Load regulation method and device for local power distribution system and local power distribution system

Abstract

The application discloses a kind of local power distribution system load regulation methods.For the deficiency of prior art load shedding frequent switching action, the application determines the preliminary load regulation instruction of current control cycle according to the demand over-limit risk assessment result of current control cycle, and on this basis, the demand over-limit risk of next control cycle is estimated, then combined with the demand over-limit risk estimation situation twice, with the optimization target of reducing load shedding and access action frequency, the preliminary load regulation instruction of current control cycle is optimized and adjusted, so that the load can meet the total power demand limit value requirement under the premise of guaranteeing, the load shedding and access action frequency is greatly reduced, the service life of each load feeder switch is extended, and the system safety and reliability is improved.The application also discloses a kind of local power distribution system load regulation device and a kind of local power distribution system.The application can reduce the load shedding and access action frequency, and extend the service life of each load feeder switch.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of local power distribution system load regulation method, belong to electric power automatic control technical field. BACKGROUND

[0002] With the continuous improvement of smart grid technology, higher requirements are put forward for the optimization and control of power management of power distribution terminal. At present, a large number of power management methods, such as maximum demand metering method, are used to promote user adjustment of power load, balance power grid load, control power peak load and stabilize power supply voltage. The maximum demand of the power metering is the average power value in a specified period of time, and the demand period is usually 15 minutes, with fixed interval type and slip type charging method. Most foreign countries use fixed interval type, and China uses slip type more.

[0003] In order to make the total load of local power distribution system run under the load demand limit value set by human, it is necessary to regulate the load of each controllable sub-load. The existing various load regulation schemes usually regulate the load according to the actual measured total power of the system, preferentially ensure the operation of high priority load, and can control the load limit value according to the time set by the user. However, if the measured instantaneous total power is used to control the load during the specified period of maximum demand, when the load has a short pulse type, if the peak value of the load is high but the pulse width is narrow, the demand power during the load demand period will not be high, which will cause unnecessary load switching on and off actions. The frequent switching of sub-loads will greatly increase the loss caused by the switching of load distribution feeder switches, thereby reducing the service life of the feeder switches and the safety and reliability of the system.

[0004] In addition, the existing various load regulation schemes all need to use the power information of each sub-branch load, which is usually obtained by measurement. However, in a load local network, if power measuring devices are added to each sub-branch load, the hardware cost will increase. Moreover, in a load distribution system that has been designed, circuit breakers and other electrical devices are usually already installed, and some circuit breakers do not have the function of measuring power. Therefore, under the condition that the sub-power information cannot be obtained, the existing load regulation method is often difficult to implement. If the power information of each sub-branch load can be obtained without installing power measuring devices for each sub-branch load, the load regulation system can be designed and configured more flexibly, and the implementation cost of the system can be reduced. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a local power distribution system load regulation method, which can greatly reduce the frequency of load switching on and off and prolong the service life of each sub-load feeder switch while ensuring that the load meets the total power demand limit value.

[0006] The present application specifically adopts the following technical solutions to solve the above technical problems:

[0007] A load regulation method for a local power distribution system, the local power distribution system comprising a group of sub-loads that can be controlled to be cut off and connected respectively; the method comprising:

[0008] Step 1, measuring total power information of the current control period of the local power distribution system and predicting total load demand power;

[0009] Step 2, performing load demand overrun risk assessment for the current control period according to the predicted total load demand power and a preset load demand power limit value;

[0010] Step 3, determining a preliminary load regulation instruction for the current control period according to the load demand overrun risk assessment result of the current control period;

[0011] Step 4, estimating total load demand power of the next control period according to the sub-load operating power information and the preliminary load regulation instruction of the current control period, and performing load demand overrun risk assessment for the next control period according to the estimated total load demand power and the preset load demand power limit value;

[0012] Step 5, if the load demand overrun risk of the current control period is lower than a preset first risk index and the load demand overrun risk of the next control period is higher than a preset second risk index, optimizing and adjusting the preliminary load regulation instruction of the current control period to obtain a final load regulation instruction of the current control period, taking the frequency of load cut-off and connection actions as the optimization target; otherwise, taking the preliminary load regulation instruction of the current control period as the final load regulation instruction of the current control period;

[0013] Step 6, controlling the cut-off and connection of each sub-load according to the final load regulation instruction of the current control period.

[0014] Further, the sub-load operating power information is estimated according to historical data of the total power information changing with the state of each sub-load.

[0015] Preferably, the load demand overrun risk is measured by any of the following ways:

[0016] The ratio of the total load demand power to the load demand power limit value;

[0017] The difference between the load demand power limit value and the total load demand power;

[0018] The difference between the load demand power limit value and the total load demand power divided by the load demand power limit value.

[0019] Preferably, the demand metering mode, the demand period, the demand power limit, the load priority of each sub-load and the load disable period are configurable parameters.

[0020] According to the same inventive concept, the following technical solutions can also be obtained:

[0021] A load regulation device for a local power distribution system, the local power distribution system comprising a group of sub-loads which can be controlled to be cut off and connected respectively; the device comprising:

[0022] a prediction unit configured to predict a total load demand power according to total power information of the local power distribution system;

[0023] a risk assessment unit configured to assess a demand overrun risk of a current control period according to the predicted total load demand power and a preset demand power limit;

[0024] a load regulation unit configured to determine a preliminary load regulation instruction of the current control period according to a result of the demand overrun risk assessment of the current control period;

[0025] an estimation unit configured to estimate a total load demand power of a next control period according to sub-load operating power information and the preliminary load regulation instruction of the current control period, and to assess a demand overrun risk of the next control period according to the estimated total load demand power and the preset demand power limit;

[0026] an instruction optimization unit configured to, if the demand overrun risk of the current control period is lower than a preset first risk index and the demand overrun risk of the next control period is higher than a preset second risk index, optimize and adjust the preliminary load regulation instruction of the current control period to obtain a final load regulation instruction of the current control period, with the optimization target being to reduce the frequency of load cut-off and connection actions; otherwise, the preliminary load regulation instruction of the current control period is taken as the final load regulation instruction of the current control period;

[0027] a control unit configured to control the cut-off and connection of each sub-load according to the final load regulation instruction of the current control period.

[0028] Further, the sub-load operating power information is estimated according to historical data of changes in total power information with the state of each sub-load.

[0029] Preferably, the demand overrun risk is measured by any of the following ways:

[0030] a ratio of the total load demand power to the demand power limit;

[0031] a difference between the demand power limit and the total load demand power;

[0032] The difference between the demand power limit value and the total demand power of the load is divided by the demand power limit value.

[0033] Further, the device further comprises:

[0034] The configuration unit is configured to configure the following configurable parameters: demand metering mode, demand period, demand power limit value, load priority of each sub-load, and load disable period.

[0035] A local power distribution system comprises a group of sub-loads that can be controlled to be cut off and accessed respectively; the cut-off and access of the sub-loads are controlled by using the local power distribution system load regulation device according to any one of the technical solutions.

[0036] Compared with the prior art, the technical solutions of the present application and their further improvements and preferred solutions have the following beneficial effects:

[0037] According to the demand over-limit risk evaluation result of the current control period, the preliminary load regulation instruction of the current control period is determined, the demand over-limit risk of the next control period is estimated, and then the preliminary load regulation instruction of the current control period is optimized and adjusted in combination with the two demand over-limit risk estimation conditions, so as to reduce the frequency of load cut-off and access actions as the optimization target, thereby greatly reducing the frequency of load cut-off and access actions, prolonging the service life of the feeder switch of each sub-load, and improving the safety and reliability of the system under the premise that the load meets the total power demand limit value requirement.

[0038] The present application further discards the traditional method relying on direct measurement, and estimates the power information of each sub-load by data analysis according to the historical data of the total power information changing with the state of each sub-load, so as to realize the identification and estimation of the load power without additional sub-load power measurement device, thereby realizing the demand load regulation of the local power distribution system at a low cost, and without too much addition and modification of the existing power distribution system, the local load regulation system can be flexibly expanded and constructed, which has excellent applicability and great popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a structure schematic diagram of the local power distribution system in the specific embodiment;

[0040] Figure 2 It is the load regulation effect in the specific embodiment, wherein curve 1 is the demand power limit value, curve 2 is the demand power, and curve 3 is the total power instantaneous sampling value Pm.

[0041] Figure 3 It is the on-off state of the switches K_1-K_5 corresponding to the five loads in the load regulation process in the specific embodiment. DETAILED DESCRIPTION

[0042] In view of the frequent load shedding and switching action of the prior art, the solution of the present application is to determine the preliminary load regulation instruction of the current control period according to the demand over-limit risk evaluation result of the current control period, and on this basis, to estimate the demand over-limit risk of the next control period, and then in combination with the two demand over-limit risk estimation situations, to optimize and adjust the preliminary load regulation instruction of the current control period as the optimization target of reducing the frequency of load shedding and switching action, so that the frequency of load shedding and switching action can be greatly reduced under the premise of ensuring that the load meets the total power demand limit value requirement, the service life of each load shedding feeder line switch is prolonged, and the system safety and reliability is improved.

[0043] Specifically, the load regulation method of the local power distribution system proposed by the present application comprises a group of load shedding which can be controlled to be cut off and connected respectively; the method comprises:

[0044] Step 1, measuring the total power information of the local power distribution system in the current control period and predicting the total load demand power;

[0045] Step 2, evaluating the demand over-limit risk of the current control period according to the predicted total load demand power and the preset demand power limit value;

[0046] Step 3, determining the preliminary load regulation instruction of the current control period according to the demand over-limit risk evaluation result of the current control period;

[0047] Step 4, estimating the total load demand power of the next control period according to the operation power information of each load shedding and the preliminary load regulation instruction of the current control period, and evaluating the demand over-limit risk of the next control period according to the estimated total load demand power and the preset demand power limit value;

[0048] Step 5, if the demand over-limit risk of the current control period is lower than the preset first risk index, and the demand over-limit risk of the next control period is higher than the preset second risk index, then the preliminary load regulation instruction of the current control period is optimized and adjusted as the optimization target of reducing the frequency of load shedding and switching action, to obtain the final load regulation instruction of the current control period; otherwise, the preliminary load regulation instruction of the current control period is taken as the final load regulation instruction of the current control period;

[0049] Step 6, controlling the cut-off and connection of each load shedding according to the final load regulation instruction of the current control period.

[0050] In order to facilitate the public to understand, the technical solutions of the present application will be described in detail below through a specific embodiment and in combination with the drawings:

[0051] The local power distribution system of the present embodiment comprises five loads, and its electrical topology diagram is as followsFigure 1 The local area power distribution system is shown. K_0 is a local load total incoming line switch, Pm is the total power measured on the total incoming line switch feeder, Load_1, Load_2, Load_3, Load_4, Load_5 are five loads respectively, K_1, K_2, K_3, K_4, K_5 are the power supply feeder switches connected to each controllable load. Pmax is the total load demand limit value required at the total incoming line. There are two ways of charging period in China, fixed interval and sliding interval, the sliding time can be set to 1 minute, 2 minutes, 3 minutes, 5 minutes, the demand period can be set to 5 minutes, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 60 minutes, the ratio of demand period to sliding period is an integer and greater than or equal to 5. The sliding period of this embodiment is 1 minute, and the demand period is 15 minutes. In actual application, the user can configure the demand measurement method and demand period according to different situations.

[0052] The load control device of the embodiment includes a prediction unit, a risk assessment unit, a load control unit, a prediction unit, an instruction optimization unit, a control unit and a configuration unit. The load control device continuously collects the total power Pm on the total feeder and stores the data information of Pm; the user can set the demand power limit value Pmax and the demand period TD, the load priority order P1, P2, P3, P4, P5 (the priority from high to low is P1> P2> P3> P4> P5) corresponding to each load Load_1, Load_2, Load_3, Load_4, Load_5 and the load disable period through the setting unit; the setting unit can be set locally or configured by the upper computer through the communication bus.

[0053] The device controls the load according to the following steps:

[0054] Step 1, measure the total power information of the current control period of the local area power distribution system and predict the total demand power of the load;

[0055] The prediction unit predicts the total power information P(k+1) of the load at the future time according to the total power information Pm stored in the storage unit, and estimates the demand power Pe(k+1) of the total current sliding demand period of the load. The specific prediction method can adopt various existing technologies, such as time series analysis method, grey prediction model, neural network prediction model, etc., and the simple and clear time series analysis method is preferably adopted.

[0056] Step 2, the risk assessment unit assesses the demand overrun risk of the current control period according to the predicted total demand power of the load and the preset demand power limit value;

[0057] The risk assessment unit assesses the demand overrun risk of the current control period according to the demand power limit value P maxand the predicted required power P of the prediction unit e (k+1) assesses the risk of required power exceeding the limit in the current control period, and the risk of required power exceeding the limit in the current control period can be designed according to actual needs, as long as the risk of required power exceeding the limit can be quantified. The present application preferably adopts the following several simple and intuitive measurement methods: the ratio of total load required power to required power limit value; the difference between required power limit value and total load required power; the difference between required power limit value and total load required power divided by required power limit value.

[0058] In the present embodiment, the predicted required power P e (k+1) and the ratio of required power limit value P max is used as a risk assessment coefficient Kg1 that can express the relationship between the required power in the current control period and the limit value; when Kg1>1, it is a high-risk risk assessment, when m<Kg1<1, it is a medium-risk risk assessment, where m can be adjusted or obtained through optimization calculation, and the value range of m is: 0<m<1, when Kg1<m, it is a low-risk risk assessment.

[0059] Step 3, the load regulation unit determines the preliminary load regulation instruction of the current control period according to the required power exceeding limit risk assessment result of the current control period;

[0060] The load regulation unit performs preliminary load regulation according to the required power risk assessment coefficient Kg1 in the current control period. If the Kg1 risk coefficient is high, the load regulation algorithm gives the regulation instruction for cutting off the load in the current control period according to the load priority order P1, P2, P3, P4, P5, and the information of disabled selection period requirements. If the Kg risk coefficient is low, the load regulation algorithm gives the regulation instruction for the load to be put into the current control period by giving priority to the load with high priority.

[0061] The load regulation algorithm (i.e. preliminary load regulation algorithm) can adopt various existing load regulation algorithms, such as the load regulation method based on peak-to-average ratio constraint condition and energy consumption limit value in the article “Load and Cost Optimization of Demand Side Management of Intelligent Buildings”; the load regulation method based on dynamic programming method in the article “Research on Economic Allocation of Plant-level Load Based on Dynamic Programming Method”; and most of these algorithms need to use the running power information of each sub-load. If the traditional direct measurement method is used to obtain this information, additional power measurement devices need to be set for each sub-load or the corresponding circuit breakers need to have power measurement function, which will obviously increase the system construction cost and reduce the scalability of the system.

[0062] To solve this problem, the application further discards the traditional way of relying on direct measurement, and estimates each sub-load power information through data analysis according to the historical data of the total power information changing with each sub-load state. More specifically, the load control instruction is issued in the current control period, the total load power changes, the total load power change value corresponding to each time before and after the load control is issued is recorded multiple times, and the data of the action of each sub-load and the total power change are recorded according to the known load input and cut-off control action. The power or range and average of the sub-load can be estimated by data analysis or solving according to the data sequence, for example: control inputting a load K_1, and then recording the total load power change value before and after the control switching as ΔP1. The power of the sub-load K_1 is once collected data L1Pm1. The total power change data of multiple sub-load switching is recorded to form a load collection data set of each load: [L1Pm1 L2Pm1 ……LnPm1], [L1Pm2 L2Pm2 ……LnPm2] …… [L1PmK L2PmK ……LnPmK]. The data set is processed to remove abnormal data points, and the estimated power range and power average of K_1 corresponding to the load are calculated through data analysis.

[0063] Step 4, the estimation unit estimates the total load demand power of the next control period according to the running power information of each sub-load and the preliminary load regulation instruction of the current control period, and performs demand over-limit risk assessment of the next control period according to the estimated total load demand power and the preset demand power limit value.

[0064] The estimation unit estimates the total load demand power of the next control period according to the estimated controlled sub-load power Pm1, Pm2, Pm3, Pm4, Pm5 and the preliminary load regulation instruction of the current control period given by the load regulation unit, and calculates the risk assessment coefficient Kg2 of the next control period according to the estimated total load demand power and the preset demand power limit value.

[0065] Step 5, the instruction optimization unit performs instruction optimization: if the demand over-limit risk of the current control period is lower than the preset first risk index, and the demand over-limit risk of the next control period is higher than the preset second risk index, the optimization target is to reduce the frequency of load cut-off and access actions, and the preliminary load regulation instruction of the current control period is optimized and adjusted to obtain the final load regulation instruction of the current control period; otherwise, the preliminary load regulation instruction of the current control period is taken as the final load regulation instruction of the current control period.

[0066] When the risk assessment coefficient Kg1 is higher or in a medium risk assessment result, i.e. higher than the preset first risk index, the preliminary load regulation instruction of the current control period is taken as the final load regulation instruction of the current control period; when the risk assessment coefficient Kg1 is lower, lower than the preset first risk index, it is needed to further judge whether the risk assessment coefficient Kg2 of the next control period is higher than the preset second risk index, if yes, it indicates that the input load will cause the risk assessment coefficient Kg2 to be high in the next control period, and the expected demand rises fast, thus it is needed to adjust the load regulation instruction of the current control period, specifically: the preliminary load regulation instruction of the current control period is optimized and adjusted with the frequency of load shedding and access action reduction as the optimization target; thereby the demand power fluctuation and the frequency of load switching action caused by load switching are reduced.

[0067] Step 6, the control unit controls the shedding and access of each sub-load according to the final load regulation instruction of the current control period;

[0068] The control unit controls the opening and closing of the feeder switches K_1, K_2, K_3, K_4 and K_5 corresponding to each controlled sub-load according to the final load regulation instruction of the current control period optimized and adjusted by the instruction optimization unit, so as to realize that the total power load demand is lower than the load demand power limit set by the user.

[0069] Figure 2 、 Figure 3 The load regulation effect of the above embodiment is shown. As shown in Figure 2 , although the total power instantaneous value occasionally exceeds the demand limit during the load operation process, the total power demand power is always lower than the demand limit under the load regulation. As shown in Figure 3 , from the switching state of the load switch, load 1 is preferentially supplied, and load 5 is cut off earlier when the load demand risk coefficient is high. After the load regulation, the total load demand power is stably operated below the demand limit, and the load does not have very frequent switching action.

[0070] From the above preferred scheme, it can be concluded that the load regulation method and device of the present application do not need to sample the power of each sub-load, which reduces the purchase and construction cost of the load regulation system, and the user operation is simple. Only the required demand power limit, metering period, load priority, time period requirement, etc. need to be configured, and the local load regulation function can be automatically realized, the priority high load is preferentially powered, and the switching action frequency of the load is reduced. The load regulation method can effectively regulate the load to ensure the demand limit requirement, and the load regulation system is easy to expand and realize.

Claims

1. A load regulating method for a local power distribution system, said local power distribution system comprising a set of sub-loads, each of which can be controlled to be disconnected and connected, respectively; characterized in that, The method comprises: Step 1, measuring total power information of a current control period of the local power distribution system and predicting total load demand power; Step 2, performing demand overrun risk assessment of the current control period according to the predicted total load demand power and a preset demand power limit value; Step 3, determining a preliminary load regulation instruction of the current control period according to the demand overrun risk assessment result of the current control period: if the demand overrun risk of the current control period is high, the preliminary load regulation instruction is a regulation instruction for cutting off loads in the current control period; taking the preliminary load regulation instruction of the current control period as a final load regulation instruction of the current control period, and proceeding to step 6; if the demand overrun risk of the current control period is low, the preliminary load regulation instruction is a regulation instruction for putting in loads in the current control period, and proceeding to step 4; Step 4, estimating total load demand power of a next control period according to each sub-load operating power information and the preliminary load regulation instruction of the current control period, and performing demand overrun risk assessment of the next control period according to the estimated total load demand power and the preset demand power limit value; Step 5, if the demand overrun risk of the current control period is lower than a preset first risk index, and the demand overrun risk of the next control period is higher than a preset second risk index, optimizing and adjusting the preliminary load regulation instruction of the current control period to obtain a final load regulation instruction of the current control period, with the optimization target being to reduce the frequency of load cutting-off and connection actions; Step 6, controlling the cutting-off and connection of each sub-load according to the final load regulation instruction of the current control period.

2. The method of claim 1, wherein the local power distribution system load regulation method further comprises: The each sub-load operating power information is estimated according to historical data of changes in total power information with each sub-load state.

3. The method of claim 1, wherein the load control method is applied to a local power distribution system. The demand overrun risk is measured by any one of the following ways: a ratio of the total load demand power to the demand power limit value; a difference between the demand power limit value and the total load demand power; the difference between the demand power limit value and the total load demand power divided by the demand power limit value.

4. The method of claim 1, wherein the local power distribution system load regulation method further comprises: The demand metering mode, the demand period, the demand power limit value, the load priority of each sub-load and the load disabled period are all configurable parameters.

5. A load regulating device for a local power distribution system, said local power distribution system comprising a set of sub-loads each controllable to be switched off and switched in, characterized in that, The device comprises: a prediction unit configured to predict total load demand power according to total power information of the local power distribution system; a risk assessment unit configured to perform demand overrun risk assessment of a current control period according to the predicted total load demand power and a preset demand power limit value; a load regulation unit configured to determine a preliminary load regulation instruction of the current control period according to the demand overrun risk assessment result of the current control period: if the demand overrun risk of the current control period is high, the preliminary load regulation instruction is a regulation instruction for cutting off loads in the current control period, and taking the preliminary load regulation instruction of the current control period as a final load regulation instruction of the current control period; if the demand overrun risk of the current control period is low, the preliminary load regulation instruction is a regulation instruction for putting in loads in the current control period, and inputting the preliminary load regulation instruction into the prediction unit and an instruction optimization unit; The estimation unit is configured to estimate total load demand power of the next control period according to the partial load operation power information and the preliminary load regulation instruction of the current control period, and perform demand over-limit risk assessment of the next control period according to the estimated total load demand power and the preset demand power limit value; The instruction optimization unit is configured to, when the demand over-limit risk of the current control period is lower than a preset first risk index and the demand over-limit risk of the next control period is higher than a preset second risk index, optimize and adjust the preliminary load regulation instruction of the current control period to obtain the final load regulation instruction of the current control period, with the optimization target being to reduce the frequency of load shedding and access actions. The control unit is configured to control the shedding and access of the partial loads according to the final load regulation instruction of the current control period.

6. The load regulating device of claim 5, wherein the load regulating device is configured to regulate the power supplied to the load by the power supply device in response to the power supply device being in the power supply mode. The partial load operation power information is estimated according to historical data of total power information changing with the states of the partial loads.

7. The load regulating device of claim 5, wherein the load regulating device is configured to regulate the load by controlling the power supplied to the load by the power supply. The demand over-limit risk is measured in any of the following ways: a ratio of the total load demand power to the demand power limit value; a difference between the demand power limit value and the total load demand power; the difference between the demand power limit value and the total load demand power divided by the demand power limit value.

8. The load regulating device of claim 5, wherein the load regulating device is configured to regulate the load of the local power distribution system by: The local power distribution system load regulation device further comprises a configuration unit configured to configure the following configurable parameters: demand metering mode, demand period, demand power limit value, load priority of each partial load, and load disable period. ​ The shedding and access of the partial loads are controlled by using the local power distribution system load regulation device according to any one of claims 5-8.

9. A local power distribution system comprising a set of sub-loads which can be controlled individually for switching off and switching in; characterized in that, ​

Images