JP4348450B2 - Controllable load power consumption control method and controllable load control system - Google Patents

Description

  The present invention relates to a controllable load power consumption control method and a controllable load control system that optimizes the supply and demand balance of a power system.

  In order to reduce the consumption of finite fossil fuels and reduce carbon dioxide emissions that cause global warming, it is possible to combine power generation using renewable resources such as solar and wind power and effective use of exhaust heat. The widespread use of combined heat and power to increase efficiency is important. These are “distributed power supplies” that are usually dotted with small capacities, and many of them are operated without the output changing according to weather conditions or receiving an instruction to adjust the output from the system operator. For this reason, if a large number of distributed power sources are connected to the current power system, it becomes difficult to maintain the supply and demand balance of the entire system. If the supply and demand balance of the entire system is not maintained, the frequency of the system will change, and the large capacity thermal power generation unit will be stopped urgently in order to prevent the turbine blades from vibrating and causing fatigue failure.

Therefore, power consumption adjustment of a controllable load has been proposed. The controllable load is a load that can achieve the intended purpose even if the power consumption p at each time t is fluctuated, although it is necessary to input the specified energy e _est within the specified time t _limit. Applicable to air conditioners. For example, an electric water heater needs to input energy necessary to raise water to 85 ° C from 11:00 pm to 7:00 am the following morning, but the heater is always turned on at, for example, 2 am There is no need. Therefore, by increasing the power consumption of such controllable loads when the total generated power in the system is excessive, and reducing it when the total generated power is insufficient, the supply and demand balance of the entire system is maintained. However, it is intended to suppress the frequency deviation. However, in order to achieve the purpose of use of each load, the constraint condition that the specified energy e _est is input within the specified time t _limit must be observed.

  As such a controllable load control method, a grid information monitoring system in which a grid operator collects operation information of each controllable load and issues a command has been proposed (see Patent Document 1). Then, taking the case of an electric water heater as an example, it is confirmed by numerical calculation that the supply and demand balance can be maintained by this system information monitoring system and the frequency deviation of the system can be sufficiently suppressed (see Non-Patent Document 1). ). In addition, a method has been proposed in which each controllable load measures the frequency deviation of the system without using communication means, and performs on / off control based on the magnitude relationship with a specified range of the frequency deviation (Non-Patent Document 2).

Japanese Patent Application No. 2004-0776847 Junji Kondo, Hirohisa Aki, Hiroshi Yamaguchi, Masanobu Murata, Satoshi Ishii: “Study on control method of controllable load to maintain supply-demand balance” (2004 Annual Meeting of the Institute of Electrical Engineers of Japan, 470, August 2004) ) Naoyuki Moriya, Satoshi Arimitsu, Satoshi Uemura, Ryuichi Shimada: “Frequency control using system loads such as electric water heaters” (1993 Annual Conference of the Institute of Electrical Engineers of Japan, 1163, March 1993)

  However, in the system information monitoring system as shown in the above-mentioned Patent Document 1 and Non-Patent Document 1, communication means that always exchanges information and commands in real time between each controllable load and the system operator is necessary. There are almost no examples of such communication means already installed, and there has been a problem that enormous investment is required for the new establishment.

Further, as described in Non-Patent Document 2, it is possible to control without using communication means, but in this method, a specified energy e _est is input to each controllable load within a specified time t _limit. There is a problem that it is not guaranteed that the constraint condition is satisfied, and there is no guarantee that the purpose of using the controllable load can be achieved.

In this way, while satisfying the constraint that the specified energy e _est is input within the specified time t _limit , the supply and demand balance of the entire system is maintained without using communication means that exchange information and commands in real time. At present, a control algorithm for controlling the controllable load has not been established.

In view of the above problems, the object of the present invention is to satisfy the constraint that the specified energy e _est is input within the specified time t _limit , without using communication means that exchange information and commands in real time. An object of the present invention is to provide a controllable load power consumption control method and a controllable load control system capable of maintaining the overall supply and demand balance.

The present invention employs the following means in order to solve the above problems.
The first means obtains information such as the target temperature of the controllable load and its set temperature without exchanging information between the system operator and the controllable load via the communication means in real time, and the specified time. Estimate the stipulated energy e _est that must be input before t _limit, calculate future average power consumption p _tar = (e _est -∫p dt) / (t _limit -t), and calculate the frequency deviation of the power system Measured power consumption of the controllable load so that when the frequency deviation is within a specified range, it approaches the future average power consumption, and when the frequency deviation is outside the specified range, the frequency deviation is suppressed. This is a method for controlling the power consumption of a controllable load, characterized in that

The second means includes a controllable load, a detection means for acquiring information such as a target temperature of the controllable load and a set temperature thereof, and measuring a frequency deviation of the power system, a system operator and the controllable load. Based on the acquired information, the specified energy e _est that needs to be input by the specified time t _limit is estimated and the future average power consumption p _tar = (e _est -∫p dt) / (t _limit -t) is calculated, and control means for controlling power consumption in the controllable load from the future average power consumption and the frequency deviation is possible. Control load control system.

  According to the controllable load power consumption control method and the controllable load control system of the present invention, it is possible to suppress the frequency deviation of the system without newly providing a communication means between the system operator and each controllable load. The power consumption of the control load can be adjusted. In an electric power system in which this load is widely spread, the ability to maintain a balance between supply and demand of the entire system is greatly improved. As a result, the amount of installable distributed power sources increases and energy can be used effectively.

A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing a configuration of a controllable load control system according to the invention of this embodiment.
In the figure, reference numeral 1 denotes a temperature sensor 2 for measuring a temperature that is controlled by a controllable load 4 (for example, air in an air conditioner installation room, hot water in an electric water heater, air in a refrigerator, etc.) and its set temperature. For detecting the frequency deviation of the electric power system 6, and 3 is required to be input by the specified time t _limit based on the acquired information such as the temperature sensor 2 of the controllable load 4 and the set temperature. The future average power consumption p _tar = (e _est −ep dt) / (t _limit −t) is calculated by estimating a specified energy e _est and measured by the future average power consumption and the detection means 1. Control means 4 for determining the power consumption in the controllable load 4 from the frequency deviation, 4 is a controllable load such as an air conditioner, water heater, refrigerator, etc., 5 is a controllable load control system, and 6 is a power system.
As shown in the figure, this controllable load 4 is, for example, in real time with a system operator such as a central power supply command station that issues a command for monitoring and maintaining the balance between the total generated power and the power supply demand. The load does not have a communication means for exchanging information.

The controllable load 4 measures the frequency deviation Δf of the power system 6 and the power p consumed at that time. Here, the maximum power consumption of the controllable load 4 is p _max , the minimum power consumption is p _min , the prescribed lower limit of the frequency deviation is Δf _l , the prescribed upper limit of the frequency deviation is Δf _h , α is a positive value less than 1, and β The positive value is less than α. The controllable load 4 obtains information such as the temperature sensor 2 and the set temperature in the detection means 1 and estimates the specified energy e _est that needs to be input by the specified time t _limit . The future average power consumption p _tar = Calculate (e _est -∫p dt) / (t _limit -t). In general, when a large number of controllable loads are prevalent in the system, the p _tar of each controllable load is dispersed. Therefore, the specified lower limit Δf _l and the specified upper limit Δf _h of the frequency deviation are determined as a function of p _tar . This is because if Δf _l and Δf _h of each controllable load are not dispersed, a large number of controllable loads suddenly adjust the power with a certain frequency deviation, which may cause a reverse frequency deviation. .
In the control means 3, when Δf> Δf _h , the power consumption is increased by α (p _max −p _min ), and when Δf <Δf _l , the power consumption is decreased by α (p _max −p _min ), and Δf _l ≦ If Δf ≦ Δf _h and p <p _tar, increase the power consumption by β (p _max -p _min ), and if Δf _l ≦ Δf ≦ Δf _h and p> p _tar, decrease the power consumption by β (p _max -p _min ). Decide that. The controllable load 4 sets the power consumption according to the command from the control means 3. This series of operations is repeated at regular time intervals. A flow chart of the above control is shown in FIG.

Next, numerical calculations performed to confirm the effect of maintaining the supply and demand balance and suppressing the system frequency fluctuation in the system in which many controllable loads are introduced will be described with reference to FIGS.
The system capacity of the model system taken up in the calculation is set to 150 MW, and this value is used as a standard in% MW. The reference frequency of the system is 50Hz. Suppose 5000 controllable loads with a rated power consumption of 2.6 kW are installed. Its total capacity is 13 MW, corresponding to about 9% of the system capacity. _Let P _arc , P _load , P _adj , P _edc be the total power consumption by all controllable loads, the total power consumption by all other loads, the output of the regulated power generation unit, and the economic load distribution operation output, respectively. At this time, the frequency deviation of the model system is expressed by equation (1). Here, K _L is a load frequency characteristic constant, and K _L = 2% MW /% Hz.

As the controllable load, an inverter type air conditioner capable of continuously changing power consumption was assumed. All controllable air conditioners are rated power consumption p _max = 2.6 kW and power consumption during ventilation p _min = 0.15 kW, and power consumption can be adjusted to any value between p _min and p _max . Each controllable air conditioner operates in either a general mode or a regulation mode. It is assumed that the power consumption of 5000 controllable air conditioners is distributed according to a normal distribution.

Each controllable air conditioner in the general mode predicts power consumption e _est from time t to t _limit = 15 minutes every 5 seconds, and future average power consumption p _tar (t) = e _est / t Calculate _limit, and calculate the future average power consumption ratio γ (t) using equation (2).
The specified lower limit of the frequency deviation is Δf _l = −0.2γ (t) Hz, and the specified upper limit is Δf _h = 0.2 (1-γ (t)) Hz. Then, the frequency deviation Δf is measured, and when Δf ₁ ≦ Δf ≦ Δf _h , the operation is continued in the general mode. However, at the time Delta] f> Delta] f _h or Delta] f <Delta] f _l, the process proceeds to adjustment mode operation. After that, it continues to operate in the adjustment mode for the specified time t _limit = 15 minutes, and then returns to the general mode.
In the general mode, it operates so that the room temperature approaches the set temperature regardless of the frequency deviation. That is, in the general mode, power is consumed in the same manner as a conventional air conditioner that does not adjust power consumption based on frequency deviation.

In the adjustment mode, using the time t ₀ when the adjustment mode is entered, the future average power consumption p _tar (t) at each time t is calculated by Equation (3), and p _tar (t) obtained by Equation (3) is calculated. Is substituted into equation (2) to obtain the future average power consumption ratio γ (t).
The specified lower limit of the frequency deviation is Δf _l = −0.2γ (t) Hz, and the specified upper limit is Δf _h = 0.2 (1-γ (t)) Hz. And, increasing the power consumption every 5 seconds when the Δf> Δf _h Δp = 0.1 only (p _max -p _min), reduce power consumption in every 5 seconds when the Δf <Δf _l only Δp.
In addition, when Δf _l ≦ Δf ≦ Δf _h , the power consumption p If is smaller than p _tar (t), the power consumption is increased by 0.1Δp every 5 seconds, and if it is larger, the power consumption is decreased by 0.1Δp every 5 seconds.
However, regardless of frequency deviation, when γ (t) = 0, power consumption is p _min, and when γ (t) = 1, power consumption is p _max , and time t becomes t ₀ + t _limit . Keep that state until.

The total power consumption P _{arc for} all controllable loads at each time is the sum of the power consumption p of 5000 controllable air conditioners.

In the power consumption P _load by all loads other than the controllable load, the power generation output from the distributed power source is subtracted. The maximum value of the assumed power consumption during the summer full load (P _arc + P _load) is 130MW is a (strain 87% of the volume), and by mass introduction of distributed power P _adj variation amount of P _load is described below It was assumed that it was larger than the variable range.

The power generation output P _adj of the regulated power generation unit was limited to an output range of 0 ≦ P _adj ≦ P _adjmax = 8.0 MW and a rate of change to | dP _adj /dt|≦3.0% MW / min.
The variation [Delta] P _adj of P _adj is the governor-free operation amount P _gov the sum of the load frequency adjustment component _{P lfc (ΔP adj = P gov} + P lfc). The governor-free operation is performed with the generator frequency characteristic constant K _G = 5% MW /% Hz. Load frequency control is performed using equation (4), but Δf is the value 5 seconds before. Note that Δ used above means a difference.
Here, c ₁ = −0.8 K _L and c ₂ = 1 × 10 ⁻³ % MW / (% Hz · s).

Economic load distribution operation output P _edc is actually adjusted based on demand forecast several minutes ahead, but in this calculation, the rate of change is limited to | dP _{edc /} dt | The characteristics were simulated. Then, in order to secure the operating capacity of the regulated power generation unit, P _edc was adjusted so that P _adj was _brought closer to P _adjmax / 2 based on the above-mentioned restrictions.

FIG. 3 shows the result of analyzing the 12-hour frequency deviation from 8 o'clock to 20 o'clock by the above calculation method. In addition, u in a figure is a ratio of the air conditioner which is performing adjustment mode driving | operation among 5000 air conditioners. For comparison, FIG. 4 shows an analysis result in the case of using a conventional air conditioner that does not adjust power consumption by frequency deviation instead of the air conditioner of the present invention. 3 and 4, the time change of P _load is exactly the same. Moreover, the demand of the power consumption at each time of each air conditioner is exactly the same, and the total power consumption is also the same.

In the case of FIG. 4, a large frequency deviation occurs especially when P _adj becomes 0 or P _adjmax and all the _remaining operating capacity is _exhausted . On the other hand, in the case of FIG. 3 using the controllable load of the present invention, not only P _adj but also P _arc changes so as to suppress the frequency deviation, and the frequency deviation is significantly larger than that of FIG. Reduced.

  FIG. 5 shows the frequency distribution of the frequency deviation measured every 5 seconds in the case of FIGS. From FIG. 5, it is clear that the frequency deviation can be sufficiently suppressed in the power system in which the controllable load of the present invention is widespread.

Note that, with an actual controllable load, the predicted value of the specified energy e _est that needs to be input by the specified time t _{limit in the} future may include an error with respect to the actually required value. However, if the value of e _est is corrected when the error is found, the above control method can be applied as it is.
Further, the values of α and β need to be determined in consideration of the scale of the system and the penetration rate of the controllable load, and need to be changed as the penetration rate increases. This adjustment is performed manually or by communication means, but the change is not made frequently, and real-time communication means are not required.

It is a figure which shows the structure of the controllable load which concerns on invention of one Embodiment. It is a figure which shows the flow of the power consumption control algorithm of a controllable load. It is a figure which shows a time change in the ratio of the frequency deviation, electric power, and the controllable load of an adjustment mode in the model system | strain which calculated as an Example of this embodiment. In the model system when a conventional load that does not adjust power consumption by frequency deviation is used instead of the controllable load of the present invention, the time variation of the frequency deviation, power, and the ratio of the controllable load in the adjustment mode is shown. FIG. It is a figure which shows the frequency distribution of the frequency deviation measured every 5 second in the case of FIG. 3 and FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Detection means 2 Temperature sensor 3 Control means 4 Controllable load 5 Controllable load control system 6 Electric power system

Claims (2)

A controllable load that is connected to the power system and that inputs the specified energy e _est within a specified time t _limit , obtains information on the change value of the state variable according to the power consumption of the controllable load and the threshold value of the state variable, Based on the detection means for measuring the frequency deviation of the power system and the above-mentioned information of the controllable load at time t, the specified energy e _est that needs to be input within the specified time t _limit arbitrarily set from the arbitrary time t ₀ estimating a by future average power _{p tar = (e est -∫pdt)} / (t limit - (t-t 0))
And comprises control means for determining power consumption at a controllable load from the future average power consumption and the frequency deviation Δf measured by the detection means,
The control means obtains information on the power consumption p of the controllable load, the value of the state variable that changes in accordance with the power consumption, and the setting value of the state variable, and the specified time from time t ₀ that becomes a control unit Estimate the specified energy e _est that needs to be applied to the controllable load within t _limit ,
Future average power _{p tar = (e est -∫p dt} ) / (t limit - (t-t 0))
And future average power consumption ratio γ = (p _tar -p _min ) / (p _max -p _min )
And the specified lower limit Δf _l = −kγ and upper limit Δf _h = k (1-γ) of the frequency deviation from the frequency deviation management target value k,
When the frequency deviation Δf is Δf> Δf _h , the power consumption of the controllable load is increased by α (p _max -p _min ),
The frequency deviation Delta] f is the case of Delta] f <Delta] f _l, the power consumption of the controllable load decrease α (p _max -p _min),
When the frequency deviation Δf is Δf _l ≦ Δf ≦ Δf _h and p> p _tar , the power consumption p is reduced by β (p _max −p _min ),
When the frequency deviation Δf is Δf _l ≦ Δf ≦ Δf _h and p <p _tar , the power consumption p is controlled to be increased by β (p _max −p _min ). Power consumption control method.
However, the frequency deviation management target value k is a positive value, the coefficient α is a positive value less than 1, and the coefficient β is a positive value less than 1. A controllable load that is connected to the power system and that inputs the specified energy e _est within a specified time t _limit , obtains information on the change value of the state variable according to the power consumption of the controllable load and the threshold value of the state variable, Based on the detection means that measures the frequency deviation of the power system and the above information on the controllable load, the estimated average energy e _est that needs to be input within the arbitrarily set specified time t _limit is estimated and the future average power consumption p _{tar = (e est -∫p dt)} / (t limit - (t-t 0))
Comprising control means for determining power consumption in a controllable load from the future average power consumption and the frequency deviation measured by the detection means,
2. The controllable load control system according to claim 1, wherein the control means is configured to execute the controllable load power consumption control method according to claim 1.