JP4093481B2 - Self-generator control method and control device - Google Patents

Description

In the case of supplying power to the customer's power equipment by performing grid-connected operation of the commercial power supply and private power generation system (private power generator), it is comprehensive for the consumer according to the unit price of the commercial power supply and the contract status. It is related with what controls the operation form of an economical private power generation system.

As the power generation control device of this kind of private power generation facility, those described in the following publications are known. (See, for example, Patent Document 1) (paragraphs 0010 to 0014)
Japanese Patent Laid-Open No. 10-80061

FIG. 5 shows a system configuration of the generated power control device of the private power generation facility 21 described in the above publication.
In FIG. 5, the private power generation facility 21 is provided in a factory, a hospital, a building, or a certain area.
The private power generation facility 21 supplies power to the plurality of loads 24 and 25 via the on-site distribution network 23 while performing grid-connected operation with the commercial power source 22.
The loads 24 and 25 are connected to the local distribution network 23 via circuit breakers 26 and 27, respectively.
The generated power from the private power generation facility 21 is supplied to the local distribution network 23 via the circuit breaker 28.
A circuit breaker 29 is provided between the commercial power source 22 and the local distribution network 23.

In the private power generation facility 21, the opening degree of the fuel valve 32 provided in the fuel supply system to the engine 31 of the internal combustion engine that drives the synchronous generator 30 is adjusted by the controller 33 to control the generated power.
The generated power measuring instrument 34 measures the voltage and current generated by the transformer 35 and the current transformer 36 provided in the power supply line from the synchronous generator 30 to the premises wiring network 33, and converts it into electric power.
The received power measuring device 37 measures the voltage and current received by the transformer 38 and the current transformer 39 provided in the power supply line from the commercial power supply 32 to the local wiring network 33 and converts them into electric power.
The controller 33 controls the output of the synchronous generator 30 so that the received power measured by the received power measuring instrument 37 matches the set received power.

In this configuration, the above publication states that “a power generation control device for a private power generation facility that supplies power to a premises load while performing grid-connected operation with a commercial power source, and the time of the maximum load fluctuation range that has been investigated in advance. Based on the pattern, the time pattern predicting means for predicting the received power in anticipation of a margin within a predetermined range for the maximum fluctuation range in the time zone to which the control time belongs, and the power receiving predicted by the local load power and the time pattern predicting means "Control is performed so as to generate electric power of the difference from electric power".

In addition, in the conventional private power generator, there is a problem that reverse power flow is likely to occur when a part of the load on the premises stops operation and the load power is suddenly reduced.
That is, even if the load power suddenly decreases, the generated power of the generator cannot change suddenly. Therefore, if the load power becomes smaller than the generated power, a reverse power flow occurs at that moment. If the load power changes moderately, it can be dealt with by reducing the generated power, but it cannot deal with sudden changes.

On the other hand, a reverse power relay is installed at the power receiving point of the customer to trip the power receiving breaker and stop power reception when the reverse power flow continues for a predetermined time or more.
There is a problem that the trip of the power receiving circuit breaker may spill over to a total outage accident on the premises and is not allowed. A method described in Japanese Patent No. 3038475 is known as a method for solving this problem.

In the above patent No. 3038475, “a set of a generator, a prime mover that drives the generator, a governor that controls the rotational speed of the prime mover, and a setter that sets the rotational speed reference value of the prime mover is provided. In a control device for a private power generator that performs constant control of received power to adjust the generated power so that the generator is connected to the commercial power grid and power is supplied to the premises load, and the received power is constant. Since the received power reduction amount is calculated based on the capacity of the generator, the received power reduction value is subtracted from the received power reference value to output the received power target value, and the generated power command value is adjusted by this signal. Even when the received power decreases due to a sudden fluctuation in the premises load, the power is controlled at a high speed by changing the rotational speed command to the governor at a high speed, and the received power is quickly restored to the set value. Is disclosed The

As described above, the operation of the conventional private power generator is basically based on the time pattern predicting means for predicting the received power and the power difference between the on-site load power and the received power predicted by the time pattern predicting means. Therefore, when the received power (used power) goes up and down from the contract power, in order to keep the received power within the contract power, unnecessary start / stop of the private generator is frequently performed. .

If the private generator is started and stopped frequently, there is a problem that due to the early arrival of the specified maintenance execution time, it causes an increase in maintenance costs and an increase in operating costs such as an increase in fuel consumption.
In addition, frequent operation of the circuit breaker to prevent reverse power flow causes problems such as increased maintenance costs due to increased damage to the equipment and increased power costs due to increased supply of commercial power until reconnection. It was.

The subject (object) of this invention is reducing the total cost in the whole installation by reducing the unnecessary starting and stopping of a private generator in the private power generator control method (device).
Another object of the present invention is to reduce the operation of the circuit breaker for preventing reverse power flow when the received power suddenly decreases, thereby reducing the damage to the equipment.

In order to solve the above-mentioned problem, a method for controlling a private generator of a private power generation system in which a load and at least one private generator are connected to a commercial power source,
Performing a unit price comparison for each time zone between the unit price of the commercial power source and the unit price of the private generator;
The comparison result in the step of performing the unit price comparison is such that the received power from the commercial power source is maximized in a range that does not exceed the contract power with the commercial power source in a time zone when the power unit price of the commercial power source is low. A control step of the private generator for controlling the private generator;
A comparison result in the step of performing the unit price comparison, in a time zone in which the unit price of the commercial power source is high, including a private generator priority control step that prioritizes power generation of the private power generator,
The control step of the private power generator in a time zone where the unit price of the commercial power supply is low, the excess power amount from the measurement start time for the contract power for each demand monitoring time is a value corresponding to the power generation capacity of the private power generator At the point of time, the self-generator is started, and the control of the self-generator is executed by stopping the start-up of the self-generator that has been started until part of the next demand monitoring time. To do. (Claim 1)

In addition, the priority control step of the private power generator in a time zone in which the power unit price of the commercial power supply is high controls the private power generator so that the received power from the commercial power supply is minimized within a range where reverse power flow does not occur. Execute. (Claim 2)
The priority control step of the private generator fixes the power output of the private generator by fixing a governor against a short-term peak fluctuation of the load. (Claim 3).

A control device for a private power generator of a private power generation system in which a load and at least one private power generator are connected to a commercial power source,
Unit price comparison means for performing a unit price comparison for each time period between the unit price of the commercial power source and the unit price of the private generator;
In the time period when the unit price comparison means does not exceed the contract power with the commercial power source in the time zone when the unit price of the commercial power source is low, the power received from the commercial power source is maximized in a range that does not exceed the contracted power with the commercial power source. A private generator control means for controlling the generator;
A comparison result of the unit price comparison means includes a private generator priority control means for preferentially controlling the power generation of the private generator in a time zone when the unit price of the commercial power supply is high .
The self-generator control means is configured such that when the amount of excess power from the measurement start time for the contract power for each demand monitoring time reaches a value corresponding to the power generation capacity of the self-generator, the self-generator And a means for stopping the operation of the private generator activated at each demand monitoring time after continuing to a part of the next demand monitoring time, thereby controlling the private generator. Configure. (Claim 4 )

In addition, the priority control means of the private power generator during a time period when the unit price of the commercial power supply is high controls the private power generator so that the received power from the commercial power supply is minimized within a range where no reverse power flow occurs. do. (Claim 5)
The private generator priority control means includes means for fixing a power output of the private generator by fixing a governor against short-term peak fluctuations of the load. (Claim 6)

The invention according to claim 1 is a method for controlling a private power generator of a private power generation system in which a load and at least one private power generator are connected to a commercial power source, and the unit price of the commercial power source according to time zone In the time zone in which the comparison result in the step of executing the unit price for each time zone with the operation unit price of the private generator and the step of executing the unit price comparison is a time zone in which the power unit price of the commercial power source is low, the commercial power source The comparison result between the control step of the private generator that controls the private generator and the step of executing the unit price comparison so that the received power from the commercial power supply is maximized within a range not exceeding the contract power. in electricity unit price is high time period of the commercial power source, and controls the private power generator in a priority control step of priority private power generator the power generation of the private power generator, unnecessary starting and stopping of the private power generator Together eliminated, at power unit price is high hours of the commercial power supply, since the power generation with priority generation of private power generator, it is possible not only to reduce the total cost of the entire facility, the power unit price of the commercial power source The control step of the private generator in the cheap time zone is that the excess power amount from the measurement start time with respect to the contracted power for each demand monitoring time is the power generation capacity of the private power generator (note that the power generation capacity here is The private generator is started when it reaches a value corresponding to not only the maximum generation capacity of the generator but also a preset target generation capacity below the maximum generation capacity. In addition, the control step of the private generator is further started at every demand monitoring time. By continuing the operation of the private generator to a part of the next demand monitoring time and then stopping it, for example, the operation is continued for about 2 minutes, and the average power of the next demand monitoring time is “ In this case, it is not necessary to start the private generator when the received power exceeds the margin of 2 minutes. There is an effect .

In the invention according to claim 2, the priority control step of the private generator in a time zone in which the unit price of the commercial power supply is high is such that the received power from the commercial power supply is minimized within a range where no reverse power flow occurs. Since the private generator is controlled, it is not necessary to operate the circuit breaker for preventing reverse power flow when the received power is rapidly reduced, so that damage to the device can be reduced.
According to a third aspect of the present invention, in the private generator priority control step, the power generation output of the private generator is fixed by fixing a governor against a short-time peak fluctuation of the load. Thus, an increase in load for a short time can be dealt with by increasing the received power from the commercial power without following the power generated by the private generator.

The invention according to claim 4 is a control device for a private power generator of a private power generation system in which a load and at least one private power generator are connected to a commercial power source. Unit price comparison means for performing a unit price comparison for each time zone with the operating unit price of the private power generator, and a contract with the commercial power source in a time zone when the result of comparison by the unit price comparison means is that the power unit price of the commercial power source is low The comparison result between the private generator control means for controlling the private generator and the unit price comparison means so as to maximize the received electric power from the commercial power supply within a range not exceeding the electric power, By configuring the private generator control device with the private generator priority control means that prioritizes and controls the power generation of the private generator in a time zone when the power unit price is high, unnecessary activation of the private generator Few stops In addition, in the time zone when the unit price of the commercial power source is high, power generation by the private generator is given priority, so that not only can the total cost of the entire facility be reduced, but the control means for the private generator is The amount of excess power from the measurement start time for the contract power for each demand monitoring time is the power generation capacity of the private generator (note that the power generation capacity here is not only the maximum power generation capacity of the generator, When a value corresponding to a preset target power generation capacity equal to or less than the maximum power generation capacity is reached, by providing means for starting the private power generator, the start and stop of the private power generator is minimized (ideal In addition, the self-generator control means further includes a self-starting operation at each demand monitoring time. By providing a means to stop the generator operation after continuing to a part of the next demand monitoring time, it will not start the private generator when the received power exceeds the “margin”. There is a further effect that it is completed.

In the invention according to claim 5, the priority control means of the private generator in a time zone in which the unit price of power of the commercial power source is high is such that the power received from the commercial power source is minimized within a range where reverse power flow does not occur. By controlling the private generator, it is not necessary to operate the circuit breaker for preventing reverse power flow even when the received power is suddenly reduced, so that damage to the device can be reduced.
In the invention according to claim 6, the priority control means of the private generator is means for fixing the power generation output of the private generator by fixing a governor against a short-time peak fluctuation of the load. Thus, an increase in load for a short time can be dealt with by increasing the received power from the commercial power without following the power generated by the private generator.

The basic concept of the control of the private power generator of the present invention is based on the following two points.
The first point is that the contract power in the contract of commercial power with the power company is the average power for 30 minutes, which is the demand monitoring time based on 0 and 30 minutes per hour. Even if it becomes electric power, there is no problem in terms of contract if the average electric power for 30 minutes falls within the contract electric power.

The second point is that when a commercial power contract with an electric power company is made and a power contract is made according to seasons and time zones, the unit price of the power charge varies greatly depending on the season and time zone. (For example, about 7 yen / kwh during nighttime (22:00 to 8:00) when power consumption is low, and about 15 yen / kwh during daytime (8-22: 00) in summer (July to September), peak time in summer (13 o'clock to 16 o'clock) is about 20 yen / kwh (the target time zone and power unit price are different depending on the electric power company, business use and industrial use))

Therefore, comparing the operating cost of private power generation facilities (total cost including not only the operating unit price of fuel etc. but also the maintenance cost) with the unit price of commercial power, the unit price of commercial power at night is low. In the time zone, the power generation time of the private power generation is minimized as much as possible, and the number of times of starting and stopping is reduced, so that the maximum commercial power is received.
In addition, in the time zone when the unit price of commercial power is higher than the operating cost of private power generation, the power generation time of private power generation is maximized as much as possible, and the number of start / stops is reduced to minimize the commercial power generation. Control to receive power.

First, what limits the amount of commercial power received within the contract power will be described.
FIG. 1 shows the time course of the amount of commercial power received.
As shown in the figure, even if the received power w1 exceeds the contracted power wo until the time t, the private generator is operated during the period (30-t) up to 30 minutes which is the demand monitoring time, and the generator output It is only necessary that the average power of the received power for 30 minutes is equal to or less than the contract power by generating the power wg and setting it to w2 that is equal to or less than the contract power w0.

In FIG. 1, the received power is shown as a constant value. However, since it actually changes with time, as shown in FIG. 2, the received power of commercial power for measuring received power that changes with time is contracted. The excess of the contract power is measured by integrating (integrating) the power every second from 0 minutes and 30 minutes per hour as the base point with (+) as the portion exceeding the power and (-) as the lower portion.

Depending on the rated output of the private generator (not necessarily rated, it is possible to set the output to 80% or 90% of the rating), the excess of the received power exceeding the contracted power is set as the remaining period (30- The operation of the private generator is started at a time (t) that can be canceled at t) (the average power for 30 minutes, which is the demand monitoring time, should be lower than the contracted power without being strictly canceled).
By controlling the handling point of the private generator in this way, it is possible to limit the start / stop of the private generator to once in 30 minutes, and unnecessarily start and stop according to the load fluctuation Will not be done frequently.

It should be noted that the stop of the private generator is ideally at the starting point of measurement at 0 and 30 minutes per hour as shown in FIG. 1, but after the private generator is started as shown in FIG. When the load is significantly reduced than expected, the load may be stopped at 30-t which is the demand monitoring time.
Since such control contributes to maximization of received power, it is effective for minimizing the operation time of the private generator, and is suitable for control when the unit price of commercial power is low, such as at night.

The self-generator of the present invention does not need to be a single unit, and a plurality of self-generators are provided according to the application or load capacity, and according to the measured value of the contracted power of the received power, Each generator can be started and stopped at the same time, or can be started and stopped individually.
Also, in order to prevent excess contract power, the on-site load is divided into multiple parts and each load is connected via a circuit breaker, and the predicted excess amount is likely to cause reverse power flow. Depending on the situation, it is also possible to use a method of cutting off a load with low priority (such as lighting in a room without people).

When the private generator is stopped, as shown in FIG. 3, the demand monitoring time of 30 minutes is exceeded for t hours (for example, about 2 minutes) and the operation is continued, and the average power of the next demand monitoring time is It is also possible to “allow” (offset the excess of contract power).
In this case, there is an effect that it is not necessary to start the private generator when the received power exceeds the “margin” of 2 minutes.

Next, what prevents the circuit breaker from being interrupted based on the reverse power flow during startup of the private generator will be described.
In the operation of the conventional private power generator, when the load power fluctuates, the private power generator is frequently started and stopped in order to keep the received power within the contract power. Control was performed according to the fluctuation of the load power.
A sudden change in load power (a sudden generation of load and a sudden decrease in load) (that is, a short load peak) is dealt with by controlling the governor of the engine directly connected to the generator. When the load suddenly decreases, the engine control cannot follow, and the generator output cannot follow the decrease in load. Therefore, a reverse power flow is generated from the private generator to the commercial power side.

In the control of the self-generator of the present invention, when a peculiar pattern (such as a short-time load peak) such as a rapid load generation or a rapid decrease occurs, the power generation output of the self-generator is fixed and the fluctuation of the load is reduced. Do not follow.
In other words, since the power generated by the private generator is not increased following the increase in the load for a short period of time, the reverse power flow from the private generator to the commercial power side even when the load decreases sharply. Can be prevented from flowing.

Note that the output of the private generator is fixed when the load fluctuation within a certain time (for example, about 0.5 seconds) exceeds a certain value.
That is,
W0 for a certain time load,
If the load after 0.5 seconds is w1,
When (w1 / w0)> x, the governor control is fixed.
x is a predetermined value determined in advance.

In this case, an increase in load for a short time can be dealt with by increasing the received power from the commercial power without following the power generated by the private generator.
Even if the contracted power may be exceeded momentarily due to the increase in the load in a short time, the adjustment can be made by operating the private power generator during the demand monitoring time of 30 minutes as described above.

Next, with reference to FIG. 4, a comprehensive description of the procedure of the private generator control method (apparatus) of the present invention will be given.
FIG. 4 is a flowchart for explaining the operation (control) operation of the private power generator of the present invention.
・ Perform a comparison of unit prices for each time zone between the unit price of commercial power and the unit price of private generators. (Step S1)
If the power unit price of the commercial power source is lower than the operating unit price of the private power generator (Yes) in step S1, the received power from the commercial power source is maximized within a range not exceeding the contract power with the commercial power source. The private generator is controlled so that it becomes.
-Control of the private generator determines whether or not the amount of excess power from the measurement start time for the contract power for each demand monitoring time has reached a value corresponding to the power generation capacity of the private generator. (Step S2)
The private power generator is activated when the excess power reaches the value corresponding to the power generation capacity of the private power generator as determined in step S2. (Step S3)
・ After starting the private generator, determine whether the demand monitoring time has been reached. (Step S4)
If the demand monitoring time is reached (Yes) in the determination in step S4, the private generator is stopped. (Step S5)
In addition, it is also possible to stop the private power generator after the operation of the private power generator activated at each demand monitoring time is continued to a part of the next demand monitoring time.

・ If the unit price of the commercial power source is higher than the unit price of the private power generator (No) in the judgment in step S1, aim to reduce the total cost by giving priority to the power generation of the cheap private power generator. .
In that case, it is desirable to control the private generator so that the received power from the commercial power supply is minimized within a range where no reverse power flow is generated by the private generator.
When controlling the private generator, it is determined whether or not there is a short-term peak fluctuation of the load. (Step S6)
If it is determined in step S5 that peak fluctuation occurs for a short time (Yes), the governor of the private generator is fixed and the power generation output of the private generator is fixed. (Step S7)

In the private generator control method and control device according to claims 1 to 6 , an unnecessary start / stop of the private power generation system private generator in which a load and at least one private generator are connected to a commercial power source. At the same time, since the power generation of the private generator is prioritized during the time zone when the unit price of the commercial power supply is high, the total cost of the entire facility can be reduced.

It is a figure which shows the time course of the amount of commercial power received. It is a conceptual diagram which measures exceeding receiving power for contracted power. It is a figure which shows the time of starting and a stop of a private generator. It is a flowchart which shows the operation | movement of the driving | operation of the private generator of this invention. It is a figure which shows the system configuration which connected the load and the private power generator to the commercial power source.

Explanation of symbols

S1 Step to compare the unit price of commercial power and the unit price of private generator
S2 Measuring the amount of received power exceeding contract power
S3 Steps to start a private generator
S4 Step to determine whether the demand monitoring time has been reached
S5 Steps to stop the private generator
S6 Step to determine if a short-time peak exists
S7 Steps to fix the generator governor

Claims (6)

A method of controlling a private generator of a private power generation system in which a load and at least one private generator are connected to a commercial power source,
Performing a unit price comparison for each time zone between the unit price of the commercial power source and the unit price of the private generator;
The comparison result in the step of performing the unit price comparison is such that the received power from the commercial power source is maximized in a range that does not exceed the contract power with the commercial power source in a time zone when the power unit price of the commercial power source is low. A control step of the private generator for controlling the private generator;
A comparison result in the step of performing the unit price comparison includes a private generator priority control step that prioritizes power generation of the private generator in a time zone in which the power unit price of the commercial power source is high, and
The control step of the private power generator in a time zone where the unit price of the commercial power supply is low, the excess power amount from the measurement start time for the contract power for each demand monitoring time is a value corresponding to the power generation capacity of the private power generator The private generator is started, and the operation of the activated private generator is continued until a part of the next demand monitoring time and then stopped. Control method.   The priority control step of the private power generator in a time zone when the unit price of the commercial power supply is high controls the private power generator so that the received power from the commercial power supply is minimized within a range where no reverse power flow occurs. The self-generator control method according to claim 1. 3. The private generator according to claim 2, wherein the private generator priority control step fixes a governor to fix a power generation output of the private generator with respect to a short-time peak fluctuation of the load. Generator control method. A control device for a private power generator of a private power generation system in which a load and at least one private power generator are connected to a commercial power source,
Unit price comparison means for performing a unit price comparison for each time period between the unit price of the commercial power source and the unit price of the private generator;
In the time period when the unit price comparison means does not exceed the contract power with the commercial power source in the time zone when the unit price of the commercial power source is low, the power received from the commercial power source is maximized in a range that does not exceed the contracted power with the commercial power source. A private generator control means for controlling the generator;
A comparison result of the unit price comparison means includes a private generator priority control means for preferentially controlling the power generation of the private generator in a time zone when the unit price of the commercial power supply is high.
The self-generator control means is configured such that when the amount of excess power from the measurement start time for the contract power for each demand monitoring time reaches a value corresponding to the power generation capacity of the self-generator, the self-generator And a means for stopping the operation of the private generator activated at each demand monitoring time after continuing the operation to a part of the next demand monitoring time. Control device.   The private generator priority control means in a time zone in which the unit price of the commercial power supply is high controls the private generator so that the received power from the commercial power supply is minimized within a range where no reverse power flow occurs. The self-generator control device according to claim 4, wherein: 6. The self-generator priority control means includes means for fixing a power output of the private generator by fixing a governor against short-term peak fluctuations of the load. The control device of the private generator described.