JPH02193530A - Receiving end reverse transmission preventing and controlling device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention is intended for use when a commercial power source and a private power generation facility are connected in a power distribution system, and when both are operated together, the private power generation facility The present invention relates to a power receiving end reverse transmission prevention control device that prevents so-called reverse transmission in which power is supplied reversely from the source to the commercial power supply side.

(Prior Art) Generally, in the industrial field that consumes a lot of power, private power generation equipment is provided in addition to the commercial power supply from the electric power company. In recent years, in such industrial fields, in order to reduce power costs, there has been a noticeable movement to increase in-house power generation equipment and to minimize the amount of power received from commercial power sources (hereinafter simply referred to as received power).

For this reason, when the received power is always small, for example, several thousand kilowatts, and the large power load equipment in the factory is stopped, if the power used by this power load equipment exceeds the received power, the commercial power Increasingly, a so-called reverse transmission situation, in which power is sent out to the receiving end of the power supply, is increasing.

This reverse transmission state is prohibited under the contract between the power user and the power company, and in order to prevent this, the power receiving end is
A reverse feed prevention relay is provided. This reverse feed prevention relay is normally configured to disconnect the power receiving end if the reverse feed prevention relay continues to operate even after the timer setting time, e.g. 4 to 5 seconds, has elapsed after a reverse feed state occurs. It has become. This disconnection of the power receiving end means that only the private power generation equipment in the power system on the user side is operated independently, which may cause the power supply frequency and power supply voltage to become unstable.

Figure 6 is a typical user-side power system diagram to specifically explain what has been described above.The power bus P to which power is to be supplied is connected to the receiving line of commercial power from the power company. The received power supplied via R and the generator I of the private power generation equipment
Privately generated power is supplied from G, 2G, . . . nG via the connection line W. Then, power load equipment IL, 2L...mL are connected to the power bus P through feeders IF, 2F, ...mF, respectively, and desired power is supplied to each load equipment IL-mL, respectively. It looks like this. Note that a breaker CB is connected to the power receiving line R, the feeder IF-mF, the generator IG-nG, and the power bus P, respectively.

In Fig. 6, when a certain load equipment, for example mL, suddenly stops while the relationship between power demand and supply is balanced, the power in the system on the load equipment IL-mL side becomes surplus, and at this time, This will be instantly absorbed as a decrease in the amount of received electricity. In this case, when the amount of power used by the stopped load equipment mL is greater than the amount of received power, the power is reversely sent to the power receiving end on the commercial power source side, resulting in a reverse feeding state.

Figure 7 is for explaining this relationship, and (a) shows the relationship between received power and time, and the current received power *BN has fallen below the received power limit value (a certain specified value of received power) BLL. At this point, the timer of the anti-reverse feed relay starts operating. The setting time (usually 4~
If the received power does not recover to the power receiving limit value BLL or more within 5 seconds), the power receiving end enters the disconnected state.

This disconnected state of the power receiving end means that only the private power generation equipment in the power system on the user side is operated independently, which may cause the power supply frequency and power supply voltage to become unstable.

Therefore, in order to prevent the power receiving end from being disconnected, the following may be considered. That is, at the same time as the reverse feed state occurs, the start signal of the timer of the reverse feed prevention relay is taken out and inputted to the output controller (usually a governor controller) of each generator IG-nG to prevent the occurrence of reverse feed. The purpose is to reduce the output of each generator IG-nG all at once as a trigger to balance the supply and demand of electric power.

However, each generator has a limit (output lower limit value PL) for output reduction, as shown in the relationship between each generator output and time in FIG. 7(b).

That is, each generator I G -n G has an output lower limit value PL, and since it cannot be operated below this lower limit value, there is naturally a limit to the control amount. At the same time, due to limitations in the operating characteristics of each generator I G -n G, there is also a limit to the output width (controlled amount by the generator) that can be reduced within the set time of the reverse feed prevention relay.

The power of the stopped load equipment mL is greater than the amount of power obtained by adding the power reception surplus ΔB, which is the difference between the current power reception amount BN and the power reception limit value BLL, to the control total value of each generator IGxnG within the range that satisfies these conditions. If the load amount is large, it is impossible to recover the current power reception amount BN to the power reception limit value BLL, and the power reception queue is reached.

(Problems to be Solved by the Invention) As described above, disconnection of the power receiving end means that the power system on the user side will be operated solely by the private power generation equipment,
This leads to a decrease in the stability of the power supply frequency and power supply voltage, so it is desirable to avoid disconnection of the power receiving end as much as possible.

However, no device has been developed to prevent disconnection of the power receiving end.

Therefore, the present invention makes it possible to manage the required amount of received power from a commercial power source and the amount of power generated by private power generation equipment in response to momentary changes in the situation, and provides power receiving end reverse feed prevention control that can prevent the occurrence of a power receiving end reverse feed state. The purpose is to provide equipment.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides an electric power system that uses electric power from a commercial power supply distribution system and a private power generation system having a plurality of generators. In a power system capable of supplying power to power load equipment connected to each feeder via a bus, a process of respectively taking in the received power of the power receiving and distribution system, the load power of each of the feeders, and the output of each generator of the private power generation system. φ data acquisition means; maximum load selection means for selecting the maximum load amount among the load power of each feeder taken in by the process data acquisition means; Among them, a received power surplus calculation means that calculates the received power surplus from the difference between the current received power amount and the received power limit value, and the current output of each generator and each generator among the outputs of each generator taken in by the process data import means. A generator control surplus capacity calculating means that calculates each generator control surplus capacity from the difference between the output lower limit values of , and compares the maximum load amount with the total surplus capacity value of the received power surplus capacity and the generator control surplus capacity, and calculates this total surplus capacity. When the value is larger than the maximum load amount, the generator controllable amount (the received power surplus + the generator control surplus, the generator output upper limit - the generator output lower limit, the generator output reduction limit) is calculated from the maximum load. (minimum value within)
a power reception minimum target value calculation means for calculating a power reception minimum target value by subtracting the amount of power received; , and when the current amount of power received is smaller than the minimum power reception target value, a generator output value that calculates each generator output value to be distributed in proportion to each generator surplus capacity value that has not been converted to the generator controllable amount. The generator includes a calculation means and a generator control means for controlling each generator output based on each generator output value from the generator output value calculation means.

(Function) According to the present invention, when the total remaining capacity value of the received power surplus capacity and the generator control surplus capacity is larger than the maximum load amount, the generator controllable amount (received power surplus capacity + generator control surplus capacity, power generation If the minimum target value of power reception is calculated by subtracting the minimum value of the machine output upper limit - generator output lower limit, generator output reduction limit, and the current amount of power received is greater than the minimum power reception target value, this power reception Calculates the output value of each generator to achieve the minimum target value, and when the current amount of power received is smaller than the minimum target value, distributes it in proportion to the remaining capacity of each generator that has not been converted to the generator controllable amount. Calculate the output value of each generator,
The output of each generator is controlled based on the output value of each generator.

By doing this, it becomes possible to manage the required amount of received power from commercial power sources and the amount of power generated by private power generation equipment in response to moment-by-moment changes in the situation, and it is possible to manage the amount of power received from commercial power sources and the amount of power generated by private power generation equipment in response to moment-to-moment changes in the situation. Even if the equipment stops, it is possible to prevent the occurrence of reverse power transmission at the receiving end.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the present invention, which has the following configuration.

That is, the process data importing means 10 collects the process φ data necessary for calculation, such as the received power (commercial power) from the electric power company shown in FIG. 6, the output of each generator I C-n G, and each load equipment IL-mL. It is designed to take in each feeder load power supplied to the feeder.

Further, the maximum load power selection means 20 selects the maximum load amount that satisfies the following equation (1) from among the feeder load powers taken in by the process data importing means 10.

Maximum load: Lmax -max (LL, L2.-, Lm)
−(1) Here, max (xl, x2, −
xk) is xl, x2. ...means a function that extracts the maximum value in xk.

Li: Electric power load (KV) of the first load equipment (
1-1, 2, -m") ・=measured value Further, the received power surplus calculation means 30 calculates the process data acquisition means 10.
From the process data taken in, the following equation (2) is used to calculate the received power surplus with respect to the current reception limit value of the received power amount.

Received power thread crab ΔB-BN-BLL...(2)
Here, BN: Current power reception jl (KW)...Measurement value BLL: Power reception limit value (KV)...Fixed value determined in advance Each generator control surplus capacity calculation means 40 is the process data acquisition means 10 The control margin for the output lower limit value PL of each generator IG-nG is calculated from the process data taken in by the following equation (3).

Each generator control thread crab ΔPi PNl-PLi...(3) Here, i: Generator No. (i-1, 2, -n) P Ni: Current output of each generator (kW)...Measured value P
LI: lower limit value of output of each individual electric generator (W)...predetermined fixed value Total value of generator control surplus power: ΔP-ΣΔPi...(4) In addition, the power reception minimum target value calculation means 50 calculates the maximum load Various data from the power selection means 20, the received power surplus calculation means 30, and each generator control surplus power calculation means 40 are input, and the minimum target power reception value is determined to ensure the necessary received power surplus ΔB + generator controllable amount. is calculated as follows.

The power reception minimum target value calculation means 50 has the following two calculation cases.

a) In the case of Lmax≦ΔB+ΔP (a case where it is possible to recover to the power reception limit value when reverse transfer occurs) minimum target power reception value (power reception amount that must be ensured): Bo − m a x < BLL
I BLL+ LIIax-Σmin [PTl,
(PHI-PLI) ] l) - (5) Here, BLL: Power receiving limit value (kW) ...Fixed value determined in advance PTl: Can be changed within the allowable time of the reverse feed prevention relay of each generator Output range limit (KV)...Predetermined fixed value P Old: Upper limit of output for each generator (KW) min (xi, x2.-xk) means a function that takes the minimum value from Xl to xk do.

FIG. 2(a) is a graph for explaining the meaning of equation (5), and FIG. 2(b) shows an operation simulation in the case of FIG. 2(a).

Note that (ΔB+ΔP) is not included in equation (5) because (ΔB+ΔP)>Lmax in the state of FIG. 2(a).
This is because the relationship holds true.

b) In the case of LLIax > ΔB + ΔP (a case in which it is impossible to recover to the receiving limit value BLL when reverse transmission occurs) In this case, a message is output to the effect that the reverse transmission state has occurred and that it is impossible to deal with it, on a CRT, etc. This is displayed on the display means to notify the operator, and the received power surplus ΔB + generator surplus power Δ
It is necessary to determine the amount of received power in advance so that all of P can be used as a controllable amount when reverse transfer occurs.

Minimum power receiving target value: Bo -max (BLI4 <BN-Σ (min[(PLi+PTi), PMII
-PNll>) ・”(6) Figure 3 (a) is (
6) is a graph showing the meaning of formula, and Figure 3(b) is a graph showing the meaning of formula 3.
This figure shows an operation simulation for the case shown in FIG.

Further, each generator output value calculation means 60 calculates as follows in order to realize the minimum power reception target value from the power reception minimum target value determined by the power reception minimum target value calculation means 50. That is, the power reception minimum target chain part BO calculated by the power reception minimum target value calculation means 50 is calculated as follows c) and d) with respect to the current power reception amount: BN.

c) In the case of BN>Bo...the target value has already been achieved (the current output of each generator is maintained).

d) If BN<Bo...the target value has not been reached.

The amount of change (BO BN) for converting BN to BO is allocated to each generator IG-nG as follows.

Target output of each generator for maintaining the minimum target power receiving value; P'N1 - PNl - (Bo - BN) In other words, it is distributed in proportion to the control surplus value of each generator that has not been converted into a controllable amount.

Each generator control means 80 is composed of, for example, a turbine generator controller (usually a governor controller), into which each generator output value from each generator output value calculation means 60 is inputted, so that each generator The output of the machine IG-nG is controlled, thereby making it possible to balance the supply and demand of electric power.

FIG. 4 is a block diagram showing an embodiment of the present invention, in which the target process, that is, a plurality of units installed in the commercial power supply, in-house power generation equipment, and load equipment configured as shown in FIG. Various signals consisting of the received power from the sensor 1, the load power of each feeder, and the output of each generator are input to the computer 3 via the process input device 2. And the functional means 10, 20° 30 of the present invention described above.
．． 40, 50, and 60 are all realized as programs inside the computer 3. Therefore, various numerical values calculated in the computer 3 are, for example, a CRT (cathode ray tube) 4
The information is displayed on a display device consisting of a

Therefore, the operator can adjust the output of the generator IG-nG by looking at the display contents of the CRT 4 and take measures to prevent reverse power feeding at the receiving end, if necessary.

Hereinafter, the operation of the embodiment of the present invention will be explained according to the flowchart shown in FIG. First, process data such as received power, each feeder load power, and each generator output required for calculation is read (SO). Next, select the maximum load jiL*ax using the above equation (1) (s1), and calculate the received power reserve ΔB using the above equation (2) (s2)
. Then, the generator control surplus power ΔP is calculated using the above-mentioned equations (3) and (4) (s3). Then, compare the maximum load ffiLmax selected in sl and the total surplus power of the generator control surplus power ΔP calculated by the received power surplus power ΔB + s3 calculated in s2.54)L, if the total surplus value is large,
Calculate the minimum target power receiving value BO using the above formula (5) (
s5). In addition, in s4, if the maximum load amount is larger, the minimum target power receiving value BO is calculated using the above-mentioned formula (6) (s6), and a message is output to the CRT4 to the effect that it is not possible to prevent backfeeding. Display (sl). next,
Compare the current received power jlBN with the minimum power receiving target value obtained by calculation in (s5) and (s6).s8) If the current received power amount BN is larger, the target generator output value is the current output. If the minimum target value of power received is large, the target output 1''Ni of each generator to raise the current received power amount BN to the minimum target value is calculated using the above equation (7) (slO ).The calculation results obtained as described above are displayed on the CRT 4 (s11).

By repeating the operation from 5TART to END shown in the flowchart of FIG. 5 at a desired period, for example, every minute, the minimum target power receiving value BO and each generator target output P You can get the old one.

Each generator target output determined in this way is input to each generator turbine controller, and thereby each generator I
G = n The output of G is controlled, and it is possible to balance the supply and demand of electricity.

[Effects of the Invention] According to the present invention described above, it is possible to manage the required amount of received power from a commercial power source and the amount of power generated by private power generation equipment in response to momentary changes in the situation, and the occurrence of reverse power feeding at the receiving end can be avoided. It is possible to provide a power receiving end reverse feed prevention control device that can prevent this.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the power receiving end reverse feed prevention control device according to the present invention, and FIGS. 2 and 3 are diagrams for explaining the function of the power receiving minimum target value calculation means of FIG. 1, respectively.
FIG. 4 is a diagram showing an example of the power receiving end/power distribution system of the present invention, and FIG. 7 is a conceptual diagram showing the time history of received power and generator output to explain the conventional problem. DESCRIPTION OF SYMBOLS 10... Process data importing means, 20... Maximum load power selection means, 30... Receiving power surplus calculation means, 40... Each generator control surplus power calculation means, 50... Power receiving minimum target value Calculation means, 60...Each generator output value calculation means, 80...Each generator control means. Applicant's agent Patent attorney Takehikoji Suzue's smallest circle! There is a Katsuki Muneta LLR with five shots. Figure 1 Figure 2 (KW) Figure Time Figure 4

Claims (1)

[Scope of Claims] A power system capable of supplying power from a commercial power distribution system and a private power generation system having a plurality of generators to power load equipment connected to each feeder via a power bus, process data importing means for respectively importing the received power of the power receiving and distribution system, the load power of each of the feeders, and the output of each generator of the private power generation system; and the load power of each feeder taken in by the process data importing means. maximum load selection means for selecting the maximum load amount among them; and received power surplus calculation means for calculating the received power surplus from the difference between the current received power amount and the received power limit value among the received power taken in by the process data importing means. and generator control surplus capacity calculation means for calculating each generator control surplus capacity from the difference between the current output of each generator and the output lower limit value of each generator among the outputs of each generator acquired by the process data acquisition means. , Compare the maximum load amount with the total remaining capacity value of the received power surplus capacity and the generator control surplus capacity, and when this total surplus capacity value is larger than the maximum load amount, calculate the generator controllable amount (the received power capacity) from the maximum load amount. Minimum power reception target value calculation that calculates the power reception minimum target value by subtracting the minimum value of the power surplus + the generator control surplus, the generator output upper limit value – the generator output lower limit value, and the generator output reduction limit amount. means, when the current amount of received power is greater than the minimum target value of received power;
Calculate each generator output value to realize this minimum power reception target value, and when the current power reception amount is smaller than the power reception minimum target value, each generator surplus capacity value that has not been converted into the generator controllable amount. a generator output value calculation means for calculating each generator output value to be distributed in proportion to the generator output value; and a generator control for controlling each generator output based on each generator output value from the generator output value calculation means. A power receiving end reverse feed prevention control device comprising: