## 3 Demand-Side Resources in Active Distribution Systems
### Communication Standards for Active Distribution Networks  
The IEEE 1547 [57] is a standard that offers rules for interconnecting various DRs to electrical power systems. It is distinguished by various forms of DRs operations and their interconnecting issues. It sets forth the guidelines for DG participation in voltage regulation, active power management, grounding requirements, and integration of DR islands with the existing power systems. The guidelines for monitoring, control, and information exchange among the DG and existing power systems are also provided by the standard. The IEEE 1547 standard series possesses various parts dedicated to the issues related to DR interconnection to existing power systems. They are as follows:  
* IEEE 1547.1: IEEE Standard Conformance Test Procedures for Equipment Interconnecting Distributed Resources with Electric Power Systems. * IEEE 1547.2: IEEE Application Guide for IEEE 1547, IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems. * IEEE 1547.3: IEEE Guide for Monitoring, Information Exchange, and Control of Distributed Resources Interconnected with Electric Power Systems. * IEEE 1547.4: Draft Guide for Design, Operation, and Integration of Distributed Resource Island Systems with Electric Power Systems. * IEEE 1547.5: Draft Technical Guidelines for Interconnection of Electric Power Sources >10 MVA to the Power Transmission Grid. * IEEE 1547.6: Draft Recommended Practice for Interconnecting Distributed Resources with Electric Power Systems Distribution Secondary Networks. IEEE P2030 standard [58] is the first standard drafted by IEEE for providing smart grid interoperability. It provides a blueprint for creating the framework for developing IEEE national and international body of standards aimed at developing standards for smart grids which unites the disciplines in power applications, information technology, and control through communications. The IEEE P2030 standard establishes the smart grid interoperability reference model, which develops a base terminology for providing functional performance, characteristics, and engineering principle evaluation related to the smart grid interoperability. IEC 60870-5 standard [59] was developed by IEC Technical Committee to provide protocols for sending basic telecontrol messages from the telecontrol master station to outside stations, which are connected through some form of permanent communication link. The telecontrol messages are transferred between the telecontrol equipment in the form of coded serial data which are used for monitoring and controlling wide area processes. Part 5 of 60870 defines the interoperability among the telecontrol equipment. This standard is a combination of the application layer of IEC 60870-5-101 and the transport layer of TCP/IP standard. Within the TCP/IP, there is an independent choice of telecommunication networks, such as X.25, ATM, and Frame Relay. The IEC 60870-5 supportsbalanced and unbalanced modes of data transfer and provides unique addresses for master telecontrol stations, time synchronization facility, data classification facility, and cyclic data updating facility. The IEEE C37.118 standard [60] is the standard drafted by IEEE for synchronized phasor measurement in power systems. It is the main standard that oversees PMU operations. The IEEE C37.118 standard is split into two parts, viz. IEEE C37.118.1 for synchrophasor measurement and IEEE C37.118.2 for synchrophasor communication. These parts of IEEE C37.118 standard form the backbone of PMU operations and communications in power systems. The IEEE C37.118.1 [61] defines synchrophasors, frequency, and rate of change of frequency (ROCOF) measurements. IEEE C37.118.1-based measurements made at various locations by the PMU can be readily obtained and interpreted at the Phasor Data Concentrator (PDC) accurately due to the presence of GPS time tagging on PMU information. The IEEE C37.118.2 [62] standard defines a method of exchange of synchrophasor data between the power system devices.