Mas

Power System/Smart Grid Lab.

Multi Agent System for Distributed Voltage Regulation

TRINH Phi Hai


Content

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1. Introduction

2. MAS technology

3. The Construction of Smart Grid based on IOT

4. Design and Implemen-tation

5. Conclusion


Introduction

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• Multi Agent Systems (MAS) have recently emerged as a new paradigm that can facilitate distributed control. The MAS can be used to en-hance many of the system operation and control function

• The voltage regulation on a distribution feeder is provided mainly by the load tap changing (LTC) substation transformer. However, this de-vice does not provide fast enough voltage regulation

• Therefore, MAS approach is used to share the voltage regulation ef -fort and perform the coordination of distributed generators with flex-ibility and reliability in distribution network


MAS technology

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• MAS technology is an emerging modern technology which is based on agent oriented programming.

• Agent definition: An Agent is a software or hardware entity situated in some environment and is able to react to change in its environment (reactivity), be driven

Agent bene-fits

Fault toler-ance Flexibility

Extensibility

DistributionOpen architec-ture

MAS is able to take agents out of op-eration easily and adds new one while the others are running

it is ability to add new func-tionality to a system without the need to re-implement the existing functionality

which is the possibility to be placed in differ-ent environments and still have the same goals and abilities

Ability to understand different programing languages and to communicate in a flex-ible way between any agents

Which is possibility to seek alternative agents to pro-vide the requirement ser-vices when the appointed agent fails


Voltage Regulation

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• Voltage deviation at the customers’ point of connection is one of the most important aspects of the supply voltage/voltage quality.

• According to the standard, the voltage magnitude variation on the network is limited within % of the nominal voltage during 95% of the time of week

• Main solutions for controlling voltage deviations in a distribution network are summarized as follows:

Voltage control by the OLTC of the transformer substation Reactive power control with DGs and compensators DG active power control


Voltage Regulation (Cont.)

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• Feeder voltage regulation: The voltage on a conventional distribution feeder (with no DG) is controlled by the Load Tap Changing or Voltage Regulator (LTC or VR) placed at substation. On the feeder with multiple DGs, LTC or VR, these devices are not fast enough voltage regulation.



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The LTC can adjust its set point to bring the voltage profile of feeder 1 back in the normal voltage range but this decrease in the voltage profile of the feeder 2 is dominated by load consumption



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• LTC and VR cannot provide the quick voltage support needed to re-store the voltages Absorbing active and reactive power is normally considered as a solution to deal with this voltage rise problem

• To provide an improve voltage regulation scheme with plug and play feature, we need the following:

A communication link between the VR and DGs: it will allow us to dis-patch DGs to provide voltage support when needed

Base on the capability of DGs to provide the active and reactive power support during emergency conditions that are too short for the VR to react.


Autonomous voltage regulation

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A configuration of Multi Agent System to regulate autonomously the cell of network



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• The combination of active and reactive power dispatch schemes can give better solutions to deal with different kinds of voltage changes, the main idea is to reach the optimal control as follows:

Min power flow at each node voltage const. at each node reactive power generation of DG j and its limits active power generation of DG j and its limits

The objective function represents the cost of dispatch, which is the total amount of active and reactive power needed from all DGs.



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• Power sensitivity factor: The sensitivity of bus voltage due to the changes of active and reactive power generation can be presented by linear equations as follows:

are elements of the Jacobean matrix corresponding to derivations of the active and reactive power

and

• With the assumption that the active power loads and active power output of the DG will not change:

• The reactive power sensitivity factor for a voltage change at node k is

determined:



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• Similar, we have the active power sensitivity factor for a voltage change at bus k is determined :

• The bus voltages can be controlled by a active and reactive power dispatch based on the ranking of the sensitivity factor and


MAS – Based dispatch

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• Voltage violation occurs at the last node An, this agent detect the problem and sends modera-tor an information message

• Moderator sends a Request for Proposals (RFP) to each agent within its cell

• Each DG agent updates the value of its sensitivity factor and responds with a proposal message including its possible capacity to control the voltage at bus n or a refuse message

• The moderator decides on dispatch on the dispatch order of the proposals of the DGs, agents in the list of selection will receive an Accept_Proposal message from the moderator

• This process is repeated until the is less than 0.001 or all DGs real and reactive power outputs both reach their limit.

Mas

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