment parameters include transformer parameters and line parameters, and the operation data includes load operation data and distributed power. Power supply operation data, the initial power of the energy storage device includes the initial active power of the energy storage device and the initial reactive power of the energy storage device.

In the above S102, the operation scenarios determined according to the operation data include a large load and small power generation scenario, a large load fluctuation power generation scenario, a small load large power generation scenario, and a small load fluctuation power generation scenario.

The schematic diagram of the load operation scenario formed by the load operation data is shown in Figure 3. Two boundary curves can be taken as the load operation scenario, in which the dotted line represents the high-load operation scenario, and the solid line represents the small-load operation scenario. After sorting out a large amount of photovoltaic power generation data, it is found that the output of photovoltaic power generation is random, and some curves have great volatility. When analyzing the capacity of distributed photovoltaics, the fluctuation output curve and the maximum sunny day output curve can be considered as photovoltaic operation scenarios. The photovoltaic operation scenario formed by the operating data of , is shown in Figure 4, in which the dotted line represents the large power generation operation scenario, and the solid line represents the fluctuation power generation operation scenario (rated capacity 100kW).

In the above S102, the power flow calculation is performed on the power distribution network after the distributed power supply is connected to the grid according to the equipment parameters of the power distribution network, the topology structure and the initial power of the energy storage device, and the power flow calculation results in each operation scenario are obtained. The specific process is as follows:

According to the equipment parameters, topology structure of the distribution network, the initial power of the energy storage device, and the time sequence matching between the load curve and the output curve of the distributed power supply, the power system simulation software is used to analyze the power distribution after the distributed power supply is connected to the grid. The network performs power flow calculation, and obtains the power flow calculation results in each operating scenario.

In the above S103, the grid-connected capability of the distributed power generation is evaluated according to the power flow calculation results in each operating scenario, and the specific process is as follows:

1) Determine whether the use capacity of the transformer and the use capacity of the line meet the corresponding constraints at the same time, if so, go to the next step, otherwise reduce the preset installed capacity of the distributed power supply;

2) Judging whether the node voltage and the node voltage fluctuation amount are not exceeding the standard, if so, go to the next step, otherwise judge whether the energy storage device satisfies the corresponding constraint conditions, if the energy storage device satisfies the corresponding constraint conditions, determine the actual power of the energy storage device value and the actual value of the state of charge, otherwise the preset installed capacity of the distributed power supply is reduced;

3) Determine whether the use capacity of the transformer, the use flow of the line, the node voltage or the node voltage fluctuation are equal to their respective limits. If so, output the final installed capacity of the distributed power supply, and evaluate the distribution network after the distributed power supply is connected to the grid. Acceptance capacity, otherwise increase the preset installed capacity of distributed power generation.

In the above 1), the constraints corresponding to the operating capacity of the transformer are as follows:

S _T < S _{T amount}

Among them, S _T represents the operating capacity of the transformer, and the _{amount of S T} represents the rated capacity of the transformer;

The constraints corresponding to the use capacity of the line are as follows:

S _L < S _{L amount}

Among them, _SL represents the use capacity of the line, and _SL represents the rated capacity of the line.

In the above 2), it is determined whether the node voltage and the node voltage fluctuation amount are not exceeding the standard. The specific process is as follows:

且

节点电压及节点电压波动量都不超标，其中V_k表示节点k的电压，

和

分别表示节点k的电压下限值和上限值，dV_k表示节点k的电压波动量，

表示节点k的电压波动限值。

(参照国标对电压波动的要求，波动频度1＜r≤10次/h，电压变动限值3％，考虑一定安全裕度取为2.95％)。if satisfied

and

The node voltage and the node voltage fluctuation are not exceeding the standard, where V _k represents the voltage of node k,

and

respectively represent the lower limit and upper limit of the voltage of node k, dV _k represents the voltage fluctuation of node k,

Represents the voltage fluctuation limit at node k.

(Refer to the requirements of the national standard for voltage fluctuation, the fluctuation frequency is 1<r≤10 times/h, the voltage fluctuation limit is 3%, and a certain safety margin is taken as 2.95%).

In the example of the present invention, without considering the energy storage configuration, the maximum capacity of the distributed photovoltaic power generation system that can be accommodated by the 10kV distribution network in this area is 3.2MW; considering the energy storage configuration, the maximum capacity of the 10kV distribution network in this area is 3.2MW. The capacity of the distributed photovoltaic power generation system is 4.44MW.

In the above 2), the corresponding constraints of the energy storage device are as follows:

S _SOCmin ≤S _SOC0 ≤S _SOCmax

Among them, P _E0 represents the active power of the energy storage device, Q _E0 represents the reactive power _{of the energy storage device, P represents the rated power of} the energy storage device; S _SOC0 represents the initial value of the state of charge of the energy storage device, S _SOCmin and S _SOCmax represents the lower limit value and the upper limit value of the state of charge of the energy storage device, respectively.

In the above 2), the actual value of the active power, the actual value of the reactive power and the actual value of the state of charge of the energy storage device are determined as follows:

Among them, PE represents the actual value of the active power of the energy storage device; ω _c represents the cut-off frequency of the filter in the energy storage device, and ω _c is 3.33×10 ^-3 Hz; P _k represents the active power of node _k , and s represents Lapp Lass operator, h represents the power adjustment coefficient, k is 0.0028; S _SOC represents the actual value of the state of charge of the energy storage device, and Δt represents the sampling time interval of the operating data.

In the above S103, the acceptance capacity of the distribution network after the distributed power generation is connected to the grid can be evaluated from the perspective of economy or reliability:

1) The specific process of evaluating the acceptance capacity of the distribution network after the distributed generation is connected to the grid from the perspective of economy is as follows:

1-1) Calculate the grid-connected benefit of distributed power generation as follows:

C=(c _p +c _b )E _s +(c _g +c _b )E _p

Among them, C represents the grid-connected income of the distributed power supply, _Es represents the self-consumption electricity of the distributed power supply, _Ep represents the on-grid electricity, _cp represents the electricity price, and cp is _0.895 yuan/kWh; c _g represents the on-grid price, c _b represents the subsidy price, and c _b is 0.42 yuan/kWh;

1-2) Determine whether C≥C _set is satisfied. If yes, the acceptance capacity of the distribution network after the distributed power generation is connected to the grid is good; otherwise, the acceptance capacity of the distribution network after the distributed power generation is connected to the grid is poor, and C _set represents the grid-connected revenue threshold .

As mentioned above, the grid-connected revenue of distributed generation is 2.676 million yuan/year without considering the energy storage configuration, and the grid-connected revenue of distributed generation is 3.748 million yuan/year when energy storage configuration is considered. It can be seen that considering energy storage In the case of configuration, the benefits of grid-connected distributed generation are better.

2) The specific process of evaluating the acceptance capacity of the distribution network after the distributed generation is connected to the grid from the perspective of reliability is as follows:

2-1) Calculate the average power supply availability rate of the distribution network after the distributed generation is connected to the grid as follows:

Among them, ASAI represents the average power supply availability rate of the distribution network after the distributed generation is connected to the grid, N _k represents the number of users of node k, and U _k represents the annual average power outage time of node k, and its unit is hour/year;

2-2) Determine whether ASAI≥ASAI _set is satisfied, if yes, the acceptance capacity of the distribution network after the distributed power grid is connected to the grid is good, otherwise the acceptance capacity of the distribution network after the distributed power grid is connected to the grid is poor, where ASAI _set means that the average power supply is available rate threshold.

Based on the same inventive concept, an embodiment of the present invention also provides a distributed power grid-connected capability evaluation device, including an acquisition module, a power flow calculation module, and an evaluation module. The above modules are described in detail below:

The acquisition module is used to acquire the equipment parameters, topology structure, operation data and the initial power of the energy storage device of the distribution network after the distributed power supply is connected to the grid;

The power flow calculation module is used to determine multiple operation scenarios according to the operation data, and perform power flow calculation for the distribution network after the distributed power grid is connected to the grid according to the equipment parameters of the distribution network, the topology structure and the initial power of the energy storage device. Obtain the power flow calculation results under each operating scenario; the power flow calculation results include the use capacity of the transformer, the use capacity of the line, the node voltage and the node voltage fluctuation;

The evaluation module is used to evaluate the grid-connected capability of the distributed power generation according to the power flow calculation results in various operating scenarios.

The equipment parameters obtained by the above acquisition module include transformer parameters and line parameters, the obtained operation data includes load operation data and distributed power supply operation data, and the obtained initial power of the energy storage device includes the initial active power of the energy storage device and the energy storage device. Initial reactive power.

The above-mentioned power flow calculation module includes a determination unit, and the operation scenarios determined by the determination unit include a large load and small power generation scenario, a large load fluctuation power generation scenario, a small load large power generation scenario, and a small load fluctuation power generation scenario.

The above power flow calculation module also includes a power flow calculation unit. The power flow calculation unit performs power flow calculation on the distribution network after the distributed power generation is connected to the grid according to the equipment parameters of the distribution network, the topology structure and the initial power of the energy storage device. The specific process is as follows:

According to the equipment parameters, topology structure of the distribution network, the initial power of the energy storage device, and the time sequence matching between the load curve and the output curve of the distributed power supply, the power system simulation software is used to analyze the power distribution after the distributed power supply is connected to the grid. The network performs power flow calculation, and obtains the power flow calculation results in each operating scenario.

The aforementioned evaluation modules include:

The first judgment unit is used for judging whether the use capacity of the transformer and the use capacity of the line meet the corresponding constraint conditions at the same time, if so, go to the next step, otherwise reduce the preset installed capacity of the distributed power source;

The second judging unit is used to judge whether the node voltage and the node voltage fluctuation amount are not exceeding the standard, if so, go to the next step, otherwise judge whether the energy storage device satisfies the corresponding constraint conditions, if the energy storage device satisfies the corresponding constraint conditions, determine the storage device The actual value of the power and the actual value of the state of charge of the energy device, otherwise the preset installed capacity of the distributed power supply is reduced;

The third judging unit is used to judge whether the use capacity of the transformer, the use flow of the line, the node voltage or the node voltage fluctuation amount are equal to their respective limits, if so, output the final installed capacity of the distributed power supply, and evaluate the grid connection of the distributed power supply The receiving capacity of the distribution network, otherwise, the preset installed capacity of the distributed power supply will be increased.

The constraints corresponding to the operating capacity of the above transformers are as follows:

S _T < S _{T amount}

Among them, S _T represents the operating capacity of the transformer, and the _{amount of S T} represents the rated capacity of the transformer;

The constraints corresponding to the usage capacity of the above lines are as follows:

S _L < S _{L amount}

Among them, _SL represents the use capacity of the line, and _SL represents the rated capacity of the line.

The specific process of the second judgment unit judging whether the node voltage and the node voltage fluctuation amount do not exceed the standard is as follows:

且

节点电压及节点电压波动量都不超标，其中V_k表示节点k的电压，

和

分别表示节点k的电压下限值和上限值；dV_k表示节点k的电压波动量，

表示节点k的电压波动限值。if satisfied

and

The node voltage and the node voltage fluctuation are not exceeding the standard, where V _k represents the voltage of node k,

and

respectively represent the lower limit and upper limit of the voltage of node k; dV _k represents the voltage fluctuation of node k,

Represents the voltage fluctuation limit at node k.

The constraints corresponding to the above energy storage devices are as follows:

S _SOCmin ≤S _SOC0 ≤S _SOCmax

Among them, P _E0 represents the active power of the energy storage device, Q _E0 represents the reactive power _{of the energy storage device, P represents the rated power of} the energy storage device; S _SOC0 represents the initial value of the state of charge of the energy storage device, S _SOCmin and S _SOCmax represents the lower limit value and the upper limit value of the state of charge of the energy storage device, respectively.

The above-mentioned second judgment module determines the actual value of active power, actual value of reactive power and actual value of state of charge of the energy storage device as follows:

Among them, PE represents the actual value of the active power of the energy storage device, ω _c represents the cut-off frequency of the filter in the energy storage device, P _k represents the active power of node _k , s represents the Laplace operator, and h represents the power adjustment coefficient , S _SOC represents the actual value of the state of charge of the energy storage device, and Δt represents the sampling time interval of the operating data.

The above-mentioned third judgment unit can evaluate the acceptance capacity of the distribution network after the distributed power generation is connected to the grid from the perspective of economy or reliability:

1) The specific process for the third judgment unit to evaluate the acceptance capacity of the distribution network after the distributed power generation is connected to the grid is as follows:

1-1) Calculate the grid-connected benefit of distributed power generation as follows:

C=(c _p +c _b )E _s +(c _g +c _b )E _p

Among them, C represents the grid-connected income of the distributed power generation, Es represents the self-consumption electricity of the distributed power supply, _Ep represents the on-grid electricity, _cp represents the electricity price, _{c g represents} the on-grid price, and c _b represents the electricity subsidy price;

1-2) Determine whether C≥C _set is satisfied. If yes, the acceptance capacity of the distribution network after the distributed power generation is connected to the grid is good; otherwise, the acceptance capacity of the distribution network after the distributed power generation is connected to the grid is poor, and C _set represents the grid-connected revenue threshold .

2) The specific process for the third judgment unit to evaluate the acceptance capacity of the distribution network after the distributed power generation is connected to the grid is as follows:

2-1) Calculate the average power supply availability rate of the distribution network after the distributed generation is connected to the grid as follows:

Among them, ASAI represents the average power supply availability rate of the distribution network after the distributed generation is connected to the grid, N _k represents the number of users of node k, and U _k represents the annual average power outage time of node k, and its unit is hour/year;

2-2) Determine whether ASAI≥ASAI _set is satisfied, if yes, the acceptance capacity of the distribution network after the distributed power grid is connected to the grid is good, otherwise the acceptance capacity of the distribution network after the distributed power grid is connected to the grid is poor, where ASAI _set means that the average power supply is available rate threshold.

For the convenience of description, each part of the device described above is divided into various modules or units by function and described respectively. Of course, when implementing the present application, the functions of each module or unit may be implemented in one or more software or hardware.

As will be appreciated by those skilled in the art, the embodiments of the present application may be provided as a method, a system, or a computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions The apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in the flow or blocks of the flowcharts and/or the block or blocks of the block diagrams.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Those of ordinary skill in the art can still modify or equivalently replace the specific embodiments of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that depart from the spirit and scope of the present invention are all within the protection scope of the claims of the present invention for which the application is pending.

Claims (14)

1. A method for evaluating the grid-connected capability of distributed power sources, comprising: Obtain the equipment parameters, topology, operation data and initial power of the energy storage device of the distribution network after the distributed generation is connected to the grid; Determine multiple operating scenarios according to the operating data, and perform power flow calculation on the distribution network after the distributed power supply is connected to the grid according to the equipment parameters of the distribution network, the topology structure and the initial power of the energy storage device, and obtain the power flow calculation under each operating scenario. Result; the power flow calculation result includes the use capacity of the transformer, the use capacity of the line, the node voltage and the node voltage fluctuation; Evaluate the grid-connected capability of distributed power sources according to the power flow calculation results in each operating scenario; The equipment parameters include transformer parameters and line parameters; The operation data includes load operation data and distributed power supply operation data; The initial power of the energy storage device includes the initial active power of the energy storage device and the initial reactive power of the energy storage device; The operation scenarios include a large load and small power generation scenario, a large load fluctuation power generation scenario, a small load large power generation scenario, and a small load fluctuation power generation scenario; The power flow calculation is performed on the power distribution network after the distributed power supply is connected to the grid according to the equipment parameters of the power distribution network, the topology structure and the initial power of the energy storage device, and the power flow calculation results in each operation scenario are obtained, including: According to the equipment parameters, topology structure of the distribution network, the initial power of the energy storage device, and the time sequence matching between the load curve and the output curve of the distributed power supply, the power system simulation software is used to analyze the power distribution after the distributed power supply is connected to the grid. The power flow calculation is carried out through the network, and the power flow calculation results under each operating scenario are obtained; The evaluation of the grid-connected capability of the distributed power source according to the power flow calculation results in each operating scenario includes: Determine whether the use capacity of the transformer and the use capacity of the line meet the corresponding constraints at the same time, if so, go to the next step, otherwise reduce the preset installed capacity of the distributed power supply; Determine whether the node voltage and the node voltage fluctuation amount do not exceed the standard. If yes, go to the next step. Otherwise, determine whether the energy storage device satisfies the corresponding constraint conditions. If the energy storage device meets the corresponding constraint conditions, determine the actual value of the energy storage device power and The actual value of the state of charge, otherwise the preset installed capacity of the distributed power supply is reduced; Determine whether the capacity of the transformer, the capacity of the line, the node voltage or the node voltage fluctuation are equal to their respective limits. If so, output the final installed capacity of the distributed power supply, and evaluate the acceptance capacity of the distribution network after the distributed power supply is connected to the grid. , otherwise increase the preset installed capacity of distributed power. 2. The method for evaluating the grid-connected capability of a distributed power source according to claim 1, wherein the corresponding constraint condition of the used capacity of the transformer is as follows: S _T < S _{T amount} Among them, S _T represents the operating capacity of the transformer, and the _{amount of S T} represents the rated capacity of the transformer; The constraints corresponding to the usage capacity of the lines are as follows: S _L < S _{L amount} Among them, _SL represents the use capacity of the line, and _SL represents the rated capacity of the line. 3. The method for evaluating the grid-connected capability of a distributed power source according to claim 1, wherein the judging whether the node voltage and the node voltage fluctuation amount do not exceed the standard, comprising: if satisfied

and

The node voltage and the node voltage fluctuation are not exceeding the standard, where V _k represents the voltage of node k,

and

respectively represent the lower limit and upper limit of the voltage of node k; dV _k represents the voltage fluctuation of node k,

Represents the voltage fluctuation limit at node k. 4. The method for evaluating the grid-connected capability of distributed power sources according to claim 3, wherein the corresponding constraints of the energy storage device are as follows:

S _SOCmin ≤S _SOC0 ≤S _SOCmax Among them, P _E0 represents the active power of the energy storage device, Q _E0 represents the reactive power _{of the energy storage device, P represents the rated power of} the energy storage device; S _SOC0 represents the initial value of the state of charge of the energy storage device, S _SOCmin and S _SOCmax represents the lower limit value and the upper limit value of the state of charge of the energy storage device, respectively. 5. The method for evaluating the grid-connected capability of distributed power sources according to claim 4, wherein the determining the actual value of power and the actual value of the state of charge of the energy storage device comprises: Determine the actual value of the active power, the actual value of the reactive power and the actual value of the state of charge of the energy storage device as follows:

Among them, PE represents the actual value of the active power of the energy storage device, ω _c represents the cut-off frequency of the filter in the energy storage device, P _k represents the active power of node _k , s represents the Laplace operator, and h represents the power adjustment coefficient , S _SOC represents the actual value of the state of charge of the energy storage device, and Δt represents the sampling time interval of the operating data. 6. The method for evaluating the grid-connected capability of a distributed power source according to claim 1, wherein the evaluation of the receiving capacity of the distribution network after the distributed power source is connected to the grid comprises: Calculate the grid-connected benefits of distributed power sources as follows: C=(c _p +c _b )E _s +(c _g +c _b )E _p Among them, C represents the grid-connected income of the distributed power generation, Es represents the self-consumption electricity of the distributed power supply, _Ep represents the on-grid electricity, _cp represents the electricity price, _{c g represents} the on-grid price, and c _b represents the electricity subsidy price; It is judged whether _{C≥C set} is satisfied. If yes, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is good; otherwise, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is poor. 7. The method for evaluating the grid-connected capability of a distributed power source according to claim 1, wherein the evaluation of the receiving capacity of the distribution network after the distributed power source is connected to the grid comprises: The average power supply availability rate of the distribution network after the distributed power grid is connected to the grid is calculated as follows:

Among them, ASAI represents the average power supply availability rate of the distribution network after the distributed generation is connected to the grid, N _k represents the number of users of node k, and U _k represents the annual average power outage time of node k, and its unit is hour/year; Determine whether ASAI≥ASAI _set is satisfied. If yes, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is good, otherwise the acceptance capacity of the distribution network after the distributed generation is connected to the grid is poor, where ASAI _set represents the average power supply availability threshold. 8. A device for evaluating the grid-connected capability of distributed power sources, comprising: The acquisition module is used to acquire the equipment parameters, topology structure, operation data and the initial power of the energy storage device of the distribution network after the distributed power supply is connected to the grid; The power flow calculation module is used to determine multiple operation scenarios according to the operation data, and perform power flow calculation on the distribution network after the distributed power grid is connected according to the equipment parameters of the distribution network, the topology structure and the initial power of the energy storage device. The power flow calculation result in the operation scenario; the power flow calculation result includes the used capacity of the transformer, the used capacity of the line, the node voltage and the node voltage fluctuation; The evaluation module is used to evaluate the grid-connected capability of the distributed power generation according to the power flow calculation results in various operating scenarios; The equipment parameters obtained by the obtaining module include transformer parameters and line parameters; The operation data includes load operation data and distributed power supply operation data; The initial power of the energy storage device includes the initial active power of the energy storage device and the initial reactive power of the energy storage device; The power flow calculation module includes a determination unit, and the operation scenarios determined by the determination unit include a large load and small power generation scenario, a large load fluctuation power generation scenario, a small load large power generation scenario, and a small load fluctuation power generation scenario; the power flow calculation module includes a power flow calculation module. unit, the power flow calculation unit is specifically used for: According to the equipment parameters, topology structure of the distribution network, the initial power of the energy storage device, and the time sequence matching between the load curve and the output curve of the distributed power supply, the power system simulation software is used to analyze the power distribution after the distributed power supply is connected to the grid. The power flow calculation is carried out through the network, and the power flow calculation results under each operating scenario are obtained; The evaluation module includes: The first judgment unit is used for judging whether the use capacity of the transformer and the use capacity of the line meet the corresponding constraint conditions at the same time, if so, go to the next step, otherwise reduce the preset installed capacity of the distributed power source; The second judging unit is used to judge whether the node voltage and the node voltage fluctuation amount are not exceeding the standard, if so, go to the next step, otherwise judge whether the energy storage device satisfies the corresponding constraint conditions, if the energy storage device satisfies the corresponding constraint conditions, determine the storage device The actual value of the power and the actual value of the state of charge of the energy device, otherwise the preset installed capacity of the distributed power supply is reduced; The third judgment unit is used to judge whether the use capacity of the transformer, the use capacity of the line, the node voltage or the node voltage fluctuation are equal to their respective limits, if so, output the final installed capacity of the distributed power supply, and evaluate the grid connection of the distributed power supply The receiving capacity of the distribution network, otherwise, the preset installed capacity of the distributed power supply will be increased. 9. The device for evaluating the grid-connected capability of distributed power sources according to claim 8, wherein the constraints corresponding to the operating capacity of the transformer are as follows: S _T < S _{T amount} Among them, S _T represents the operating capacity of the transformer, and the _{amount of S T} represents the rated capacity of the transformer; The constraints corresponding to the usage capacity of the lines are as follows: S _L < S _{L amount} Among them, _SL represents the use capacity of the line, and _SL represents the rated capacity of the line. 10. The device for evaluating the grid-connected capability of distributed power sources according to claim 8, wherein the second judgment unit is specifically used for: if satisfied

and

The node voltage and the node voltage fluctuation are not exceeding the standard, where V _k represents the voltage of node k,

and

respectively represent the lower limit and upper limit of the voltage of node k; dV _k represents the voltage fluctuation of node k,

Represents the voltage fluctuation limit at node k. 11. The device for evaluating the grid-connected capability of distributed power sources according to claim 10, wherein the constraints corresponding to the energy storage device are as follows:

S _SOCmin ≤S _SOC0 ≤S _SOCmax Among them, P _E0 represents the active power of the energy storage device, Q _E0 represents the reactive power _{of the energy storage device, P represents the rated power of} the energy storage device; S _SOC0 represents the initial value of the state of charge of the energy storage device, S _SOCmin and S _SOCmax represents the lower limit value and the upper limit value of the state of charge of the energy storage device, respectively. 12. The device for evaluating the grid-connected capability of distributed power sources according to claim 11, wherein the second judging unit is specifically used for: Determine the actual value of the active power, the actual value of the reactive power and the actual value of the state of charge of the energy storage device as follows:

Among them, PE represents the actual value of the active power of the energy storage device, ω _c represents the cut-off frequency of the filter in the energy storage device, P _k represents the active power of node _k , s represents the Laplace operator, and h represents the power adjustment coefficient , S _SOC represents the actual value of the state of charge of the energy storage device, and Δt represents the sampling time interval of the operating data. 13. The device for evaluating the grid-connected capability of distributed power sources according to claim 8, wherein the third judging unit is specifically used for: Calculate the grid-connected benefits of distributed power sources as follows: C=(c _p +c _b )E _s +(c _g +c _b )E _p Among them, C represents the grid-connected income of the distributed power generation, Es represents the self-consumption electricity of the distributed power supply, _Ep represents the on-grid electricity, _cp represents the electricity price, _{c g represents} the on-grid price, and c _b represents the electricity subsidy price; It is judged whether _{C≥C set} is satisfied. If yes, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is good; otherwise, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is poor. 14. The device for evaluating the grid-connected capability of distributed power sources according to claim 8, wherein the third judging unit is specifically used for: The average power supply availability rate of the distribution network after the distributed power grid is connected to the grid is calculated as follows:

Among them, ASAI represents the average power supply availability rate of the distribution network after the distributed generation is connected to the grid, N _k represents the number of users of node k, and U _k represents the annual average power outage time of node k, and its unit is hour/year; Determine whether ASAI≥ASAI _set is satisfied. If yes, the acceptance capacity of the distribution network after the distributed generation is connected to the grid is good, otherwise the acceptance capacity of the distribution network after the distributed generation is connected to the grid is poor, where ASAI _set represents the average power supply availability threshold.

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