Noting that far more students attend charter schools in Philadelphia than are enrolled in the state's second-largest school district, a group has formed to represent city charters.

Founders of Philadelphia Charters for Excellence say they want to publicize the successes of charter schools and reassure the public that most of the 74 charters are not being investigated for possible corruption.

The organization requires member schools to meet strict ethical standards and plans to create a website to help parents compare the performance of charter schools.

The nonprofit organization was scheduled to be announced Friday.

"There are 74 of us, and in a typical school district with 74 schools, there would be a public-relations representative," said Jurate Krokys, chief executive officer of Independence Charter School in Center City and the group's vice president. "The idea is to be a resource about charter schools in Philadelphia."

The group's mission statement calls it "an alliance of high-performing public charter schools committed to creating a path toward academic and personal excellence for all students."

The number of city students attending charter schools could jump to nearly 39,000 next month when seven underperforming Philadelphia School District schools become charters under Superintendent Arlene Ackerman's Imagine 2014 initiative.

That total far outstrips the 26,000 students in the Pittsburgh public schools, the state's second-largest district.

Organizers said their group would complement rather than compete with the Pennsylvania Coalition of Public Charter Schools, which represents 117 charters.

Naomi Johnson Booker, chief executive of Global Leadership Academy and president of the new city group, pointed out that she served on the board of the state organization.

"That is a statewide coalition," she said. "They lobby and handle policy-oriented events. Philadelphia is its own world."

Philadelphia Charters for Excellence traces its beginnings to a small group of charter executives who began talking about creating a group more than a year ago. They said it was time for Philadelphia charters have an organization of their own.

"Sometimes we are mischaracterized, and I think we need to be able to speak for what is going on in Philadelphia," Krokys said.

A federal criminal investigation is examining at least 17 city charter schools, according to sources with knowledge of the probe. Two former officials from Philadelphia Academy Charter School in the Northeast were sent to federal prison after pleading guilty to fraud charges last year.

"I think it is time that our story is told, and that story shows the positive things we're doing," said Booker, whose charter has campuses in the Northeast and West Philadelphia.

In the last few weeks, letters were sent inviting all charter schools in the city to join. So far, 19 have signed on, including the Mathematics, Sciences and Technology Community Charter School in the Far Northeast, Russell Byers Charter School in Center City, and Green Woods Charter School in Roxborough.

Each school has pledged to adhere to strict ethical standards, including making sure board members and administrators do not benefit financially from school decisions and demonstrating good stewardship of taxpayer money.

Contact staff writer Martha Woodall at 215-854-2789 or martha.woodall@phillynews.com.